What is the difference between the D amp chips?

Is the CS8673 inferior to the TPA3116?

I cannot read Chinese Data sheet - who can say something on this chip?

@Karlsonate gave me a hint:

https://www.diyaudio.com/community/threads/unboxing-zk-mt21-tpa3116.403857/post-7467281

Some subjective comparison between mini amps:

https://www.diyaudio.com/community/threads/unboxing-zk-mt21-tpa3116.403857/post-7501910

SOLD
Used lightly and limitedly for various applications/experimentation.
Reboxed and ready to ship

Shipping:
€16 within Ireland
€30 to a few of the nearest european destinations (UK, Germany, France, Netherlands, Belgium), otherwise very expensive.

Bob Cordell's Linear Audio Vol 4 article 'VinylTrak - A full-featured MM/MC phono preamp' led to a discussion that resulted in much additional material.
Bob has been so kind to place this on his website.

I'll shortly put up a link from linearaudio, but if you are interested in this stuff the additional material itself is well worth a read.

And, of course, if you want to reach out and actually touch the equipment (or Bob 😉) find us in the lobby at the RMAF coming weekend!

jan didden

Hello - I'm restoring a Dual CV40 amp to use with a Shure M95 G-LM cartridge (requires 47k input load).

I have a question regarding the modification of the resistive input load in the phono preamp (schematic attached).

If I understand correctly, in the set up shown, the signal sees the resistive load formed by the series resistor R2 and the parallel network of R1, R3+R8 (1.5k + approx 77k) - is this correct?

If I wanted to bring the load down to approx 47kohm, changing R1 to approx 53k should do the job?

Thanks in advance for your help!

Martin

There are a couple of these receivers listed on that auction site, but at prices a little higher than I'd like to spend. Do any of my fellow DIY'ers have one of these collecting dust that they wouldn't mind parting with?

I saw a post asking about a datasheet for an obscure component - that I happen to have. So I created an account and am currently jumping through whatever hoops necessary to actually help the fellow out.

Cheers.

Hi,

I have an Wadia DAC with broken VFD NEC FC20X2JA-AA. Does anyone of you know where to get one?

Thank you very much.

PhanTran

THESE BOARDS ARE SOLD. THANKS FOR LOOKING. These amplifier boards are the universal mount style from the diyAudio store. The jFets are original Toshiba 2SJ74/2SK170 that I had left over from earlier projects. They are matched. The IRFP240 Mosfets are quad matched with all 4 on a channel matched. Putting the funds toward an SET tube amp project.

The price is $50 plus shipping and I am shipping from Michigan US.

Hi diyaudio!

it's been a while since I've posted but I was wondering if any of you might be able to chime in on my latest research project.

Last time I was writing here I was looking for help on a hi fi amp i was building for my undergrad senior thesis. A few moves and thirteen years later I'm now a researcher at the Canadian museum of science and technology working to reverse engineer Hugh Le Caine's electronic sackbut instrument, which is part of their collection.

https://en.wikipedia.org/wiki/Electronic_sackbut#

My circuit analysis friend and I are a little stumped by the suggestion of a colleague that the 6as6 tubes in the oscillator section of the device are frequency counters: no feedback, no RC circuit with a time constant to flip flop a square wave at a defined rate. Just resistors:


I'm including two of the four stages. the caps on the left of the 6as6 stages go to a transformer coupled blocking oscillator. The output exiting left of the plate goes to a mixer-so the stages don't cascade. I really think this is just a buffer / gain stage to couple the aforementioned blocking oscillator to the strange resistive mixer that follows these pentodes.

I realize this is more of an amp forum than a synth forum, but since these pentodes really do look like a coupling stage to me (rather than a counter stage) I think we are squarely in the amplifier section of the tube circuit topology realm.

In short though - is there any conceivable way a pentode, wired like this or something like this (the circuit tracer may have missed something!) could act as a clock divider (e.g. take a square wave and output other square waves at ratios of the original frequency)?

Thanks in advance for your perspective, and let me know if there's additional info you might like to answer this more accurately!

Hi all,

I am trying to modify the attached circuit to use two parallel section of a 6922 tube for the gain stage instead of the 6GK5 while keeping the second 6GK5 cathode follower. In a previous version of this mod I had the two parallel section of the 6922 followed by a mosfet buffer and all worked fine.

The heaters are 12.6 DC regulated DC heaters with the tube connected in parallel. The original circuit had the two heaters for the 6gk5 on each channels connected in series. With the first tube a 6922 I can no longer do this as the 6922 and 6gk5 heater have different impedances and thus the voltage on each heater will not be the same. I modified the heater supply to feed two 6922 in series and the two 6gk5 heaters in series. both of these are connected in parallel to the 12.6v regulated supply. In doing so I am getting a high buzz on the output of the preamp. Music is playing and it looks like the voltages measure OK but the buzzing is very high. Any idea what's going on?

