​

When I select the first cd It collects the second and if I select the 2nd cd it collects the 3rd and so on any help much appreciated I'm quite technically minded so any repairs shouldn't be a problem once iv found out how to repair the problem. it's like the timing has gone wrong but don't know how to fix it

Hi,

Right now Peppy audio player assumes that the whole ALSA configuration should be done manually.
To simplify that task I'm trying to investigate what is the best way to show the list of available ALSA cards/devices in Peppy Player UI using Python.
Also ideally it shoud be possible to switch between cards/devices without rebooting a Raspberry Pi.

I'm not sure how to add a dtoverlay entry (/boot/config.txt) for a specific audio board.

Here are the options which I've found so far to display the list of cards/devices/mixers and set the default card:

1. Parse the output of the 'aplay -l' command. It provides the info about card/device/subdevice:

Very similar approach is to read/parse ALSA files. Though there is no just one file which could provide full info about card/device/subdevice (like aplay). For example the following file shows only card info. To get the info about devices another file should be parsed. There is no file with subdevices (?)

To assign new card/device to the default ALSA device the corresponding values should be defined in the file .asoundrc

Pros:
No need to use any third-party library
Cons:
Works only on Linux (not Windows, not sure about Mac OS).
Need to modify the config file (.asoundrc) to switch to another card .
Fragile text parser, not sure if the aplay output has the same format on all Linux flavors.
Should the system be rebooted after changing the .asoundrc file?

2. Use pyalsaaudio library. Here is the example of using the library:

Pros:
Very small ALSA binding Python library.
Provides card name and mixers info.
A mixer object can be used to mute/unmute and change volume.
Cons:
Works only on Linux.
Doesn't provide card ID (e.g. PCM2702). The card ID could be used in .asoundrc file.
No info about devices/subdevices.
I didn't find info how to change a 'default' ALSA device to different card/device using the library. Though that would not be helpful as the player is using .asoundrc file.

3. Use sounddevice library which is a PortAudio (don't confuse with PulseAudio) binding Python library. Here is the example of using the library:

Pros:
Multi-platform, works on Linux, Windows and Mac OS.
Can be used to switch to a different ALSA default device
Cons:
Depends on PortAudio
Outputs a very confusing list of cards/devices. For example in the above example it's not clear that device #2 (sysdefault) is actually the USB device.
It's not clear if mixer can be handled by the library.

I’m experimenting with Tda1541A in simultaneous mode. I already have the i2s to pcm board, sounds promising so I will go the full stack. Thanks!

Yeah, I know, wrong site. But, you guys are the smartest people in the room...
My other hobby is photography. I'm trying to service a Kodak 4400 slide projector. The service manual says remove the six screws and the case should come apart. Not happening. I can't get the handle area to separate. Can't figure out the trick. The earlier models look easy to get apart, but this one, with the tapered handle, seems to have some additional lock, tab, hidden screw, glue or something. Anybody ever have one apart? No amplifier was ever this difficult!

I am planning on building a cabinet around the JBL 322c. The cabinet will be 15.5" W X 25" H X 13.5" D (roughly heresy iv size) with an internal volume of 3948 cubic inches, just a hair under the 2.4 cubic feet of the enclosures JBL sells. I'd like to get down as close as possible to the 30hz measurement in the JBL specs. I am not sure how to go about calculating port dimensions, and was hoping someone here could help. My intention is to build this cabinet entirely out of 3/4" ply. Any help would be greatly appreciated!

Hi,

It is not the pre not the dac, I already made the tests by swaping the links between the pre and dac and pre to amp, to see if the louder channel swapped between L and R, but no.

I checked impedance of mid and treble with DVM and sweep with ARTA : seems ok both side. So I assume a channel of my SMPS Chord that has 25 years play a little louder on a channel maybe ?

How to check the symetry of the amp output with a DVM please (have no scope) ? Can I inject via the Arta or the pre a signal à la Pink or else and check if the votage on the binding posts are the same L and R, please ?

Many thanks

PS : the passive filter value of caps are the same to 0.1 uF , film caps. It is not the room , the difference is listenable the ear on the mid drivers for instance.

Yes yes
In the Netherlands there ara 800 libraries and among themselves they have 1 of this
So I can educate myself

Hi I just got FORTE MODEL 7 from scratch and I found all IGBTs was burn then I need to modify output with MOSFETs. But I can't find its schematic does anyone can help me ?

Hi.
Recently I got this small old mixing console.
It has 6 channels with Haufe mic input transformers and Alps faders.
It is probably made in Germany.
Anybody recognize this consile and is it worth to use.
Thank you in advance!

So I got a friends 500/1 Rev.10, Power Supply blew up, literally, I pull the PS FETs, probe everything, all measuring good, so I reattach daughter board, test idle function and see PS is switching, so I install PS FETs, boot up, I see some switching on output FETs, probe terminals and see square wave in terminals? Weird, so I kill power. Reprobe everything …and see I didn’t put back the damn cardboard divider between the daughter card and POTs in main board 🤦🏼 (Didn’t see any reaction like sparks, etc and don’t even know if I actually did cause anything but assuming I did🙁 Amp idles at .5a with green LED only, but I have nothing going on in the output section now, the 4427 doesn’t even have a wave going into it, let alone out. I test my signal and check switches, all looks good, I probe RCA outputs and that isn’t getting a signal either . I’m pretty sure something is dead within the preamp on daughter board? Which I may have caused? Which is killing me right now, I VERY rarely cause more problems, I think this is like my 3rd time ever, and every time it hits so hard 🙁

Nothing seems to be dead (transistors, JFETs, the stuff you can probe with a multimeter. I’m such at a lose to know where to even start, and it’s a JL Audio bespoke design, but I’m guessing since RCA out isn’t getting a signal along with the 4427 getting nothing on the in pins as well should help point me in a direction? Any help would be amazing, I can’t believe I might have caused this, cuz I saw waves on the output when I first booted it …man what a dolt move.

So I got a 300/4 in from a friend, 1st Gen. Top channel (as in picture orientation, Q300/Q301 channel) blew, pulled all outputs and checked resistance between gate and source on all FET sockets and all high sides (bottom Fet sockets of each pair, Q301, Q305, Q501, Q405) match at about 5.6mil Ω, yet all low sides (Q300, Q304, Q400, Q404) were off? Between 7mil to almost 18mm. So I powered it up to test gates cuz everything else probes ok/not dead (resistors, BJTs, etc) and I get a wave at each low side gate, yet each of low side waves are higher/lower voltage versus others on my Scope screen, guessing bias? Does bias control the gate voltage on these amps? After testing and confirming to make sure drive is working and is sending signal to each of the low side gates (albeit all at different voltages) now the resistance is much lower on each low side gate to source after draining rail voltage, and the “bad” channel that blew is still the lowest but at 700k Ω now, but the middle 2 low side gate to source channels probes at 8mil Ω and the bottom channel measures at about 10mil Ω. What is giving me these crazy all over the place Gate to Source measurements yet everything seems to be working? I did notice the BJT in front of the top/bad channel’s output card (Q306) is reading 30 Ω between drain and source and the other 3 channels BJT are all reading 20ohm. I’ve just yet to come across anything like it.

