Hi All,

Florent here, Frenchie living in London at the moment.

I had different little handmade but bought sound systems in the past and decided now to build my own little stack..
Plan is for a pair of Keystone, a pair of HD15 and a pair of SyntripP.
Wood is just getting cut and I have a few queries to get through this project !

Best

Florent

Here is a new project, virtual for the time being, but I'll certainly give it a try one of these days.

It is a current dumping amplifier, but with an originality: the class A amp is based on a boosted-rails opamp. This means that the signal part of the amplifier is minimal, and that any standard opamp having a maximum supply of 36V (or even less) is suitable.

The pic shows the circuit and its operation, with the supply rails moving in a "telescopic" fashion about the output voltage, and keeping their difference ~constant.

The basic principles of the technique are detailed here: http://joebrown.org.uk/images/DualPSU/BootstrappingOpAmps.pdf

Unlike a conventional opamp amplifier, two resistive dividers are involved in the gain, and the actual gain is determined by the difference in the ratio's of the dividers.
If we call K- the ratio of the divider of the (-) output and K+ that of the (+) input, the gain can be written as (1 - K-)/(K- - K+).

I have some questions (to this always greatly helpfull community!):

1. How do I overcome the nasty impedance peak of the Tang Band W3-881SJF Full range unit? I was hoping to use this as a mid driver from 400Hz to 4000Hz in a 3 way design. But I am worried about the huge impedance peak this driver has.

2. A lot of people are writing or talking online about complex crossovers sucking the life out of the sound.. (am I thinking about impedance correction networks and notch filters here?)

I would like to pair a 10" sealed or 8" ported woofer to this driver, and have a tweeter take over on top where the 3" driver starts loosing on dispersion of energy.
but I am very uncertain how to go about this.. Any thoughts are welcome! (By the way, the speaker is to be used in a domestic situation for stereo music listening in a livingroom. My main goal here is to have as wide a range of frequencies come from a very small point, to obtain fantastic stereo imagery.

Signal transformers made according Deutsche Post specifications via Pflichtheft so very stringent high quality requirements.

I have F&G, Sedlbauer and a few other brands. Pairs are of course both the same brand and year of manufacture (most are made in 1985).

All measure equally well. They are flat from 20 Hz to 20 kHz. They weigh 970 gram a piece. When you are used to Aliexpress stuff these are something else with 0.00xx% distortion at 2 Vrms in the whole audio band. They can be used 2:1, 1:1 and 1:2. They are 80 x 90 x 40 mm. Please note that they have all the mechanical and electrical items one likes to have like shielded casing, static screen and incredibly good performance. Maximum voltage is 60V 😀 Sound quality simply is excellent.

I think 150 Euro a pair ex shipping within mainland Europe is a fair price. They won’t be shipped to any destination outside Europe.

Hello

I have WinISD installed on my MacBook Pro 16, via Bootcamp and Windows 10- when I open it, the screen is zoomed out so far that I can't even read it with readers on. I've tried changing the screen scaling, but that just zooms in on a portion if the window and doesn't allow me to scroll to the fields I need to access. Is there a solution to changing the resolution that I'm missing? System preferences doesn't seem to work, what else can I try? will installing an older version help?
TIA

I have built some speakers by combining parts of two others, using SEAS and Vifa drivers. First impressions were quite positive, however after a while they can be a but tiring/harsh. I'm interested in thoughts on my approach.

I started with some Interdyn P32's with blown tweeters and melted crossovers. These use a SEAS 25 F-EW 10" woofer. It's a small-ish sealed box which appears similar to Dynaco A25 and has fibreglass insulation. I decided that keeping this box would ensure the right parameters for the driver.

Separately, I had some Sony SSU-280 speakers that were missing the 10" woofer. These are unusual for Sony in that they used scandinavian drivers, a Vifa K10MD-18 mid range and D19TD-05 tweeter. I'm almost certain the original driver is a Peerless 830668 based on the size of the cutout and what was around at the time they were made, but I can't be 100% sure.

In any case, what i did was pulled the tweeter, midrange and crossover from one box, to make sure the cutoff frequencies were right, and put them in the other box that had the woofer matched to the enclosure. Should work ok, right?

Hello, I'm Focus! I am a mobile DJ with a passion for subwoofer construction and audio electronics. I enjoy experimenting with sound, understanding the mechanics, and optimizing equipment for maximum performance.
I'm excited to be part of this forum, where I can find a wealth of valuable information and inspiration for my projects

I have a substantial amount of these lovely transistors. Very low Cob, 1p8-2p5.

Sold in 50 quantities. $5/pair.

R

18Sound 1.4'' drivers NSD1480N 8Ω, Pair and their match Horns XR1464C . All in their boxes.
Only Europe Area. Price for all 1.000 Euros plus shipping.

https://en.toutlehautparleur.com/br...n-compression-driver-8-ohm-1-4-inch-exit.html
https://en.toutlehautparleur.com/18-sound-xr1464c-horn-for-1-4-inch-compression-driver.html

As per thread title, am trying to repair a Classe CA-2300 and any info on this amp would be great to help sort it.
Many thanks

Hey Guys
I am trying to come up with a 1 inch
Compression Driver on a budget here
Trying to stay around $100 per driver.
Is there anything that you would say is on the Warmer Smoother side of the spectrum ?
Trying to stay away from ear fatigue here.
I will be using it with
The B&C me45 horn.
Thanks

I've come up with a possible new topology for the input stage and VAS of an amplifier using opamps well above their normal voltage limits.

Background:

A negative impedance converter (NIC) is an opamp circuit that synthesizes a negative input impedance. In the diagram point A is the where the negative impedance is created.



the input impedance formula is: - R1 * R3 / R2

Here that's - 15k x 10k / 5k = -30k

So I add +30k as R4 to this, creating zero impedance at input - or put another way a current-mode input. With this circuit each milliamp of current at the input gives 40V at the output, and the opamp magically keeps the input at virtual ground.