Thanks,
Ron

I'm the new owner of a Magnavox CDB460 (one of the models with a TDA1541 inside) that I picked up for $80 shipped. The seller said it "works great" but of course now that I've got it here, it won't read any discs. It wasn't packed super well, so something could have rattled loose in transit.

It powers on, the tray opens and closes, the disc spins, but then reports "ERR" on the readout. Interestingly, it does the same thing without a disc inserted -- motor spins for a couple seconds, then reports "ERR".

I popped off the cover to observe, and I don't see any light from the laser at any point in the process. I don't have a service manual, so I haven't broken out the multimeter just yet.

The seller is offering to refund 20% and let me keep it, or refund the whole amount if I send it back.

I'm a tinkerer -- I've cleaned and recapped a Marantz 2215b, I've put together a shortwave radio from a kit, and I've built some simple guitar pedals. I don't have any experience servicing CD players, but I'm happy to learn. Does this sound like it's worth repairing?

Another possibility is to harvest the relevant bits from this unit and put together a TDA1541-based standalone DAC for use with other digital sources. But I don't have any experience with that, either.

Bought a pair of these yesterday. Looking forward to restoring them. Having said that, they seem in very good condition. Does anybody have any information of these. When were they made, driver set up...? The 'condenser' I can see has '1943' on it. Surely, this isn't the date the speakers were made?

I want to build this circuit. My question is, are the two protection diodes no longer needed?
Thank you in advance for your answers.

Here are a few groups of things hopefully someone can find use for. Each group / item is priced individually with USA shipping included. I will give a shipping discount for multiple items purchased.

1) Twelve 25 or 50 watt wire wound aluminum chassis mount power resistors. If you cannot read the values, let me know. Asking $20 shipped.

2) Twelve Tantalum resistors, older Audio Note and Shinko: 1/2 watt: two @ 390R, two @ 1K. 2 watt: two @ 47K, two @ 100K, four @ 300K, asking $20 shipped. SOLD

3) Large cement 8 ohm leaded dummy load, 6 1/2 x 1 1/2 inches. 100W free air, 200W sinked. Asking $10 shipped.

4) Sixty older Kiwame japanese carbon film resistors, good to at least 750 volts. 46 @ 2 watts, 14 @ 5 watts, if you need a list of values, let me know via PM. Asking $50 shipped. SOLD

5) 4 or 5 - nines silver wire remnants with 20 gauge insulation tubing included: 4 ft. of 24 ga mundorf gold/silver alloy, 7 ft. of 24 ga, 4 ft of 20 ga. Also a spool of over 50 feet of 30 ga teflon coated instrumentation wire that now goes for 8$ a foot....Asking $50 shipped. SOLD

payment via Zelle or Paypal.

USA Shipping only.

61yo male from Athens, Greece. Mostly into vintage stuff.

Hello,

I'm looking into possibly using a compressor/limiter between my souncraft signature12 mixer an my F5m amp. I want to primarily use it as a "Brickwall' limiter to ensure the amp never sees more than 3V.

I want to be able to set a threshold voltage, in my case 3V as opposed to setting a ratio like 10:1 or 20:1 since that is less accurate. I'm also looking a solution which has short attack and release times. I rather not design my own hardware for this, but would be willing to build a DIY.

I've looked at Rane, DBX, Empirical Labs Distressor, Waves C4 and a few others but they are packed full of features I don't need or want. I just want the Brickwall limiter and not color the signal.

Does anyone use such a device or have suggestions where I can find a simple device with not so many additional features? ( I plan on getting a 19" rack to mount my amps and other related gear )

Howdy!

I recently acquired this non-functioning PA cabinet that I've heard awesome reviews about but have no way of using. After a deep dive into plate amps and DSP, I've decided to see if I can use a Fusion FA253 (250w, 250w, 100w triamp) to power this MTM 2.5-way cabinet. One of the two identical Celestion midbass TF1020's gets a lowpass at 250hz, the second one gets passed at maybe 2kh and the 1" horn picks up the rest. I'm jumping off the deepend but I think I have the gumption to learn how to measure response and EQ with REW and the DSP onboard the Fusion amp. I'll be using this for simple live solo gigs with guitar, vocals, and some low bass and kick percusion (one-man band) and am hoping I can make this thing useable.

As it is, it's obviously been designed to be midbass/top and to be paired with a sub if needed. My options forward feel like either:

A) return this cabinet to it's original internal volume and don't touch anything else. Design the crossovers/EQ to mimic what I believe to be the original specs.
or
B) modifiy this cabinet/porting to lower the frequency range as much as I realistially can and design the crossovers/EQ anyway, new drivers (lightweiht neos maybe?).

