Hi, I'm here because I'm interested in home theater. I have a simple one that is working at the moment but I have a few items I'm looking to replace/upgrade through DIY route.

I'm continuing to downsize my equipment collection, so I have two Audio Precision System One Dual Domains for sale. The first one is a SYS-322G and in very good condition, passes the analog and digital self checks with no issue. It comes with many accessories including several cable kits, original manuals, documentation, technotes, APIB PCI card. I'm also including an APIB USB cable which works with windows 10 and the Audio Precision software.

The attachments include the self check reports, and pictures of the machine and accessories.

These are located near San Luis Obispo, California.

I have taken the liberty of making a new thread just for the new Mark Audio MA200 8cm driver rather than have it hiding on page 122 of the MA New Drivers thread. This makes it (and projects that use it) easier to find. Details of the MA 200 here:

https://www.markaudio.com/online_shop/20-cm/ma200-m-multi-midnight-copper/

I'm hoping that people will post their projects and ideas here on how they plan to use this driver. I'm hoping that when they have a moment Scott and Dave will also give their thoughts on this driver and possible usage cases.

I'm particularly interested in the cabinets Scott has designed for this driver (especially the one going down to 25Hz!) and what sound characteristics each box might have. What are the pros & cons of the single versus double ported versions and how much flexibility is there to change box shape (curved sides, rounded baffles, ovals, triangles etc.) provided box volume is maintained? What scope is there to combine this driver into a 2-way or even 3-way system?

There is an inter-active page at the NYTimes which allows you to audition 3 Steinway "D"s which the Frick Museum had up for consideration and vote for the one you consider best. I got it right, but would have preferred a smaller instrument for this 200 seat hall.

https://www.nytimes.com/2025/04/22/arts/music/frick-piano-jeremy-denk.html

Presented here is my lastest DIY audio project. Actually, this is my 2nd preamp I've built using the base preamp PCB that was designed by my friend and fellow DIYer, Jan Hofland. This has turned out to be an ultra-quiet preamp board built around the OPA1656. It is stunningly quiet. More information about the PCB can be found over in this thread here. The preamp offers a lowpass subwoofer output, selectable at 80, 120 or 200Hz. In addition, it also offers selectable gain at 0, 6, or 12dB. I find with most of the inputs I use 0dB works just fine.

For this project I had a few objectives. Use the same model case I had used for an amplifier and streamer I completed last year. Integrate a new and improved(modernized) source selector, and add a Bluetooth adapter PCB.

The case is a Goodisory mini-ITX case. There was different mechanical casework, and 3D panels that required unique customization. The most exciting objective was met with my design(functional) of a 4-input pushbutton selector switch. Pushbutton selectors are not new, but I wanted one that did not use relays, or would make a noticeable click when changed. I also wanted to integrate a visual queue(LED) into the pushbutton itself indicating the active input. Another criteria was the switch needed to be small and operate with slight tactile feedback. After a bit of looking, I found the perfect little micro switch with built-in LED on Aliexpress. I also didn't want the switch module (PCB) to introduce any audible artifacts into the circuit. I turned to my designer friend and ran my idea by him. He was up for the challenge of designing a circuit board that would perform to my specs.

His final solution provided a nice, small PCB with no clicking added to the circuitry. And, as required for any audio application, the switch is silent, and does not add any noise to the switched input going to the output stage of the preamp. To get the pushbutton switch to integrate into the pre I had to put a couple jumpers on the pre board to force an 'unmute' function that was designed into the preamp PCB. And, for obvious reasons, I'm only using one of the original inputs for the output of the pushbutton switch PCB. All the RCA source connectors now wire directly to the silent switch PCB using MolexKK male headers.

Front side of Silent Source Switch(SSS)


The other feature I wanted to add to this preamp was to make it Bluetooth capable. Once again, Aliexpress to the rescue. I found this LDAC that was 5.3 compliant and seems to work as advertised. Now, I'm not under any allusion that Bluetooth provides a super quality audiophile experience - even with hi-res tracks. However, the latest LDAC Bluetooth standard sounds decent enough for casual or convenience listening. With 4 young adults children visiting from time to time(whom live by their cellphones) 🙂, this adds a nice touch to my system. I also have a DAP that I can now connect to this preamp with ease. It was an effortless experience pairing to my phone and DAP.

LDAC 5.3 Bluetooth module.


With my 2 major features met, I proceeded to assemble the preamp using my standard support hardware (remote switch and soft-start board). I also designed the back panel to accommodate the typical IEC inlet, and RCA jacks. This was then 3D printed and fitted to the case as shown. The most challenging part of the case work was fitting the pushbutton PCB to the front panel super-structure. I ended up using kind of a kludge solution, but it works. I used JB Weld adhesive to secure 6 brass standoffs to the inside front piece of metal. There is no binding at all on the little plastic switch covers, as there's essentially no travel depth of the switches. I had some practice using this technique with 2 other standalone switch-boxes I built. After much thought about internal layout, I decided on what is shown. I wanted to keep all the AC connections in the right-back corner. It was a tight fit for the IEC inlet, but doable as can be seen. To save space I've also adopted the method of raising my remote start PCB using standoffs. I've found that I can usually fit the PCB(remote start) using 2-3 standoffs anchored to the bottom, while a nylon standoff can easily rest on an open spot on the pre PCB. I've used this method in a couple other builds where horizontal space was limited.

In all, I'm pleased with the final result. It sounds great - as I've come to expect with Jan's designs - and the pushbutton selector is very functional, and cool. My next project will be to go digital with a UI - that has yet to be developed.

Hi, I'm Neil from North West England.

I've been tinkering for years, and often find this page a place of inspiration. At the start of lockdown, I restored the Thorens TD-150 Mk II that my Dad bought new in 1970. It didn't need a lot doing, but Rubber parts, the PSU and a few other things needed attention.

So, I am here to learn more (we can always learn more), ask questions, and maybe able to help others in their DIY audio journey!!

The Live Edge Dipoles took 1st Place at the Parts Express Speaker Design Competition August 4-5 in Ohio. 59 contestants. My Open Baffle design on a slab of live edge birch won top score in the Open Unlimited category.



Judge Jerry McNutt said, “The best way to not sound like a box is: Don’t use a box.” Listener comments: The Beryllium tweeters are extremely transparent; bass is rich, expansive and authoritative; thorough top-to-bottom coherence and integration; warm, ambient and enveloping stereo image. Can effortlessly fill a large room to overflowing with palpable output and dynamic range.



I hosted the Chicago Audio Society a few weeks prior. Listeners were consistently impressed not only with rock and jazz but string quartets and large orchestral works. One listener said they combine the open, room-filling sound of Magnepans with the slam and dynamics of a JBL. Sound stage is huge.

The Live Edge Dipoles were featured on the cover of AudioXpress January 2021. The article there provides a thorough description of the system as it was at the time: https://audioxpress.com/article/you-can-diy-perry-marshall-the-live-edge-dipoles or tinyurl.com/LiveEdgeDipolesAudioXpress.



I have since made numerous upgrades. Before I dive into details, a few insights about speaker design; and why, out of thousands of possible choices, I selected the format I used here.

Why ordinary speakers are doomed

When you visit any audio show, 90% of the speakers share the same weary collection of baked-in assumptions:

• They all have boxes
• They all sound boxy
• Wife Appreciation Factor is low or sub-zero
• Simulated woodgrain finish
• On-axis frequency response is obsessed about
• Off-axis response is ignored
• Radiation pattern is ignored
• Bass is omnidirectional
• Drivers interfere with each other
• They have 1” dome tweeters
• Crossovers butcher impulse and phase response
• There is one “center of the will of God” sweet spot
• The room is ignored (and room acoustics are voodoo)
• Inefficient: 1 watt / 1 meter is often mid- to low-80s
• Hard for amps to drive because of extreme impedance variations
• Drivers are small and sound anemic with real (non-audiophile) music

This consigns you to one predictably boring demo room after another. The Live Edge Dipoles sidestep every pitfall listed above. Giant notes roll out of the speakers. You enjoy a huge sound stage. You are immersed in 3D ambience, clarity and resolution. Dry recordings become spacious. Drums and toms hit with visceral, fist-on-sternum impact.

I don’t believe vocals are the toughest thing to get right in a speaker. Percussion is the hardest! Especially with other instruments. Most speakers fail to excel at percussion because they butcher time response; you can easily measure it.

Check the sidebar that reports Step Response in every Stereophile review and witness the butchering with your own eyes. Woofers and tweeters fire with opposite polarities on different dates. Average speaker designers claim you can’t hear the difference. I insist you can. Once you hear the “boxiness” of box speakers, you can’t un-hear it.

With the Live Edge Dipoles, the most delicate of sounds, the wires and shell of a snare drum, are reproduced the startling precision. When the drummer slams the floor tom (like in “Hatesong” by Porcupine Tree), you feel it in your bones.

40 Years of Design

My early teenage years were, shall we say, less than fun. I escaped into Audio projects. I fell in love with a pair of Boston Acoustics A60s but couldn’t afford ‘em. Laid my hands on a McGee catalog and made my own with a Peerless polypropylene woofer and the same Tonegen tweeter as the A60s.

I sold my first pair of speakers to a paying customer when I was 14. I briefly sold my own brand through a local dealer alongside B&W, Denon and PS Audio when I was a senior in high school. Then an Electrical Engineering degree with accent on Control and Communication Systems. Worked as an acoustical engineer for 3 years at Jensen designing OEM drivers for Honda, Ford, Chrysler and Acura.

Since then, audio has been my hobby, with occasional articles in Voice Coil and AudioXpress. I’ve made almost every type including acoustic suspension, reflex, bandpass, transmission line, horn, dipole, ribbon and shaded arrays. I’ve built Motional Feedback subwoofers and used active, passive, analog and digital crossovers. Homes, cars, churches, studios and live bands.

A memorable leap in my journey as a speaker designer was my first Open Baffle design using 12” Faital coaxials. The huge size of soundstage and the lack of boxiness made a striking impression on me, playing quiet classical guitar music at 7 o’clock in the morning. The energy of pro-sound drivers without compression sealed the deal.

Radiation Pattern

Polar pattern is one of the great underappreciated secrets of great speaker design, and it’s a secret to these speakers’ performance. The capacity to deliver low distortion, flat frequency response, transient response, etc. is admirable. But to achieve an excellent distribution pattern at the same time separates the men from the boys. When response is only flat on-axis, your design will sound more like a speaker and less like real music.

When room reflections don’t match direct sound from the speaker, it sounds unnatural. Textbook speaker designs pretend the room is not there. But not only does the bass have room modes and standing waves, but the mid and high frequency reflections add LOTS of clues for your ears. Good clues make your ears happy.

PERFORMANCE SUMMARY

• 30Hz to 25KHz with silky-smooth response in a real room that has real reflections. Not just in an anechoic chamber.
• True Constant Directivity sound pattern 30Hz to 25KHz so imaging is superb anywhere in the room
• Open Baffle Dipole sounds great even behind the speakers
• High Efficiency – 95dB 1 watt/1 meter. Sounds great and plays loud even with “flea watt” single ended vacuum tube amps
• High Power Handling and High Output – 100 watts & 115 dB running full range; 500 watts & 120 dB with subwoofer
• Near-perfect impulse response
• Near-perfect phase response
• Low Distortion (<2% above 60Hz; <1% above 150Hz at 90dB)
• Easy to drive
• Live Edge wood is so beautiful, non-audiophile wives of non-audiophile men gasped when I showed these on a screen in a Zoom meeting.
• 3-way system is bi-amped (not tri-amped) using a MiniDSP 2x4HD.