Note that the opamp inputs are at 30V when the output is hypothetically at 40V - in other words if we can bootstrap or float the opamp supply suitably this circuit only sees a differential of 10V across its terminals for each mA of input current.

Given a real opamp capable of running at +/- 18V, and able to drive to within 3V of each rail, we have 30V of voltage differential available, so this circuit with 3mA input would see point A at 90V and the output at 120V (and similarly for negative swings).

I split R3 into two equal parts to provide a bootstrap voltage that's midpoint between the inputs and output of the opamp, and use zeners and BJTs to bootstrap the supply so it can swing up and down with the signal.




The left hand opamp does the input and loop feedback, the right hand one is the NIC.


Note that the bootstrapping takes a small amount of current from the network, distorting the behaviour slightly. However the first opamp closes a feedback loop around the whole circuit (its the input stage in effect) which re-linearizes this. Driving the current into the negative impedance converter effectively boosts the open loop gain as this integrates the input opamp's voltage signal.

I fiddled around with compensation in an ad-hoc manner, to get the simulation stable and not too horrid on clipping or square waves, but there's lots more fun to be had working on compensation on a breadboarded version I think 🙂

The ratio R1+R2 : R2 sets the voltage swing magnification factor of the circuit. This can be tailored to the voltage rails - here 120V = 4 x 30V (where 30V is my opamp signal swing range), so I've used a ratio of 4, ie R1 = 3 * R2.

I've added rudimentary diode input and output protection to the opamp stages, and the high value of the inter-stage resistor allows this to limit currents to safe levels - again experimentation with a breadboarded circuit as to the robustness of the scheme is needed.

The output stage and biasing arrangements are just lashed up as a demo for simulation - for instance voltage limits and secondary breakdown limits are no doubt completely exceeded and there's no thermal compensation! I'm not so interested in comments about these parts of the circuit 🙂

But comments on the idea are very welcome!

[PS Some of the images from posts below seem to have vanished recently, I'll include them here:

NIC_plot.png:

NIC_wave.png:

NIC_wave_detail.png:

NIC_scope.png:

The schematic I downloaded from the internet differs substantially from the amplifier I have on my bench. It shows MPSA42 devices and a different number of diodes, as well as different capacitors. The unit I'm working on has MPSL01 devices, so I suspect it's an older model than depicted on schematic I have.

Problem in brief>

Right channel clipping positive peaks at 80 watts output (observed on bench). Customer complains it's sometimes making loud static/noise.

This far, I have checked voltage drop across all .33-ohm emitter resistors. Also did an ohmmeter check of same parts. It looks like all the output devices are functioning, based on seeing about 300mV across all resistors. This draws my attention to a possible problem on the driver PCB piggyback. Unfortunately, my schematic is the wrong version.

If someone (Nelson?) has the right one for s/n 770811, I would appreciate a copy, Thank you!

Hello,
This is a quick GB, I'm going to be ordering from Prufusion in early May, so if you'd like to join in, ...deadline is May 10.

If you want anything answered here in the thread I'll add it to the list in the first post. On May 10, I will be contacting interested parties through a private message.

1, HRDSTL
KTA1837 - 50pcs (1x tube)
KTC4793 - 50pcs (1x tube)
KTC3503 - 60pcs (1x tube)
KTA1381 - 60pcs (1x tube)

Hi! My name is Vit, I'm from Amsterdam. I am interested in electronics and assembling amplifiers, DACs and other devices. Here I want to find a solution to issues related to the currently available applications for playing music - Moode Audio, Volumio.

For years, I’ve been looking for an affordable device that can extract multichannel audio from HDMI and output it digitally for further processing, specifically for DSP. Keeping everything in the digital domain ensures the best possible audio quality.

My goal was to create a high-quality multichannel audio system that was also affordable, modular, and user-friendly. However, this proved to be quite challenging. The closest I got to achieving that goal is the setup described below:

Flow Chart:

1. Smart TV (Spotify and video source)
   ↓ (Audio via SPDIF)
2. Raspberry Pi
   • Receives SPDIF output from the TV.
   • Applies DSP (Digital Signal Processing).
     ↓ (4 Audio Channels via USB)
3. Okto DAC8(8 Channel DAC)
   • Receives 4-channel audio via USB from Raspberry Pi.
   • Converts digital audio to analog.
     ↓ (Analog Audio Out)
4. 2 DIY Mono Block Amplifiers + 2 Active Subwoofers
   • Each amplifier receives one analog audio channel.
   • Amplifies audio for output to speakers.

Unfortunately, this setup resulted in stereo audio only, which didn’t meet my expectations. It could have been improved by using something like FFMPEG (thanks to @phofman for suggesting this) on the Raspberry Pi to process Dolby-encrypted audio over SPDIF for surround sound. However, I didn’t have the skills or the motivation to dive into that. Getting Camilla DSP working on the Pi and getting it to process the TOSLINK input was already a tough challenge. Once set up, though, Camilla DSP proved to be a great piece of software. The TOSLINK input had a specific quirk, requiring a special power-on sequence to work, which wasn’t very user-friendly for my household.

I considered the Vanity PRO, which seemed like the best affordable high-quality solution, but for my use case I couldn't justify the cost.

Then, I discovered a post from @yulen (on DIY Audio) promoting his 5AES to HDMI Black Box, which caught my attention, @mdsimon2 expressed an interest in the device as well. The product, a converter from HDMI to 5 AES, also includes optional DSP processing via Sigma Studio. It features 2x HDMI input and 1x HDMI outputs, with up to 4K @ 30Hz output. (Note: I have since edited this post to reflect the correct HDMI connections as I made a mistake in my original post)

While the product was intriguing, I had some concerns as it didn’t support Dolby decryption. However, the built-in DSP was a big plus for me. After several emails back and forth with Yulen (thanks for your patience!), I decided to try the product. Yulen assured me that it would work well with an Apple TV set to LPCM out, which was a perfect source for my needs—Spotify, Apple Music, Netflix, etc.