I've been trying to figure out what I can do with this size of cabinet. A rough measurement yields about 1.25cuFt internal volume after accounting for driver displacement/internal baffles/hardware. The depth of the enclosure will limit the depth of the port so that is a hard limit. My assumption is that Line 6 did a great job of designing this but they may have also limited it due to costs and or wanting to position it within their product line to be paired with additional subs and boxes. I'm just wondering if there's value in working within this canvas and eeking out more performance (in exchange for SPL, I'm guessing) or just going with what's already been done.

I'll be building and glueing in a sealed compartment where the plate amp will be housed (the original plate amp is not the same frootprint so I can't use the original cast insert unfortunately).

Is this absolutely silly? I've already bought the new plate amp and am comitted but I'm also handy with tools and could use this amp in a new build. I just really want to use this form factor and see what it could offer. Thoughts?

Here's a link to the original manual (product is now discontinued, btw)
https://line6.com/data/6/0a06434d11...e6 L3t Specifications - English ( Rev A ).pdf

Hello all, I have a curious issue I am wondering if anyone here has advice or a solution.

I am finishing the restoration of a Sansui AU-919, recap, removal of problematic black flag capacitors, etc. The amp is finished and working, powers up, comes out of protect, bias and offset on the amplifier working.

I have low volume distortion that I have narrowed down to the flat amp / tone control board that disapears when the volume is turned up. I have been chasing my tail trying to find the issue... there are DC Offset trimmers on this board. When set to 0V DC the distortion is present, when I tweak the offset to allow for 50-60 mv of DC the distortion goes away. I'm wondering if this might be a lack of power to some of the transistors that is keeping them from turning on...

Schematic of this board below. Any ideas greatly appreciated. Thank you!

I am using EXICON ECX10N20/ECX10P20 in an endstage. +/-16 Volt.

What would be the optimal adjusted quiescent bias for these transistors?
They are Lateral MOSFETs.

And do I use any gate resistors?
100 Ohm?
Or no resistors?

I decided to start a new thread on this amp as the other thread dealt mainly with replacing the AM-1, AM-2 sealed predriver modules.
So going back, I received this unit knowing that the owner mentioned it got wacked with over 130VAC during a storm and a power surge.
It took out all 4 front 6 amp fuses for the -50,+50 supply . He had someone look at it and some output transistors were blown on the right channel and then it was never finished and sat for 10 years. So I thought I would take a chance and see if I could repair it. As I mainly repair tube gear, I haven't really worked on any SS amps with this many transistors in it.
Not sure if anyone is familiar with this unit, it has a massive power transformer and caps creating -50, +50 for the power transistors and also feeding back to the predriver board and also +75, -75 volts also feeding the predriver board. Taking the power module apart is quite a task in these amps. You have to unscrew the predriver module( more on that later) , then there are 4 PC board which are soldered and have to be removed before getting access to the power output transistors. Then you have to unscrew each heatsink for 3 transistors.
Each channel has a pair of NPN feeding 4 PNP(-50) and then 2 PNP feeding 4 NPN (+50). The right far bank had 2 transistors removed (which had been worked on), and in a bag came with a few more NPN predrivers and a blown PNP and some screws.
So what I really should of done was just order all new transistors from Mouser/DigiKey On semi makes them. The part #'s on the original transistors are AR part numbers and here are their equivalents for reference.
300024(NPN) MJ15015
300025(PNP) MJ15016
300027(PNP)MJ15004
300028(NPN)MJ15005
There are total of 24 transistors in the power section of this amp. My mistake was to look for and shorted or out of spec transistors and replaced them. As only having a cheap transistor checker I got them as close as I could matched (hfe) and there were no shorts and more. I then got reading that a lot of issues were caused by the predriver board.

The predriver board consists of 2 sealed AM-1, AM-2 IC type modules which have quite a few transistors in it and cannot be purchased any more. One fellow on another thread(repairing the AR 110 modules) has designed some replacement modules to replace the AM-1, AM-2 units.
I verified that mine were ok and I had signal through both. After fixing the bad transistors I fired the unit up slowly on a variac and no shorts or smoke and voltages were ok.
I had gain in both channels . The left seemed a bit bit lower but with a 1kHz signal across a 100 watt 8ohm load , I scoped the outputs and sine wave looked good, but I had some neg DC offset, meaning some DC was leaking onto the speaker terminals. In some amps there are gain and DC offset controls to adjust this, but in these amps there are none.
Reading more, the DC offset in the output is most likely caused by mismatched transistors, or in reading the other post some of those AM-1. AM-2 modules could cause the neg offset.
I went over the output section again replacing a few more transistors and then somehow turning it back on I was getting the full -50v on the output. It looked like a short somewhere.
Well pulling my hair out I decided to replace all the outputs and now I have less than 20mv on each channel. One or more of the original transistors must of have been bad and not picked up by the tester until full DC power was applied to the output.

