Hi mates,

i'm interested in Hi-Fi since my early youth. Started with Dual, changed to Denon and bought a Michaelson & Austin M100 + TVP-X combo in the early nineties, because they where the best sounding amps i've ever heard, but always broke. So the friend didn't wanted to keep them.
First i changed parts, fixed connections, changed the burnt, broken pcbs in the M100s and had a good working pair for some years. Then one audio transformer blew up and i had the chance to buy a new pair from the manufacturer of the originals. Now the second one blew up and took the pcb with it.

Another permanent project is a Sherwood S-5500 III and a tuner of that age. Worked like a charm even with nearly non functioning tubes and capacitors. Changed some of the capacitors and used it for some time to drive a pair of Martin Logan CLS, but suddenly it stopped working. Found a bad tube and changed it. Had one channel back, but the other was dead and some deadly current on the chassis. Found a broken heater connection with a cable loose, fixed that and had the voltage on the rca inputs after that.

So there are two projects to work on.

I am from Germany and just tried to answer to a thread as someone did search for a schematics and give him some tips for repair. But I have learned that I have first to provide some introduction of myself.

Hello,
I was listening to a headphone amp today, which was quite good. The maker says it is an IC amplifier, DSL differential line driver like TPA6120, but not the TPA6120, something better.
I was told the output impedance is very low too.
I could not compare it to any other amp, but I know it was good to listen to.
Regards,
JG

I have built the prototype transformer for a 1.2 kW LLC converter. I use an ETD49 core of 3C94 material. The primary is 35 turns. The secondary is 70 turns. My input voltage is 400V from PFC stage. The output is 400V.

My math shows I need about 11.5 uH of leakage inductance and 50 uH of magnetizing inductance. I have attained the required leakage inductance by using overlapping and offset windings. Currently I have 14uH of leakage inductance in my design. My transformer is margin wound with about a 5mm margin.

In my transformer, it takes a large gap in the core to attain the required magnetizing inductance. The gap is on the order of 0.25 inches to get 50 uH of magnetizing inductance. The leakage inductance is not affected much by varying the core gap.

My question is this: Is using such a large gap likely to cause a problem? Is it common to use a large gap in these designs?

What effect does changing the value of Ln (the ratio of magnetizing inductance to leakage inductance) have? My current design value of Ln is 5. Is this a decent place to start? For smaller values of Ln, I will require a larger and larger core gap.

I have a ZRT build with two Scanspeak Revelators bass elements on each side. Last time I went to use them there was no bass. Initially I thought there was something wrong with my NAD D3020, but tried with a different amp and realised the problem were the speakers. They are about ten years old, from Madisound Speaker store.

When taken out and measures with a multimeter, they all show open circuit. They have, to my knowledge, not been playing loud and I can see absolutely no damage on any of them (except two of them which has some unrelated cat scratch cone damage). I read somewhere that these might have issues with absorbing moisture, causing rust? I'm just very confused about why they would all fail at the approximate same time. We're in Australia, and the weather here changes from humid part of the year to quite dry and hot.

There's some discolouration on the labels, am wondering if that can indicate moisture? Any ideas?

Hi everyone, Thanh (pronounced Tawn, like wonton) here. I'm new to this board and was brought here by Wayne's BA2018. I'm hoping to get some advice to complete the build and look forward to discussions for future projects as well.

Hi all!

Been into audio/stereo/radio, etc since I was a little kid and now getting deeper into the DIY aspect. I have built a couple of tube amp kits (incl. a Parks Audio ST-35 clone), just finished a pair of GR Research LGK 2.4 speakers and am currently rat-rodding an ADCOM GFA-535, with the assistance of Chris Hoppe.

Looking forward to getting into it, with the group.

Cheers, chrx

Hello,

I'm looking for a DAM 1021 SK Lite for my Soekris project. I know I'm late to the game, but maybe someone has one they never used or has an extra they want to sell.

Thx!

I have been completely rebuilding a pair of dbx 234XL analog crossovers.

I swapped all the TL074 types for OPA1644, & LM353 for OPA1642 dual - all worked very well in that position.

The output opamp drivers were more hassle - replacing NE5532 using a mix of OPA828 for the high end/ upper mid, OPA627 for the bass and Burson v7 Vivid discrete for the sub - all these opamps are working at their peak in these frequency ranges.

I had to make up some custom boards (white/ gold) for the OPA828's with the heat transfer pads, and a transfer plate for the 1644 SMD taking it back down to fit the 14 pin DIL sockets.

Caps were changed to WIMA FKP, and the decouple caps to Nichicon UKZ. Bridging/ bypassing the UKZ decoupling caps are Mundorf EVO Silver/ Gold caps 0.47uF for the high frequency channel.

External dual R-core PSU replaces the standard onboard transformer - the R-core has 14,000uF capacitance per +15/-15v side and is dead silent.

The speed and pin sharp detail and clarity of the OPA 2828 's is on a completely different level from other opamps/ discretes.
Possibly because of its ultra-fast slew rate of 150v/uS & 45Mhz bandwidth gain, but its bass is almost non-existent, so can't be used full bandwidth.

Quite a story all told, but sounds a real WoW - at the end you couldn't believe its the same circuit.
The crossover drives 16Kw of Alcons amps and the speakers are a modified Alcons Pro-ribbons.

* if anyone wants to buy either of the 2 PCB types or mounted OPA2828 you can message me.

Some of you know I'm making some monitors for my office. I've been playing with mostly 6" drivers with plans to vent them. Well, Madisound put the 8" version of SB Acoustics Ceramic on sale and it looks like it will work.

Question is if I can get away with this for nearfield listening? I'll be crossing at 800 hz. I can cross a bit lower at 650-700 if needed. I know there is some calculation for how close drivers need to be to meld for nearfield. Does anyone know it well and can explain to me how that works, if this would work, and why?

Also, my baffle will be tiny. And I mean TINY. This whole thing I want to fit in the 350mm cubed print bed of my new 3d printer. Its probably a good restriction since it will force me to keep all the drivers very close together.

Here is the driver in question:
https://www.madisoundspeakerstore.c...oustics-sb23cacs45-8-8-ceramic-woofer-8-ohms/

Here is Joseph Explaining that it will work well within the range I plan to use it. I do plan to use it sealed. My enclosure will only be 0.5 cubic foot. That should be enough I think
https://josephcrowe.com/blogs/news/sb-acoustics-sb23nbacs45-8-8-woofer-review

Hey everyone! I’m wanting to swap my speakers out in my car with some Dayton audios

I have currently swapped out focals for JBL GTO components as one had a blown tweeter anyways

I’m running a PPi 900.4

Channels	4 ch. Class D
RMS Power 4Ω	145 x 4
RMS Power 2Ω	225 x 4
RMS Power 4Ω Bridged	450 x 2

and I run deck power for my rear speakers which is 50 watts peak

I’d like to get some Dayton audios and a tweeter problem is
I need a passive crossover, I understand by using DSP I’ll get better fidelity but I also am using my rear bridged Channals of the amp to bridge for a sub

So I’m limited on inputs and outputs and want to stay passive

Can anyone help me with designing a passive crossover ? Or teach me and explain how I can create a butterworth filter (at least I believe what it is)

Please suggest part number of this NPN with small voltage like this in amp.

Thx

I’ve had the LS50 meta’s now for a few months and feel these are my endgame speakers (Better than what I’ve owned, BMR, Revel, Focal, Kef R3, PSBs and many more). They’re absolutely perfect in every way except for the bass. So, I want to build a 3-way woofer module of some kind. My space for SUBS is limited therefore a subwoofer stand is ideal. Also, I want it to cross around 200hz with 1st order filter to avoid changing the overall character of the LS50s as the tonal balance is spot on, but want to cross higher than a typical sub to improve max spl and reduce IMD. These are my options and I wanted to see what you guys think. Since nothing is commercially available DIY is my only option.