I marked on picture what each low side was probing at after testing to ensure drive is working.

Going to sell the drivers and cabinets separate now.
£SOLD pending. for the 208s
SOLD for the t90a
£100 for the bare cabinets.

Still have fostex 208 boxes..

Weird one, new amp, very little play time, I get it in, can see nor probe anything damaged. I notice output is not switching but power supply and rectifiers have proper waveforms. Also weird is each IR2110s on each card is getting -102v to everything, vCC, In, Out, etc. gates of low side FETs getting -102v and middle leg of high side getting -102. When I pull the output cards output high side gets +102v (from what scope is telling me) Also when trace back preamp I get this wave from 1st opamp all the way to output riser cards even tho is is getting fed a proper 75Hz sine wave @ 1v.

Never seen an amp give -102v to so many complements and leads, or even one for that matter, and never seen a preamp sinewave like that. No idea where to even start as I’m used to the version 2 3kDSPLX where the middle riser card feeds the low side signal after getting it from preamp. Seems they totally changed the design (and used weaker FETs)

Is that 38483B supossed to be what feeds the low side drive wave to output section? Datasheet says pin 6 is output (direct drive power mosfet) but it doesn’t look like anything I recognize. So many firsts for me on this amp, really reminds me how much I still have to learn.

Some of you might have seen my previous post about what I should choose as my first DIY Speaker build and I think I've settled on Paul Carmody's "Pit Vipers". Currently I own a pair of Radiotehnika 35 AC-1 and they have a switch as far as I understand Min, Mid and Max I highly prefer the sound of when the switch is set to Max and treble on my amp is set to the max. I want to figure out in more simple terms what this switch does and I want to know if it’s possible to achieve a similar sound with the Pit Vipers, when the switch is set to fx. Min or Mid music simply sounds empty. This is the resources I could find about the switch (further down the page) however I don’t quite understand and wanted to know if anyone is able to explain it in .. well simpler terms.
https://ldsound-info.translate.goog...l=auto&_x_tr_tl=en&_x_tr_hl=da&_x_tr_pto=wapp
Thanks T.

I have a MiniDSP 2x4 (non-HD). The line level input is the regular 2Vrms, but unfortunately it only outputs 0.9Vrms. Because of this, a more powerful power amp is required to compensate.

So I was wondering. Would it be hard to make a simple op amp based circuit board to increase the output to 2.0~2.1Vrms? It would be nice if this can be DC powered. The MiniDSP itself can be powered with anything between 5 ... 24VDC, it would be nice to use the same power source.

I have a wooden table that I would like to have a nicer surface to work on. Something soft and tough, but not something that can slide.
I was thinking of sticking on carpet tiles but a friend recommended against that.

what do other people use?

Pete Brown has died aged 82. Long title collaborator with Jack Bruce.

https://www.msn.com/en-gb/entertain...r&cvid=b07134155a2846eead9dae716a83e861&ei=45

Hi, DIY'ers! I'm trying to build a raw DSD source (left/right/clock), and need a little help finding a test DAC. It doesn't have to be anything special, just take in DSD and give me some kind of results 🙂 DSD64 is just fine & I can extrapolate from there.

Any suggestions would be great. Older, used, cheaper the better and I'm thinking an eval board to save on costs. Anyone have an unwanted old board sitting unused?

Hello,
After whole decade of using flash storage I'm back to audio CDs.

I have a problem with audible static when playing back CDs that I had burnt.

This only happens when playing on my recently bought Alpine 7294r with 5952v cd changer. It doesn't happen on my new Yamaha cd player (for obvious reasons, I can only be happy that my old Alpine can even read burned CDs)...

I had cleaned the laser & checked that grease didn't go hard on the changer.

I had discovered online that slowing burning speed to 2x would solve the problem and also that old worn out drive burner can cause this.
Slowing down to 10x helped alot.

As only burner I still have is in cheap Lenovo laptop and it doesn't allow burning speeds slower than 10x, I need to buy either external burner or standard SATA burner.

Can I buy just any new cheap burner either internal or external that can burn at slow speed and expect good results or is there anything else that I need to watch for?

Also for blank CDs, will I benefit any if I choose some fancy audio CDs over cheap Verbatim stuff?

And finaly what software are you using for converting / burning FLACs as audio CD?
I'm using Power ISO, I know that compression / decompression and also cause artifacts & quality loss...


Thank you for anwsers.

I knew the Chinese had it in for Mr Nelson Pass, but this is just rude. Nelson in Cantonese apprently means:

I found this very interesting especially considering the hifi world. Not only can there be a mechanical difference in hearing i.e hearing damage etc. But our brains literally interpret sound differently depending on our upbringing, environment, plus some yet to be understood reasons. https://www.pbs.org/wgbh/nova/video/your-brain-perception-deception/

Hello all,
Noob here ( for this board) but long time audio guy. I have a pair of RCA LC9 cabinets, currently loaded with JBL drivers, but I have all of the original RCA parts (11419 NIB, 11420 Xovers, 11421 15" in good repaired shape). My dad, Hans Dietze, worked in RCA Sound Products with Volkmann, Olsen, May and others and I grew up with AJ May as a family friend.
I had been using the LC9s for PA back in the 80's and they are shot in black lacquer, but are in otherwise good condition.
They are in Eastern PA gathering dust in my warehouse.
I also have several of the prototype 15" horn driver which my dad developed to replace the 11421/ 9449 horn drivers. RCA was going to transition to this driver when they rather abruptly closed the division in the early 70's. Those could go in the LC9's as well.
If you have any interest, please let me know at dietzechris30@gmail.com.

Here’s a nice simple ripple eater

https://hifisonix.com/projects/hifisonix-micro-ripple-eater/

I’ve called it the ‘Micro Ripple Eater’ (MRE) because it’s compact but it can deliver up to 10A per rail with a decent heatsink.

Any questions, I’ll be happy to answer them

🙂

This is a generic board from a speaker which has been botched, I'm trying to repair it as i do know it sounds a lot better than the ones you can buy cheap from lots of places! what i want to know is does it all look okay in terms of how everything is setup? it should be noted that a pam8403 is currently soldered to it, the board is about 10 years old if memory serves me right so excuse my terrible younger solder skills! should be noted as well i do intend on cleaning it all up as i know some traces are connected that shouldn't be! the issue was i connected a battery the wrong way round once upon a time 🙁

I don't have a schematic so I'm having to guess everything here and just wanted a little guidance 🙂 it does have a charger circuit as well as a pot, the pot is not connected nor battery!