I made the purchase, it cost me $278 US or ~ £220GBP for the unit with the DSP module, this included tracked shipping to the UK, and within a week or so, the Black Box arrived—well-packaged and complete with the parts as discussed, along with the DSP board. I also ordered an Apple TV to pair with it.

To connect the Black Box to my DAC, I had to find a suitable DB25 to XLR cable. I then had to re-solder the connections to match the pinout of the Black Box (Yulen does sell premade cables if needed). This was my first time soldering a DB25 connector, so managing the soldering iron temperature and ensuring correct pinout was a bit tricky, but I got it done in a few hours.

Without the DSP board, the Black Box is plug-and-play and works flawlessly. It automatically adjusts audio output from stereo to multichannel depending on the content being played (e.g., Apple Music defaults to stereo, while movies play in 5.1). I’ve even seen it handle all 8 channels of audio. Since everything remains in the digital realm, there is no loss in sound quality.

I’m currently running a 3.2 audio system. Since I haven’t set up the DSP yet, I’m only getting stereo sound and 3.1 channels for movies. Once the DSP is configured, I plan to add room correction and blend some of the rear surround channels into the front speakers. I also hope to split the LFE channel between the two subwoofers and add crossovers to the stereo signal to make full use of both subs.

Here’s the current setup, outlined in the flow chart below:

Flow Chart:

1. Apple TV (Spotify and video source)
   ↓ (Audio and Video via HDMI)
2. Black Box
   • Receives LPCM HDMI output from Apple TV.
   • Applies DSP (not yet implemented).
     ↓ (4 Audio Channels via AES/EBU) + (HDMI video signal to TV)
3. Okto DAC8(8 Channel DAC)
   • Receives 4-channel audio via AES/EBU from Black Box.
   • Converts digital audio to analog.
     ↓ (Analog Audio Out)
4. 1 DIY Mono Block Amplifier + 1 DIY Stereo Amplifier + 2 Active Subwoofers
   • Each amplifier receives one analog audio channel.
   • Amplifies audio for output to speakers.

Images of it in my application:







I ordered the required DB25 cable from here:
DB25 Cable

Additionally, I’ve ordered a generic UART USBi module and DB9 connector to communicate with the DSP board.

I support small manufacturers and appreciate the creativity and support from the DIY community, so I highly recommend checking out Yulen’s Black Box if you’re looking for a similar solution. Yulen also makes and sells other innovative products, which you can find on his blog (use a browser translator) and on his TikTok page, @SoundProAudio8.

He also has some upgrades for the black box in the pipeline, one is including HDMI ARC. Personally I would like to see 2x HDMI input with one being HDMI ARC, a boost in the frame rate at 4k to 60hz even though 30hz has proved fine so far and HDCP decryption. Overall I'm very happy with product though and even without any upgrades it's perfect, I'm looking forward to utilising the DSP in the near future. Note the unit already has 2x HDMI input and 1x HDMI output

Yulen is very patient and helpful but please be mindful of the language barrier.

Has anyone else used the Black Box and if so what's your application?

Last week TI put a preliminary datasheet online for the OPA1656, a low noise, very low distortion op amp targeting audio applications and fabricated in a CMOS process.

http://www.ti.com/product/OPA1656

I just checked and the sample button for the prototype devices is now active:

http://www.ti.com/product/OPA1656/samplebuy

I started this project in 2017 with the designer of the OPA1622, and although I had a change in my role at TI before the device was released to market, I'm still very proud of what was accomplished. The goals of the project were fairly straightforward:

1. Start with the OPA1688 architecture which gives very good distortion performance, even with low-impedance loads. Beef up the output stage even more.

2. Push the input voltage noise down as much as possible. Ideally below the OPA1652 and OPA1678 levels, which are fabricated in the same process.

3. Don't let power supply current limitations get in the way of performance. OPA2134 and NE5532 both have power supply currents of about 4mA per channel, and have been widely adopted in the market (understatement). That seemed like a reasonable target for the supply current of the OPA1656 as well.

A quick snapshot of the OPA1656 performance specs:

• 2.9nV/rtHz broadband voltage noise
• 6 fa/rtHz broadband current noise
• -131 dB THD+N at 1kHz, 600 ohm load, 3.5Vrms signal, 80-kHz measurement bandwidth
• 53 MHz gain bandwidth product, 24V/us slew rate
• >100mA output current
• 4.0mA typical supply current, 4.5mA max

I'm looking forward to seeing what people think of the device, and hopefully it finds its way into a few projects on here!

Christmas comes a bit early this year! The single channel version of the OPA1656, called the OPA1655, released yesterday and the product page is now live on ti.com: https://www.ti.com/product/OPA1655

It doesn't look like units have been stocked yet for ordering, but they should be in-stock soon.

Hi there,

I'm confused with Surface Mount electrolytic capacitors identification : are those 33µF/10V or 68µF/10V ? Please note I've been unable to measure any of them as they are all dead, their electrolyte leaked all over the PCB, causing a lot of damage.

Thanks !

Hello all
The racer8 driver that I am testing is measuring at 2R impedance using DATS. Looking for recommendations on a good amp module to suit. Around 50-100w would be plenty

Seems the TPA3118D2 is 2R capable, but not sure which boards support this properly and are reliable for long term use

Will be run of a 12v battery via a DC upstepper

Anyone know how these two compare? Obviously the LM3886 is Class AB, and the TPA3255, Class D? But I've read good things about the TPA3255, and I even saw a TI expert in a forum recommending ditching the LM3886 for the TPA3255. Anyone heard both and can comment?