LS50 measurements (sensitivity ~83.5dB @200hz): https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/

• Kits – all have passive crossovers
• Jeff Bagby - https://meniscus.lightningbasehoste...he-Kairos-and-Continuum-Three-Way-Writeup.pdf
• 1.78 cu ft or 50-liter cabinet
• Continuum 3 way module by Jeff Bagby – CSS SDX10 - Might match well with the 83.5dB sensitivity of the LS50M. (Can do ported, sealed or PR.
• Kairos 3 way module by Jeff Bagby – Seems to similar in sensitivity in the crossover regions but a bit more bass below 150z (I can always use DSP to fix boominess etc, and it’s free SPL.
• Troels (SBA10) or CSS bass modules – both of these have sensitivities above 85 dB, so a passive crossover is unlikely to work with the LS50M.
• Design my own
• Crossover - I don’t really have time to tinker for family reasons, so I have to try and get this right on the first try. If I did my own crossover, I would have to do it in the digital domain with a Minidsp 2x4HD.
• I was hoping to make my box taller than the 3 way modules listed above. This means I would end up with a larger internal volume. I could port it or run it sealed or run a PR, but again I have to get this right on the first try. Alternatively, I could use Jeff bagby’s design, increase the height but reduce the depth to keep the same internal volume.
• 12x14x32” = 2.3cu ft or 65 liter cabinet

OPTIONS:

• Build a passive kit as is
• Can the passive crossover have a detrimental affect on the LS50M impedence?
• Use JBs cabinet design but use a minidsp (someone on another forum said that the minidsp would add delay vs a passive crossover… but from what I’ve read it’s not too different than delay added by a passive crossover)
• Design my own box using a simulator to get the dimensions I want, and use the minidsp for crossover. I have read that the simulations are not accurate re port length etc. So I don’t want to mess this up. (Port noise scares the **** out of me, but I could always stuff the port and use dsp to boost the lows 😊)

Please help!

I've got a custom build project on my to do list, which involves an output stage with quad 6L6-GC output tubes.

I want the amplifier to have a full power bandwidth of 7Hz-50KHz, like the old UTC True Fidelity output transformers could provide.

Primary: 3300 ohms
40% screen taps
Sec: 4/8/16 ohms
Power handling: 100W
Budget: <$1,000 each

All of the generic transformers made today seem to be limited to 30-15,000 cps and suffer notch distortion at the low end and slew rate limiting with signals above 4Kc.

I know there are maybe one or two companies (perhaps in Japan?) that know how to make quality transformers on the level of the old UTC parts, but I don't know the names or where to contact them.

Prefer potted to match the existing power transformers.

Any leads on a high end manufacturer that can make us custom transformers within the modest budget outlined, would be appreciated.

Hi! I'm working on a small but time-accurate speaker project, and the problem with small speakers is bass. However a speaker brand called Devialet ( Mania, Phantom, Dione are all very small without passive radiators) has small speakers but impressive bass, can someone tell me how they did it? I've tried every DSP algorithm I have ( maxxbass, Rbass, BBE phase, TruBass, dynamic bass, Dolby) it seems that TruBass works but not as expected, I tried playing a recorded track through the phantom and it worked great, (I tried it on a devialet mania subwoofer driver). I would be very grateful if someone could tell me what Devialet did with the DSP

Hi,

I was digging through some junk the other day and found a pair of interesting chokes that I bought some time ago and then more or less forgot about. Signal Transformer CL-2-4, a rather small piece of airgapped iron with two 10mH windings that can be wired in parallel for 10mH 4A or in series for 40mH 2A.
40mH 2A sounded close enough to the specs of the Triad choke used in the Zenductor amp and those dual windings struck me as interesting.

Over at the tube forum, we would call this a "Parafeed output stage with 50% cathode feedback" or perhaps "a single ended version of the Macintosh Unity Gain output stage" or maybe even "What the hell is that, and why doesn't it glow?":


Fortunately, I had a pair of old 2SK133 mosfets with bias circuits and everything already attached to heatsinks after my attempts to duplicate Hiragas Nemesis amp a couple of years ago so wiring up a prototype was easy:



No measurements yet but I've been listening for an hour and it sounds surprisingly good, running at 12V 900mA, which should be good for around 3 watts into 8 ohms.
The point here was to build something that is essentially a simple follower but with ~6dBs of gain. The experiment is successful so far, we'll see what the oscilloscope says...

JH Reproducers Synchronous Turntable with Formula 4 Arm; Australia’s Linn Sondek. Uprated model with springs.

Excellent reviews, especially the Uni-pivot arm. Motor runs, plater runs, belt OK missing a screw for the cartridge, anti-skating bucket is there just needing attachment.

Photos from part of the description. No warranties, no guarantees, no returns.

I am no expert. What you see is what you get.

Dirt cheap at AUD465, plus shipping/insurance/box. Bank Deposit or PayPal Family & Friend for Overseas people.

Negotiable. But if not sold by 16th December, it goes to the charity shop with the other things.

After a bit of work by some tuning with Nichicon UKW Caps and a great new Bourns Trimpod (that makes the Power-drive sense. adjust. now and fixed a diode problem in the Amp everything worked fine and i was pretty happy and couldnt wait to listen...

Till...
...I wanted to dial in the idlecurrent before and by that I shorted the Amp at the TP Points.

I kind of feel I damaged the Amp seriousely and would appreciate if its possible to help me out a bit to determin which parts got probably damaged by the cuircuit I've created, by showing you what happens, because my shematic reading abilitys are kind of limited.

I marked the short with the black line in the following pictures [the DMM clamps, I surely think touched TP2 and than the 0.1 Cap in front of it - TP1, was not hooked up at that point]




So as the short happened the blew was pretty heavy and I shut down the Amp immediately. After turning it on again, I saw smoke coming from R243[marked it with the red cross(the resistor is surely burned)] and then instantly the main Fuse at the PS burned trough also.

So by looking at the Images can someone determine what will be surely damaged especially? (maybe the following Transistors? Output Transistors?)

So I have the 0.1uf cap and the resistor here and about to change them, but im too afraid and don't have the courage to try turn it on yet as I don't know if following parts in thr cuircuit are pretty surely dead.

Thanks!

Hi, I'm new. I'm looking for some help repairing a sony receiver. Hoping this group can give me some guidance.

Hi, I am brand new here, and to speaker design.

Hello

The thread is dedicated to AP ATS-2 analyzer.

1. Anyone who have the 120KHz-option?
2. Are there service manuals available?

Best regards
Edgar

Can someone help me identify what size JST connector I need to order for this? I am new at this stuff. Thanks.

Hello,

I want to get an idea about whether this circuit will work in reality. The LM337 is seen to be working as a current source in the simulation, so the gate voltage of the mosfet is high.

What I am trying to do is actually make the tubecad circuit simpler.

https://www.mouser.se/ProductDetail/Texas-Instruments/LM3886T-NOPB?qs=QbsRYf82W3EwP/XUhaZp9w==
https://www.toroidal-transformer.co...5va/82/2x-18v-toroidal-transformer-225va.html
Circuit:

Hi guys,

I have this media player, unfortunately the bluray player doesn't work properly, once you insert the disc into it, it says "no disc to read".
I would like to replace its internal reader, but there are no specifications on it online.
What advice is there on a compatible player?
Thank you

I'm Sam and am interested in upgrading my system from vintage to modern, e.g., streamer, DAC, etc.