Cheers guys 🙂

I have a large amount of resistors that I need to sort. Most of these are in the 1/8-1/2 watt range. I can read the bands to determine value and tolerance. Is there an easy way to distinguish between carbon film and metal film resistors? Is it as simple as a tolerance value? Some of the resistors are in marked packages but most are on tape and unmarked. Thanks.

The MC cartridge that I want to buy and is compatible with my tonearm has an output voltage at 1000 Hz, 5cm/sec. - 0,25 mV.

My preamp's manual says MC input option: sensitivity adjustable 38 – 210μV for 5cm/s @ 1kHz.

Is that acceptable or should I look for 0,3 mV and up?

Regards,

I have just got a Leader LMV-186A where only channel 1 is working. Are anyone familiar with these? I also have a orange light on the power bulb, should probably be green light..? Channel 1 is working correctly, but there is no signal on the channel 2 meter. I cant even get the channel 2 meter-needle calibrated to zero.

Hello all,

I have this LM3886 amplifier with integrated NE5534 preamp and power supply. This is what it looks like:



I have been using this for a while with an old non-toroidal transformer, without a case. I did not take care to ground it, as it was without a case (I should have). I never had problems with noise.

Since I like it a lot, I decided to purchase a nice toroidal transformer and an aluminum case to put everything in. However, I am faced with trouble when trying to connect it to my sound source. The problem seems to be related to grounding. I hear the term ground loop noise but I am not sure if this is the problem I am dealing with.

The toroidal transformer is 2x30V, 160VA power. I have joined the primary coils and insulated the connection. I also connected the secondary coils and got a center tap to connect to the middle socket of the power supply input. Obviously, this is the three prong terminal at the lower left of the board. Speakers are connected to the right side of the board.

Now when it comes to choosing a ground point to connect to the case, the manufacturer recommended the bottom left hole. Indeed there is a visible trace there that makes that point electrically very close to the grounded sides of the two big capacitors. I had soldered a lead there before I asked him the question, so I left it there considering it ok:




Now, as to how I am connecting to source, I use these screw type RCA terminals with the 3-pin connector supplied with the board. You will notice it is currently outside the aluminum case as the noise problem I am about to describe is so severe and not affected by having the board inside or outside the case.



So, what I am dealing with, is noise. Again, I mention that I never had this problem before, because it was outside a case and things did not lead me to consider grounding it with the IEC inlet ground. The thing is, if I leave it ungrounded, there is just a slight noise from EMI because it's not in a case. The moment I connect the IEC ground lead to the ground point show above, I get a lot of noise.

I am not sure it is EMI noise. Because the amp board is connected to an audio interface and then electrically with a computer, I 'm dealing with noise that seems to originate from the computer. Essentially I am hearing all the electrical activity of the computer as quite loud noise. You can imagine the volume levels of listening to some relatively low to mid volume calm music, only it isn't calm. By electrical activity of the computer I mean for example, I can hear the wireless receiver of my mouse when I move it, or a difference in noise when I turn on the computer keyboard LEDs on/off (on means more noise). Again, this is much louder than say, some residual EMI of a fairly well put together setup.

The moment I disconnect the IEC inlet ground from the board, the noise goes away, and there's only very low residual noise, I presume EMI. Also, to be noted, if I connect my mobile phone at the input, I can ground the board via the IEC inlet ground with no probems whatsoever. Obviously the phone operates from a battery, and is floating without a ground.

Can you firstly help me identify the type of problem here? Is it a so called ground loop noise issue? Both the computer and the amp are on the same multi socket inlet connected to mains.

Obviously, I am still expecting various parts to complete my amp, most importantly proper RCA terminals to connect to the back panel. But this thing is so severe that I think it requires immediate investigation since it happens both inside and also outside the case.

Are there things I should make sure before starting to troubleshoot this? And how would I go about doing that and hopefully fixing this? It is so prominent an issue that it must be solvable.

Many thanks for reading, any pointers/help are more than welcome.

Excellent condition. Pair (quantity 2) of custom filament transformers. 2 primaries and 6 secondaries. See 4th photo for details of specs. 5 day money back guarantee, less shipping.

$475 OBO + FOB

banpuku@mac.com

Would a pro audio driver “sound” any different than a pro audio driver when using it for the low end of a 3-way main?

In the photo below you’ll se my already built HTM12’s are paired with pa460’s for an already incredibly good sounding 3-way speaker for my front three LCR speakers. The htm’s are a two way (internal xo) 12” monitor capable of down to 60hz …. AND….. I have built a 42hz ported box for each of my three pa460’s, these are XO at 350hz into the HTM’s and on an inuke 1000DSP for each speaker (three 1000DSP amps - LCR). The 18” pa460’s only play from 42 to 350hz (actually 80-350hz) and the HTMs 350hz to 20k.

>>>>>>>> My question revolves around some Dayton 15” rss390HF home theater drivers I have laying around, probably a perfect driver for a design like this. I’m wondering if I should switch the pa’s to these Home Theater drivers, what would I gain? SQ, smoothness, maybe better dynamics? <<<<<<<<<

Click to expand...

Before you jump in with comments on things like extension, I only run these from 80 to 350hz so I don’t care how low or how high they go, most of that is already covered in the drivers design. Efficiency? I only need them to play at normal movie listening levels plus a little more and that is already built into them as well and I have the power to back that up being on an outboard amp.

I’m just tryin to figure out if it’s worth the effort to change anything? Will my htm’s pro audio driver clash with a HT driver? Is the “all pro” design better?

My thought is…. (This is not relevant to the question) I would like to take all my pa460’s (6 of them) and stack them up in boxes between my LCR in 2-3cuft sealed boxes and use my HF’s as a low end driver for my mains, but I also don’t want to ruin anything in the process…. Just trying to clean things up in my room and use up some things I have laying around.

Hello fellow members

It's been a while since my last visit... but none the less, I've kept my self busy with the several project I have.

I was wondering if anyone here could help me out, I'm repairing one of my vintage CD Players (Pioneer P-D1) and would like to know the manufacturer and part number for the optical block...

Thanks in advance and I hope everyone is well.

Stay safe!

Tested and reguleated at 320V /50ma prefix.
Original kit .
Pm please.

I have a question about a subwoofer I am planning to build in a 350 liter cupboard space in the corner of my room (15 x 3.5 feet). The idea is to make a transmission line of 3 meter with a target of 30 Hz. I have four small 6 inch woofers (Sonic SLE 60/120), old and no specs, I only know they have a high QTS of about 0.7 and a Fs around 30 hz. The four small woofers together have a 400 cm2 total surface. Could this work? What are your thoughts...

About 20 years ago I bought a pair of the original version of PMC's DB1 loudspeakers, from a local hifi shop which has since closed.

Over the years I've really enjoyed using them both for recreational listening, as well as for more critical recording and mixing purposes. I've also driven them to extremely loud volumes on the odd occasion, but never for long and definitely never to the point where I could hear any strain put upon them. These speakers have done sterling service, hence I'd like to replace the broken parts and get them back to good as new condition.