The Live Edge Dipoles exhibit true Constant Directivity from 20Hz to 20KHz on both sides of the speaker. Full dipole behavior front and back with a Figure-8 radiation pattern. Constant Directivity means the speaker is consistently directional. Much louder on axis than off, and levels drop consistently across the whole range as you move off axis, instead of only dropping at the top end of the woofer and tweeter’s range.


Above: Polar spectrum of the Live Edge Dipoles, 150Hz-15KHz. Beamwidth is defined as -6dB points relative to 0 degrees, which is the cyan color in the graph. Beamwidth stays between +/-30 and +/-60 degrees across the entire range.



Above: Frequency response in a real room at 0, 15, 30, 45, 60, 75 and 90 degrees. The number of commercially available speakers that come close to these off-axis curves, you can count on one hand. I discuss the polar pattern below. They have a rear-firing “ambience” tweeter which makes the rear radiation very similar to the front. To my ears, dipoles without this don’t sound right. A level pad lets you tailor the ambience to taste.

A true Constant Directivity speaker yields good stereo imaging even if you are standing right next to one of the two speakers. It delivers outstanding sonic images to every seat in the house. When arranged in a triangle pattern with the speakers pointed towards the listener position, every seat sounds great.


Below is a crayon drawing of a room with Constant Directivity Dipoles. It shows why Open Baffles with uniform response, toed in about 30 degrees, image better than every other type of speaker.



Stereo imaging is strong anywhere inside the yellow boundary, starting at A.

B, right in front of one speaker, is the only spot where imaging isn’t good.

When you stand at C you hear the right speaker across the room just as well as the left. And yes, you get a decent stereo image there.

Same is true even at D. You can hear the right speaker clearly, even standing just behind the left speaker.

There are no sidewall reflections at the wall near C because it’s in the null plane of the dipole.

1, 2, 3 and 4 illustrate that rear radiation reflects from the wall back into the room. This provides ambience but does not override direct sound.

The “sweet spot” is somewhere between F and G, depending on how “headphone-like” you want your sound.

Place your turntable at T, the null for both speakers. Cuts acoustic feedback 10-15dB.

As you walk from C to E to H, the stereo image remains stable and the volume grows louder. E and H, though much farther away, are louder than C because the directivity pattern is so well-controlled.

Very few speakers do any of this. To my knowledge the number of available commercial designs that achieve constant directivity across the entire spectrum is zero.



Above: Frequency response of the Live Edge Dipoles, on axis at 1.5 meters in my room. No attempt to gate or eliminate room reflections. Room response should taper downward slightly as frequency rises. Some speakers measure more perfectly in an anechoic chamber… but these measure very well in real rooms. Not just in one spot but everywhere in the room! This EQ sounds most neutral to my ears.

In this design I optimized the physical design and shape for radiation pattern, and then I corrected the problems this incurred with Digital Signal Processing.

Upgrades Since the 2021 AudioXpress article:

• I upgraded the aluminum dome in the Radian 5208C to beryllium. The beryllium has very similar frequency response but sounds quite a bit different. Extremely clear and transparent. Sounds “buttery transparent” and not analytical. The tweeter just disappears.
• I changed the tweeter wiring and several EQ settings in the DSP crossover.
• I added Bass EQ options. The stock design is flat down to below 30Hz. This is great for small rooms and listeners who are not “bass heads.” However, if you push them super hard with lots of deep bass, the subs will complain. I added a “Rock and Roll” EQ setting that rolls off below 35Hz. With this setting you can play loud music in a large room and the speakers will handle the full dynamic range without effort.

Aluminum vs Beryllium

The standard version with aluminum dome sounds fantastic and I have no criticisms. Though the beryllium diaphragms cost several hundred dollars apiece, they are well worth the dinero. They deliver extreme transparency similar to ribbons and electrostatics, without harshness. The tweeters just disappear and let the music flow through. Finally, they’re not merciless. Many high-def speakers are harsh and unforgiving of ordinary recordings, but the Rolling Stones and AC/DC sound great too.

High SPL Drivers, Amps and DSPs

The Eminence 18 Kappa LF woofers produce 98dB SPL / 1W. The Radian 5208 coax puts out 95dB from the woofer section and ~100dB from the 16-ohm tweeter section.

High efficiency makes them extremely sensitive to electronic hum and noise. Amps with noise and grounding problems, not evident in typical 85-90dB audiophile speakers, are exposed. Furthermore, the MiniDSP 2x4HD has some noise which is not obvious with most speakers, but evident with high efficiency horns.

You can solve this by using an amp with an input control and turning it down a bit (Adcom GFA2535 is a great 4 channel amp and has level controls) or with a padding device like a Harrison Labs 12dB attenuator.

An even better solution is the MiniDSP Flex Eight, which has higher resolution and lower noise floor. I have configuration files for this too, discussed below. I further minimized the noise problem by wiring the rear tweeter (PRV WG175PH) and front tweeter in series, with parallel resistor networks bringing the total impedance down to 11 ohms. This tames the tweeter output to 95dB.

Only the most basic functions are performed by passive components: 200Hz crossover between woofer and midrange; tweeters are wired in series with an L-pad for adjusting level of the rear tweeter; a 20uF capacitor simply protects the tweeters from accidents. All heavy lifting is done by the DSP with 2KHz crossover with FIR phase correction.



Noise sensitivity notwithstanding, the energy, dynamic range and effortless performance you get from efficient pro drivers like Eminence and Radian more than compensate for the noise precautions you have to take. Speakers with vast dynamic range and low distortion sound so effortless and open, you feel compelled to crank the volume up.

Most audiophiles are so conditioned to buckets of intermodulation distortion, they’re stunned when a system doesn’t have it. I call it “Dynamic range to burn.” Once you’ve experienced it, you never go back.

The “Lambda Slab” U-Frame



The triangular sides on the bottom of the cabinet on each side of the 18” woofer pushes the dipole roll off frequency lower. Without them the roll off would start around 100Hz; with them it’s around 60Hz. The wings buy you almost an octave of bass.

It’s easy to get deep bass from an Open Baffle speaker… you just need a Digital Signal Processor and heavy EQ. You pay a price, however, which is that your woofer can easily bottom. Distortion spikes at low frequencies. I have paid close attention to this issue. The bass EQ begins in earnest below 60Hz. This is the curve for the standard “Jazz EQ” DSP file:



Above: EQ reaches 20dB at 29Hz, then rolls off gently below. Yep, 20dB is a ton of EQ, but remember that these have 95-98dB sensitivity, so across 90% of the spectrum they require very little power. Extra power is only demanded by occasional deep bass passages.

I call this the Jazz EQ setting. It’s optimized for lowest group delay and least ringing in the step response. Most speakers have gobs of phase shift at low frequencies which you easily hear on well recorded bass drums. The steeper the filter, the more phase shift. Steep slopes like in actively assisted 6th order reflex designs add many tens of milliseconds of phase delay. This design sidesteps that.



Above: Phase is +/-30 degrees from 40Hz to 20KHz with a max of only 120 degrees around 20-30Hz. Very, very few speakers match this. This cuts group delay and maximizes bass resolution.



Above: Step response. Fast rise time followed by steady descent with no phase reversals. Drivers fire in perfect time with each other. There is little low frequency ringing because the design minimizes phase shift and group delay. Very few speakers match this. This is one reason why clarity and imaging are so precise.



Above: Impulse response. Most speakers shred impulses, which should look like an upside down “T.” The Live Edge Dipoles deliver 80% of their energy in a tight 0.1 millisecond slice. This makes lightning fast transients and exquisite detail.

Bass from most subs, even celebrated designs, sounds more like well-articulated thumps than genuine instruments. Open Baffle speakers bring a welcome exception and sound extremely natural. The Jazz EQ setting achieves flat response to below 30Hz with minimum phase delay. Perfect for listeners with small rooms and / or do not demand the pantleg-flapping bass of car stereo shows and rave clubs.

However if you have a big room and/or want to shake the house with loud rock or electronic music, I added a 2nd EQ configuration file called “Rock & Roll EQ” that adds a dual shelf filter (instead of standard high pass) at 35Hz, with a slight lift between 40-60Hz and above 5KHz:



With this one tweak, the speaker can play 10dB louder than the Jazz setting. So if you like your music loud, even in a large room, this EQ setting will keep your woofers from bottoming or wincing in pain.



Above: Low frequency drive signal from amp. Blue = Jazz EQ. Orange = Rock & Roll EQ. Reduces woofer excursion by 70%, allowing up to 10dB greater output.

This matters in an Open Baffle design. That’s because an acoustic suspension woofer’s max output falls at the rate of 12dB per octave. That is challenging enough if you’re trying to shake the house. But an Open Baffle woofer loses traction at the rate of 18dB per octave (12dB from standard radiation resistance, plus an extra 6 dB due to rear wave cancellation). So every 1/3 octave of bass you ask of an Open Baffle speaker demands +6dB which requires 2X the excursion and 4X the power. One full octave costs you 18dB: 8X excursion and 64X power!

By relieving the 18” woofer of everything below 35Hz, you buy yourself 10dB more dynamic range. The 18” Eminence woofers, bolstered by the U-frame wings and 35Hz roll off on the Rock & Roll EQ, use 14dB of boost at 39Hz and generate high SPLs without effort. You can load both settings into your MiniDSP 2x4 HD and switch between them at will.

Low Distortion

Below: Distortion measured at mid-band output of 90dB SPL/1M in a real room; SPL climbs to 100dB at 40Hz. This is with the Rock & Roll EQ setting. Distortion is under 2% above 60Hz, under 1% above 150Hz. (Data also includes rattles and buzzes of the room itself.) The darker curve is 2nd order, lighter 3rd order:



(continued in next post)

anyone have the winsd file for the 12br70?
I try to enter the data in winsd but it doesnt seem to work at all

Im about to build a floorstander, ported. and im debating in my mind if I want 60L or 100L ported cab.
any thought?

This is a design I've had in use for rather a long time. It started life as a design exercise to see if I could do a more space-efficient board for my original AEM6000 based amps, as I wanted something that would fit on a 50mm high heatsink. It's a very, very close friend to my 50W version with a couple of extra output transistors and a bit of a compensation tweak. Along the way it changed a little from Tilbrook's original in topology, and rather a lot in component choice. It has better performance than my original design, both through a better tighter layout and also through the use of faster transistors.

I've built a few of these. Nowhere near as many as the 50W flavour.

Lots of component substitution is reasonable. I like to use MELF resistors, but that's mostly just bloody-mindedness. An exception is the feedback divider. No, it won't work with vertical MOSFETs.

I have checked just now, and every single component is currently (December 2020) available.

The design is free for use for non-commercial purposes.

In the design folder I have placed:


Google Drive link to design files

Hello, All!
Just joined today as I found a very useful guide here on using Hypex Filter Design, thanks to DannerD3H.