Sam

As per title, or similar offboard decent quality and accurate speed motor.
Cheers.

Hallo,

I need to repair my friends amplifier. It's a Kenwood KA-5040R.
Problem is that I don't have the schematic. Anybody who could
help me to get the schematic please?

Thanks on advance,

Briek.
🙁

Hi all

Well ok this thread is not about a tube amp, but I guess it might be the right place to get in contact with other HSPY 400-01 users, as it is very useful for diy tube amp creators. With its 400V 1A and approximately 250$, it suits perfect for tube lab projects!
One of mine did so for close to 3 years, but the last time, it took several attempts to release output. And since some days, it strikes totally. When turned on and released, in changes immediately into "CC" current limit mode, but no voltage at all is provided.

Does anybody experienced similar behavior?
Is there any chance to repair it?
Does somebody own a schematic?

Thanks for all hints!

BR Adrian

I know, I know, call Dave. Well I emailed him and haven't heard anything back. I was just wondering if anyone here at DIY had any information on this classic gem of an amp?

I just bought it on Ebay and assume it is 200wpc, but have no other information on how its built and the specs associated with it. It has replaced my Yamaha M85 as the amp for my mains. The Yammie is 265Wpc with Class A to 30W.

The Belles doesn't quite have the same punch, but it is smoother with better soundstage imaging and instrumental separation. I couldn't be happier with the sound, now if I could just get a few details on this thing.

Anyone? 😕

I got this Fosi 2.1 amp because of the controls it has, and the power output specs are likely good for the cost, even if it only outputs 25% of the advertised specs RMS. https://www.parts-express.com/Fosi-...mplifier-165W-x-2-350W-x-1-235-258?quantity=1

Unlike a similar $30-40 2.1 caseless amp that has independent volume controls for treble and subwoofer, and no bass adjust for the treble, but it does have a master volume knob, the Fosi has the treble bass, but no treble volume. The problem is that I can't turn down the treble independently of the sub without turning the sub down.

Any ideas about how to safely go about finding out how to send signal past the master volume to the sub volume knob? Maybe probing around with a resistor? Any idea of where to start other than likely between the master and sub volume?

Left to right: Sub Freq, Sub Vol, Treble, Bass, Master Volume.




I'm not sure what this little switch is for, it was up against a little patch of clean aluminum on the otherwise entirely black front plate. Maybe an anti tamper self destruct switch?

I'd like to know how you have heated 6AS7.
There must be several ways to do it.
It needs as much as 2.5 A current. That is very much.

Thanks

Good morning Everyone😊. So am looking at building a small book shelf speaker for Tv and background music duties. I know SB Acoustics is A great company to buy from. I like this driver because with different Temperatures in Michigan it will not effort the sound of a these drivers (like paper which is one of my favorites). So is this driver worth$75.00 each At Madisound? The driver is the SB 12CACS25-8 is the model number of the speaker driver am looking at and I included the picture and specs and Frequency graph. Am again not looking to shake the pain off my walls or try and blow my out of my room. Does anyone know the sound of these drivers? I know each company has a signature sound to their driver brand. Am looking doing a passive crossover 12 DB on the tweeter and 6 DB on the woofer. Am looking at building a rear ported box or port slot? I Do Have a Vifa Ring tweeter but, am looking at an Morel tweeter for their flat frequency response and a smooth sound. Please let me know your thoughts? Any advice would be greatly appreciated. Towards this new project am starting. 😊. Be blessed. Jeff

Before you are 2x 12”, 4Ω, dual voice coil subwoofers that are individually wired for 8Ω each and then wired in parallel to a Class D mono block amp for a total resistance of 4Ω. The amp is powered by a power supply that’s rated at 12V 125A 1500W DC.

The subs are these: Rockford Fosgate P2D4-12

This will be going into a closet behind my A/V wall.

This will be used in my home theater using a Marantz NR1403 as my receiver (NR1403 - AV Receivers)

My main speakers are these: CBM-170SE BOOKSHELF MONITOR PAIR


Here are a few more pics of the subwoofer itself: Login to view embedded media
What would be a good baseline to start at? I am not looking for over the top volume and crazy attack like I used to when this was in my trunk.

you can see the amp adjustments in the pic

I would like something more subtle that focuses mostly on super deep frequencies for the movie action.

Of course there will be some Jazz and Death Metal happening as well.

Thanks for reading!!

Hi guys, I'm currently creating a ESP32-MP3-Player and don't know what the pin for the "-" of the Headphone jack is(AGND, DGND or what?). And how the fck do i create a low-pass-filter for that!?

Hi to everyone.
Today dead one my output tube - 6П14П (6P14P USSR). Made by 1985 year.
I decided to buy a pair of these tubes as a replacement.
Which one is the best in terms of sound, what manufacturer, year, series?
Mullard? Tungsram? Tesla? GE? RCA? Telefunken?
Thanks for your`s response.

While finalizing the recap of my Accuphase C200 pre amp I’m looking at purchasing the last bits and bobs, which are the main PSU capacitors. For one position I’m looking at Nichicon LGX. They are fairly long life and have high temperature capabilities. They don’t state any ESR values in the spec sheet tho. Anyone here that have any experience with them that can chime in? In Nichicons own words they’re supposedly ”Ideal for rectifier circuits of general inverters and switching power supplies”. Here’s the data sheet for anyone interested: https://www.mouser.se/datasheet/2/293/e_lgx-3082384.pdf

I'm entering the final stages of my floorstanding 3-way tower build and I'm starting to thinking about making a nicer set of speaker wires to hook them up with. By "nicer" I simply mean terminating the bare wire ends to that I'm not clamping down on bare stranded wires which will eventually break off.

My cabinets will have these Dayton Audio binding posts which accept banana plugs or large fork terminals.

I'm hoping to find some solder-on banana plugs or appropriately sized fork terminals to make a nice tidy termination, however everything that I'm finding on Parts Express are set-screw style.

Does anyone have any leads on where I might look to source some nice solder-on terminals? I'm a bit particular with having my wiring look neat, similar to these:SVS SoundPath Ultra Speaker Cable

Dear all,

This is a group buy for ZVN3306/ZVP4424 matched sets for the FC CEN TH group buy.

Priority first for European based 1st GB participants. All Euro based GB1 participants - If I do not hear from you by Friday 25th November (next Friday) then I move on to GB2 participants - I expect I will be near shipping of the GB2 boards at that stage and it is only reasonable to send out the mosfets with those at that time.

GB1 European participants are:


How much do they cost?

A set of matched mosfets for 1 stereo pair of FC CEN IV will be 12e. The killer here is shipping - the cheapest tracked shipping I can find is €9 - having said that, every single pack was delivered quickly and securely during the group buy. So the total price for a stereo set is €21.

Add your name below here and indicate how many sets you need (ie 1 set = 1 stereo pair, 2 sets = 2 stereo pairs or 1 balanced pair). Shipping is the same whether you are buying one or two sets.


Folks - with these two group buys we are straddling two different sets of people, with separate billing and shipping. It will take a little extra organisation and I ask for your patience as I get it together.

Fran

FS: Complete Parts kit for the USSA5 amp, including the output Mosfet, difficult to source K2013/J313, JFET and matched hfe input pairs.

Asking 250U$ + Shipping + 3.5% Paypal fee (or use Friends or Family)

Kit also includes detailed assembly instructions from Fab the designer.
The circuit needs adjustment on some parts in-circuit (CCS current, Vgs, etc). It is well explained in the assembly procedure.

Thanks
SB

For Sale, SKA150 amplifier PCB kit, with GB150D2 PCB, with matched input transistors, directly from SKA, incl. most of the parts to complete the amp PCB, such as the Bourns trimmer, caps and some high end parts such as Takman & PRP resistors.