I have attached the schematics. I am now in the process of working on the predriver board with the new boards that another member designed.
I will continue this later, hopefully this helps someone else.You can get bigger versions of these schematics from the AR site.

Interested in seeing who is using any of these three tubes for a line stage, preamp or driver stage. Ale Moglia is a fan of both 46 and 47, see here...

https://www.bartola.co.uk/valves/?s=46
https://www.bartola.co.uk/valves/2020/07/25/300b-se-amp-47-driver/

I have also used 46 and 47, but not 49. The 46 is better sounding to me, but has a mu of 5.6 whereas 47 is 8. Same filament supply. Ale has used filament bias on these tubes despite the big heatsink and cathode resistors required, but gave up on it. I'm persevering with filament bias - it's always my choice where possible.

Here's a driver stage for my 2a3 outputs, with a 1:4 SUT for added gain. I also use a 10Y driver stage for the 2a3 but they're getting very expensive so I need an alternative as a daily driver. Big heatsink required for Rod's regs, and something like 100W metal clad cathode resistors.

I have a long history of hi-fi audio, I started with classic 80s stereo, then over time I moved on to heavy, esoteric hi-fi audio. I repaired the Marantz Cd94 with my own hands, opening and closing the CD tray, replaced the rear RCA flats - replaced the capacitors of the Carver M 1.5t and replaced the two RCAs for it too - repaired/replaced the ferrofluid of the T33 Tweeter of the Kef 104/2 - again for the Kef 104/2, made and replaced the donuts on the center of the Kef B200. I also built the boxes for the LS 3/5a with my own hands on BBC specifications to which I mounted the respective T27 + B110 + 15ohm crossovers.
and recently I created a hybrid Linn Sondek turntable with a Rega Rb250 arm which I then combined with a 21.5" carbon arm, on a rigid base, also built and assembled by me.

thank you

I have ~300 pcs.
Price 0,6 Eur + PP and shipping fees.
Only EU for now.

Siegfried Linkwitz wasn't happy with the how the energy from bass drivers in the Orion OB speakers caused the upper baffle to vibrate. To counter this, in version 3.2, he & his buddy Don Naples came up with a mounting bracket that holds the 8" mid driver by its magnet. The basket doesn't touch the front baffle at all; it only touches a gasket in the hole that the driver appears to be mounted in. The top baffle is still attached to the bass bin, so it doesn't eliminate all bass vibration, but at least reduces the vibrations reaching the tweeter from both the mid 8" and the woofers.



In the LX521, with a less well supported minimal upper baffle, he abandoned this idea. Instead the upper baffle is mounted on a completely separate structure that makes no direct contact with the bass bin. But the 8" low mid driver is mounted on that minimal baffle, and there's no question its energy, with a high pass @ 120Hz, still causes that baffle to vibrate. The "bridge", as SL called it, also looks inelegant and becomes awkward when you try to re-position the speaker -- there are 2 structures to be moved.

In the project for my friend Mark, I wanted to combine the Linkwitz-W-frame of dual-opposed OB bass (used in Orion v 3.3) with the magnet mounting scheme. The bracket would be secured to the heavy top panel (24mm BB + plate of supporting steel or aluminum), and the low-mid driver would not touch the upper baffle. The W-frame's dual-opposed bass drivers dramatically teduces the vibration from the woofers, too.

The chosen low-mid driver is the Satori WO24TX. It will cross at 110~140 Hz (TBD experimentally in situ). Even with a steep LR4 filter, there's still a fair amount of vibration in the driver frame when it's working hard.

The Satori cone drivers all feature a cast aluminum frame with spokes that wrap around the magnet. This is a design that goes back to Peerless, VIFA, ScanSpeak, even JBL.

Here's a Peerless/VIFA NE149 using this design. This is meant to eliminate the "bell-like ringing" of a big heavy magnet that usually hangs off the back of the frame.


The WO24TX (and other WO24 variants) looks similar, like the Peerless driver above and its other Satori mates. But it's an illusion.


The ribbed black portion around the magnet is actually made of molded rubbery plastic & is easily peeled off.


This proved to be a saving grace for the magnet mounting modification that Mark undertook with his talented machinist friend. The rest of the pics should be self explanatory.








The BB plywood frame is temporary and will be replaced in the final version with an aluminum or steel structure with less acoustical resistance.

Hello !
I've got a broken L-3. The right channel fuse keep blowing.
So far I've checked :
1) power circuit is good at 38.0 V on +B and -B at idle without LS. Also the -46 V is OK
2) as the fuse on the speaker line blows, I've checked that the switching to select A or B speakers has no fault.
3) I've checked the right channel power transistors. They are fine on my little Chinese tester.
There is no mechanical damage nor obvious leaking capacitor. The amp appears like it has never been opened.