I recently let a very close friend use them when I was away for work. They conceded that "partying" got out of hand, but that the DB1s did a great job turning my front room into a dancefloor, with a solid 12+ hours of duty pumping out loud trance and hard techno.

I've no idea if was that which took its toll, but I was told that once folks had calmed down and started coming down - the deep organic bass from tunes like Spiritualized's epic Come Together and Cop Shoot Cop was turned up sufficiently loud to horribly shred one LF driver, whilst presumably burning out the voice coil on the other (which no longer works) before any physical damage could appear.

I contacted PMC direct, but was shocked to find that once VAT and shipping are accounted for, they charge nearly £500 just for a pair of their replacement drivers!

I originally only paid around that amount for these fine speakers. The manager offered me an extremely decent discount on his lightly shop-soiled pair of the hifi version, explaining he'd only sold the regulation black studio model since their release.

I've found threads here that suggest the correct replacement drivers are Vifa M13WG-08-09, but outside of buying a fully functional used pair - I've had no luck locating those replacement drivers anywhere.

The closest I've come is an Australian vendor who offers the M13SG for around AUS$90 each, before shipping, taxes etc. My understanding is those drivers are replacements for the DB1 models with the S suffix, denoting the magnetic shielding required way back when we still had huge CRT televisions. I'd be happy with that option at a fair price, but I'm located on the UK mainland. These would have to be transported from Australia...the irony of which nevertheless still makes me chuckle!

Can anyone here help me find some version of the correct LF driver for a DB1, that doesn't involve shipping them half way around the world, or paying the high prices that PMC themselves demand?

Has anyone else who is invested in PMC encountered a similar situation, either with the DB1 variations or another model? If so, were you able to buy replacement drivers at a reasonable price, or forced to pay the high prices charged when buying from PMC themselves?

Any and all help and advice will be gratefully recieved!

Howdy everyone,
I have a pair of old ESS AMT-5 speakers that I'd like to improve reworking/changing the crossover and/or adding a mid driver.

I know, they are not very good speakers.
But they have been purchased almost 50 years ago when I was born by my father & grandfather.
For me, they have an immense sentimental value.
They have been with me since ever; I started listening to music with them and they are still today my PC bookshelf speakers.

The woofer suspension foam, like I believe almost all very first AMT-5, got rotten about 25-30 years and my father got them replaced.
Not sure what was put in but they are still working very well, I assume same or equivalent to the original.

Unfortunately, the only person with actual deep knowledge in Europe about the AMT-5 was Mr. Hoffmann and he passed away last year.
I've been an idiot, I've been living a few kilometers from him for years and I always postponed the call.
I knew he was doing often a rework adding a mid driver with excellent results.
Can only blame myself, carpe diem...

It would be great if someone with knowledge of the Hoffmann's mod could share the details, maybe I could try to do it by myself.
But I don't have much hope to find someone that actually did it and knows the details. It's a very long shot...

I also don't have much free time to spare for such a project.

What I'd like to do in the short term is to rework/replace the crossover.
It has been always quite bad and clearly the components are in a messy state of degradation after almost 50 years...

As a quick win I'd like to just replace it with an already assembled crossover, like a Dayton.
But I don't remember so much, last time I've built a speaker was almost 30 years ago.
I'm not sure what could be right or not.

I see that mostly all these crossovers, if they support 4 Ohm, it's only on the woofer.
The Heil AMT tweeter is, for what I've read, a 4 Ohm.
I've seen some other tweeters, also AMT, and they are all 8 Ohm.
Not sure if I'm wrong but I have the impression these crossovers are meant for 8 Ohm tweeters.

Also I don't know if it could be better to move the crossover point from the original 1500 Hz or keep it.
And if it could be moved a little bit higher, up to which point?
I use them in a small room at a very very conservative volume level.

Any help would be really appreciated 🙂

Otherwise my backup would be to just take out the original crossover and replace the original components with something new and better.
But I'd really like much more the quick win solution and then plan how to make them 3-way.

Thanks a lot in advance!

Too many headphone amplifiers, so parting with this one.

This is a downscaled version of the legendary F5 power amplifier by Nelson Pass, the amplifier circuitry is the brainchild of EUVL.
I do my entire listening with two other amps (DAO and UTHAIM) that are wired for a Lemo connector, so the F5HA gets too little
use and is too precious to just sit on the shelf.

This is an all FET amplifier schematic based on the Toshiba 2SK170BL and 2SJ74BL complementary pair as front end, output devices
are either the popular IRF9610/610 or Fairchild. Those really interested please read up on my little webpage (www.original-ton.net)
or on the thread here on Diyaudio. Semiconductors are matched to better than 1%, the power supplies are so called Nazar regs
delivering +/-15V.
The amplifier also sports an active crossfeed circuit (4 more 2SK170BL) powered by a pair of super regs that are absolute overkill here
but were at hand at the time. Custom made and double shielded toroid wired for 230V mains voltage, but with two primaries so could
be rewired for 115V mains.

All cased up in a totally custom and massive case weighing quite a bit..please consider heavier shipping costs (probably 8kg...16lbs).

Of course working flawlessly with the signature sound of a minimal parts count schematic using genuine Toshiba semiconductors, drives
almost all headphones (mine are Focal Clear, Senn HD800 and AKG K550) with no noise.

No need to say that this one is absolutely unique and 'one of a kind', so coming up with a price it not easy.

600$ OBO plus shipping from Germany

Hello,

i wonder if someone could help me on this regulated psu. I purchased a while ago a Vincent SA-93 Preamp. My plan is to replace the OP Amp linestages with a descreet class-A linestage, but i need plus-minus 20-24ish Volts. Originaly symetrical 15 Volts are the output.

I asume that D109/D110 and also R140-R138 / R149-R151 "clamp" the LM317 and LM337 into plus/minus15Volts. Changing these values coult also change the railvoltages up to 20-24 Volts?

Hello,
I want to build the coax output circuit (D) found on page 22 of the attached service manual of Pioneer PD-S507 CD player. My unit does not have coax out; I want to add this circuit so I can connect it to my DAC's coax in (toslink is already occupied).
L334 is listed as PTL1003 but I can't find this pulse transformer anywhere or any info on it.
I'm not good with digital circuits and would appreciate your help where to find such transformer or what specs should an equivalent have.
Also, logic converter IC331 TC74HCU04Ax is not available at Mouser or DigiKey. I can get TC74HC04Ax. It seems to be the same. Would you know how these 2 differ and if they are interchangeable in this circuit?
Thanks,
Bill

Hello all, I'm looking for the service manual or schematic for this unit.

I had a blast in my one day visit. I was up for about 22.5 hrs pillow to pillow.

I took some photos of some of the more notables I experienced... in no particular order.... Forgot to others...