I have always been a music and audio fan and find acoustics and speakers particularly fascinating. I always wanted to design and build my own speakers but never got to it, mainly due to lack of space to use for woodworking (I live in a small flat). But still decided to go for it. I will work around the difficulties somehow. If there is a will, there is a way.

I have reasonable understanding of audio, electronics and design process and ok to use my hands, but I have almost no experience, so face a steep learning curve.

First thing I did is buy the Loudspeaker Design Cookbook. Reading it now. Learning curve.

I have a pair of old slim floorstaders (description to follow) that I intend to convert to actives. This will help to initially avoid much woodwork, while still learning about drivers, crossovers and amps and box interaction. This will be done in two steps:

Step 1 - add Hypex Fusion amp and use existing drivers and enclosure as is

Step 2 - replace the drivers for better specced ones, modify the box

This will hopefully take me to a future point of fully building larger speakers and maybe a sub. One day.

So far I have bought a Dayton UMM6 mic, a Fosi V3 amp and just about managed a few measurements in REW of the speakers in passive form and of individual drivers. I managed to install on old version of HFD software on an old Win XP (!) laptop and hope to use that to program the FA253s when they arrive later this week.

I do stumble a lot and have lots of questions and definitely need some help. I will be asking here and would appreciate any help from the more experienced members.

I will make a post with the existing speaker details and maybe a few other things I am struggling with.

FWIW I do have some forum history on a couple of HiFi forums: Hifiwigwam and Audiosciencereview.

So, wish me luck.

http://www.fidelitatem-sound.jp/fidelitatem-NC/n_detail_NC11.html


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Product specifications​

• Model: NC11_MOP_MC /NC11_MOP_MC
• SP unit: MAOP_11 v2
• Playback frequency: 35 Hz - 25,000 Hz
• Maximum input: 35W (cont.)
• Output sound pressure level: 87dB /1w@1m
• Rated impedance: 7.2Ω
• Mms = 7.90 g
• Xmax(1way) 8.0mm
• Dimensions: (width x height x depth) 245 x 450 x 295 mm
• Weight: 11.5 kg x 2

What is the best way of reducing the Bass - load on a pair of Spender BC1's to protect them from excessive transients when driven at high - ish levels?

Option 1 - A separate Bass Speaker Enclosure with crossover feeding the BC1's, without modification to their crossovers.

Option 2 - A separate Bass Speaker Enclosure, driven by a 405, with filtering at source to split drive between Main Amplifier and 405?

For sale are 2 Babelfish J boards adjusted to 1,8A bias.
They are tested and ran for aprox 100h in my setup. They sound great!
With XLR inputs and Semisouth outputs.
And before you ask - yes, these are originals, I bought them directly from Semisouth when the company still existed 😉
You can buy it with or without the heatsinks. The heatsinks are thought for 80mm fans.
I would like to have €250 without and €300 with heatsink (without fan!) plus shipping costs.

Hello,

I have a T+A 1220R that always displays "no disc."
It doesn't even try to spin.
I can see the lens 2-3 times, but I can't see any red light.

I replaced the laser unit with a "new" one, but the error remains the same.

I then measured the LDON signal on the SAA7372, but it stays permanently low. That can't be normal, can it?

Unfortunately, the manufacturer doesn't provide any documentation about the device.

But maybe someone here can help.

Regards

Mario

Dears,
This is second (and last) blast from the past project that I will publish. Its from early 2000's when I was very much into doing different audio things.
Other of my old projects have no much difference from usually seen executions, so I will skip those.

As elementary school kid (in 1977), my older sister left me her BSR turntable system (in Yugoslavia than called Tosca) and some 50LP's, good stuff of the time, Leonard Cohen, Dylan, Cat Stevens, Janis Joplin, Roberta Flack, Jimmy Smith, some classic and so on... Anyway, I felt in love with LP's and HIFI forever, this still goes on.
Anyway, few friends (actually their parents) had Thorenses, Sondeks and Duals, , I always wanted proper turntable. By the time I made my own money, CD came into play and I bought one of the first Philips CD player.
Few years after I still wanted TT, bought one crappy example, throw it away and decided to make my own. Intention was not to make hi end piece, but to make vintage looking TT similar to those that I was wishing for:
This is the result:

Kondo KSL-M77 phono and preamp clone project

Hey guys. It's been a while. 🙄

I got burnt out from audio and sort of took a break. Multiple reasons, and too many other things going on.

I recently put up some speakers for sale, and managed to find a deal with someone who wanted to make a trade. So for a pair of Aucharm full range 12" speakers I wasn't going to use, I got a B&K AVR 202 with hum problems, a vintage Trygon T50-2 power supply, and this KSL-M77 project. I'm happy with the trade, and it gives me some stuff to play with as I find the time. I should have a power transformer that would be suitable for this kit. Just in the value of the caps and enclosure alone I think this was a decent trade, even if I gut it and build something else without boutique parts or circuitry.

Does anybody happen to have details on these? All I really find is PCB photos but no real detailed specs on them. I'll post what I could find.

Looks like this is very close to my kit-
Audio KONDO AUDIONOTE M77 Line and Phono AMP HiFi Tube Preamplifier Board - Free Shipping - ThanksBuyer

Anybody recognize those pots used here? Looks like one volume, one balance, and a source selector.








I think this is the correct schematic. From what I can tell this sucker takes eight (8)! 12AY7 tubes!!??! I may see if I can modify it to take something like 6N1P or 6CG7 since I can mix and match those with some parts value changes.

I'm looking for a midrange cone, up to 6.5"dia to fit into a Bandpass enclosure which will fire into an odd unity horn (odd because its being re-shaped to fit into a car, but its using the unity concept).

Basically (I think) I need a midrange driver with a relatively high Fs and low Qt, to work in a 4th order bandpass (sealed rear chamber and ported front) and give me a lower cut off of about 200Hz and upper cut of of 1400Hz (-6db) if I can get more bandwidth all the better.

I'd like to go for a single 6.5" driver or smaller, multiple 2" or 3" drivers would be quite acceptable. I would ideally like something that is available in the UK though, importing from the states is an option but something easily available would be prefered. Someone is having reasonable success with multiple AuraSound NS2 'Whisper' drivers, I'm looking at the Eminence Alpha6 as they are cheap and easily available. any other suggestions please?

Erin Hardison made a video in 2023 of a ported tweeter. He said it was made by someone named "Alex" who was going to file a patent.

I haven't seen anything more on that since then, so I thought I'd take a crack at reverse engineering it.



This is the ported tweeter that Erin reviewed.

Pic is from his FB.

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Here's Alex's website: www.referenceacoustics.com



Here's a graph from Alex's website, illustrating the difference in SPL.



Here's a graph from Alex's website, illustrating the difference in excursion.


This is a ScanSpeak D3004/6600. For sale at Madisound for $228: https://www.madisoundspeakerstore.c...inator-d3004/6600-aircirc-tweeter-textile-dom



In order to make a Ported Tweeter, I believe Alex simply drilled holes through the faceplate, to allow the radiation from the rear of the diaphragm to "vent" through the faceplate.

Scan Speak hasn't published full Thiele Small for this tweeter: https://www.madisound.com/pdf/scanspeak/D3004_660000.pdf

But I think that's kinda irrelevant. I have an idea of how you could port it:

Basically, you buy a set of drill bits, and then you drill progressively larger ports, until you get the frequency response you're looking for. As with any ported box, you can trade efficiency for bandwidth.

If you don't want to spend $230 on a tweeter, this "trick" should work with any tweeter that you can expose the back side. IE, if the magnet is solid, it won't work. But most of the 1" and 1.125" SB Acoustics Tweeters, they'll work. I used the SB29ADC in my experiments with metamaterial absorbers:

Some time ago, I was walking on a parking lot and heard music coming from the adjacent building 20 meters away. Its doors were open. What struck me, was that I could hear that the cymbals sounded like the real thing, without being able to see what made the sound. It turned out to be a dance organ. In a large, reverberant room.

For those who do not know what a dance organ is, it is awesome:

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Now, I am curious why it was clear that a real instrument was playing and not a loudspeaker.

• Can it be related to an instrument being 'faster' than the same instrument, recorded and played back over a loudspeaker? I do not think this could explain it here, because there only was a mix of reflected sounds to hear.
• Can it be related to directivity pattern? I doubt it. There is no way to distinguish between different directions. All I knew was that sound was coming from some doors 20 meters away.
• Can it be the sound pressure level? Real cymbals are loud. But it was not that loud outside.
• Can it be the dynamics? Real instruments have no compression applied to them. Maybe?
• Can it be the spectral content of the sound? Being outside of the building, I must have heard the power response. Cymbals are quasi-omnidirectional over their full frequency range, while most loudspeakers beam at high frequencies and have a downward trend in their power response. But would not have it been altered to an unknown amount, by the room acoustics?

Any thoughts are appreciated.

Hello friends

as the title says, I am looking for a nice, mid-priced ( < 500.- ) over-ear headphone with noise cancelling, as birthday present for my better half... I am not really into HP, although they sometimes come in veery handy. She's not admitting to be into audio (listening through laptop/handy and other calamities, but let's ignore this for a second)

I personally would go after soundquality first, she OTOH weighs the aesthetics rather high (me too, but second to sound)...

If I'm right, the usual suspects are apple's things, bose and sony? Anything but them?

Thank you

:

I remember very well when the A40 was presented in AA/78. Gee, that’s a healthy while ago! Evil tongues might even mention generations.

Ok, the years to follow have been filled with what they have been filled with.

Short story, I never got around to build one, and now it’s time to pass, pun intended, it on.

You get two new boards, NOS (with golden legs) MPSLs, and used, original, Lambda output TO-3s.

2N5248 and the other components you have to supply yourself.

$200 + shipping at cost.

R

Hello!
I've read Marcel van de Gevel's EW-2003 article "Noise and moving-magnet cartridges", I'd like to ask several technical questions about the schematic there.

After I build all and deploy, I don't see qcc3034 working, I tried high trigger for pio0 - SYS_CTRL but found the device. Can anyone tell me what I'm missing?

Hi! Before I go into the Anthology build, I'm trying to first carefully calculate costs and predict possible ways in which I should go.
To start off, I have some questions:
1. For building the crossovers, I have found out that Jim stated in his plans that the tweeters should have 8.800uF capacitors. I assume he means 8.8uF (European notation is a little different with , and .) but I find no capacitors of such size. Should I therefore buy 2 capacitors and try to find ones that would add to each other to get exactly that measurement? Or should I rather buy 9.0uF or 8.2u F?
2. I tried to find some objective talk on which parts matter in quality and which don't (like super expensive cables which is propagated by a lot of people, so I don't know who to trust with capacitor quality). Could someone guide me on which parts matter? Capacitors, resistors, inductors... I'm trying to be on a budget but since I'm building Anthologies... I can spend a bit more on these electronic parts if it really is worth it. I saw some people claiming they hear differences between high grade capacitors of different lines and some claiming that as long as the quality is good (like ClarityCap PX), it's not worth paying more because there will be no difference. If it makes a difference, which ones are worth upgrading? I see people usually get these 82uF ones cheaper like ClarityCap PX or even Audyn Q4 (that would reduce the cost dramatically). Where does it make a difference? Will it make a difference where the capacitors are wired between signal wire and ground? (Woofers and mids have these 82uF capacitors mounted like that, the 8.8uF and 20uF are directly on the signal line)
3. Can I purchase capacitors of a reputable brand like ClarityCap and assume the capacitance will be correct without having to buy 5x more parts and picking ones closest to each other? Will that also work for Audyn?
4. If the components do matter, would it be possible to make an external upgradable crossover so I could switch these parts to better ones later on? As far as I understand, when I glue the speaker and install drivers, to upgrade the crossovers I would have to remove the drivers? Which are blocked by the front baffle? I don't understand the purpose of dual baffles sadly, could anyone explain how these are mounted? I thought the front baffle would cover the drivers but it seems it doesn't, so what purpose does it serve?
5. Could someone recommend me some inductors and resistors that I could buy in Europe or from China? Madisound wants 250$ for shipping to EU...