All I can do and check has been checked. So I _do_ need your help and advice !
Many thanks in advance for your help !

P.S. : the amp is version E with the 2550 transformer (which was set for 220 V and I switched it to 240 V as I live in Europe.)

I was trying to add an index to the first post of my long thread. When I copy a link to a post and paste the link, the site software embeds a significant portion of the linked post, not just a clickable link. This adds significant clutter. Am I doing something wrong.

example: I want to link to this post

Here I would like to address the little known events of the early (1973-75) V-FET history.
While it is not very logical to discuss these issues on DIY forum, considering the international
membership and technical expertise, and in the interests of the history preservation I decided
to do it on this forum.
Besides, history + archeology = treasures.

Those years were, in fact, the peak of the industry interest and involvement with the V-FET.
And that all started, as we know, in Japan. The first name we should start with is Toshiba.

Creating in 1973 their high-end audio division Aurex they immediately set standards
very high with the very advanced tuner ST-910. On the audio front they were busy developing
their V-FET (complementary outputs and drivers), which they had in the beginning of 1974.

By 1975 they have the production prototype amp SB-620, (here is their prototyping circuit):


and then...something strange have happened: the SB-620 was completely redesigned into
all BJT design! As we will see this was progressing like a plague...

Talking about Toshiba components in those years, I would ask: shouldn't there be a control
amplifier SY-910 (to supplement their tuner and power amp SC-910, mentioned on the TVK)?
↴

Hello folks, Richard here. I have been into hifi for over 50 years and seen all sorts of trends come and go, but as always, I go my own way and listen to decide whether I like something or not. These days there is to much hype, make your own decisions, I say! Anyway, I want a dig headphone amplifier and i saw the Gilmore, hence joining here.

It is claimed an Augmented Damping Technology by the Chinese designer which is different from Class A or Class AB. I wanted to know more about this so I posted here to get to know better of the technology, dive in and take a look at it, and play around in a DIY bench test if possible. I learned class-L, heard its performance, interviewed the designer in the past November 2024 Guangzhou High End Show in China. I want to DIY build one.

Sale:
5C3S black plate - 20 pcs. for $15/pc.
6N13S - 100 pcs. for $10/pc.

For those who might be interested, I have prepared an open project of the phono preamplifier for MM cartridge. It has very low noise and very low distortion. Gain is 40dB/1kHz. Output is capable to drive 50 ohm load, so one may directly connect headphones via 100 - 220 ohm pot. Please feel free to download documenation from

Preamplifier for MM cartridge

just need one. A or non-A is fine. thanks!

Hello everyone, when you turn on the ml 35 dac, the channels were noisy. I removed the compound with a hair dryer for three days. The fault lies in the cracked solder on the central resistive node... We need to disassemble the second assembly, and it's terrible... I was thinking about replacing it with a pcm1704 board. Does anyone have a layout of such a board? I read that the madrigal was officially put in place of the ultraanalog d20400. I also disassembled the 20400 to a bare board, I have an idea to copy it. Do those present have a desire to make a copy? I am ready to provide high-quality photos and sizes.

Dear friends!

Many members are encouraged me to use the phono boards for D3A.

I was make it for my system, it is simple and the sounds is very good, i lke it You can see this Phono in the image and design in this link:Hi-end phono preamplifier

I have for sale assembled power supplies for a power amplifier. Only high quality components are used in the power supply, main capacitors 4x 15.000 uF/50V.

I have for sale 2pcs, price for each 50€ + shipping
Payment wire transfer or PayPal.

Does anyone know a good part number for D11? It's marked 5A but when I search it I get mixed results. I've already replaced:

Q207-Q210 (IRFP3415) Shorted

C31,C33,C35,C36,39 (330uF 63v) Open

C23,C25 (4700uF 80v) Out of tolerance

D23 (Blue LED) Open

While cleaning up from all that I noticed D11.

Works great but has a constant humming sound. I've played with all the pots and switches but it won't stop.

I am looking for Hypex FA253 amplifiers (one or pair).

I have a motorized pot that I want to detect the position. The pot has four-gang two of which are hooked up to the receiver. I was that I can get a reading of the levels by attaching a linear pot. How do I wire that up?

Hello DIYers,

Are there any ready-to-use vibration sensors/accelerometers available? I would like to use one for the analysis of panel vibrations, and for planning and executing effective vibration control. I like to be proactive about design planning to determine if there is an improvement to be made before advancing to the to next stage of the design.

Hi there,

I recently built a hybrid circlotron based on a schematic by "circlotron audio". It actually works, but I'm wondering whether the MOSFET bias will be long term stable given that it is set by the constant current sources for the tubes. I'm hoping that the current feedback to the tube cathodes might stabilize the arrangement, but I'd be grateful for any feedback here as I'm sure there are some hidden gotchas.