Hello. I have a question about modeling the acoustic design for a low-frequency speaker. I am confused by the different final frequency response with and without the "show effect of inductance" function. Which of these options will be closer to the real response?
Blue line with inductance effect. 2 dB differecnce at 55 Hz 😕

Over the years Ive built many indirectly and directly heated amplifiers, and always if some dht was in the system, it sounded better in a way I cant quite explain. A lot of people build amps with them, they even started to be made again for new amplifiers etc. From the builders standpoint it has only disadvantages - you need separate filament supply for each tube, well filtered, current regulated in the best case, everything that happens on the cathode, every small hum or noise gets amplified. They are more microphonic than indirectly heated tubes. Now I have DAC output stage with the 45 tube used as a preamp tube. (if anyone wants more details, its choke loaded with output capacitors). And the same thing happened.
Like I said I can not even properly describe the sound. It never is boring every track is interesting, I actually enjoy music now. I stopped thinking about how to better the schematic, I just dont know what to play next. The sound is big, like even at lower listening values. Like it comes from nothing in the air. The voices and treble are heavenly. Music is now actually touching me emotionally way more than before. Like the simplest description that Im always saying is magical emotional sound. That just is not quite there with other tubes.

My big question is WHY, what electrical factors are different than from indirectly heated amplifiers? I really want to find out why this happens. I wondered the same thing in electrolytic vs foil caps in the power supply, but the explanation here was quite simple, being way lower losses in the dielectric, vibration not being a problem cause the foil caps are sinked in oil. The tangens delta difference between electrolytic and foil cap is like 0.3 vs 0.001. Plus the foil caps are way better at filtering higher frequency noise etc. But with DHTs I still dont know. Why nobody measured this?
Its the exceptional linearity (the curves are perfectly spaced and also as flat as a ruler).
Or its some microphonic feedback from the speaker vibrations getting to input tubes?
Or its the special care that you must take while building a DHT amp compared to indirectly heated amp?
Or its a different cause? I still dont know, does anybody has any ideas?

I want substantial horns for a home cinema speaker project, from JBL 2384 size as a minimum up to Klipsch K402 size. I won't buy from the US while they slap us with trade war tariffs, so do any Aussies either have, or know of any for sale already in the country? Or can recommend a local equivalent? Or even have a horn to loan that I can pull a mould from? (I expect it's too much to hope to find a ready-made mould)
If not then I may do a mould from scratch perhaps modeled in ATH software.
I would probably try a foam male mould, simple wet layup carbon fibre/Kevlar (well, not actually Kevlar,😉 probably a tariff free Chinese equivalent)
Would there be any interest in such a project? It's practically a patriotic duty🇦🇺😃

David

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I know this forum excludes politics, but I don't consider this a political issue, rather a universal existential threat. This is devastating news and I feel it's important to spread awareness over every avenue I can.

I'm doing some playing around with active filter designs, and I'd like to get swept filter responses, showing the frequency response of the filters. I'm used to using a vector network analyzer for looking at RF filters, and I'd like to do the same at audio frequencies.

I've got a Focusrite Scarlet 2i2 3rd gen that should be able to do this, but I'm having trouble figuring out what software to use. I've spent some time poking at REW, and it doesn't look like it supports measurements like that. Are there other packages that will do that?

bye

I would like some input on this.
I am repairing a build of this amp where it is humming badly as the regulator transistor is blown. The particular device is hard to obtain so I tried something similar npn of 120v rating and it worked for a while but then blew as well, I imagine due to over voltage as the B+ is 350v in operation and about 400v at switch on.
The build had worked ok for six months or so but I wonder if the design is a bit vulnerable and could be improved.

Are there any similar amp designs I should consider for inspiration on improving this?

Many thanks

I've got a couple crates just sitting on the floor that I'm already outgrowing. So I needed something with a bit more capacity, and getting the vinyl up off the floor would be nice too...

I used the design here as inspiration. I don't anticipate needing that much capacity anytime soon, and I didn't want something that bulky sticking out into the room. Stacking single rows left-right simplified the design, omitting the center divider.



Lumber was sourced from Menards. I can give more details if needed.

The width of the lumber I used for the side panels and bottoms allowed for a small ledge out front to display the "on deck" sleeves. I ended up routing out a flute along the top edge to create a lip that keeps the sleeve from sliding onto the floor.



I decided to give the side panels some shape. I made a template/profile board and used a flushing bit on the router to transfer the shape to either side.



Simple dowel pin and pocket screw construction.





To prevent the bottom panels from sagging from the vinyl weight, and stiffen up the structure: I added some screws from underneath the bottom panels up into the front and back boards (not shown). It just wasn't needed for mockup purposes so I drilled the holes later.

I noticed that Amazon UK had some In Phase Car Audio XTC17.2 woven glass fibre coned drivers for £ 21.11p, so I decided to order them and make some omnidirectional speakers with them

The driver is mounted on a small chamber that is connected to another, larger chamber by an aperiodic vent. My initial plan was to support the top chamber on coil springs with a foam seal, however the cast iron weights that became available ( the scrap bin at work ) are to heavy, and the temporary foam spacers that I used for initial testing work quite well

Stumbled upon this interesting board on aliexpress, comparing the prices with other ADSP21489 sharc boards this is peanuts, and already with 2 ADC and 3 PCM1798 DAC boards for a 4in/6out system. Anyone have this?

Lusya ADSP21489 development board ADC PCM1804 Input board+DAC PCM1798 output board 4 in 6 out processor B4 007-in Replacement Parts & Accessories from Consumer Electronics on Aliexpress.com | Alibaba Group

MUSES02 is currently $44 each plus shipping at Mouser. Anybody know where to get genuine MUSES02 instead of fakes at a lower price? 4 x 44 + 8 shipping = $184 for four op amps plus tax so ~$200. Not willing to pay that.

I have a 5v regulator with a 2 wave rectifier.
The secondaries powering it are from 12.6vac heater secondaries. (tube amp)
The heaters have been elevated with DC so now I am trying to connect the reg board.
I have been told that I should float the ground of the regulator and relays but not sure how that is done.
Do I ground the the relays to the ground on the regulator board and nothing ground to the chassis?
Do I make the ground reference the junction point of the two 100ohm resistors from the heaters where they connect to the DC?