Thanks in advance! I hope to find some knowledge here, the entire thing is very confusing to me as of right now... Sorry for the question dump 🙁

Wizards being known as retainers of knowledge I hate to second guess but I'd like to put it on my first build instead of the standard 68 rainbow.
HIs logic is:

Does anyone have a PDF copy of the user manual for the Aikido all in one with tube rectifier? Purchased this years ago and lost the manual.

This is the next step from the plastic horn I made as the very first prototype: https://www.diyaudio.com/community/...-neile-alo-horn-by-sphericalhorns-net.390581/

In this thread, I would like to show the workflow. I really enjoy watching other people's work, so I hope you will enjoy this thread as well. First, some overall data. The horn is ca 64 cm wide, 47 cm deep and 29 cm high. Each is made of 16 layers of 18 mm birch plywood and weights around 20 kg (estimate, did not weigh one). One horn needs two 1500 x 1500 mm sheets with a bit of leftovers. In total, the plywood bought was over 120 kg of material.

The workflow need to fit my hobby CNC. First, I cut all the single layers and rough the 3D parts. This was done by a 1/8" milling bit. Then, the layers are glued by two together and machined with the finishing pass with 6 mm bit. Glue up of the dual slices follows, during the project a friend of mine developed a unique press using water pressure to clamp the curved surfaces perfectly together. Then it is sanding, sanding and more sanding, gluing the two halves together, fitting the driver flange and more sanding.


Ready to start round one.


The slices are arranged to minimize waste.


Another layer cut.

Glue the two roughed layers together.

Hello all, long time listener first time caller. So as a hobbyist I finally decided to get one of those diy kits from China thats loosely based on the marantz 7c. I have made some modifications but my problem is with this wiring diagram. I can read them OK but Ive never seen electrolytic capacitors shown thiis way, just hanging there. Specifically the top 3. What is the polarity? If I was to guess, positive to 1 and 6 (12ax7 triodes), but I hate making things explode so I thought Id ask people smarter than me. I'm sure this is a rookie question, but ive searched a lot and dont see anything like it. Is positive to both sides and that shorthand for nagative to ground?

Hello to everyone in this forum, I'm Eduardo, 25 years old from Italy! Nice to meet you. I've been reading this forum and found a lot of interesting arguments and knowledge. I have a strong passion for electronics, and i'm currently trying to repair my grandfather's old Rega system. I'm looking forward to learn new things!

Since the de lite thread is archived i decided to start a brand new thread for lighbulb loaded amplifiers.

I'll start and i present you the "De broke" an cost cut version of the delite using a darlington transistor and a car turn signal lightbulb (that was cheaper than a headlight one and has a diffrent glow) and running on 12V making a whopping 1,5W of power at 8 ohms.

A few years ago I purchased some drivers from PartsExpress, and one of the drivers were these Seas H1500 tweeters.
The PE part number was 299-760 and stated "Seas H1500 1" Aluminum", and the sticker on the side shows "29TTFCD/G H 1500-6ohm. Made In Norway".

I can't seem to find any spec sheets on this specific driver though? Does anybody know more about this driver, or have a copy of the spec sheet/pdf file?

Thank you

Yesterday I got lucky, scored a pair of roadkill KEF C40s.

Unfortunately, the tweeter coatings are dodgy, almost completely dissapeared on one, highly cracked on the other.
Careful work with Shellite (What us in Aus call Naptha) got the remains off.

So, the next step is to re-coat them, following the ideas in this thread:
https://pinkfishmedia.net/forum/threads/restoring-kef-c40-loudspeaker-system.293967/

But it occurred to me that I could use Damar varnish as an alternative to Shellac (I have both), however neither are ideal; I assume both will set hard, whereas the original coating appears to have been somewhat flexible. Opinions?, comments?, Alternatives?

(if the worst comes to the worst, I have other alternatives I could use behind the original KEF faceplates. Plan is to restore them to original to see how they sound, more to come whn I've got some pics & measurements sorted)

The author of HQplayer Jussi Laako released design of this dac on Apr 18.
It's a pure DSD 1-bit 33-level dac with full support from HQplayer.
Signalyst
Anyone interested?

Interested in getting boards? http://www.diyaudio.com/forums/digital-line-level/254935-signalyst-dsc1-6.html#post4175377

Important grounding and gain modifications: http://www.diyaudio.com/forums/digital-line-level/254935-signalyst-dsc1-2.html#post4104608

Glad to be here and hope I can be of some help. I've been repairing audio since the 1970's.

I am looking to learn everything about building hi-fi systems.

Hi,
I am a new member of diyAudio although I have browsed the site many times over the years. I have 25 years experience as a technician in the consumer electronics field (HiFi, VCR, computer monitors and television). I decided to join after finding a thread here about the YH11068A DC converter which gave me plenty of information. I now wish to contribute to this thread.

I have recently learned about the DIY audio world, and got immediately hooked. I really want to build a set of powerful speakers this summer, but I cannot seem to get started with it all. There are plenty of kits online and other designs, but I want to make my own and be proud of it. I have found some drivers that I think meet my requirements, but when I try to use software like Xsim4 or VituixCAD, I cannot make a crossover. I understand how the crossover needs to be built, but the frequency response graphs do not update when I make changes to the circuit. This happens in both programs and I cant seem to find any fixes online. Its very odd because the impedance graph will update with components being added and changed but I cant see the frequency response changes. I have tried using different drivers but it has the same result.

I found 2 Dayton audio drivers on Parts Express. I got the frd and zma files from Dayton Audio's website, and I uploaded them into the software. It seems like there is some setting not checked, or the software version is buggy. I don't really know what to say, the issue is because I have tried other drivers with different frd and zma data, and it still doesn't work. I get even more confused because I can see the simulated system frequency response when the drivers are simply connected to the amp, but that graph remains unchanged if I add any crossover components.

What's wrong with the kiss,boy ? ........ or - How I gained a gain ,little before Lee De Forest and little after Papa

lookie : Iron Pre | Zen Mod Blog

I already posted that link in few places here , but as it seems ,few Greedy Boyz are greedy for more info

cheap and clean way of having 6db (or little more ,with different gain device)

it's already everything written in that blog post , but to recapitulate :
-pot , then buffer of your choice , then 600:600 xformer connected as autoformer , voila! -there is 6db gain

if approach was good eons ago , when microfarrads and active gain devices were much more expensive than chunk of copper and iron,if approach is good for numerous mic input stages , if approach is good for F6 and especially M2 (buffer-autoformer-buffer) , it must be god for line stage too.

and yes , with 1+1 autoformer , Rout is four times Rout of buffer itself

xformers : Edcor have few , Jensen , Sowter, Lundahl etc.............

-do not expect that more expensive ones are necessary better sounding,
-do not expect maximum verity from buffer if you not use decent (shunt , my poison) reg.
-you can go wild and make your own autoformer , equipped with 24 taps , so skip pot on input and use autoformer at output, as volume attenuator and gain device ,as one device
-or you can make it this way - buffer -commercial AVC (200$ Slagle?)-output autoformer
-or you can go wild and connect commercial AVC to appropriate tap , as output autoformer and have 6db gain ...... that would be buffer -commercial AVC connected on proper tap

now I'm working on balanced Iron Pre ..... will post that soon too

edit on 11.10.2020. : last files for SE and Bal iteration are in posts #1149 and #1150

I've been wanting to try this for a while. I've been building the knowledge (generous help from DIYaudio members) and acquiring the pieces for it over the last year.

I call this a "work in progress" because I'll be changing drivers and configurations until I'm happy with it. A modular design should accomodate this. So no pretty packaging for now.

--------------------------------------------------------
- V1 : woofer=tc6028, midrange=pc83, tweeter=td20f :
Modular active 3 way - work in progress
- V2 : woofer=tc6028, midrange=rs52an, tweeter=td20f
Modular active 3 way - work in progress
- V3 : 2x woofer=tc6028, midrange=rs52an, tweeter=td20f
Modular active 3 way - work in progress
- V4 : 2x woofer=tc6028, midrange=rs52an, tweeter=td20f
Modular active 3 way - work in progress
- V5 : 2x woofer=W20RC380, midrange=rs52an,tweeter=dc28f
Modular active 3 way - work in progress
- V6 : 2x woofer=W20RC380, midrange=rs52an,tweeter=dc28f
Modular active 3 way - work in progress
- V7 : 4x woofer=tc6028, midrange=rs52an,tweeter=dc28f
Modular active 3 way - work in progress
- V8 : 4x woofer=tc6028, midrange=prv290 + sh402, tweeter=cd130+h07e
Modular active 3 way - work in progress
- V9 : 4x woofer=tc6028, midrange=prv290 + phrn1014, tweeter=cd130+ebay slotted
Modular active 3 way - work in progress
- V10: 4x woofer=DSA175, midrange=RS52an, tweeter=DC28f
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6310628
- V11: 4x woofer=DSA175, midrange=ZXPC-11x17 + D2200Ph, tweeter=Dayton H07E + CD130
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6914493

---------------------------------------------------------
Misc other tools and equipment
- turn table for polar measurements
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6238989
- circle cutting jig
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6246764
- fan speed control for amplifiers
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6337253
- plain wave tubes (built 1inch and 2inch)
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6544772
- acoustic impedance measurement tube
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6553137
- UMIK1 repair
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6899378
- optical intf DAC
https://www.diyaudio.com/community/threads/modular-active-3-way-work-in-progress.326926/post-6899483

---------------------------------------------------------

• Donor boxes and the initial drivers : silk purse from sows ear contest?
• Active analog 3 way XO : Budget active 3 way crossover - buy, eval, mod
• Active analog subwoofer adj bandpass : Budget active subwoofer lowpass, buy, eval, mod
• Class D amps : OmniDirectional - work in progress
• RPI3B + Piano DAC : Raspberry Pi with Piano2.1 DAC DSP and Volumio2

Hello chaps, long time listener first time caller.
I am here needing advice on crossover circuits, repairing KEF 103/4 speaker drivers and to build the Mechano23 as my first project. 🙂

Does anyone offer a service to test out a horn design I have been working on? I'm happy to pay someone for their time, and I do not have the time to learn a new program/workflow. Thanks!

I don't need a hundred watt per channel amplifier but I want one. The siren's song is very alluring and I can't resist, so my next project is a Tokin 2SK182ES SIT amp which I hope wiil be able to output 100 watts into 8 ohms.