I use Janzen Superior Caps in my crossovers. I see that the sky is the limit on this stuff. I was considering Miflex, Audyn or Jupiter. THey are very expensive. Would there be an audible difference? I would only use it in the tweeter circuit.

I start by saying (writing actually) that this is more of a philosophical question than a problem.

I'm taking time to test ALWSR regulator which I've previously used but with CapM at the input so this time I thought I might as well leave it be and go along with the standard LM317T doing the duties as pre-reg
Strangely enough this circuit was revised with higher than normal adj-out resistor (1K for both adj-gnd and adj-out, it supposed to be more beneficial than the original 499) and even more strange in testing procedure it states no load (passing the test it will connected to the Super Regulator circuit). I thought myself 'what the heck' and tested this way with no load and the output was not the anticipated 2.5VDC but above 4VDC, which is something I was expecting. Lowering Rs below 500R or having a small load got it right.

Forgive my long introduction, here's the question: How come the version of LM317T from ST don't mind having no load with high output resistor (having 2.5VDC output) while the On Semi in question certainly does (the 317 mentioned above).
Same min load current requirements, same Adj current, same everything as fas as I can see. am I missing something ?
The datasheets:
On Semi
ST

Edit: this test is been done to a bunch of regs from both companies which are new most probably from Mouser, same result
On semis behave differently from STs.

Hey, in a small town in Sweden there was an auction house selling assorted knick knacks on regular basis.
For some reason these ended up there and I bought them mostly out of curiosity.

Now I sit with these behemoths and no clue what to do with them.

Does anyone have any advice? I cant seem to find any diy plans using them.

I have managed to find out that I need something for around 500hz and lower.

Is it even possible to build something slim and discrete for the living room with these? 🙂

Hello
I am selling my brand new Pearl 3 phono preamp. It cost a bit above 900CD$ (620 US$) and I hope to sell it for the price of the parts. It has matched film caps in all positions, it has no xlr outs but i can remedy that if you re patient. It has a very long Canare umbillical cord and blue leds. It sounds excellent and is dead quiet. I have only tried it with my MM cartridge. I believe it is not fully broken in and the plastic wrap is still somewhat on the faceplates.

Hello, I am searching for max420 cpa.
If anyone have. [2 pieces]

Has anybody actually replaced the suspension "wire" on a MA-505 tonearm? Someone gave me one (I believe it is the
mkI due to the on the fly VTA adjustment) and the suspension wire for tracking force is broken. After researching
on the web, there were posts that it is tungsten and people have used corona wire out of a laser printer.

Well, I really don't think its tungsten or metal for that matter. I measured the thickness of the still attached
broken piece and it was like 0.18 mm thick. I ordered some 99.99% tungsten wire and it came today. It is way to
stiff. So I started slimming it down by running a length through sandpaper pinched between my fingers. I got it
down to 0.12 after remeasuring the existing wire multiple time.
So then I went to install it and went to attach the new wire to the spring. Well, it does not solder so I looked
close at the old one and there was a tiny crimped ferule. But I also looked close at the broken end and scraped it
with an exacto. The end kind of frayed like a piece of thread and I could see the many individual strands!

Anyway I attached the spring and routed it to the tension pulley. Even though I have thinned it down by a
third, it still seems way too stiff to work properly. The wire actually deforms semi-permanently as it is pulled
over the anti skate rods by the pulley. Lowering the tension does let the spring pull the wire back in but you
can see the residual bends in the wire. This to me does not seem correct if this mechanism is to control tension
real time. The spring actually does that I know, but if this wire doesn't actually conform easily to its path
through the tensioner, I would also think I has to much stiffness and therefore drag where it emerges from the
barrel holding the spring.

Can anybody really confirm this is tungsten wire ( as nylon thread would seem more appropriate)? If so, what is
its true thickness. To be flexible enough it would have to be an order of magnitude thinner than what I have
measured. I am pretty sure what was in the TT when I got it is the original as the tensioner related set screws
still had the bluish glue/threadlock in their holes so it appears to never having been replace. The "wire" looks
more like thread or silk as it frays and it is not shiny like the tungsten (after thinning)

Thanks much!

What the heck is that doing to the signal (dayton dsp LF in the super squiggly bottom two measurements )?

Hello! I've got an Altec 604-8G speaker and the horn is loose. It rocks back and forth side to side and I'm wondering how to tighten it. The upper part of the horn is still firmly glued in place, so I imagine it's the lower section. I've seen pictures and videos and mentions of two accessible screws that should be visible when looking into the horn; however, these don't exist on my speakers. Seems like this is some variant without accessible screws. That said, how do I tighten down the horn? Thanks!