I liked the new Seas carbon fiber drivers. See more info in the Seas thread...Regretfully, I did not snap a photo.
Troels Ellipticor 4 ways were also present (shipped in by SS) but I only heard those at low volume.

I did not snap a photo of CSS Typhon ($5.5k), but those really sound great.

PE is soon to release a new speaker line called "Signature", that has been in the works to fill in the gaps left by Tymphany Peerless as they slowly MOQ into OEM only territory. They are close copies of the HDS frames with a different mounting ring. Performance has been Klippeled.

The Estelons were HUGE, like 7.5 footers. I had no idea they were that big. ($200k+) They sounded very good.

The Xylon Yamahas ($15k) were one of the better sounding pair present. I got to see the dome drivers and their tuned chambers, as well as the cabinet cutaway, damping tube, and xovers.

The BAYZ "C-tubes" sounded ($160k) excellent as well. A pair of Satori 9.5 woofers, and a tubular AMT between them really integrated well, and were very dynamic. I spoke with the designer and inventor of the tweeter/speaker to glean how it operated. Very well done!

MoFi 8", the new model ($3k) were present. I did not get to hear the 10 ($4k) Wow. These really are the stuff. Controlled, focused, and clean. If you purchase a commercial pair out there, these are worth the asking price and more. Andrew Jones has delivered the goods here, and I like them more than anything else I have heard from him in the past.

Triangle Art had a speaker called Metis, with an AE 15", a Beyma TPL150, and an unidentified horn loaded wide range for the mid. The clarity in the lower mids was really good, and the speaker as a whole was no slouch. I think they are meant for near wall placement, as they were basically setup that way.

Goble speakers sound very dynamic and clean, but you'll need a forklift to move them. I was surprised how good they sounded.

Clarisys dipolar panels really need to be seen and heard to be believed. I heard the 'little' ones yesterday ($33.5k), and they are so clean and transparent. I heard the Auditorium ($140k) edition a few years back, and the bass those were capable of was astounding and made the large room shudder.

Several ATC models were present and I really like the 3" mids every time I hear them. The powered 100 was quite good, but i felt the driver integration was just shy of where I prefer. The handoff was noticeable mid to tweeter. I think it was the 50 I felt lacked bass warmth, and the 11 was was good. The 11 would likely benefit from a larger cabinet as well as a slightly larger or lower capable reaching tweeter. I'm critically splitting hairs here, as they all sound good.

Another company I had not heard of that was pretty darn impressive was these. Korean source, and used 32dB/Oct elec slopes. The 4ways called Nostalgia Jr really impressed me.
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Please see attached photos...

building sub because mains are distorting bass but not sure how to prevent bass from going to mains and still producing the same distorted sounds. My amp does not have sub out just line out so all speakers are getting same signal I think. Do you have a specific product recommendation for a novice. Thanks

I have a fair amount of NOS/Old stock tubes that have all been recently tested with a uTracer curve tracer.
This is a tentative list of tubes available, please inquire about a specific item for price and pictures.
Price will depend on actual tube condition/measurement. I have researched prices extensively across all the usual dealers and can guarantee a better price.
Each tube costing over $20 will come with a detailed measurement print out (if desired)
Feel free to ask about other stuff you need that is not listed.
Matched pairs are marked with (MP)
-------------------------------------------------------------------------------------

D3a (MP) Valvo. NOS in original boxes. (10 matched pairs available)

12AU7 (MP) RCA Cleartop. USA. Side D-getter (2 pairs available)
12AU7 (MP) Mullard. Blackburn/UK. Long Plates.
12AU7 (MP) Westinghouse. Canada. Long Black Plates, Halo getter
12AU7 (MP) Westinghouse. Canada. Long Black Plates, D-getter
12AU7 Mullard. Blackburn/UK. Long Plates.
12AU7 Siemens. Germany. Nickel plates (2 singles available)
12AU7 Misc. Tung-Sol/RCA/GE/Sylvania/Phillips/other made in USA/Canada/Japan
CV491 Mullard. "Gf2 B"

12AT7 (MP) Siemens & Halske. Germany. Telefunken label, no diamond.
12AT7 Telefunken. Germany. Diamond bottom (2 singles available)
12AT7 Mullard. Blackburn/UK. Knight label
12AT7 Amperex Bugle Boy. Heerlen/Holland. Foil D-getter
12AT7 Sylvania. W. Germany
12AT7 Misc. RCA/GE/other made in USA/Canada/Japan

12AX7 (MP) PSVane. China. Gold pins. Comes in decorative box
12AX7 (MP) RCA. USA. 1960s (Singles also available)
12AX7 Telefunken. Germany. Smooth plates, Diamond Bottom. (2 singles available)
CV4004. Mullard. Box Plates, Mitchum plant. (3 singles or 1 single and MP)

6922 (MP) RCA. USA. Gold pin.
6DJ8 (MP) Amperex Bugle Boy. Holland/Heerlen.
5842 (MP) Amperex
5842 (MP) GE/Amperex
6C45-Pi (MP) Reflektor. Russia

EL34 (MP) Svetlana Winged =C=. Russia.

6L6-GC (MP) Phillips ECG
6L6-GC RCA. USA. Black plates (Single)

EL84 (MP) Telefunken. Germany. NOS in original boxes
EL84 (MP) Amperex. Holland/Heerlen. Hammond labels
EL84 (MP) RCA. USA.
EL84 Misc. singles. Mullard/GE/RCA made in UK, Germany, USA and Japan.

5U4GB GE or Phillips (3 3 available)
5Y3GT RCA. NOS made in UK (2 available).

Saw this today and thought some you people might be interested..

https://en.kunststoffe.de/a/special...SybTHjqr&sc_llid=1302&sc_eh=89d3c0bcaf71b76e1

I have a 5.25” mid-woofer driver and a 8” passive radiator. Also, I already have a 0.75 cu.ft. sealed enclosure.

If I build a subwoofer with these existing components, will it work fine?

I mean the sub will be passive radiator system with a 5.25” active driver and a 8” PR driver in a 0.75 cu.ft. closed box.

My concerns are:
1. Will the 5.25” active driver be capable of driving the 8” passive driver? In other words, is the 8” passive driver too big for 5.25” active driver?
2. Is the 0.75 cu.ft. enclosure too big for 5.25” active driver?
3. How much stuffing should be used in PR system?

The parameters of each driver are below:
1. Active driver
fs = 68 Hz
Vas = 0.23 cu.ft.
Qts = 0.45
Xmax = 6 mm.
Imp. = 4 Ohms
Power = 65 W

2. Passive driver: DAYTON DSA-215 PR
https://www.daytonaudio.com/product/1591/dsa215-pr-8-designer-series-aluminum-cone-passive-radiator

I've never done a speaker replacement before so trying to cover my blindspots by coming here.

Here's what I know and am thinking.

Faceplate
100mm faceplate. The hole pitch is 90mm but I guess I don't have to reuse the existing holes.
I could go bigger and forego just reusing the existing lip, but then I imagine I'd need a gasket of some sort. There is room for up to say 110mm, maybe a tad bigger.