Not only do I not need a hundred watt amplifier, I really don't need another amplifer, so I am planning to modify my BAF 2015 THF-51S monoblocks. I like these amps and I've got them currently in my bi-amped system. But I overbuilt the cooling system in them and they barely get warm after extended operation, which makes them the perfect platform for the high power dissipation requirements of the new design.

The other plus is that with some juggling around, I can use a lot of the existing pricey parts. I really don't want to spend a lot of money up front on a design that is unproven.

I knew I needed more voltage than the 62V power supply of my BAF2015 amps. Each monoblock is powered an Antek AN-6450 toroidal transformer. That is a 600VA transformer with 2 x 50V secondaries. Currently, they are wired in parallel. If I wired them in series, PSUD Designer predicts about 135 volts. That's the value that I used for the basis of my new design.

I spent many hours with LTspice trying various circuit topologies. I tried mu follower, choke loading, ccs loading, common drain, and common source. The most promising was the mu follower. I really wanted the common source mu follower to work, but I could not get as much power out as with common drain (follower). The common source version would be easier to implement as it has voltage gain.

So although LTspice said that a mu follower follower could produce 100 watts into 8 ohms, I wasn't sure if that was worth anything if I couldn't come up with a voltage amplifier to drive the output stage to full power. A hundred watts at 8 ohms is about 40 volts peak or 80 volts peak-to-peak. And, the 80 volts peak-to-peak should be fairly low distortion.

Luckily, I remembered that I had been exploring the use of the United SiC power JFETs in preamplifier and amplifier duties and that they performed quite well in those tasks (https://www.diyaudio.com/community/...loring-the-uj3n065080k3s.409636/#post-7624728). In fact, I still had a working prototype of a United SiC JFET preamp sitting on my workbench. So naturally, I decided to explore the upper limits of this preamp.

My previous experiments showed that I could get a clean 50 volt peak-to-peak signal out of the preamp when driven by my test oscillator at maximum output. I have an old Acurus preamp that I know to have low distortion so I set up a test with my test oscillator driving the Acurus preamp which fed into the United SiC preamp.

On checking the output with my oscilloscope, I was very pleased to see that the 1 kHz sine was amplified to about 190 volts peak-to-peak before noticeable distortion was visible. The Acurus preamp supplied about 26 volts peak-to-peak to the United SiC preamp. That encouraged me enough to get out my distortion test rig and take some measurements.

To make things simple, I set the preamp chain to output about 100 volts peak-to-peak for the FFT test. I figured that would be enough voltage swing to drive the follower output stage to 100 watts output with some safety margin. The results show a nice distortion profile with 0.029% Total Harmonic Distortion. This is significantly lower than the expected greater than 1% THD from the amp output stage at full power. So, this was good news.

With all this preliminary work done, I think that it will be possible to reach the goal of 100 watt into 8 ohms with this Tokin SIT. However, the SIT and CCS MOSFET will be operating near their limits, so there are unknowns and rough waters ahead.

But the sirens sing so sweetly.

Does anyone know a reasonably-priced speaker cabinet painter in the GTA area? I want to get some baffles painted with spray-grade Duratex.

I just need a reasonably uniform coat. I don't need anything fancy.

Thanks.

The most common crossover problem in the world is taming cone breakup and removing peaks from woofer response.

Many designers use 18dB and 24dB crossovers simply because they have to get rid of a peak and they don't have a better way to do it. But in general I don't like steep filters. All other things being equal (which of course they rarely are) I think shallow filters sound better to my ear.

My philosophy as a designer is "don't use brute force when finesse will do" and "don't use nuclear weapons when you can use a bow and arrow."

One of my favorite ways to get around this is with shelf and notch filters. At the Parts Express Midwest Audiofest in August, I won a pair of Ciare HWG160-4 woofers. These are excellent drivers. Like most woofers they have some peaking at the high end. This is the Ciare spec sheet:



In a bass reflex box in my room, data imported into VituixCad, the response looks like this, below:



A 6dB filter would level the response overall, but you'd still get that peak at 5-6kHz showing up in the response.

Most folks, then, would apply a low-Q 12dB filter. That would work just fine, but a 12dB filter adds to the driver's 12dB rolloff making a 24dB/octave final slope which has 360 degrees of phase shift. I feel that is undesirable. Given that the woofer is already 2cm behind the tweeter physically, it adds group delay and makes the crossover integration even more difficult.

A notch filter is a more gentle approach.

Schematic:



Signal at driver terminals:


Above is the drive signals at the woofer and tweeter terminals. You see a notch filter at 5.5kHz which cancels out the peak without adding even more phase shift at higher frequencies.

You might think that the -35dB depth of the notch is too much, and initially I did too. But when experimenting with real life measurements I found that it minimized interference with the tweeter.

Below is the schematic of the filter. I have a zobel across the woofer terminals, and a 4 ohm resistor in series with a 0.75uF capacitor, and those are in parallel with the 1.2mH inductor:

As you see above, I get a flat response up to 2K and a very nicely behaved downward taper above that point.

The tweeter is a SB Acoustics SB29BNC. The total circuit and modeled response are below:


The actual measured response of the system, at 1M distance in my room (no gating or attempt to reduce reflections) is here:


These speakers sound fantastic. The woofers reach down to 35Hz in an 18 liter reflex box. 86dB SPL. The tweeters have all of the holographic imaging and detail you'd expect from an SB Acoustics beryllium tweeter. They have precise 3D imaging and a "high resolution monitor" sound signature.



I chose off the shelf Iwistao cabinets https://www.iwistao.com/collections...15l-for-tube-amplifier?variant=31964739993715 - Iwistao will custom cut the driver openings for you before they ship, and it took less than 2 weeks from order to delivery. The build quality is not impeccable - you can see a tiny little mark just above the speaker grille socket for example - but the quality is quite good and the speakers are beautiful.

My son inherited a Fisher Model 173 and loves its sound. It is a nice sounding amp from 1973 with a warm tube-like character and works well with his vinyl and FM playback.
It's sounding a little soft and is lacking a bit of detail and punch. I found a guy, Todd of Timerider.net, who performs full restorations of vintage gear, but he broke a finger and can no longer do the work. I'm looking for someone who would be willing to do the restoration. I have the schematic and service manual.

He offered to perform the following work:
• Fully disassembled and clean. Inputs/outputs cleaned.
• All switches cleaned (pulled, if possible) and lubricated internally.
• All capacitors on all boards replaced, including main filter capacitors (Audio-quality and/or stacked film capacitors in tuner, pre-amp, amplifier, protection, power and tone stages (WIMA, Kemet, Nichicon and/or Panasonic capacitors).
• All Zener and Schottky diodes replaced.
• All trouble-prone or hot-running transistors replaced with modern, low noise units.
• Output transistors pulled, cleaned and re-set with new thermal pads and thermal grease.
• Heavy-duty regulator transistors on power supply board.
• New power regulator resistors on power supply board.
• New rectifier diodes x4 on power supply board.
• Adjust amp circuit with new Bourns trim-pots.
• Adjusted Bias to factory spec.
• New lamps.
• New snubber circuit on power switch.
• Circuit boards inspected for any cracking, burning, etc. Any cracked solder joints re-flowed, especially in high-heat areas.
• Bench tested for 12 hours under an 8 ohm load.

Need/Use Case: I’ve always wanted a decent bluetooth speaker that I could carry when traveling/hiking/camping/etc. but could never find one that really provided a quality listening experience. Most of the larger manufacturers with bluetooth devices seem to be dubious with their ratings and make speakers that appeal to the mass market with little regard to any sort of controlled directivity (not that omni is necessarily a bad thing when it comes to BT speakers).
In addition to this, I run a sound system for small-medium sized events and have been looking for a no-frills fill box that I can throw in a corner and feed a signal to without having to worry about it, so the appeal of a battery powered “set it and go” box is high for me.

Background: I’ve had a fascination with multiple entry horns over the last year or so having prototyped a few larger format MEHs at this point. If you know anything about MEHs, there are some considerations regarding the size, flare rate, and horn profile to achieve what they do. Going small with a MEH means you do lose out on some of these benefits if you plan to do a full-range build.
However, the primary guiding reason of this speaker’s arrangement is not necessarily to benefit from hornloading the 6.5” woofers, but to offer a highly compact arrangement that wouldn’t be possible with a flat baffle. As an additional benefit this places the acoustic centers of the drivers very closely and provides a good directivity match between the woofers and compression driver, despite the steep crossover. What it doesn’t do is give a substantial sensitivity boost/impedance match to the woofers that you would get from a larger conical MEH.

Build Requirements: I set out to design a speaker that would attempt to hit these metrics:

• Full range with at least 100dB output down to 50Hz
• Wide 60x90 pattern with well controlled directivity in both horizontal and vertical axes
• Highly portable (<15 LBS and <25 liters)
• At least 8 hours battery life

The Design
Acknowledging that I wasn't constrained by a straight wall conical horn, I opted to utilize Ath to design a waveguide that would provide a more uniform wavefront than would be possible with a pyramid shaped horn. For this reason, I’m hesitant to call it a horn and lean more towards a waveguide (I’m loosely defining this based on my understanding of Geddes’ classification).
For components, I opted towards using the new B&C DH350 compression driver, two 6NDL38 6.5” woofers, and two Scanspeak SB16PFCR-00 passive radiators (ports were out of the question due to the small enclosure size). This blend of components lends itself nicely to a crossover point somewhere in the 1.0-1.2kHz region, so that is what I targeted in Ath/Hornresp.
To achieve that, there was a good deal of fine tuning/tweaking the models in Ath/Hornresp. The basic idea was to really nail the directivity/impedance curve in Ath, then (loosely) translate that profile into Hornresp so that I could leverage the MEH wizard to integrate the woofers and find the point at which they could meet the CD.
Knowing that my crossover would be somewhere in the 1-1.2kHz area, I then sized out and placed the woofer taps in Fusion along the corners of the horn where the centroid of the taps is about ¼ wavelength @xo from the CD exit. I then modeled a flange for mounting the woofers leaving a flat area open so that I could come in later on and add cone fillers if needed.

My 3D printer bed isn’t large, so the model is split into 3 pieces - a left and right half with a throat adapter. I used 2 part clear epoxy to join the halves together. The woofer mounting nuts are heat-set M4 inserts.

Because of the proximity of the drivers, the 2 M4 fasteners holding the compression driver in may be hard to reach. I used a stubby hex drive to get to them when installed into the enclosure.

The enclosure is a simple hexagonal shaped box made from 12MM birch plywood with about a 15 liter volume after accounting for the displacement of the horn/drivers.

Unfortunately I misjudged the amount of clearance I'd need for the passive radiators, so they do butt up against the rear of the woofers when installed. If I do another box, I’m going to add a couple extra mm clearance there. The good news is that there is a hole in the basket of the passive radiators that lines up perfectly with the 6NDL38’s pole vent, so I don’t anticipate any overheating issues there.

During the initial testing I taped the front of the waveguide to the enclosure. This went about as expected, but I was at least able to get the data I needed. I use an outdoor ground plane measurement setup according to this guide from Scott Hinson. Measuring with a Dayton audio UMM-6 with a 20 cycle FDW applied at 1 meter (2 meters for off-axis). 30°C at 72% humidity.