All the remaining parts are easily available. To complete the PCB you'll need the final MOSFET, the usual IRPF240, IRFP9240, some MFR25 Metal film resistors and a few other bits.

These PCB came with a detailled assembly guide, and I'll include all my own detailled docs, such as my own detailled BOM, PCB silkscreen, schematics, etc.

This amp was well reviewed, is easy to build. A steal at this price, paid 108$ for the two pcb and matched transistors only. Too many projects already, this one need to go.
The assembled PCB picture is included only as a reference.

Asking 100U$ + shipping + 3.5% Paypal fee

Thanks for looking
SB

LOWER PRICE: PA03 60W Chip Amplifier, from Sjostrom Audio, LM4780 Chip Amp PCB kit and all parts (incl. the LM4780 chips)

The kit inludes a pair of very high quality amp pcb, the now obsolete LM4780 amp chips and all the parts to complete the amp (excluding the heatsink). All parts are original bought from Mouser and Digikey at the time. The amp has the option of Single-ended or balanced input. It also includes the speaker protection circuit and relay. The assembled pictured are for reference only. Full schematic and BOM included with the sale. You need an external power supply (transfo, rectifier, caps) to complete the amp...

I have an Antek 300VA, 16V (Part No. AN-3216) in stock that can sell for this amp at a good price, if interested. Shipping cost would be higher though...

Asking NEW LOWER PRICE of 200U$ o.b.o + shipping + 3.5% Paypal fee

Thanks for looking
SB

NEW LOWER PRICE For sale a fully assembled pcb kit for the Hifisonix nx-Amplifier: A High Performance 100 W class AB Current Feedback Amplifier. Hifisonix still sell the bar pcb kit, and support it.
The kit contains 2 amp PCB and the PSU with speaker protection. The PSU PCB already contains the rectifier and filtering caps.

To complete the amp you only need the usual power transformer, and chassis.

I have the full documentation, detailled BOM. See hifisonix website for details at https://hifisonix.com/projects/nx-amp-audio-amplifier/

All the pcb are professionnally assembled, with high quality parts. Selling for the price of parts.

Great kit, but need to reduce my projects. sorry to let this one go. Your chance for a great kit...

Asking 250U$ o.b.o + shipping + 3.5% Paypal fee

Thanks for looking
SB

For a number of years I've wanted to build a single-ended EL84. This particular design has been been built many, many times successfully: it's simple, inexpensive to build and has an interesting plate-to-plate fb scheme.(This design and it's designer have generated a fair amount of discussion over the years. I don't want to get into any of that in this thread)

There are two official versions of this amp: I built the newer, second version which employs an LM317 cathode bias scheme and the grid resistor being replaced by 21v zener. I do plan on swapping the zener with 3w power R to hear the difference.

There are a couple of BOMs posted online, so you can do a quick Google search to find those. Just beware that one BOM will be version 1 and another for version 2.

I chose the direct heated Type 80 (5y3 equivalent in a UX4 pin base) for several reasons: I buddy gave me some (Thanks Dr. Steve Curry!) and they have a high anode impedance, which may lead to a quieter supply, hence a better sounding supply. Also, I think the ST bottle is really cool looking and it's 1920's technology, with the design really beginning in late '23 and finalized as the 280 in 1927.

There's a lot of disagreement on the forums regarding types of supply and components. I won't get into that here, but the supply with the Type 80 rectifier turned out to be incredibly quite. Therefore, a quieter supply would absolutely contribute to a better sounding amplifier.

The are two downsides of the Type 80: it dissipates a very large amount of energy, making it incredibly inefficient. Therefore, you need to consider the heat output in your layout or how that will work in your environment. Living in Arizona this is a factor. I do run a very quiet ceiling fan in my audio room that helps tremendously during summer months, however, this will end up being a winter amplifier. I needed to use PSUD and get some advice on Vdrop: The Type 80 has a very high voltage drop (at least 60vdc), hence lower power output. I chose an over-sized Hammond 273BX, which has 700Vac center-tapped secondaries. I think that 650Vac center-tapped would have been just adequate. I did have to reduce my B+ some 45 volts. In any case, the RH84 circuit presents approx. 100mAh load, therefore, there was plenty of current delivery for the audio circuit!

During this time period, I read Morgan Jone's book and I highly recommend it, it's a fabulous read. I've built a lot of SS amps, but this was my first tube amp from scratch. So, I needed some help!

The top plate was just scrap metal, holes were perfectly opened with a cheap stepped bit that I've used for lots of projects. The bottom of the plate was cera-coated to prevent unwanted grounding (not really necessary but buddy offered). The top was sprayed with my time honored method of finishing metal: self-etching primer shot from a rattle can, sanded, shot again, to fill scratches in imperfections in the metal. Then rattle canned with Rustoleum Hammered finish. This stuff is awesome, and even in sunlight you see no imperfections. My 3rd coat is always a heavy wet coat that floats the hammered flake really nicely. I always allow this paint to dry for at least a week. The drying time is critical an it's also critical that you shoot quick enough to burn subsequent coats into one another. Otherwise, I wait at least 48 hours to shoot another coat. Otherwise, even after 100,000 years, underlying coats will still be wet!



Here's the the beginning of the audio circuit with heavy ground bus bar:


Next was to carefully layout the heater wiring, with at least six turns per inch.:


The base was made from Black Walnut sourced very inexpensively from Ebay. I chamfered the edges to protect against shop "rash" and used my standard and anyone-can-apply-it General Finishes wipe on poly. You simply wipe the product onto the prepared surface, and wipe off the excess, doing so several times creates a beautiful wax finish, with lots of grain pop and depth and no glossy hardness!

The base housed both the very large choke for the Pi filter and Edcor 10w, 5k, 4ohm OPTs. This product is a bargain, and I would argue is as good as exotic output transformers for one main reason: very low primary inductance. Please read this article:

A Consequence of The Quest for 20Hz Roll Off | Cascade Tubes

The completed amplifier:



The only exotic thing I used that could not be ordered from Mouser was Cardas Star quad. This shielded assembly allows for very quit signal transmission.
Outputs tubes are Russian NOS 6p14p, which are supposed to be 5k hour tube. The driver is a Mullard CV4024.
How does it sound? (as you rapidly scroll past my boring prose)? In a word: fabulous. My loudspeaker employs a powered woofer and presents a very easy load for flea-watt amplifiers. Therefore, the amp presents a huge, top to bottom and left to right image. Everything I've read about EL84s being compressed has not been true of this amplifier / speaker combination: the RH84 presents a visible layer of elements with excellent depth. Pockets of individual instruments appear and then step back into darkness.

Tube amps remind me of seeing a play: actors appear in the room and then exit. That is exactly what this amplifier does. Believe me when i tell you that not every amplifier I connect to this speaker does this: I've heard lots of lifeless and flat presentations. My reference is a SET 6B4G that I have modified. How does it compare? It's awfully close. So close, that that psychological thing that happens to us when we listen to a particular piece of gear occurs: after listening for awhile you simply enjoy listening and stop thinking about building something better! Also, it's different then the 6B4G: it's cleaner from mid to top. The 6B4G is stronger in low frequency extension. So, there's always trade offs. However, with my corrected for the room subwoofer, I'm not missing a lot of low end at all with this amp. In fact, running the system without the sub only leaves the very lowest music information out of presentation.


Nothing sounds as good as a direct heat triode, but DHT tubes are scarce and expensive. So, I love that this sounds awfully close for way less $$.

If you want to build this amp, please reach out and I will gladly help you make the journey.