Opening
The cutout opening is 80mm, making the lip 10mm. I could drill holes or cut space in the lip for connection leads if I had to.

Original tweeter
The current tweeter has a 26mm dome voice coil and dual magnet.

The system
It's a two-way system with a crossover and the input is labeled as having an 8-ohm impedance.

Having a hard time finding a nice drop-in replacement. And I don't know how to prioritize trade-offs well here.
I don't know the original wattage of the tweeter either and not sure how important that is.

Any insights or options appreciated. Thank you!

Hi,
we are looking forward to a 1:10 high-voltage step-up transformer. The application is in a physics laboratory.

The input(primary) will be driven with up to 150V from this amplifier: https://www.falco-systems.com/High_voltage_amplifier_WMA-300.html
and up to 1.5kV is the desired output voltage.
The load is a high impedance sample of a least 10MOhm and we are working typically between 500 to 20-30kHz.
It would be great if a specialist out here could give me a suggestion.

Thanks
GM

I need to stick some new drivers in a pair of Castle Severns.

Usually I'd go for Monacor - and most people recommend SPH-135AD as being direct replacements. Just came across the FaitalPro 5FE120 as a potential replacement - much cheaper than Monacor and the numbers don't look too bad


Anyone any ideas if FaitalPro speakers are any good?
.

I have an FET 10 / HL I just picked up. For the first 3 minutes of operation it will have a high pitched "squeal" from the right channel. Not 60 or 120 Hz hum, this is a higher frequency. It does not change with input or input selection, volume, balance or any of the signal distribution (tape deck) or signal mode (stereo, mono, reverse) settings. I've been reading several threads here on the FET 10/HL and plan to do a cap swap but wanted to take care of this first. Attached are a few pictures as it seems there are a few variations of this unit.

Hear the "Squeal" here:
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Any ideas to remedy this would be appreciated.

Also, if anyone has a schematic of this particular FET 10/HL, I'd love to get a copy. I've downloaded a few from here but none seem to match.

Thanks for the help.


5/19/23 (THE FIX IS ON PAGE 2 OF THREAD)

This is way off the cuff but we can't understand what's going on. In his tv room, my son has an older Sony CD player hooked up to an amplifier (used both an old Onkyo integrated and presently a newer Marantz). He is an opera lover so he plays opera on the CD player and if he listens in a long session, the next time he turns on his amplifier not always but often, the opera music starts to play where he left off and the CD Player has yet to be turned on and even if he removes the CD from the player that isn't turned on. Can anyone explain this phenomenon. When he told me that I laughed at him so when I visited him he demonstrated and sure enough it happens. The CD player is only hooked to the amplifier through the rca plugs and are powered from the same power strip but separate plugs. If anyone can make a semblance of sense out of this I would appreciate it.

Rogers AB3a clone for the ls3/5a


Hi! Got a vintage Rogers LS3/5a in transit, I’ve heard this speaker before and they have excellent mids but are lacking in the critical 60-80hz bass region for kick drums.

Came across the Rogers Ab3 and I don’t think the price tag is justified ($4000++ WTF).
ROGERS AB3A

I do like the idea of of a bass unit that can also serve as the stand of the LS3/5a since my space is quite limited but due to the size of the driver it can accommodate it would be a stretch to call it a subwoofer. That is okay though since I would just like to hear a proper kick drum and don’t feel the need for subterranean lows nor high spl since the Rogers are not amenable to being driven to deafening levels.

So. Is it worth it to clone the AB3a?

Seems doable as I plan to make a passive version with and just have a minidsp and a Plinius SS amp to drive them. I can probably track the B110 woofers via ebay and have a carpenter build out the sealed cabinets.


But it says on the Rogers site that it’s a “special” doped version of the b110 woofer (doubt it) to give it bass.


So my question is: with the AB3a dimensions (H 23.62” x W7.48” x D6.5”) would I be better off just using a more modern woofer in a sealed enclosure or should I just stick to using two pairs of B110 woofers like the ab3a.

Any driver or build suggestions? Would want to maintain the dimensions for aesthetics and space and the thin wall sealed construction of the AB3a


Thanks!


PS: Also aware that the plans for the AB1 passive (the ported one woofer predecessor of the AB3a) are floating in the internet and that is also an option, but I think I will have better luck with a sealed implementation to integrate it better to the LS3/5a for when I want to listen to rock music.

Hi all.
Does anyone have schematic diagrams for an Akai AM-26 Stereo Integrated Amp.
I've searched the internet with no luck.
Only found AM-25 and AM-27

Cheers, Mark

I have a chance of getting a 12" cube of elm from a barn beam. I was thinking of mounting an old console FR driver to make a funky tabletop speaker for a mono setup. I don't have any power woodworking tools, but my brother-in-law has a router and a Porter Cable circular saw. Anyone have any ideas on how to bore a 7" hole in a 12" deep block of wood?

Greetings,

I have a mint silver/gold Denon DVD 2900 230v unit and I have a broken 120v unit that powers on.

Although not technically DIY to the letter, is it possible that the power supply boards between the 120v and 230v are the same, and will “auto-sense” the incoming voltage?
I was gonna swap the two power supply boards, then noticed that they have exactly the same part numbers, but data tags on the back of the units specifically say 120v and 230v.
Photos of the two boards are attached, and there’s a little strip of paper identifying which is which.

Thanks in advance for any help!

Nice clean attenuators, used in my last stereo preamp.
1 x DCP-322-P Dual Channel / 20K / 1.5dB per step -> 28.5dB+off
2 x SPEC 4097 Single Channel / 50K / 1dB per step -> 19dB+off

Make an offer.

Will ship within CONUS

Planning to sell my Korg B1 to build other stuff which I have not been using since few months now. Used all high quality parts (Dale RN60 resistors, Nichicon/Elna Silmic II caps) and had got the board + transistor kit from the store. Made a custom aluminium plate on the back side to hold the DC socket in this nice beautiful chassis which is pretty heavy and sturdy for the Korg. No hum/hiss issues in the build as well as no microphonics. Have used a spare 20k original Alps potentiometer and more than enough for most sources. Also using the filter board kit from the store along with the Meanwell 24vdc 0.75A rated power supply adapter. Can be shipped within the US at the actual shipping cost (USPS flat rate box) but would prefer local pickup or close drive/meet-up near 60564, IL.
Please PM me the offers.

Purchased directly from Burwen along with matching plug-in boards for easy/safe soldering. Currently, the boards have the passive elements for a 47k MM phono stage. This is the device used in the original Levinson LNP-2.

Make an offer.

Will ship to CONUS.

Looking for the below voltage regulators from On Semi...