Hi to everyone,

I'm looking for the service manual of an old DBX 224 mkI (round buttons, none on/off mains switch).

Thx a lot in advance

Hi,
I was searching for a good quality sound card with SPDIF input so that I can source audio from my TV (with SPDIF out) and provide 6 discrete good quality DACs for an active 3 way stereo speaker project. I am expecting quality than minidsp (ADAU1701 based ones).

Is this sound card Creative Sound Blaster Z SE good enough and a step above minidsp?

Thanks and Regards,
WonderfulAudio

Hello, my name is Jean-Michel and I very pleased to join this forum. I own an AXL amplifier from Elektor that I built more than 30 years ago!
I am not using it for many years but I plan to update it with non inductive 0.22 Ohm / 5W resistors and recap it.

I’m interested in Pro Audio/Home Theater solutions to upgrade my Tannoy Ellipse 10 iDP & TS212 iDB 5.2 and 2.2 studio monitor systems shown below 🔊😍🔊

It is possible to compensate so the input current becomes zero.
I don't really know what this should be good for.
At least there is one capacitor less 😀
This circuit simulates THD 0.000062% at 1Vrms into 1kOhm.

Hi, my name is Björn, living in Germany.

I am looking for interesting discussions about audio/hifi equipment and sound improvements that I can use in my home.

I just upgraded my audio system to a WiiM Ultra Streamer connected via USB to a S.M.SL. PO100pro, to a Fosi Audio ZD3 DAC in Bypass Mode. I also have 2 Fosi Audio V3 mono amplifiers that drive a pair of Wharfedale Linton 85. My Turntable is a Thorens TD 203 with a BENZ MC silver cartridge. My phono pre amp is a Project Tube Box S2.

On the off chance someone has a pair they don't think they'll get around to using. Will buy on madisound otherwise

The fundamental issue with CBT arrays, and arrays in general, is that the high frequencies aren't well behaved. In the attached measurement of the Parts Express CBT24, you can things work great... up until about 2500Hz.

A thought I had, is that you might be able to wrap a CBT array around a Unity Horn. The Unity horn would have to be very very small; basically small enough to blend with the CBT array.

But this might be a way to get "the best of both worlds:"

1) Based on years of experimentation, I've found that speakers with wide horizontal directivity and narrow vertical directivity are ideal

2) But if you want to achieve that goal with a conventional Unity Horn, you end up with a mouth that's about the size of a door, like a Danley Jericho

Hi everyone,


I'm working on a Sansui AU-D9 that had several issues, most of which I've resolved:

• Replaced leaky capacitors
• Removed the infamous "black flags"
• Replaced the burnt output transistors
• Replaced the drivers
• Also replaced the distortion correction stage transistors

Here's what I’ve already checked:

• Verified all flame resistance
• Checked voltages across preamp, differential stage, and power stage
• Found inconsistent voltages on two transistors (I can provide details)
• The protection relay engages normally
• All solder joints and PCB traces appear fine

The current issue is that the output transistors do not amplify.


Using an oscilloscope, I can confirm that the signal reaches the base of the output transistors, but it does not get amplified. At the output, I can only see the signal from the distortion correction stage, as if the power transistors are not conducting at all.


Bias is set according to the service manual, and the power supply voltages are correct.


Has anyone experienced a similar issue with this model? Or any suggestions on what to check next?
I'm happy to share measurements, circuit photos, or relevant parts of the schematic if that helps.


Thanks in advance for any help!

Hello everyone, can anyone help me with the DP48X driver and FIR48 firmware? I also don't know if my board is version 1.0 or 2.0. I hope everyone can help me. Thanks for reading.

I have a new build.

Schematic attached EL34, 12AX7 (preamp), 12AT7 (inverter)

There is a massive hum that changes pitch and loudness with the tone stack.

Trebble off, there is no hum, defiantly in signal path

With both preamp tubes out there is no hum.

With the 2nd tube in there is a little bit but not much at all.

When I put in the first tube the hum is there, and it is huge.

Master is up all the way, gain is off. ( first stage not the issue)

This has to be between the 2nd and 3rd stage.

My thinking is bad component or ground loop issue. Everything is new.

Currently R40 and D4 have been removed.
C22, C23, C13 are not installed yet

There is a grounding buss bar for the preamp section, the ground icons are where they connect to the buss, and I have noted how I have them grouped before connecting to the buss.



I have resoldered everything.

Not sure if this matters but C18 makes noise through speaker when tapped.

I changed that component, no change.

Amp does play

Swapped preamp tubes around but no effect.

Hi everyone,

My name is Alex and I currently reside in Belgium. Started doing electronics projects while I was a teenager in Greece and when I have some spare time I like to play around primarily with audio projects, repair electronics.

I have currently 2 amps that I fully completed and are functional on my workbench:

• A dual lm3886 built around 2012 (still need to add speaker protection though... I will eventually kill my speakers 🙂 )
• A K502 kit with a quad of 11BM8 tubes (triode + pentode) that I built buil back in 2008 while I was in Canada

Hey everyone, I just finished my first diy project which consisted of the Gabster Td1 V3.4 dac and Ian Canada's boards. Since I only needed it for usb and optical use a raspberry pi was not included in the build. Building the Td1 was fun and a little challenging; I would strongly urge any new builder to use fine low melting point solder, a small tipped soldering iron and flux on everything being soldered. The key for first timers is to follow Gabster's videos on his site when assembling. As for connecting Ian Canada's component boards it is critical to look up each board on his site and read the instruction manual for each product there. My interest in this project started when I stumbled on a Gabster video on YouTube. I thought Gaby was sincere in presenting his dac. As it turns out all of his claims about Gabster Td1 are true; it produces a huge sound (soundstage) with remarkable imaging that is almost addicting. I find myself listening music now way into the night. I use the Gabster dac in conjunction with my NSMT model 100 speakers which are known for their accurate sound and superb imaging.