Cheers,

Greg


Equipment:

Speakers: Martin Logan Montis
Sub: SVS 13" subwoofer
Dac: DIY TDA1541 with hybrid SS to 5687 cathode follower I/V
Music source: Tidal->Roon->Euphony Stylus

I have a Harmon Kardon AV-133 to repair ..
The driving transistor 2SD947F got broke while twisting the amp board from heatsink ,
While searching for equivalents I found BD139 and BD 679 to be very close alternatives.

But BD139 has 0.5A of less Collector current(Ic) when compared to orginal 2A,but has 190Mhz fT

While the BD679 has all specs good ,except the unknown transition frequency just mentioned as High .
Attaching the Datasheets ,hope someone would clarify.

I'm tired, long day

So, not too much babbling , for change

Objective: make it before Pa, and (normally) make it more complicated than Pa

What: amp using Germanium Biguns

schm:



edit: while I was dreaming about and working on this amp, I was often thinking about Pa's Joe and Jack

friendship, love and appreciation are very important parts of life


edit on 24. April 2021: THD measurements with 1T813 ( USSR!) instead of 2N1099 , post #68 Old Soul


edit on 15.09.2021 - few general setting procedure tips and tricks; be sure to read to the very bottom of post:



-will not teach ya how to solder everything properly - as always -Assembly of Japanese Bicycle Require Great Peace of Mind


-prior to powering up, be sure that you have trimpots set properly:

P102 (P202) - irrelevant
P101 (P201) - set to max; confirm with ohmmeter across R104 - in vicinity of 28R
P103 (P203) -irrelevant
P104 (P204) - set to min ; confirm with ohmmeter - improvise where to put probes

- jumpers JP101/201 - open/not mounted

-as always - best to work with one channel connected to PSU at time; in fact - first step just one channel , in second step - you can freely leave powered/connected already set first channel

- one VMeter across output ( DC offset) , second VMeter across any of current sense 0R22 resistors; use mini-clips/probes

- no load on output, input shorted to GND

- power up thingie; observe DC offset - it will rise slowly and everything up to several volts is normal in this moment

observe VMeter across 0R22 resistor - it will be Dodo reading for some long time; after 60-90-120sec - if you don't see any substantial reading , start fiddling with P104 (P204), one turn at time; of course - you did remember where you rotate itr to set to min value, now rotate in counter direction; - don't ask me which - I don't care, I can't remember, simply because I'm always trusting in DMM, not in my memory how to orient damn trimpot to have screw in proper place ....... and my logic what needs to be decreased and what needs to be increased is always ooked, vs. overall consensus

allow 30sec or so between 1-turn steps, to observe when and how much mV you're getting across 0R22

goal is , , say for 1A of Iq - 1A * 0R11 = 110mV

keep fiddling to get mV creeping up, and once when you see steady rise for each turn, set da thingy to - say 80mV

(if you're using Si Bigun in place of lower output, feel free to go to 1A5 as target, pre-set to 1A3)

once when you're there - fiddle with P103 to get as close to 0mV of output DC offset

that would be preliminary setting of OS, now to input buffer setting :

- power off , put mVmeter across R106(206) test pins ; put second mV meter on jumper pin marked "B" and GND

power on, fiddle with P101 to set 20mV across R106(206) ; done - fiddle with P102(202) to set as close to 0mV for buffer output offset ( second
mVmeter) ; when done - power off, close jumper


*************** connect second channel to PSU, repeat entire procedure******************

when done with both channels , power on , re-set Iq of both channels to have 1A ( thinking mostly of life of venerable Ge - but don't fret - Square Law OS is crazy thing) somewhere in temp equilibrium, check output DC offset

slide of both Iq and DC offset - cold vs. hot - is really minimal, but I'm mentioning thermal equilibrium more thinking of importance of final temperature of heatsinks - observe, observe also temperature of outputs , that will give you info/confirmation how good and uniform is thermal interface between parts and heatsink

**************

when done, connect signal, speakers, flip da switch, and enjoy

don't forget Da Porn - no Porn, no Glory



***************

pinout of 2N1099 is in post #299



*********************************

M101/201 not having type on schm - it is IRF9510

**********************************

Hi. For sale high quality (2mm PCB), exact clone pcb of the original Accuphase A-65 class-A Mosfet amplifier. The PCB are so exact that you can use directly the orginal Accuphase A-65 Service manual. I also made a detailled BOM to match these these pcb with current parts.

The main amp PCB can also be modified rather easily (not a beginner job), to be rather a P-7100 transistor final stage (adding some transistors, cutting and routing some traces, etc) The main power Mosfet or Transistor have the same pinout, so you can solder either of them.

The kit includes the two amplifier PCB, Output speaker connector & speaker relay PCB, custom Zobel inductors, Input & Front-end PCB, detailed BOM and the original A-65 service manual (pdf). Not shown on the picture, I'll also include the rotary selector switch that goes on the input PCB, no extra charge...

What is missing are the main amp pcb bus bar, but that can be easily replaced by short section of good quality wires. It will probably be better sounding anyway than the crapy original bus bar. If interested I can add at no cost a good lenght of large gauge enameled solid core wire for this.

As reference only I also posted some pictures of the original assembled pcb...

To complete the amp you just need a soft-start and DC protection circuits. Naturally if you want front meters as the original, you'll also need meter driver pcb, but this is optional.

I paid 200U$ for the kit + extra shipping.

Letting it go for 100U$ + shipping + Paypal fee. My loss, your gain...

Thanks for looking
SB

Looking for a pair for 300B set design, thanks

SOLD!!!

This is my first post and I don't know if this is the right location to post this subject but didn't see radios?

I am on my 4th old radio repair and now I have this radio working but it has an extremely sharp, like a crack, thin, tunning width. There is no width at all, it's like tunning a crystal detector, it's either on or off frequency. The sound of the audio is somewhat distorted after the radio is warmed up. If I turn it off and let it cool, the audio is excellent when it is turned back on. It starts to deteriorte after about 3 minutes.
This radio has been completely re-capt. There are no original wax capacitors in it. All the capacitors are blue, Aerovox, capacitors that must be 40 years old. I have tested most of them under voltage for leakage and they all seem quite good and spot-on. I have replaced the capacitors adjacent to the audio tube anyway, because of the distortion thing, but no improvement was made. It's not fun to replace absolutely good parts, but I did it anyway. I can put an audio signal into the 2nd detector and the radio sounds as excellent as an old radio can sound.
The resistors are a different story they all seem to be original, dog bones and most are reading from a little bit high to somewhat high and I plan to start changing them out. I don't feel though that the resistors are causing this sharp band width problem, so I am trying to figure that out separately. I forgot to mention that as the radio warms up it will drift from its sharp tunning point and as the distortion begins.
When I bring it back to tune again, the signal is still quite strong but with more distortion. I have aligned the IF and RF. The IF went well and came up and peaked quit easily but the the RF tuning was sluggish and had little responses to trimming adjustments. I don't know if I have 1 or 2 issues here.
So after all of this being explained, I am in hopes that someone can guide me to the next thing I should be looking into?
Bruce B

Radio RCA 120, Riders, V4, page 4-62..

Hi all,

Thanks for accepting me.

I have been into music all my life (no doubt ever since my mum discovered that placing me in a moses basket and plonking me on top of the 70's sideboard stereo with music playing stopped me crying without fail).

Now in my early 50's I have recently gone on a bit of an audiophile journey and started to build a relatively decent quality hi-fi. Coming to the realisation that a lot of retail speakers are massively over priced (with relatively poor crossovers and drivers in some cases) due to cabinetry costs and middle men etc. I have started looking into building my own speakers - I do a lot of joinery for work, have trade discounts on materials required and will really enjoy that aspect. I won't be going down the route of designing my own speakers, certainly not initially, but looking for advice on well respected designs with build plans that I can replicate which will suit my system and tastes. I have some experience with electronics and happy soldering but it doesn't go much further than that.