On Semi LM337/LM317

MC7815ACTG/MC7915ACTG

Received and installed in a single-ended pentode first of April. Painted as close as possible to Edcor Blue in Krylon True Blue. No more than 5 hours on. 125vAC Primary, made 450vDC B+ no problem. Now no longer needed.
Shortest Primary lead is 5 1/2", others uncut. Shortest Secondary lead 5 1/2", others longer.

Primary VAC Universal - 100, 110, 120, 200, 220,230, 240 VAC 50/60 Hz A.C. High Voltage Secondary RMS 750V C.T. @ 201ma. Bias Tap on High Voltage Secondary w/ C.T. Grounded (VAC) 50 Filament #1 (VAC) 5V C.T. @ 3A Filament #2 (VAC) 6.3V C.T. @ 6A Mounting Style Vertical ("X")



New price $151.40, Asking $95.00
Buyer pays shipping from 28704: 10 lbs., 8 1/2" cube original box and packing.
Paypal or USPS Money Order
I have Audiogon and Ebay feedback as Kitch29

I have an ESS Eclipse 2241am 2-way electronic crossover unit for the AMT-1am and AMT Monitor loudspeakers. It was manufactured with an 800 Hz crossover point at a 12dB per octave slope. After reading numerous threads about the monitors sounding better if crossed over at a higher frequency, I would like to change cap and resistor values to try crossing over at 1kHz and 1.2kHz. In later versions of the AMT Monitor, ESS had raised the crossover to 1kHz. Can someone kindly look at the attached schematic and calculate values for 1 and 1.2kHz? ESS no longer has schematics for the revised 1kHz version. Thanks so much in advance.

Rick

Hello!

Class AB amplifiers are gradually being replaced by class D amplifiers. More and more old AB amps are being thrown away. But this is toxic waste for the environment. Alternatively you can significantly improve the sound quality of the first watt and keep using the old amps. The circuit is in the appendix. You can make from it a piggyback-board. It is connected parallel to the bias network. But before that, set the quiescent current to about 1A. After connecting the piggyback-board, set the quiescent current to 20mA with the potentiometer P1 of the piggyback-board. And that's it. When the small audio signal comes, the quiescent current increases to 1A and the amplifier works as class A. If the output power is more than 1 watt, the quiescent current drops and over 10 watts is less than 0.1A. And it continues to decrease at higher output powers.

Kind regards
Walter

Any one have a use for these goofy things?
$30 shipped a piece, but would like to sell more than 1 obviously.

I’ve finished building my first 2 subwoofers earlier this week.

While setting everything up I’ve made a (dumb) mistake. I forgot to plug the power supply into the amp. I realized this after turning everything on, and then (stupidly) went on by just plugging it in.

This was followed by a “zap” sound coming from the DC jack of the amp. According to google, that might’ve been a power surge..

Now one of the subs is producing distorted sound. Everything else (the other sub, both channels
of the amp and the power supply) seems unharmed.

Now to my question: Given the information, how likely do you think it is that “zap” killed one of the subs, but not anything else? I don’t know if it worked before the incident, as this was the first time powering them on..

I’ve measured the resistance of both subs, and they are within .1 ohm of each other, 4.5 and 4.6. Reference of the speaker is 4 ohms. So I don’t think the voice coil is completely fried…

Thanks in advance

Edit:
Amp: AIYIMA A07
PSU: 48V 7A (https://www.audiophonics.fr/en/hifi...-supply-100-240v-ac-to-48v-7a-dc-p-14749.html)
Speakers: Dayton RSS210HF-4

I'm going to DIY a pair of floor-standing speakers from existing parts. Here is the part list:

Cabinets: ADS L1290/2
Midranges: 5 1/4" Boston Acoustics Pro 5.0LF
Tweeters: 1" Boston Acoustics Neo 1t
Woofers: 8" Boston Acoustics Rally RS8
Passive Radiators: 8" Dayton DSA215-PR

The L1290/2 cabinets consist of two chambers. They are actually the stack of two sealed enclosures. My plan is I'm going to use the upper chamber as a passive radiator system and the lower chamber as a sealed system. The midrange, tweeter, and passive radiator will be mounted on the upper chamber and only the woofer will be mounted on the lower chamber.

Crossovers for midrange and tweeter are complete units of Boston Acoustics Pro 5.2X. Crossovers for mid and woofer are none as the 5 1/4" Boston midrange will have to drive the passive radiator. Crossover for woofer (low-pass filter) will be a simple second order crossing at about 300Hz.

I'd like to ask everyone's opinion. Do these Franken-Stein speakers seem to sound alright? This is my very first time playing with passive radiator. I'm not sure whether the passive radiator and sealed system are fine to work together. Also, the 5 1/4" midranges are capable of driving those 8" passive radiators, or not? Advise me, please.

Edit: drawing of cabinets

Just bought best 15" musical bass speaker Dayton sells. Guys there seem really knowledgeable and helpful but i'm getting very different recommendation on cabinet size depending on who I talk to. One Dayton ad said 8.7 cubic feet for ported box. But one sales guy said that was old school and would not work. 3.8 cubes was ideal. Each guy had it different with reasons and apparently full use of bass box pro and the win... something free on net. Does anyone have a recommendation on how to proceed without me having to get involved technically? Thanks

Just want to ask you experiance people.

Whats the "most" honest/correct metod/way to mesaure when you use a big 15 inch driver from 150-600 hz, and have 44 cm between lowmid and midrange (600-7000 hz) , and also 28 cm up to tweeter ( 7K and up) ?

So i have 72 cm from center 15 inch lowmid up to center "tweeter".
obviously I can't measure from 1 meter & have the microphone between center treble and center mid range ( as i use to)

Is 2 meter enough and should i put the microfone between the tweeter and lowmid?

Best regards John

Hi folks,

although i live in austria where those desks where manufactured, i am unable to obtain the service manual.

I bought 2 desks from the austrian broadcast cooperation - they dont have any documents left because the tech department dump everything as soon as a device is not in duty anymore. 🤦

those where high-end, high priced console - only a few hundreds where manufactured - there is not much info or other users out there.

to keep this wonderful thing alive and maybe expand the working console with a few channels from the spare part console i need those documents sooner or later.

appreciate if someone could help.

i posted this on gearspace also.

thanks&cheers,
george

Hi,

I have one CA 540A v2.0 with a malfunctioning PIC, and I need the software 640AV2.hex to program a new PIC.
Can anyone help me with this ?

Thanks.

Hi,

I have a B&W PV1 that has decided to not power up properly anymore. When you turn power on now, you get a thump from both drive units, then the red LED turns blue and the electronic control display comes on, then another thump and display goes off and led goes to red again.. this then just keep cycling in this state until you remove power..

Has anyone ever come across this before and have any ideas how to fix the problem?

Thanks

Hi Folks, can anyone tell me attached circuit where the front end and driver stage SK3566 able to drive KT150, certainly I will modify t to fixed bias as - 48v.