HI!

my name is Vincent and I own and run a studio/record label in a small village in Germany called binary pleasures.
I was interested in sounds and textures from a very young age and also love repairing and modifying electronics and equipment I use to work on music.
Now I would love to slowly step into the DIY speaker game but I am very overwhelmed by all the information both in the physical (acoustical) and electronic domain.

I have several Ideas for custom designed 3D printed brackets to mount boards in power amp and preamp designs.
This is especially nice for PS boards mounted above transformers is my dual mono and quad mono power amps - 4u and 5u empty space at the top can be utilized

Bambu lab has a flame retardant filament.

Any thoughts are welcome, thank you!

How to DIY making a paper cone (or others) more stiff.

Here first example:

fast drying hairspray liquid





Never apply too much at once so the paper fibers do not become wet and weak and throw wrinkles!

Better less but several times applying

then if possible fast dry in the sun

http://www.diyaudio.com/forums/mult...coaxial-midrange-crossover-2.html#post5415661

So, now I have a pair of MR18 in my hands! My plan is to make a semiactive 3-way using it and SB29NRX woofers, floorstanding sealed box and minidsp PowerICE-125 amplifier-dsp boards.

Here are my first measurements of MR18 in a 7 liter closed box, baffle 19x28cm. We can see from nearfield measurements, that the peak at 5kHz is NOT exactly cone resonance, but more like a cavity resonance based on geometry. Look how nearfield off-axis measurement changes in normalized graph!


Looks like the tweeter shows directivity only in low treble and is exceptionally non-directive up to 10kHz. Crossing around 2,5 - 3,5kHz should be ok. Peak attenuation at 5kHz is perhaps not needed at all. Lower xo around 400Hz LR2 should be easy too.

Here some Edge simulations and a 3d sketch of the box. Top part of the baffle will be tilted and I will add diamond cuts to edges following the style of Avalon speakers. Box material will be MDF with birch veneer, tinted and waxed. These speakers will be a joint project with my older son.

Hi Thanks for reading I have a pair of 2-way b&w dm110 speakers, and a m&k active subwoofer

The amp I am using with the b&w is a topping pa5 II

I want to create a 2.1 system and make the b&w speakers reproduce everything over 200hz, and the subwoofer reproduce everything under 200hz

I’m thinking of removing the crossover from the b&w, and replacing it with a 100uf capacitor to act as a high pass filter. I’ll probably have to play around with the value of the 100uf cap to make it integrate well with the subwoofer

Q: Are big 100uf caps safe to use with amps on a long term basis, and would there be any resonance problems you can think of

Connection cable wanted to connect meridan C 207 unit A to unit B . I am located in USA northern Virginia . If some one had this cable or know a place to purchase it , I will be very grateful for your help . Thanks . Ali

Any of these dope?
Used for audio?
Make offer on anything in thread, if you want.

Hello,

I recently picked up a pair of Monitor Audio r352 speakers of eBay, but they didn't come with any stands. I like the look of the stands that came with these back in the day (see the attached photo), but I can't find any information about them online. I reached out to a couple of eBay sellers who were selling the speakers with stands, but their either didn't reply, or couldn't help. I even reached out to Monitor Audio, who after a while got back to me to say they also had no information in the archive, nor did they have a pair in storage.



It's a long shot I know, but I don't suppose anyone on here has a pair of the stands and could supply me with the relevant measurements...?

If not, can anyone recommend some rules of thumb, around the size and thickness of both the base plate and column? The base of the speaker cabinets have captive nuts, so I guess the top plate size if pretty much self explanatory. The only other thing I really need is some for some guidance over the angle the speaker sits at.

Any construction tips for stands? Is it simply a case of screwing the column to both plates and calling it done? Or is there a better way of joining everything to help dissipate, or mitigate, vibrations coming up from the floor?

Any help would be much appreciated.

Interested in buying Sony VFET amp boards for N-CH version.

Thanks.

Hi All

Please help to identify the parts marked in the Ice Power 1000a module picture they are adjacent to the input connector. I have 2 modules one the parts have unfortunately come off and got lost in transit and one module with the parts populated. Most of the components are marked and identifiable, somehow the parts that went missing are not marked.

Below is the module with the parts missing in blue

Below is a picture of the module that is with all the components.



Thanks.

Hi friends

I know it is a bit off audio, but as the best of the best are here, I dare to ask:

Does anyone of you know a coating for brass that withstands water and cosmetic chemicals (like soap, shampoos, lotion, all that gooey stuff one finds in a western bathroom...), available in switzerland/europe? If it is not glossy, all the better!

I have to protect a little shelve made in brass, that will be in the shower cubicle of a very demanding customer...
(The image depict the raw piece, it has to be sanded/bushed/polished, and cleaned of course)

Many thank for your tips and merry easter!

david

I just completed the audio portion of this build, and am quite happy with them. It uses a pair of Dayton Audio RST28F B-stock tweeters that have been modified slightly, and a pair of Dayton Audio SD270A-88 DVC subwoofers. The box is 25 ltrs loaded with an RSS265PR tuned to 32Hz. Since one of my PRs is a production sample and one was off the shelf, I don't know whether that is one or 2 weight slugs per PR. Measure the woofer impedance in box for best results. The box has offset panels in front and rear to keep the PR recessed and safe, and make the baffle area for the drivers at 1.5" with a removable baffle. The cabinet drawing assumes making the front 1.5" thick and no offset baffle or rear, but it is easy to make the adjustments should you so choose. The cabinets are fairly utilitarian looking at the moment with an unfinished MDF baffle and Butter-rum Formica inside a half inch birch plywood perimeter.

The name is derived from the bass response curve looking like the spine of a bipedal foraging Pangolin looking for insects or grubs, and that it and 10" 2ways are both kind of going extinct. I took visual inspiration from the DeVore Fidelity Orangutan 0/93 mainly, but the Dynaco and Advent large woofer designs of old are not too far from the direction.