Ultimately I want to be able to build some speakers that sound as good as or better than anything I could ever afford, and no doubt experiment in modifying the external appearance or the cabinets without altering the internal measurements.

Hello the regarded community!
I hesitated were to start the topic but deceided here because I need to attach my F5 amp at least.
My F5 project has been started 6 years ago but postponed by some reasons and at last it is almost finished now.
The problem is that I have a plan now to build a three way active speakes based on sealed box design.
So, I need two more amps now)))

If you have an idea which way is best to use my F5 here (for woofer or midrange)?
What amps you'd suggest for other ways (Firstwhatt series or other)?
If 4 Ohm coils are the problem for single ended class A (less power is expected in class A)?

I already have Wavecor WF182BD03 for midrange and Wavecor TW030WA11 for tweeters (both are 4 Ohm).
Woofer is 8 Ohm Scan-Speak Discovery 26w-8534g00 planned but not purchased yet.

Thanks for any advice about the system, Anton

At the last repair cafe (a facility where repairs are carried out free of charge and on a voluntary basis) where I work as a repairman, I had for check this multi band/SW receiver with integrated cassette recorder:
http://www.grundigradio.de/Grundig-Satellit-4000-details.html

The cassette door with insert cassette doesn't go longer open by press the associated knob.
After dismantling, removing the remaining belt and turning the flywheel by hand, I was able to unlock the cassette door and remove the inserted cassette (with a broken tape). Additional I discover a broken plastic gear (yellow-transparent).

Therefore I decided not to attempt any try for repair and to leave it to someone who has practice and experience with this model and its specific deficiencies (check out the images uploaded here, which I took from a site in the Far East, encouraged me in the decision not to attempt any further repairs).
That's why I'm posting this here to find out a good repair address in European Union or Serbia for the owner of that device from Grundig.

Grundig is known for the fact, that repairs to its cassette deck units (even as single component) from the late 70s and 80s
that a repair resp. refurbishing work can only be carried out successfully with help of replica gears (which are available from various suppliers on eBay).

Maybe someone knows a specialist who is particularly familiar with this Grundig model - thanks for your information.

Hi,

first of, sorry about long opening post. You may skip to next post it if you seek for listening tests.

I need to write about what motivated staring the thread in the first place, which is something that I think could help build common understanding through out the forum in long term and thus help all of us for what ever it is that we are seeking communicating here. So I think it's something important write, and to read, especially if you are interested in developing sound of your playback system 🙂

First some paragraphs for background followed by the more important stuff:

I've been intrigued and loving music for a long time, and interested about sound in general, thus I'm hanging around here on DIY audio at this point in my life trying to come up with a nice living room sound system.

I'm few years into building speakers and studying the stuff in general and have realized how hard it actually is to connect written concepts to perceived sound and vice versa. Like, how am I supposed to hear wide sound stage? As concept it is quite well defined and easy to understand, but am I hearing that in my system? How do I test it, how does my sound stage sound like and how do I quantify it, how wide it exactly is? Do I even want wide sound stage, narrow sounds better for some reason, why is that? How do I manipulate sound stage with practical limitations I have and what else is affected?

Sound stage is just one concept out of many and I could easily draw handful of questions from it that all require listening skills, understanding of what I actually hear! What are all the CTA2034 A standard graphs all about, how do they relate to perceived sound in my room? How does my room affect sound, how does speaker positioning change things? All of these would be quite confusing and bring questions like what am I supposed to be hearing? Do I hear my speaker controlled directivity, what does it actually sound like, what am I supposed to hear? It's very hard to get even the first start to it as more questions arise from confusion; is my system working, is my room such that it just doesn't hear, or is my hearing system different than average, or am I just unable to understand what I hear? What am I supposed to do with the CTA data, how do I evaluate what would work for me in my context? How big of a difference 1db on some graph makes, they look pretty much the same, which one is better suited for me or does it matter? What is more/less important to me, what I want to hear and what does that look like as a graph?

A lot of questions, and then a realization that I'm basically alone with this and that I need to figure out this myself as we cannot share our listening skill in a way. I mean we are talking about all the stuff and in that way it's all relatively easy to understand, but there is no shared auditory experience with the written discussion! So, since I'm having these questions do I really understand any of it? Personally, I just cannot connect auditory experience to most of it, which is core of the whole hobby, right, listening to music and also quality of it and then doing something about it?

If we were in the same room all together sharing the auditory experience and then talking it through perhaps it could be possible to share what we perceive and gain more understanding from each other. Especially if we knew each other past experience and listening skill in order to be able to communicate in a level that is suitable, not skipping whole lot of steps but gradually build understanding, stack on the current experience. Getting more experience and context dependent knowledge could help tune speakers, positioning and room acoustics leading to better sound. Not just different sound, but better sound.

But, through written text, hah, nice try 🙂 How to even start? Where am I in this, whats my current experience, what is my context? If I read other people subjective descriptions, how do I know they are relevant in my situation and in what way? Problem is, everyone likely have different speakers, different room, different listening experience, different understanding, different ideals, different standards, different everything, and atop not sharing most of it while writing about things. Without sharing context it is basically impossible to get common understanding, either a writer or a reader does not necessarily know what their context is, at worst neither one does. Some advice could be true/fine in some context while false/bad on another and not knowing which one it is makes discussion without shared understanding of context just noise. To make meaningful communication both would need to be aware of the context and that both know what the context is the discussion is framed with.

To me this issue of unknown context appears as confusing information. Ever seen a thread where some people advice something, then somebody else appears giving exact opposite advice? I would like to believe nobody is lying or misguiding purposely, which to me indicates shared context is missing. I bet that if context was clear to all, then everyone would give pretty much similar advice and proper understandable discussion about it and how different context would likely change everything. Ever seen thread like that? Now, how to identify who does and who doesn't know the context in a discussion? Well, there is no other way than to start looking into mirror, make sure I'm aware about importance of context.

Alright, where to start then? Context varies, but auditory system is something we share in common (for most part). And physics of sound! Sound behaves the same as long as we share the same atmosphere. So, I think that we could communicate more efficiently if we could somehow better understand and promote context, and to do that we'd need to reliably know what we are actually perceiving, how to actually relate written concept to perception and vice versa. Since any given context could be unknown to us, never heard, we'd might still be able to discuss about it basing discussion on some fundamentals, like the hearing system, a thing that you always carry to any context. At least some confusion ought to reduce from the discussion if context was acknowledged.

I think at the core of it is to develop listening skill to somehow learn understand our own perception, and no other way to do it than listening tests. I think that if we all got to some basic level of understanding of our own perception by using some listening tests in our own context, it might be possible to use that as basis for common understanding. If only we all could learn something fundamental of our own hearing system using our own varying contexts and have a consensus about it. I do not know what the base level could be and if there is possibility to reach consensus, but even if there was no this kind of shared common understanding I think it is useful just to be aware about how context matters everything, and how it affects discussion in general. So, thank you for reading this far!

Alright,
At this point in time it is quite obvious to me that my playback system quality is as good as my listening skills so I'm trying to figure out myself what I am perceiving in my room, with my speakers and my own ears in order to improve my listening skill and my playback system. My process is basically take a written concept and then device a listening test that would allow usage of some logic, which would translate to some understanding of what I perceive and how it might relate to written concepts, in other words improve listening skill. Sometimes I just fool around and try perceive change, then try to figure out what might be responsible for that. Sometimes I purposely change something and try to perceive change, and then apply logic on that. Sometimes it would give wrong assumptions, some times right, and there is no way to know than plowing through using logic, sharing and discussing about it, learn from mistakes, gradually increase understanding.