For this first prototype, I wanted to validate the Abec/Hornresp model and check physical fitment - wasn’t going for a final rendition. The thought was to build the initial prototype and gradually add cone filler until I achieved the desired woofer response. For the most part, this was a success, but for whatever reason there was a secondary peak in the woofer response that I hadn’t anticipated. I’m going to consider my failure to anticipate this a happy accident, because it meant that the woofers conveniently worked out perfectly to meet the compression driver on the first try. If you have any insight/theories into why that secondary peak might exist, I’d love to hear.

Barring that, the unfiltered responses of both drivers overlaid looks like this.


For the woofers, I opted for a 1st order 80Hz LPF to flatten out the response, which got me 80% of the way to where I needed to be. After applying some corrective EQ, I was able to get a solid response from 60Hz-16kHz. I’m applying a 4th order 45Hz HPF to protect from overexcursion. After generating the spinorama I realized I probably could have done more on the EQ front to correct the 500-2k region, but I’m happy enough with it and don’t really wanna do 36 more sweeps just to make a squiggly line less squiggly.

Distortion as measured with stepped sine tones:

Group Delay:

And finally polars (normalized on axis):


Given these results, I decided to go ahead and finish out this prototype. There’s some details in the physical construction of the box I might make in a future version, but overall I was quite happy with the performance. I chose a Dayton Audio KABD-4100 amplifier paired with one of their 6 cell 18650 BMS boards, mostly due to availability and balance of features. One of the outputs was left unplugged, so it's not the most efficient setup but I found it works quite well for the price. The sigmastudio file is provided in the zip file.

Regarding the enclosure, whatever you build make certain it's well sealed. You may want to modify the flange on the waveguide for a cleaner mount. These little drivers move a lot of air and I spent the better part of an afternoon working out caulking/gaskets to fully take care of air leaks.
(I've since added a Neutrik combo XLR jack to the rear)


Specs

• Frequency Response: 60-16kHz (+-2dB)
• Coverage: 75Hx60V
• Maximum SPL: 106dB (about where the 6NDL38s and PRs reach xmax - can reach higher if you HPF at 80Hz.)
• Battery Life: Subjectively well over 8 hours, but I’ll be doing an M-noise stress test later at some point to get a real validated runtime number.
• Weight: 14.9lbs (6.75kg)
• Outer Dimensions: 18.5” wide x 10.2” deep x 7.9” tall (47x26x20cm)
• Internal Volume: about 15 liters
• Components:
  • 2x B&C 6NDL38 Woofers
  • 1x B&C DH350 Compression Driver
  • 1x Dayton Audio KABD-4100
  • 1x Dayton Audio LBB-6S
  • 6x Samsung 35E 18650 cells
  • 2x Scanspeak SB16PFCR-00

Download the .STLs and SigmaStudio file here.

Compromises: These are the areas that I’ve identified as weaknesses in this build or areas for improvement.

• Coverage is a bit narrower than I would have liked it to be. I think I need to refine my Ath skills a bit more since this didn’t necessarily match the polars I generated in ABEC.
• The steep crossover slopes may not be ideal for some listeners and introduce a small amount of group delay (about 1.3ms at 1200Hz.) This could probably be corrected with FIR.
• The DH350 breaks up at around 16kHz, so don’t expect full extension up to 20kHz
• Distortion is higher than I’d like it to be on the low end - no doubt due to nonlinearities with the passive radiators. They’re cheap - buy better ones if you can. Also - you should be able to achieve much better bass performance by increasing the box size by about 25%, so if space isn’t an issue that should be considered.
• Subjectively, the DH350 lacks a sort of upper midrange clarity that I’ve heard with other (larger) compression drivers. I’d wager this is due to some diaphragm resonances, but haven’t measured it. I’d recommend buying one to prototype with other horns/waveguides to assess this yourself before determining if this build is for you.

Hello from Spain, we are a technical service. We like quality equipment, the kind manufactured in the past. We hope to learn more and share knowledge.

I have been bitten by the hifi bug again after many years. Mostly interested in vintage gear, I get a lot of satisfaction in saving old but very good quality pieces of equipment from just gathering dust or worse yet a landfill. I have a soft spot for vintage Kenwood gear, recently acquired a KA-2000 amp and added the matching KT-1000 tuner. I am currently resto-modding some Acoustic Research AR8b's. The woofers need to be re-foamed after 40+ years, the tweeters look fine. I am also going to tweak the crossover by adding a low pass and a high pass filter, the original design has only a single 5 microfarad cap in series connected to the tweeter. Cosmetically the enclosures look pretty good for their age, but I plan on replacing the grill cloth the something with a 70's vintage beige tweed. I am putting money into this project but I was given the speakers for free. Hope to chat soon and also get some valuable advice.

Hello everyone!

Has anyone tried a pentode in UNSET topology and loaded with a CCS as voltage amplification stage? I'm getting very low distortion for 160Vpp output voltage, 220K load, gain 36. The gain is controlled by R2/R4 ratio. I want to build it, but first checking whether anyone has played with this. Tried multiple pentodes, even a 6BQ5 gets around 0.08% full swing at 15ma.

Regards,
Jose

I never saw 3P compensated amplifier so I tried to build one. The basic design is come from the local forum's guru, Danhard. I made fine-tuning to adapt it to the real conditions. Three boards were built, the biggest problem was the correct placement of components and routing so as not to cause distortion degradation. The measured 1kHz/4R thd is under 0.0001%, the 10kHz/4R is about 0.0005%.



As you can seen the loopgain slope falls 60db/decadeView attachment 1044059

Hi, I have some information about the headphone amplifier clon 3850 from a thread on this forum. But I can't post there.

Hi,

I am using Ohmite brown devils [200 series] for Cathode bypass and for reducing voltage on the driver valve power supply circuit. The amplifier is a 211 and the power consumed is about 3.5W on each of the cathodes and driver valve circuit uses a resistor that consumes about 9W to drop 300V.

I am able to push air through with some convection and some from low noise fans that move air around the underside of the amplifier near the resistors so they can dissipate some heat BUT they are both placed near some potential complimentary heat sinks (Copper plate 3mm thick and large aluminium plate 19mm thick). Clearly these resistors are designed to be in free space but I can't help but wonder if it would be advantageous to use a direct contact also to the plates to take some additional heat away.

Any more useful thoughts from experienced amplifier builders?

Thanks,

Rich

Hey All, thank you for letting me be a part of this community, excited to learn from people who have been at this longer than me!

I have just completed a pair of these Hiraga amplifiers and was amazed with the sound. Was never an advocate of class A but after completing a regulated power supply and using transistors that i had available i can confirm that this simple amp,designed some 30 years ago, is one of the very best as far as sound quality is concerned .For those who want to give it a try and cannot get the specified original transistors here is what i used and its working fine with no problem in setting the bias current and the DC offset. I do not want to get into a debate about the characteristics of the transistors i used. I can only say that they complement the circuit and they do the job. Just bear in mind that you might have to adjust the 47 k bias resistor to give around 380 mv measured across the 0.33 R resistors at 30 v. I got it right at around 34.3 k.
The use of a regulated power supply is highly recommended as with it,the amp is extremely quiet,no hum etc.
Transistors used for the output is the 2SA 1942 and 2SC5200
Drivers BD237 and BD238
Inputs BC 258 and BC630. (TYPING ERROR CORRECTED SHOULD BE BC 639)

Hey, i'm a pasionate hobby speaker builder and glad that i found this big great comunity.

Greetings!

I've recently entered the vintage HiFi world, after buying 2 pairs of Monitor Audio R352 speakers - yes, 2 pairs! - plus Audiolab 8000A amp.

This community has been really helpful in helping me swap out the tweeters in one of the pairs of speakers - from metal to the original soft domes - but I'd like to learn more about replacing the bass drivers on one of the pairs of speakers, and perhaps upgrading the crossovers.

Looking forward to getting stuck in!

Neal

Hi folks!
I've been lurking around here for a long time, I am always grateful for evey useful information.

Audio circuit DIY is my main hobby, mainly guitar amps, stompboxes, sometimes headphone amps.

I’m into tube amps these days!

I have an SMSL SU-9n DAC that I've been enjoying for more than an year. A few weeks ago it stared having interruptions while playing music. Initially I thought it was something network related. So I stared resetting switches and routers but with no success. Here is my main setup: the SMSL DAC is connected via USB to a RPI3 Roon endpoint. The RPI is connected with cable to my network. I have a TrueNAS NAS that has a Linux virtual machine where the Roon core is installed. Then the DAC is connected to the amp via XLR cables. I also reset the virtual machine but with no luck. I then connected the laptop directly to the DAC via USB and I noticed that the issue was still there. This clearly means that it is something within the DAC. I contacted the support from Shenzenaudio (I bought the DAC from them) and they replied that I can send it back to them for a repair. Obviously I do not want to wait around 10 weeks to get the DAC back so I asked if they saw this issue and if they have a fix for it. Working in R&D (electronics) and having access to nice tools I can fix it myself. Or at least I can try 🙂. They replied that I can try to fix it and if I do not succeed, I can send it but they didn't say anything about the issue I mentioned.

I then started looking around the DAC. First I noticed that the AC/DC converter that should have an output of +/-12Vdc and 1A, only had the +12Vdc and it had 0Vdc on the negative rail. But I noticed that that it was jumping around as it was some kind of AC. I measured around the DC-DC converter that are on the board and I noticed that the negative rail was all shorted out. I removed the AC-DC converter and it looked like the short was on the AC-DC module itself. I thought that this was defective. I was wrong. As it turns out, there is no negative DC output at all. It is actually the voltage taken directly from the secondary of the transformer (high frequency AC in the shape of flyback converter). This AC is then rectified with a schottky diode and filtered and then a DC-DC converter generates the negative rail. So bottom line, the AC-DC converter is fine. The short I was measuring is actually the resistance of the secondary winding.

At this stage, the DAC board was powered from a lab power supply with +/-12Vdc and it seemed like the interruptions were not present anymore. But after a while, these stared appearing again. I started looking around the DAC and I noticed that when I touched one IC, the interruptions got better. This is the IC in the image below (with the part number erased):



I thought that it might be the case of bad soldering and I reordered the IC. Again, it worked just fine for the entire weekend but it did have a few random interruptions but definitely not as bad. I then asked the shenzenaudio support if they can sell this IC as I do not know the part number, therefore I can't order it myself. They said no problem that asked me to contact them after the 1st of March as they now have bank holidays. Well I said ok but I didn't really fancy waiting that long.
I then went back and removed the IC from the PCB and cleaned the PCB and the IC. I put it back on and the behavior was pretty much the same. What I noticed, is that when I put the top cover back on, the interruptions are a lot worse than when I run the DAC with the lid open. This pointed toward a thermal issue and when I touched that IC, I was actually cooling it down. I went ahead and teste this by touching the plastic part of the IC with a tip of the soldering station set at 70C. It instantly stared interrupting and then complete silence. I then touched the IC with my finger and the music was back on. So it is definitely a problem with the IC itself. Yes I can run the DAC with the top cover off but this is not ok as I have kids and there is AC mains inside the enclosure. So the only solution is to try and find out what IC this is.

I then stared looking around the IC with the scope and I see that when the IC warms up, the clock on pin 10 (49MHz) starts to jiggle and it actually interrupts as seen below. The 24MHz clock coming from the TCXO goes to pin 2 of the IC.