The sensitivity is 88-89dB range, and definitely a 4 ohm nominal system. It utilizes the second coil on the woofer as a 0.5way for BSC. Xover is set to 1470Hz, and utilizes low Q filters and a leaned in tweeter response to minimize directivity shifts, approximating an LR4 set of slopes. It is a surprisingly dynamic sounding pair of speakers, and HD is low save for a rise in 3rd order at about 700Hz. The woofer breakup and tweeter Fs are both heavily suppressed, which notch the related drivers just outside the xover and steepens the slope slightly.

About the tweeter, and what I did to it...
The initial RST28F B-Stock tweeters measured like garbage. I was able to remove the rear chamber cap, remove the foam plug in the vented pole piece, and then replace with a better cup and a 1" cotton ball respectively. I twisted the ball into place until it was flush to the back of the back plate. I also swapped out the stock chamber-damping with Ultratouch denim, placing a layer of wool batting between the denim and the backplate. The swapped damping is thick enough to need compressed while gluing on the new back cup. I used masking tape and the included packaged protection plastic to hold the cup in place while the E6000 adhesive solidified. The spec Fs is 710, and mine spec to 800 or just north of there, so the size of the chamber was not altered much. Just use a suitable cap to fit over the backplate and glue to the backplate/magnet junction. 3" PVC cap was just too small to fit over it, but a little sanding could make it work. I used some screw-on plastic caps for glass Ball Mason style herb jars, which are honestly just a little too big but worked well. Even if you don't modify the stock tweeter, I feel it will work well in this design. The Fs suppression should still work if the Fs is between 700 and 850 Hz.

Some tweeter notes;

• I feel the foam plug being changed to cotton ball is the BEST THING you can do to the RST. 9 times out of 10, I feel it is somewhat congested sounding and this is likely due to the foam pole plug.
• The cup as I removed it was not salvageable. It is very thin plastic. If you can carefully remove it, you won't need to replace it. Good luck.
• The plug can be reached by faceplate removal, but then the wool pole-cap also has to be removed to get to it. IME, I've seen different pole caps. One is more cylindrical and one is a formed-dome shape. Shaping the cylindrical wool cap like a dome carefully with a pair of scissors ensures no contact with the output dome under operation. If doing this, be careful and don't slice the sealing ring against the front plate to keep the faceplate sealed against the front plate when reinstalled. That said, the Wool Pole-cap might fray and separate if removed, so it is easier from an integrity standpoint to remove the pole plug from the rear.
• I also applied a heavy shredded-tire/sport-flooring rubber piece to the rear of the new chamber cap to deaden any resonance under operation. I have done this several times in various cases, and it always helps a little.
• see tweeter graphic for a better understanding.

Thanks for looking!

Hi,

Could someone, please, explain to me why can be seen on some design, fast op amp loaded to ground with a resistor and // capacitor before the RCA output after a serie Rsio of an opamp that already isolate it from the "true" load of the next stage ? Is it for even more stability and capacitive load ?

It's about a transimpedance circuit of a source, towards a preamp. On the preamp side it is terminated with 220R serie rigth at the input with 47K shunt and a couple of hundred pF cap to Ref as well. transmission line is a typical said 50 ohms RCA cable !

Thanks

Current feedback Mosfet Circlotron : it's alive !

Hi,

I present you the amp that I just realized.

This is a current feedback Mosfet Circlotron



Without Diyaudio forum and another French, this amp could never be created.

So thank you all the people who helped me and especially Joe Berry who gave me the Keystone of this amp, the current generator so particular that guarantee a thermal stability

A special thanks to gionag, my friend Rabbi Michele, who is the first to have made this amp and who made this great layout


YouTube : low cost phone record... but it's alive !



in real R15=500, R14=220, C3-C4= 47p







YouTube : low cost phone record... but it's alive !

I guess I never posted an intro. Oops. So much for following instructions.

I've been around other forums for close to two decades. I tend to come and go as my interests come and go. I was an electrical engineer in my first career (changed to something else after 4 years in industry watching the leadership in the companies I worked for flail and fail all over the place).

I've done quite a bit of DIY. I've built my own chip amp with my older daughter to see if she has the knack. I've built Econowaves, several lilmike horns subs, flat packs from DIYSG, and (for my first ever speaker build) a pair of desktop speakers from scratch (packed away these days and should probably be burned in a fire).

Looking at another career change after over 20 years in the current one and it'll likely be something in audio. Time will tell.

For sale is a GZLOZone PRT-01A populated preamp board with tubes and power transformer for sale. Just add RCA jacks and volume pot. I don't have any technical info as this was given to me by a friend. I will ship to you for $30 including shipping, most likely USPS priority mail flat rate box, CONUS only.

Hi everyone,

I am trying to make my own simulating tool using GNU Octave and transfer matrices methode. I am encountering difficulties in validating my simple model (infinite baffle) because it does not match hornresp results. i think i am not that far from a correct model but not here yet. as you can see phase and SPL are not the same as hornresp.

below is the code with some comments. Note that i do not think problem come from my radiatoin impedance since i used this function for analytical modeling and results mached hornresp with my analytical model.

hello everybody and thank you for taking the time to read!

I am on the quest to find some very nice studio monitors to mix on for years to come, all while not breaking the bank and not wanting to pay for things like brand image, warranty, marketing and service.
At the beginning I was on the lookout for used speakers (the likes of Amphion One15 / One18, PSI A17m, etc) as they would probably render me with most bang for buck possible, though now I have come across a few people who have decided to build their own speakers, but I have to say that finding folks who are building studio monitors specifically appears to be quite rare.
I personally am rather proficient when it comes to technology, building (woodworking), soldering, and engineering to some degree, though having looked at all the things that go into a capable and usable speaker design I am not certain building a studio monitor from the ground up that rivals the likes of ATC, PSI and Amphion is something I am capable of doing.
It seems then I will probably not go the traditional, full DIY route as for me the focus is 100% on the final product and not so much the way of getting there.
Sure, it seems interesting and romantic to design, conceptualise and build my own custom speakers, though I would probably spend a lot of money simply on all the testing, measuring and so on and so forth.