Since I've got access to only my own context (speakers, room..), I thought it would be nice to share some listening experiments that I've found useful and fun that I have been using trying to get understanding. Sharing it here so that we could learn from each other. Have fun!🙂

If you know some official listening skill resources, especially to study perception of sound, then please do share. Obviously any discussion and thoughts around listening skills welcome!🙂

Hi guys, I'm looking for some information about module LPF during the process of making module DAC recently. And I also fell in love with ERICSSON RIFA PBA3244, a product that is almost impossible to purchase in China. I wonder if friends around the world, especially those from Sweden, have detailed photos or related information of this module. I want to purchase him. Thank you again for providing assistance. I am waiting for your message in China. I love DAC modules, but I prefer LPF modules. I think you can help me obtain more information.

Hello,

I'm Felix from Berlin, Germany.
I've recently started building speakers e.g. a TH12 subwoofer and a 2x8 Paraflex Kick/Mid.
Mainly for cycling events with my cargobike but recently I've been thinking about HiFi and MEHs :-D

Cheers,
Felix

Hello everyone.
I would like to know your opinion on the equalization that has resulted from my measurements with REW and if it is correct from a technical point of view.
You can see my speaker system in this forum.

What I have basically done is equalize each speaker separately from more or less 150Hz to 20,000Hz and treat the area below 150Hz as if it were a single low frequency driver, using the joint response of the two 15" drivers measured in REW to equalize.
I use minidsp 4x10HD, and this allows me to link the two channels corresponding to the two bass drivers and equalize them together.
I hope I have explained myself correctly...😉
I leave you some measurements so you can observe the results.

RIGHT SPEAKER. Equalized response from 150Hz to 20,000Hz. Not equalized from 150 Hz to 30Hz



LEFT SPEAKER. Equalized response from 150Hz to 20,000Hz. Not equalized from 150 Hz to 30Hz



L+R response with joint equalization of bass driver.


The measurements are made from the listening point.
Regards.

Hello,

Recently I have acquired a complete Papworth setup consisting of a preamp and 2 M200 mono's. The pre was pretty much okay, the Mono's were mistreated by not changing tubes for ages.
By now I have cleaned them out and replaced some broken resistors.
It looks like these amps are fixed bias. Looking for a schematic or values for the correct bias settings.
All help is welcome.

Greetings from rainy The Netherlands
J.

I’ve been following the thread "New Audio Op Amp - OPA1622" for a while and at some point decided to make myself a new universal buffer/headamp based on the OPA1622. The idea is to use it as an output buffer for my standalone volume controller/source selector with the direct headphones drive capability. Since I already had the low noise PSU board design based on the TPS7A3001/TPS7A4901 complementary regulators I just added the buffer part to it and it seems to look good together. I also added the transformer CRC snubber to the board following the guidance in the "Simple, no-math transformer snubber using Quasimodo test-jig" thread. According to the datasheets the LDO regs which I used in the PSU should be able to drive the OPA1622 opamp to near its maximum current output. I guess I do not even need additional gain and can just configure the OPA1622 as a unity gain buffer or have a gain of 2 at most for 32 Ohm headphones which I am using.

It will be a bit challenging to solder those tiny IC packages and 0603 resistors and capacitors around the opamp but I’ve done it already on the other builds and it turned out successful after a bit of practice.

The resulting PCB design and schematic are attached. The PCB is only 3x8 cm and the mounting holes are on the 10 mm grid.

Comments and suggestions are welcome.

Regards,
Oleg

The 3rd in the series of small horns based on the Frugel-Horn Mk3 is the Frugel-Horn Lite aimed at supporting 3" drivers.

Designed to target the Fostex FF85wk, sims show that it should work with a wide range of 3" drivers (see drawings for those summed)

We built the original proto-type in early January with the FF85wKeN and have refined the design since then. As one would expect with 3" drivers bass extention is somewhat limited, but listening we were very impressed with bass reproduction. Comparing to more bass capable speakers, they produce the 1st harmonic very well, creating the illusion of deeper bass. This will satisfy many. Higher frequencies will depend on the driver used, with the F85wKeN they are very good.





With pressure on to get this out i worked on a basic set of drawings today (thanx David). Please contact me with any QC input.
http://www.frugal-horn.com/downloads/Frugel-Horn-Lite-0v9-290615.pdf

Link updated 29-june-2015

Now with its own pages on Frugal-Horn.com The Frugel-Horn

dave

I need a coffee table for my office. So I decided to make one. And I decided to make one that is also a giant subwoofer enclosure.

This is my first indoor sub build. I've built them for cars but I've never played with this much air space to play with.

The volume is 9.2' square. A lot.

Going to run 2x12" GRS subs. 6" diameter ports. Push Push alignment for both the drivers and the subs. This way it doesn't shake anyone's coffee.

The sims show this to be epic. Max I will run wattage to these is probably 200w. I based the rear port off of 250w. Its a little high but I will 3d print some extreme flares for both ends. I might even dimple them to reduce turbulence. I'll use regular 6" PVC for the actual tube.

I have build a lot of enclosures before so not my first rodeo. I'll be using screws this time around. 3/4" sanded birch. 4" R15 rockwool to line everything inside.

I really wish I could downfire the ports but I don't have the room unless I put a bend in it. Can you run a 90 degree bend in the port? I don't want the mid distortion leaking into my monitors.

Take a look at the pics and let me know if I missed something or if this is going to epic.

The drivers:
https://www.parts-express.com/GRS-1...fgt905c3scVEHKUBFMNXjEdq7lUjoBkRoCuM4QAvD_BwE

I am working on an idea for a semi open baffle speaker. The (sub) woofer is open baffle and the tweeter monopole.

For midrange I am thinking about using a Faital Pro 12FH520. I could make the midranges monopole or dipole. But more interesting to me is a gradual change over it's passband from dipole to monopole.

I sometimes saw open back or H frames with felt curtains hanging behind the driver. Sometimes more like aperiodic enclosures where the damping is in between mesh and there are no gaps but covering the whole back. Then there is true aperiodic where the vent is significantly smaller than the driver SD.

I don't have a clear outlined question but would like to hear from people who have used these kind of arrangements.

What would be the best way for the driver to gradually go from dipole to monopole behaviour from 120Hz - 1200Hz?

Hello Everyone!!

Just finished up this all original design. Been listening a few days and it sounds very good so far.

The issue with the 6S19P is it's gain is very low, 2-3x so a significant signal swing is needed to drive it. Also it's a low voltage high current tube so a low V supply is needed. It's very hard to achieve large signal swings without much voltage.

To solve this I designed a PS with 2 voltage rails. So you will see the driver supply is very large compared to the supply for the output stage.

Hope you like the amp. Questions and comments welcome!

I want to thanks Sean O'Neill for making the beautiful bamboo box.

Hello to all,

I'm new here and in HiFi audio. I have some good deal to buy Thiel CS 2.3 speakers and I need all other elements in the system.

In past I bulid one Amplifier by Instructions, PCB and list of components so I know some basics.

My plan is to buy an assembled amplifier from China - Ebay/Aliexpress. Price range around 300 EUR/USD, power around 100W A class, 300 A/B. I see some different models here: KSA100 MKII, Accuphase E505, E550 FET, T820, Swiss FM 711, Refer to Bryston 4B models, but there are few variants available. I don't know the differences between models so I will be happy if you can suggest a model, or if anybody has some knowledge or maybe anybody has already bought and tried some model of these amplifiers or do you have some suggestions which model to avoid/buy.