Good clock:



Bad clock:



So it is clear that the IC starts malfunctioning due to some temperature issue. The IC temperature is around 51C (measured with a FLIR camera) so it is not that hot. I think it is probably broken and I think that when they removed the markings from the package (probably by laser) it might have damaged it. Or it is just a bad sample (lucky me 🙂 ).

Next I tried to figure out what IC this was and after a few minutes on the webs, I think I found it. I think it is a clock generator Si5351A. Below you can see the comparison from the datasheet of the Si5351A and the PCB of the DAC. I can tell for sure that on pin 5 I have something resembling data and this would indicate an I2C SDA pin.





I will order this IC and I will test it. I will come back with the results.

Hi to all members!

My name is Gabriel, I have been a member since 2009 and lurked before that.
So far I have completed many projects to fruition thanks to others input, their encouragement, critics, and (hard) questionings!
I have been able to to gather from outside in literature missing pieces of calculations and theory to draw tube curves, calculate frequency response, cut off points, oscillation, and the hardest, amplifier gain and GNF loops, which I still don't understand, but I can measure it and listen to the difference it makes.

I have completed so far: many pre-amps (tube and SS), a hifi solid state 100 watt amp, a few 3-ways speakers (alnico, OB etc) and a 2-ways with passive radiator based on Usher drivers with XO simulators and real reactance curves measured in-room with my amplifier.
I acquired a true-RMS voltmeters, a variac, built a test station, dummy load, a dual channel THD analyzer and multiple channels SCOPES and gathered data stored in EXCEL charts, (some are lost now)
I built a few tube outputs from dacs, cd-players, but I am not a dac specialist and figuring oscillation and parasitic noise is too hard for me.
I modified 845 SET amplifier, and two solid state amplifiers.
I built a few PP amplifiers: kt77UL , el84 in triode, EL34 UL, Kt88 UL , Kt88 triode, Kt88 zero feedback, Kt88 LTP balanced input zero and with feedback, 6BL7 PPP, and a few more exotic dac tube outputs, and a Kt120 UL!!!

I have experience with a few types of transformers and many Hammond, Edcor, and high end ones.

I am lacking the experience with LTSpice and time!

The goal here is to post/develop an exotic circuit in LTSpice of a Kt120 PP amplifier which I designed and to bring it to perfection.

I set up years ago the OT to be a 5k low insertion loss high power 80W+ and high inductance design which will remain secret, let say it is similar to a Lundhal transformer. I wish other DIY members buy their choice of OTs and experiment and have the best circuit possible with tube respect to build their DIY amplifier. I have seen many designs and many commercial kits and built them, I want to build something unique which summarize the best knowledge in tube amplifier design and sound accuracy, beyond 'claims' and beyond 'exotic parts' and beyond 'this was good enough'
The philosophy here is to attain excellency by design choices which doesn't cost much as a DIY. I want us in the forum to get that extra listening pleasure that higher price amplifiers bring, not only by the choices of OT and feedback, but also by circuit design.

The amplifier would be a PP UL 70W 1% THD , B+ 600V, Bias servo 67.5 mA. GNF 10.5db or so. There is some margin and testing to do there, there should be a +/- 50 V in the B+ margin to build the amplifier, DIY's should be fine with using 40 Watts to 120 W OT , Bias would also be a choice, there should be room for experimenting by members while I build my own design.

The input tube would be by default a 6sn7gt in common cathode from TungSol or NOS of the highest fidelity, possibly using both sections as follower using the cathode part to take the signal out...
The driver tube would be overkill and easy to obtain like a LTP ECC99 and CCS EL822 (which required a tube and separate TX+PS), it could be also an alternative to use a LTP 12BH7 with LM334 CCS, experimenters could also use CCS and Drains with transistors...

Hello everyone,
I am working on a nice Adcom GFA 5800 amp. The problem I am having is that when setting the bias as per service manual instructions, the left side .5 amp regulator fuse blows hard (bright light/vaporized metal) only after about 30 minutes of running. I have amp multimeters on both regulated rails feeding the amp board also and the current is steady at 50 ma on each until the fuse blows. The fuse seems to blow when the bias current approaches about 700ma. The current on my variac, idle current, and regulated current do not rise abnormal compared to the right side until the fuse blows, then idle current goes down a bit and fan goes off. I have a thermal camera and the amp is not overheating, and the overall channel and individual components are within a couple of degrees of each other on the regulator board and amp boards. Since everything runs fine until the fuse blows I’m not seeing any odd voltages. This is a fet based amp. My question is what parts have this type of failure mode? Any clues would be much appreciated!

My name is Fabio Mascarenhas, I'm from São Paulo/Capital, I've lived in Americana, in the interior of SP for almost 10 years. I want to talk about Fullrange cabinets, BackloadHorn etc.

I move home often, so can't design speakers for a known room shape or size (and room treatments must usually be modest, too). Headphones and near-field listening have been the answer, but I miss having room-sized speakers. I suspect that horn/waveguide type speakers would have many positives in this situation, and I find MEHs especially interesting for other reasons as well.

I've not gone there because they would need to be large; unfortunately it is the somewhat lower frequencies, say at least down to 500hz or so, that would seem most beneficial for me to direct. Keel's equasion indicates something like an 80cm (32inch) wide horn-mouth for that, depending on what angle is chosen. Though they would probably need to play lower than their directvity, down to around 80-100hz, as I'd want to hand over to subwoofer(s) rather than need an additional bass driver.

However.. it occured to me that a lot of MEHs are quite sensibly sized around the actual drivers, taps and the straighter part of the horn. So, if the seconary flare and any round-overs were easily detachable and dismantlable (for transport, storage and when letting-agents come to inspect), the size might not be such a deal-breaker.

Though I've never built a MEH or even a big waveguide; there seems to be a huge amount to learn and test, especially if I'm on the wrong track.. For those who have experience of such speakers: do my hopes and expectations seem valid and reasonably achievable?
Thanks,
Kev

Hi,
I have a Parasound 2250 Two channel amplifier with a transformer i believe is dead.
I can measure 220V AC on primary side but nothing going to the rectifier on secondary side.
So i need specifications for this small transformer on pictures below.

This thread is about the hifisonix X-Altra MC/MM Phono EQ Preamplifier published in audioXpress in February and March of 2021. The design uses separate circuits for the MC and MM stages in order to optimise the noise performance amongst other parameters. On MC input, the measured 1kHz spot noise (full MC + MM signal chain) was under 250pV/rt Hz, while on MM inputs with a 1350 Ohm + 500 Ohm cartridge source, the SNR is specified at >76 dB unweighted, and >80 dB 'A' weighted.
On both MC and MM inputs, the overload margin across the audio band exceeds 30 dB (see the specifications below). The X-Altra MC/MM makes extensive use of SMD components.

Below are the links to Part 1 and 2 of the articles as printed in audioXpress

Part 1 of the article https://audioxpress.com/files/attachment/2735

Part 2 https://audioxpress.com/files/attachment/2736

Attached below is the September 17 2024 BOM ending in COPY. This is the reference BOM in the interim for the next few weeks, after which the audioXpress supplementary file will be updated and this copy removed. Any questions just message me at hifisonix.com, or better still, send me a PM here.

Here is a link to a YouTube video about the preamp - technical, so don’t expect any subjective stuff! Login to view embedded media
You can buy a PCB set (main signal board plus rear panel board) for US$49.50 + $15 tracked shipping - details on the web page below.

Link to the hifisonix X-Altra MC/MM page https://hifisonix.com/x-altra-phono-eq-preamp/

Here it is on Pinterest courtesy audioXpress https://www.pinterest.co.uk/pin/you-can-diy-xaltra-mcmm-riaa-eq-preamp-part-1--733875701785808118/

Here's the link to Andy Lowe's excellent set of measurements on his build fireanimal's independent measurements and more measurements here

Here's the link to his build photos fireanimal's X-Altra MC/MM build


ERRATUM
C9 and C25 on the circuit diagram are shown the wrong way around. PCB's shipped after July 2020 had the component orientation corrected. So, follow the PCB silkscreen which is correct.

Here are the X-Altra MC/MM specifications. Kindly note these specifications were all confirmed with measurements using the QA401. As a comparative indicator of noise performance, the MM 1 kHz spot noise (measured) >8 dB better than the OPA1652 and >10 dB better than the OPA1642. Compared to MC preamplifiers using the AD797 low noise opamp, the X-Altra MC RTI MM 1 kHz spot noise is 11.7dB quieter (0.232V/rt Hz vs .9nV/rt Hz) - this is the whole signal chain performance, so from the MC input right through to the output of the preamplifier. The 1/f noise on the X-Altra MC/MM is also substantially lower, and the knee frequency is well below 100 Hz, a trick IC-based front-end MM stages are unable to replicate. On MC input, the X-Altra offers just about the lowest noise of any commercial or DIY preamp, and on MM, it's at the theoretical limit when considering performance with a cartridge connected; on both input types, the outstanding noise performance comes with >30 dB overload capability from <20 Hz to 50 kHz.









Here are some independent measurements of various JFET's (courtesy MV Audio Labs)

Finally, here is a short introduction to vinyl recording and playback and why EQ is needed

Login to view embedded media

Selling Zhou Fang's remaining stocks including some very rare Toshiba transistors

Sale: I am getting rid of some old stocks to create spaces for new parts, sale for the following items (PS: N/P not matched). Thx
k2013 matched quad (4X): $23 (28%off)
J313 matched quad (4X): $23 (28%off)
k1530 matched quad (4X): $42 (20% off)
J201 matched quad (4X): $42 (20% off)
K170 cota (8X, Idss<7mA): $22 (30% off)

Notice: For customers who want to use courier service instead of Singpost, pls use this website to estimate shipping cost: Calculate shipping rates

Items available:Pls refer to the follow table or Click here



Matching Curves:

2SJ74BL-2SK170BL Third Batch
Take note 2SJ74 for this batch are taken out from NOS 2SJ75 (as normal J74 are running very low...), so these is no marking on them. Rest assured that these are 100% genuine 2sj74, and the quality is as good as J74 with markings. Pls refer to the excel file for matching details.
batch3_release (1).xlsx - Google Sheets

2SJ74GR-2SK170GR Matched Quad Sets ($42 per set)
J74GR_K170GR Matched Quads.xlsx - Google Sheets
Take note 2SJ74 for this batch are from mixed sources. Some are normal 2SJ74GR, and some are taken out from NOS 2SJ75 (as normal J74 are running very low...), so these is no marking on them. Rest assured that these are 100% genuine 2sj74, and the quality is as good as J74 with markings.