A few days ago, I came across the SEAS King RO4Y MkIII speaker kit and it seems to almost fit the bill.
On the surface, it looks like the most bang for buck that it is going to get for my application (a 3k kit that potentially rivals 10k+ speakers?).
I am of course aware that it is not exclusively the price that determines the value of a pair of speakers for ones application (the specifics matter: components, room, usage, etc), so I am unsure wether or not this Seas kit is my only good option and if it is even a smart idea to begin with.
For reference, I am in a rather small room 4mx3m currently, though it is pretty well treated with very dense absorbers and for what its worth I am getting a very good response with my (of course considerably smaller) Adam T5v monitors. Also note that this is not the room I will be staying in as I will most likely move to one that is a little larger in the near future, if that at all adjusts the equation.
If I had unlimited money I would probably buy the ATC SCM25 Pro monitors as I love their sound signature (clear, natural and forward mids with little distortion), but I simply cannot fork over the 7k (used price that is) they cost, so I am essentially looking for a similarly performing speaker that would fit my budget a little better (around 3k).

I would be very thankful for more experienced people to give me some sort of guidance as to what would be best in my current situation and if DIY (or building a kit) is the best option to go with, or if I should simply go out and buy a used pair of Amphions, PSI's, or other higher end speakers that fit my budget.

As title says: I want to buy a Topping D30 (no Pro) from EU. Your offers please ...

For sale 2 pairs of line output transformers Lundahl ll1517. Tested, fully working.

€75,00 per pair or €130,00 for both pairs.

1 pair of SB Acoustics Satori MW16P-4 mid-woofers. Used, working perfectly, never operated louder than 90 db/1m.

Make a fair offer ...

I'm just building a 3-way studio monitor system and came here to get some advice when needed.

Hi everyone!

My name is Markus, I am based in Munich, Bavaria.
I have known this forum for quite some time now and have finally decided that I'd like to share some projects on here as well!
Audio electronics has been my gateway into electronics and even led me to switch my major to electrical engineering. I have been designing audio circuits as a hobby for a several years now, time and time again drawing inspiration from some of the amazing projects on here too!
After being passive for so long, it really feels nice to take the step to actively sharing as well. I really look forward to the interactions on here!

Thank you all in advance 🙂

Markus

Hi,
I am Lars from Germany. I am interested in building soundsystems and setting them up. My goal is to to help improving the sound of my techno collective.

I have the project, clear and well defined - for now on paper, but I have all the ingredients or almost, the video card is missing, but it could arrive in the next few days. for now without photos, these are the components:

¹ Soundstream Reference 300 75W*2
² stabilized power supply 14Volt 50amp
³ Big Cap - large stabilizing capacitor and current accumulator

PC
|
Sound Card
|
(this Amp)
|
Passive speaker (LS 3/5a hybrid - finished)


----- software - microphone - - - & more


These will be the amplifying part of the Desktop Audio system.

Hi All, i have a Mosconi AS 200.4, channel 2 is very quiet compared to the others, around 3-4 db. I have checked and swapped everything to make sure the fault doesnt follow and fault stays the same - ch 2 only. Any ideas? thank you in advance.

I'm looking for the most suitable, commonly available op amp for driving a 600 ohm 1:1 ratio output transformer. I prefer to be able to drive it cleanly to +10 dB.

There's obviously the NE5532, but the distortion is too high for my tastes. The 4580 comes to mind, but that one isn't the best in terms of slew rate, despite the low impedance capability.

Any suggestions?

I have approximately 85 of these beauties. Ripple current 7.8A according to Mouser, who also list them at $21 in 300 quantity.

Note they come with stud, so you need a plastic nut to mount them. Or saw off and use a clamp.

Three full boxes of 25, screws and washer included. Rated at 85 degrees.

I’d like to get $10/pcs. Minimum would be like 8 of 10 pcs. Shipping at cost.

R

I have some ground control problems, but not Space Oddity of David Bowie. That can be a nice song in the background while reading this.

This is not my first amplifier build, so I have some knowledge and have had and solved some ground problems in the past, but this one is killing me.

First picture of amplifier layout:


Normally I build dual transformer/dual psu units. This time I decided to reduce cost and used one 600VA toroid. I have tried some different layouts of wiring, but same result.
1. With nothing connected to inputs the amplifier is absolutely silent.
2. With inputs connected together with cable - each to other, the amplifier is absolutelly silent
3. With inputs connected to source there is noise - bzzzzz. Source is Marantz amplifier with preouts - no issues with other amps.
I tried to change grounds from connector to just one point, a screw in the picture on top of capacitors, same problem.
Tried ground lift with greatz, same problem.

The solving of problem was removing the connection from common ground (the green yellow) to the eart point on top near the big resistor, where the chasis is grounded. You can see now the wire on top of the screw of common ground. If I connect this to chasis earthing point there is noise. On other amplifiers, without this wire I had noise, with this one the oposite.

What is the cause of this and can I just leave it like this. The chasis is grounded to the mains jack, but the amplifier 0V -ground is NOT.

Not much info yet:

the new Quad components will be available within six months. The 303 will offer 60Wpc, cost approximately €1500 apiece, and include balanced and single-ended inputs and outputs, a remote control, a phono stage, and the original Quad’s “tilt controls.” The 303 prototype was very heavier than it looked. The classic orange buttons had excellent touch.

Click to expand...

dave

I'm searching for pair of MarkAudio CHN-110 drivers.
I'm in Bulgaria, EU.
Waiting for offers 🙂

Hello! I am Tibor from Romania. I have an old passion for music and audio systems.I have build several subwoofer cabinets and speaker cabinets, but the more I learn, the more I find out there is so much more to learn..