The voltage specification for AES3/EBU is ±2V to ±7V (revised from ±2V to ±10V), this is needed for diving the cable. How could this be dropped to 0V to ±5V at the receiving end without causing damage to the signal? The drop wouldn't result in data loss, it's still a difference of ±5V, but would be more usable by μCs, FPGAs, and so on. I'm sure this is commonly done, but usually in ICs. I want to make my own receiver because every receiver IC I've used has problems/errors with it. Even the suggested pre-IC circuits are often incorrect. The specification sheets for AES3/EBU are very sparse and incomplete. Maybe a different transformer ratio (1.4?) would do the trick, but would probably need to be custom made, and for now I'm only going to be making about 10 units, so that wouldn't be an option. Maybe there's a different translator that I can use that I'm not aware of? I must use a twisted pair (CAT5) for my application, the other pairs are used for other unrelated signalling, so I can't use something like S/PDIF. Conversion to optical may be an option at the receiving device, but I think in the EBU specification, transformers are mandatory. I wonder if a galvanically isolated digital isolator qualifies as a transformer? Many can handle ±7V inputs. Some are too slow though, so if you use one instead of a transformer, take note of the speed!

I imagine that the same or similar method I'm looking for would also be applicable to "upshift" the signal for a cable driver?

Just a side note, this will be used in both consumer and professional applications (switchable).

For sale 2 NEW, NEVER USED Dayton Audio RSS390HF-4 15" Reference Series subwoofer.
Bought for a project that will never become true.

91,2 dB
Fs 18 Hz
1000W max

NEW in their original package, one was opened just for pictures. The other one was installed in a test box but never connected, played or measured.

Price for each is 350€ right now, 700€ for the pair.
I would sell the pair for 430€ +PP fees + Shipping.

I was trying to build a fullrange sealed box with the volume of 30cm*30cm*115cm.

However, I have found threads on enclosure dimensions, pointing out:

'if the length of an edge is excessively greater (3 times as a rule of thumb) than the others, the box will act as an ML-TL, instead of behaving as a sealed box.'

is this phenomenon caused from standing waves within the enclosure?

as a humble hobbyist, I am quite not sure if I have understood it correctly...

if it is, would my enclosure design work properly as a sealed box, if I put in enough stuffing, to suppress the standing waves?

judging by the Boxnotes simulation, I assume that fully (in theory, as bass absorption would be a tough task) absorbing sound waves within the enclosure from 176hz and up would eliminate any unwanted resonances caused from standing waves... but I am again unsure of whether I understand how all this works.

I was intrigued by this circuit (post #123) from forum's member Joe Berry - a novel use of Q7 (schematic below) which enables: 1) a better circlotron symmetry with single-ended input and 2) thermal stability of output HEXFETs' bias without source resistors.
And it does deliver. In my (adapted) circuit the output stage bias (set with P2) is 300 mA and it changes 20 mA for a temperature change of 40 degrees Celsius. I tested the prototype for two weeks and it behaves nicely (DC offset on the speaker is set with P1 but it wanders +/-30mV - I guess some thermal coupling should tame it).
Leaving the HEXFETs' source resistors out is really a game changer - the inevitable HEXFETs' "grain in the sound" is still there, but lower in intensity and different in character. Now it sounds like it's part of the ambient, reminds me of that analogue feeling of good vinyl and reel tape reproduction and, most important, it doesn't get in the way when listening to the music - I was able to listen to complex orchestral music for hours without complaints. Changing the OS bias to 1A brings the minuscule change in sound.

Congrats Joe Berry - your idea works lovely ! 👍

I changed the PS voltage to 2 x 20V (that's more than enough power for my needs) and the output devices are IRFP044N (Vgs=4.65V @ Id-0.3A). BF862 runs on 2.5 mA and BC560C flows the Ic of 9mA, so the values had to be adapted. I got the output stage bias of 300mA by connecting the 2k7 parallel to R1 but P2 changes it in wide range - start setting it with max. value of P2 (that gives lowest bias). It's worth mentioning that the amp is very silent - the background is pitch black, no hearable noise at all (speakers are 93dB@1W sensitive and the total PSU capacity is 64000uF - 0R1 between 22ooouF and 10000uf is not much of a filtering help but it allows easy bias measurement).

Pics show:

• schematic "as built"
• the point-to point built prototype
• 20 kHz into 4R
• 20 kHz into 1uF+4R
• 95 kHz into 4R
• hard clipped 20 kHz sine wave, into 4R

* EDIT 11-Jul-2022 :
Link to Joe's explanation of circuit's inner life, post #72

Hi everyone .
where can I find material to read to understand more about equalization ?. but something that starts from scratch because
I know very little about it , I would like to put ideas in order and remove confusion .
hardware , digital , diy , proprietary .
it's easy to get confused.
Thank you

I was sent the wrong bit the first time. I need a top bearing cutter with a 1/4" shank. Does Freud even make them in this size? An online catalog wasn't very helpful, its for a store not by Freud.

Amazon has some cheap looking one in 1/4"

Is a small 6 amp router but I only intend on cutting 1/4 plywood with it. I cut a lot thicker material with it already.

Do anyone know the oscillator frequency for the TL494 or the value for the timing capacitor (pin-5) ?
Timing resistor is 10K (103 smd - pin 6).
similar amp maybe Excursion KXA-1K.

Why does the 3.5" still sound like it's way too loud?
Is this why my EQ looks the way it does my whole life? With what I guess are flat FR speakers 🤔
I can literally just listen to a ScanSpeak 22w or 26W by itself and barely miss a mid or tweeter.

Also: should I build:
XT25 + RS52 + SB23
or
TG9 + SB23

I was also thinking 22W (which 1 now has a dent) + TG9 (or with RS52 + XT25
or
ScanSpeak 26w + TG9
or
XT25 + SB15 + 26w (box will be big)

The TG9 is 8 ohm and the SB is 4 ohm and the TG9 is still loud.
Am I a bit silly or is almost every one else? 😳 🤣

or 22W (which 1 now has a dent) + RS52 + XT25 (pics attached, yep I got one baffle/woofer offer by 1"/25mm 🤣)

Hi guys,
Long time reader, first time poster... LoL
I have an excellent little Forte 1a amp that I keep around as a spare sense I replaced it with a Threshold SA 3.9e in the main system. BC I can get another one of these Forte amps pretty easy I got to thinking, could you convert this amp to a class A monoblocks?
I've seen some 200wpc class AB stuff get converted to 50wpc class A but I haven't seen a lot of class A stuff get converted to mono's.
I am no EE so the schematic I found for the amp looks like hieroglyphs to me so hopefully one of you smarter gents can look at it & give me your thoughts 😉
Thanks!

Channel One Sound System in England

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I got turned on to these guys at a party. Who else would like to set this up in their back yard?

This is a pretty large transformer. Probably about 400 or 500 VA. 6 secondaries which can be combined if needed. Pulled from a six-channel amplifier.

Input 120v 60hz

Output 21.4v---0---21.4v

$15 plus shipping