2SJ74BL-2SK170BL Matched Quad Sets--all sold out
First batch: 2SJ74-2SK170 Matched Quad.xlsx - Google Sheets

2SJ74BL-2SK170BL Second Batch--all sold out J74 Batch_2.xlsx - Google Sheets

2SJ201-Y / 2SK1530-Y matched NNNNPPPP
power MOS matching IV.xlsx - Google Sheets

2SK2013/2SJ313
https://docs.google.com/spreadsheets/d/1Z2iR0_6jUHs4GhxxVcFBy31qbvgDGChd96arg_rm_g4/edit?usp=sharing

J75
https://docs.google.com/spreadsheets/d/1_d_jKIvsxYGP2_4FQO9mLGIBa2si7NjNsNIVM3-0TG4/edit?usp=sharing

Sample IRFP240 / IRFP9240
https://docs.google.com/spreadsheets/d/10J2-KA5yA91wPdIgeehZRQrpQr5iC-scRCto_tTg9wQ/edit?usp=sharing

2SK170 matched octal curves
https://docs.google.com/spreadsheets/d/1fcgMEsK8BPPaGctPudCtVpmgMpIr63OiyZ1MCDYtaWE/edit?usp=sharing


Thermal pad:
http://www.diyaudio.com/forums/vendors-bazaar/291486-selling-zhou-fang-s-remaining-stocks-including-some-very-rare-toshiba-transistors-17.html#post5012672

Shipping & Ordering T&C
Ordering:
pls sent me a PM with the following information:
Forum ID:
Real Name:
Shipping address:
Paypal account email:
The list of items, the quantity, and options (matched, unmatched, or special request)
Declared parcel value for customs/insurance purpose.

Payment:
Exclusively by PayPal. PayPal fee is always inclusive in prices shown.
Price are shown in USD$, but for non US buyers, I may invoice you with the USD equivalent in my local currency SDG (Singapore Dollar). This will help me to save on currency exchange fee. X-rate determined by Yahoo Finance. If any non US buyer wants to pay in USD only, please state it explicitly when placing your order.

Shipping and handling fee:
Shipment by Singapore Post International Registered mail.
Once paypal is received I will ship your package within 5 working days.
If anyone did not receive your package within 18 working days from my shipment notice, please inform me.
Free shipping for all orders >= $80, unless otherwise stated. IRFP240 / IRFP9240 are excluded from this offer.
For order between $50 and $79.9, $2 shipping/packaging fee will be charged.
For order between $20 and $49.9, $5 shipping/packaging fee will be charged.
For order <$20, additional $2 small order fee applies, plus shipping fee, a total of $7 will be added to the price.
For unusual items, shipping fee might be different, in that case, I will state it clearly in the item description.

Important Shipping Policy Change: Effective from 24 March 2017, I will not be responsible or provide refund for any lost of packages through Singpost registered mails, unless the packages are insured. Take note insurance of the parcel is not included in the shipping fees stated in the shipping T&C. Pls contact me for quote of insurance. Pls do consider using more reliable delivery service providers, such as DHL, EMS or FEDEX, if your parcel’s value is above $100. Pls only place order if you accept the condition. Thank you for your kind understanding.

Search Index: 2SK170-BL, 2SK170-GR, 2SK170-BL / 2SJ74-BL, 2SK369-BL, 2SJ103-BL / 2SK246-BL, 2SJ201-Y / 2SK1530-Y, 2SK2013 / 2SJ313, 2SJ75-BL / 2SJ75-GR, 2SJ109-GR, 2SJ109-BL, 2SK79, IRFP240 / IRFP9240, 2SC2911S / 2SA1209S, 2SA1943-O / 2SC5200-O, 2SK117-BL, 2SB737.

Hi everyone,

Id like to connect the I2SoverUSB interface module to a CS8414->AD1865 board (see picture below)

The "lazy" approach would be connecting the SPDIF output from the I2SoverUSB to the SPDIF input on the DAC board, although my understanding is that I could bypass/remove the CS8414 and drive the AD1865 directly from the I2SoverUSB. Has anyone any experience with it?

The power transformer in a Marantz PM 7000 is broken. Does somebody know the output voltages?

Hi! Im new to audio world. What to i need to make a speaker for phone/ boost audio with a d class amp. Can I use a pam8403 with a rechargeable battery and connect it to my phone using usb c to 3.5mm dac. Or should i buy a cheap pc speaker and connect the speaker part to the amplifier and then into the phone. Does it work like that. Any help is appreciated. Thanks.

My Quad 303 won't switch on and I'm just checking I'm on the right track, checked dc at main caps and got nothing

Confirmed 230vac to transformer,

Disconnected transformer secondaries from bridge and got

46vac
7.5vac

Connected them back and disconnected vdc from bridge rectifier and got

On the vac 48v and 8.1v

on the vdc outputs on the bridge measures 2.5vdc on both

I'm leaning towards a faulty bridge rectifier?

Does this sound correct?

This thread is for discussions about the new Speaker Turn-On Delay and DC Protector boards (V3). This is an updated version of the V2 boards, primarily to make them compatible with the 10x10 grid mounting pattern we've now standardized on so they can be easily mounted to Deluxe chassis baseplate, riser panels, front panels and/or heatsinks. Refer to the V2 discussion thread for additional information.

For more information on this product, please see the product page.

Change History

• 2.0 First Production Release
• 2.0.1 Added Board Dimensions
• 3.0 New Layout
  • Double sided board
  • Added Keystone connectors as option
  • Conforms to 10mm mounting grid
• For future changes
  • Add polarity markers for electrolytic capacitors

Information

• Product Page
• BOM - Attached below (Now updated to V3.0.2b) -- 3-paged BOM
• Schematic - Coming soon
• Dimensions - 100mm x 50mm

Hi, community.

What would you judge as the best (premium, but still somewhat affordable) 1" exit throat compression drivers of today? Along with a compact horn that would fit in a normal living room compatible speaker - meaning around 8" diameter max.

My first candidate pair would be an 18Sound NSD1095N on an XT120 horn. Probably hard to exceed that actually, according to its excellent Voice Coil test.

Regards
Stoneeh

This thread is for Quasimodo results ONLY.

Please NO COMMENTARY HERE. (For comments, please use the Simple, no-math transformer snubber using Quasimodo test-jig thread.)

[Note: it might be nice to highlight any non-standard Cx/Cs values in red.]

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I wish to learn how to interpret BODE plots to determine which trans to select - KSA 1015/1815 (green plot) or 2N4401/4403 (red plot).
What positive and what can be seen in each. Does one indicate it might be the more stable? The 2N4401 has lowest THD but higher voltage noise spec. Wondering which to buy...

I have two outdoors zones, one with a pair of Polk Atrium 5 and one one with a pair of Bose 251 Environmental. Neither of them have enough bass for me, power metal needs power and prog metal needs the six string bass to sound out! 😉 My plan is this:

Make a bass system that I can move where I am spending the afternoon (it all depens on the wind, one side is great for northern and eastern winds, the othe one is for southern winds. Western wind is a toss-up) and store in the shed when I'm not using it. I will repurpose a 10" JBL subwoofer box that I have from an earlier car (last ten years my cars have had those built-in audio systems that I haven't bothered to mod) and a car amp I have laying around for that, and a 220V-12V power supply (which I have on order, 25 ampere and weather proof). That will be fed by the main amp's line output for the zone. The car amp has built-in crossover so that only low frequencies will be sent to the subwoofer. So far no problem.

The problem comes when I want to crank up the bass and volume. I need to stop the lower frequencies (from 125 Hz and down, maybe?) from reaching the Polk and Bose speakers, or I will blow them. So I want to use a crossover on each speaker. Complicating things is that I can't have the crossovers indoors, because when I have a party I bring out a pair of 12" Wharfedale Titan 12 PA speakers, and they can take care of anything my amp can throw at them, so I don't want to cut the low frequencies from the amp and out. When they are out, I use relays to route the amp to them instead of to the Bose and Polk speakers. So the crossovers have to be outside, and they can't be that expensive, in case humitidy ever gets into the box. Oh, and there is no sub out on the zones I'm using (zone 2 and 3 on a Yamaha RX-V 2067).

So is there something that could work for instance on Aliexpress or eBay, that isn't all that expensive, but still won't degrade the sound more than the speakers do? They are pretty good, not high-end, but few outdoors speakers are. So that means that the crossovers would have to be able to put out sound in the same class.

I have good soldering skills, have built 10 or so tuner, preamp, amp kits in my life, both SS and tube.
But never had an identical pair of kits waiting to be built. So my question:

Should I build both kits simultaneously, or finish one before I start the second?
I am leaning towards doing both at the same time but I can see one big risk to that; if I later find I did something wrong, I likely will have done it wrong twice, and will need to fix it twice!

What say you?

What's the forum consensus on the best XLR measurement mic thats available out there? For home/outdoor DIY speaker measuring + crossover design.

I've currently got a Dayton EMM, A SoundID reference and 2x UMIKs, and while they all measure similar in the bass to mids, the highs are all over the place with about 6db variance between them (yes, tested in the same stand in the same location with the mfr cal files, at the same time in the same temp). Funny the USB* mic measures the highest treble output, sounds the most neutral to me when used to voice designs, but I need XLR for the proper 2 channel measurements.

Are the cross spectrum calibrated Daytons the go-to?

Clearing out my stash of amplifier parts. Original manufacturer parts. I am offering a substantial discount for anyone interested in buying the bundle (this is my preferred condition of sale). I am sharing a list of prices off the internet as of 1 week ago. Parts on offer have a new value of over R11000, averaged over 4 suppliers, excluding postage and duties. I am asking R5000.

I will keep the offer up for a while, with the hope that someone will take the bundle. Failing that, I have given prices per item.

To the person who takes the bundle, I will also give a bag of 15 35A bridge rectifiers and my unfinished projects of 4 stereo amplifier boards based on LM4702 driver chips (they are just missing the transistors).

Condition: New (except for 2 used items)
Price: R5000 for all
Location: Cape Town
Shipping: Yes. Pudo locker or door-to-door. Buyer's cost.

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Hi yall, I'm hoping to create a space to talk about subwoofers that reach higher than typically expected, all the while covering down 20hz/30hz without sacrificing the accuracy of its upper passband. Sealed enclosures with multiple large woofers, and high xmax are a good choice. Having pairs of these types of subs only makes things better and being that we are traveling into the realm of localization by playing so high, these types of subs are to be apart of the mains, either by proximity or appendage.

Sealed enclosures as described above make short work of the task... I'd consider something like a large sealed cab, dual 18" with >14mm xmax the status quo. Where it gets interesting is transmission line and bass reflex. Vented Designs need to be a lot more particular. Damping is needed but maybe not in every design. A front loaded horn like the known HT tuba which is an bandpass design where the front horn is entered in offset, may do well thanks to the near 0 CSA at the beginning of the line. Of course it comes with its own sets of pros and cons, the line length creates delay, for example.

I will post some designs that fit the category, and I hope that you guys have some designs that you like as well. There are details that help optimize these types of subs, lets chop it up at our leisure

I picked up some more speakers to restore this week.

Interdyn P33 which is a nice unit, when I got there the mid ranges weren’t working and the woofers had been replaced. I nearly walked away but decided the cabinets might be resurrected and/or I could use the tweeters and crossovers as spares, probably too generous but paid $50.

Well….the mids are fine but these have to be the best cooked crossovers I’ve ever seen!

I did what I could to trace the design, I was a bit worried the inductors would be damaged but they both read an identical 0.18mH/0.4 ohm so I might be lucky.

The crossover design looks interesting, first order only with some impedance compensation, nothing at all on the woofer.

Based on the sketch this would be 700Hz/5kHz, can anyone see anything wrong with my assumptions?

SEAS H086 tweeter, 10 F-M midrange and normally a 25F-EWX woofer has been replaced with a Plessey C100.

Someone already thought about this?

Would like to hear thoughts 🙂