Anyone with a bizarre, unknown, corrupted, misused, failing, whatever application of this circuit (or a 'Vgs-multiplier'), high frequency related, oscillator or modulated contraption, or whatsoever unthinkable of, I would like to know what is in the sleeves of you electronic designers garments and knowledge.
But please I beg, no explanations of how those circuits operate or what there used for. Just the circuits. Nothing more
This is part three and will be wrapped up at the closing of '23.
The former two went beserk (link,link,).

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Embarassingly this is made by a UK company.

A strange topic for this site…but I’ve seen similar. This is really the only place I “socialize” online and this is affecting every part of my life including my motivation and ability to participate in my DIYAudio hobby.

I’ve always been active and enjoyed biking, swimming and my various gym workouts. It helps me physically and mentally. That has virtually stopped all together as well.

My story:

I’ve had problems for many years with pain that first appeared in my shoulder.

Back in 2010 or so I sustained an injury working on a car that resulted in things getting much worse. I woke up and couldn’t lift my head off my pillow. Pain multiplied many times in my shoulder, arm and hand including numbness.

The cycle began with orthopedic doctors. Xrays, Ibuprophen in larger doses, muscle relaxers and referrals to physical therapy.

The therapy incuded heat wraps, light traction and stretching, electro-stimulation etc.

Eventually they had me getting an MRI with contrast of the shoulder (they hadn’t figured it was spine related) and they tried cortisone injection.

Things never really improved that much. The cycle continued to repeat with doctors and physical therapy. At some point someone did determined that I had two herniated discs in my neck.

I got frustrated with the physical therapy that didn’t seem to help. Eventually I was just trying to cope with ibuprophen on a daily basis and my activities started getting limited.

This went on for several years until I was referred to a different physical therapist that was recommended by someone I met that had similar issues.

After working with the new therapist for several months I got “back on my feet”. I was able to swim, bike and take various strength training classes (no more real heavy lifting) even got into trail running. I was still managing aches and pain with some ibuprofen, especially after more intense workouts, but for someone in their mid 50s I felt pretty damn good.

Fast forward to Spring of 2022. My wife and I encountered a new friend on a hike one weekend. A rescue dog named “Thib” that was being fostered.

We immediately fell in love with the playful little guy and for the first time in our adult lives we decided (after much deliberation) that we’d like to make him part of the family.

Thib had an untamable spirit…literally. I worked with him for months on end in classes and on my own to no avail. He was always fighting on the leash and eventually that resulted in me being injured all over again and us having to give him back up for adoption.

Since then, things have been worse. The pain expanded out through my shoulder blade and upper back. I went back to working with my therapist for a while, but made minimal improvements.

Therapy got interrupted this past year with a relocation to a new home. That just made matters worse.

I did get to the point where I could manage the pain with a couple of ibuprophen each day and started pushing myself to get active with some light swimming, hiking etc in the early summer. I almost immediately relapsed.

Since then I’ve been like a bird with a broken wing trying to get off the ground.

I’ve started trying all kinds of things…even CBD. Simple stretching, yoga or massage results in stabbing, nagging aching pain and numbness from the base of my neck out through my shoulder blade, arm and to my hand. I cannot lie on my back. I’m sleep deprived etc.

Back to the cycle.

I see a new orthopedic doctor. He takes an Xray and immediately tells me I have degenerative arthritis in my cervical spine (C4-5, C5-6, C6-7). He says the solution is to perform surgery to fuse these discs. I’ll maintain 80% motion of my head and neck. I’ll be a new man in 6 months. He says I can try Cortisone injections…some people find relief…albeit mostly temporary.

In my mind surgery should be an absolute last measure. I’m scheduled for another MRI on this coming Friday. Injections can’t start until after that anyway.

How can I not try injections? I’m hoping they might reduce inflammation and pain enough that I can achieve some real improvements again with my physical therapist.

Who has been through or is going through this?

I’m hoping I can find some light at the end of the tunnel.

I built/ding a pair of chinese quad 405-2 clone.The build is almost complete and i started to measure stuff.If i set the signalgenerator to 0.4V, 1kHz sine
i can increase the volume to ~75% then the onboard fuse blow.
I feed the amp with +/- 25.4V
And as dummyload i have 100W 8Ohm resistor.
On the pic it's 8.6V Cyclic_RMS right before the fuse blow ( at ~9.5V ) That would be ~13W if i calculated correct.
Shouldn't it be more ?
And why does the fuse blow ?
Any clues ?

Hi all, Tony from the UK, I have posted before but ages ago, interests in HiFi and guitar valve amplifiers and all things sound related really😬 and will post again needing advice with a APart Sublime subwoofer…speak soon.

I have a Denon DCD S10 that has a faint high pitched whine with static in the right channel. I've narrowed it down to the digital filter being the source. I'm not able to purchase just one except in large quantities. "I found one on e-bay."