I know that this amp is only one part and I also need good capacitors, a toroid transformer, Aluminium heatsinks...

Hello friends ...

I am Mario from the beautiful island of Crete in Greece ...
New year i coming soon wish to everybody health and happiness...

Thank you for your acceptance.

Hello!

Does anyone know where I can obtain a schematic for a Telex EV SonicXS computer speaker system? I know it's not exactly new. I have an issue with a loud buzzing sound when the unit is turned on. The Power is not directly applied through a switch, but through a low voltage setup where a switch on the volume pot powers a relay through a seperate circuit with it's own transformer, drive circuit and relay. If I bypass this power up circuit and connect the main transformer directly to power, the buzz is gone, and the amps work fine. The relay seems to work okay, and is only switching the hot side of the AC power. Don't know if the amp circuits are picking up this loud hum through a bad cap or other device in the power switch circuitry, or what is going on. Anyone with similar issues? If so, help would be greatly appreciated. Thanks.

Diyaudio store ZenMod JZM amplifier, completed and top working order for over a year now. Its big, its heaby, its top sounding papa Nelson originali designed amp. The is 30kg heavy, so shipping inside EU will be around 100 euro. Price for amp is 600 euro plus shipping. Amp is build with diyaudio store pcbs and parts. It is dual mono design. Psu is CLCLC configuration with 100000uf pro chanel capacity. Verry good sounding amplifier in class A.
More info on request.

As the title says, I'm trying to sell these. The physical condition might look a bit worrying, but I guarantee they're still fully functional.
Their capacitance is still accurate as well.

They go for $66 each at Hifi Collective, and even $69 at Madisound when new.

I'm offering them for $65 a pair (shipping & pp fees included).

PM me if interested.

Thanks

Hi - I'm back with more travails in the LM386 guitar amplifiers.

Here's the issue. In order to try to be able to play from across my living room without tripping my family, I purchased a cheap wireless Tx/Rx system from Amazon. When I plug it into my home-made, 9v battery powered LM386-based amplifier (basically a Little Gem amp below, but without the C2 capacitor), there's a horrible hiss. The hiss does change when the gain is changed, so I believe the problem to be some noise coming in on the input.

I also tested dropping a .01uf capacitor between pin 2 (guitar line in) and ground, and the hiss did go away. But I have never seen an amplifier schematic that includes a low-pass filter like that at the input, making me think it's a bad idea (e.g., killing treble before it even hits the amplifier). But maybe I'm just being paranoid.

Any thoughts on using a capacitor in this way? Any suggestions for capacitance values? Alternatively, any thoughts on alternative solutions that won't suck tone from my jamming?

Thanks in advance.

Edit to add link to video with sound: Login to view embedded media

We all have a junk drawer and if you build electronics it could have some interesting leftovers. Mine has some space charge vacuum tubes, germanium transistors and other bits. I'm also in need of a headphone amp to drive 32 ohm cans, so the goal here is to spend close to zero and make something that sounds good.

I'd like to start by acknowledging Pete Millet's 12AE6A space charge vacuum tube headphone amp design as the inspiration for this project. However, I did redesign the cathode follower buffer section so I can use a stable matched pair of AC128 transistors and hopefully they sound good in the circuit. But, because they are thermally unstable, I designed the circuit with an feedback circuit between the Collector and Base which ensures that as the collector voltage drops (or rises), the base voltage is also pulled slightly lower (or higher). This feedback effect helps to counteract changes in the collector current, which stabilizes the transistor's operating point. I also added trimmer potentiometers to tune the Base bias (to 24v rail), Emitter feedback, and the Collector feedback circuits. Hopefully my calculations and design are ok, otherwise I'm sure someone will mention something that was missed.

The regulated 24v dc power supply is currently being designed.
Spice models for the 12A6A and AC128 have to made so the circuit can be tested.

Hello, diyAudio community,

What a pleasure it is to be a part of such a large forum. I can tell, after using the search function, that there's a LOT of minutiae here and I LOVE minutiae. I look forward to learning.

- Barclay

Hi, I'm C.
I'd like to post now. We will get to know each other eventually.

- C

Folded Cascode CEN IV. Does anyone have boards or kits they would like to sell? I need four for balanced.

I have to ask a question for this thread, as my PSU went dead like this... 🙁

Take care 🙂

I've heard about this site before but just thought it was yet another forum trying to replicate what already exists elsewhere. Apparently, I was very wrong!

Hello from Dallas!

- Wil

I'm looking to calculate VAS .from the formula that is in Rod Elliot's ESP website. The formula is Vas = Vb × (( Fb / Fs )² - 1 ). I plan on making a box and inverting the speaker so it faces into the box, as per Rod's Instructions. How is Fb calculated? I don't want to calculate VAS using the added mass method. I can't find a formula anywhere to calculate FB.

There's a lot to be said for using multiple subwoofers in a room. What they don't say is that they are invisible, easy to find space for and enhance the decor.

So I have a question as I contemplate my next stereo speaker build. I'm considering bass modules with 2x 10" Dayton subwoofers per side with a 250W DSP capable plate amp, which will sit under my current bookshelf speakers. I guess my question is, does using a speaker with deep bass and EQ offer much of the same benefits of having two subs? Were you able to EQ each side separately and come to an exceptionally smooth bass response? Did it substantially help improve the integration of the speaker with the room?

I don't mean to attack subwoofers or get into a discussion about the benefits of adding 4 more speakers around the room. Please, let's not go there. Just want to understand if others have tried this and what their thoughts are having tried it.

Hi Friends;
There seem to be a lot of Yamaha CR- series receivers around, at least in this neck of the woods. They seem to have common problems in the regulated power supply for tone control etc. sections and bad solder joints in this area also. This one is being particularly stubborn.
I have completely recapped the power supply board #1 and replaced the 3 smaller caps on the main capacitor pcb.
There is a saw tooth ripple in the -25 volt output of ps pcb 1. When the load is removed (violet wire to tone control), the ripple goes away.

Still struggling with the power supply. With the violet wire (from the -25 terminal to the tone control board) lifted, both -NB and +NB rise from 34 to about 40 volts.
How can a load on the -25 side affect +BL?
Voltages on TR708 C: -34.9 B: -31.18 E: -33.4
I thought I was on to something as the voltage from B to E was 2.2 volts. The schematic calls for 0.8 v Is this not a significant difference? I removed TR708 and it tested good with my Fluke meter (diode checker mode).

TR714 C: -41.7 B: -34.8 E: -34.2

TR704 C: -34.4 B: -0.55 E: 0.0

I have a very old musician's singing system in my hobby room. Yesterday one of the speakers broke down. In search of the cause, I finally opened the speaker box and found two light bulbs inside. One of them had burned out. They are probably used as overload protection. Unfortunately, the label on the light bulbs is no longer legible. The only thing I could decipher is 24 volts. Does anyone have instructions on how to calculate the wattage of the light bulb depending on the chassis? I couldn't find anything about it on the Internet. This technology is probably pretty outdated.

I have a GAS Thoebe preamp that works but needs repair to eliminate random noise and cutting out. A local repair shop was not able to fix it so I'm looking elsewhere. Does anyone know of someone in the USA (I'm in New Mexico) who would be interested and able to repair it?

I also have a Thaedra with similar and other problems that the same repair shop is now looking at but not having much luck.

They both are normally hooked up to Son of Ampzilla amps that work perfectly. I am currently using Dynaco PAT-4 preamps in the meantime and have no problems. I'd just like to have the GAS preamps back up to snuff.

Thanks,
Dan