I replaced the power switch on an old 70's receiver and added a 40A relay (40mA coil) to preserve the switch from burning out again. After just a few months I started hearing a buzz from the relay and then the contacts chattered, indicating a failing coil. It did it with the load(200VA xformer) disconnected too. Did I make a poor choice for a relay, is it just a defective part, or should I have put a snubber across the coil? I didn't think 40mA would require one, but now I'm not sure.

I got an idea to build some full range speakers using Lowther units so I started looking for plans. I have been searching off and on for weeks and almost all of the links to DIY cabinets for Lowther speakers comes up a dead end! I have found some Medallion dwgs but nothing else. The links to Lowther's plan page on their web site and Lowther America's web site are no longer active. Is it now impossible to get any plans for Lowther speaker cabinets?

Hi everyone,

I have a Rotel RA-02 that suddenly shut down while playing music. After opening it up, I found that one of the fuses is burnt, also one of the 2SD1047 output transistors was shorted (very low resistance), and one of the 2SB817 transistors seemed to be open circuit. The surrounding resistors look fine, and no obvious burn marks are visible.



I'm looking for original replacements for 2SD1047 and 2SB817, but I'm having trouble finding them locally. Do you know where I could get them in Europe?

Alternatively, I found TIP42CG and BD244C, but they seem to have lower current ratings.

Any recommendations on where to buy good-quality replacements or advice on the best alternative transistors?

Thanks in advance!

after looking at all kinds of headphone amplifier circuits and even building few i found this one:



which i thought should work well but it had a bunch of issues including unequal clipping way too high gain and a few other issues, so i decided to put it in LT spice and change up few things and i got this:



this design works slightly better but still has a lot of issues, i tried simulating it with diffrent loads and thats why the 8 ohm load in the picture.

It looks like a 18" woofer plus a DCX464 in the middle: https://www.bcspeakers.com/en/products/triaxials/18-0/8/18HTX100-8 Price at TLHP is around 900 Eur, which is not that bad. It looks really cool and a pair in simple BR boxes could be nice.

Hi All,

Still experimenting with a pair of 2 ways and trying out some different things in DSP, in an active setup.

The creator of the below passive crossover for an Altec 14 has not been active online to respond and may have unfortunately passed or moved on to other things.

From chat forums, I do understand the following:

It crosses at 2Khz? (not sure if the woofer is running full range?)
There is a zobel network on the woofer audio path
The highs are attenuated xxx db vs the highs.

I'd be happy to put this in a simulator, but not sure where to start there as I'm a bit of a novice. Happy to provide the speaker specs, if that helps (ts parameters, impedance, etc.)
Was hoping to try to understand the slopes at the xover point, attenuation circuit and expected attenuation for the tweeter and what frequency ranges are getting to each driver. Also would be like to understand how the zobel network is impacting the frequency response and if that's needed in an active setup. Also assuming there's no EQ adjustment in the circuit, but not sure?

Hiiiiiii!

I'm tying to get the maximum level from a Source player that has both options of RCA's and XLR's outputs. The Balanced out is a higher line level that suits my equipment, the unbal line output is to low an output.

I would like to unbalance the balanced source, does that mean a straight short between pin 1 and 3 or ...

Decoupling capacitor between pin 1; Negative and pin 3; Gnd ? If so what type, material, size?

I'm used to studio gear and this Source player is a quasi balanced CD player, too sensitive for my likings.

O/C between 1 an 3 results in buzzzzzz

Hi,

my Name ist Mat and I am new here and hope someone can help me to connect my Philips Variac type 2422 530 23411 the right way.

My question, where I have to connect the mains and where the variable output?

I think the left side is input and the right side ist output (the top screw in the middle and the right screw on the bottom) I am right?

Thank you so much for help.

Have a nice weekend!

Cheers,

Mat

I recently decided to have a dabble with a tube amp to see if I can make a reasonable design myself.
As a total tube newbie I started with the veritable 6J1 bile amplifier from China.

I didn't have an AC transformer but I got a smps with hv and heater outputs.
I've prototyped the design, adding gain, tone and volume controls. I changed the tubes to GE5654.

But it sounds... Bad. There is no hum but the distortion sounds crude and rough, more like a bad fuzz pedal.
I'm not totally sure it's being biased right and I'm still reading up on load lines etc
I've captured the schematic and build in case I'm making newbie mistakes!

I know I need to change the caps to polymer - they are on order.

Has anyone built one like this specifically for overdrive distortion?

Cheers

Hello,
UCD180ST X2
UCD400ST X2

Hello is anyone have seen that before ?

Perfect working pair of these hard to find hf units will ship worldwide £350 the pair.

I'm building a pair of LS3/5a speakers. Currently trying to decide on components. I see dozens of suggestions and parts kits available. Seems the top choice might be Falcon. But at $1000 for drivers and Xover, a bit rich for this project. On Ebay I see Taiwan knock-off drivers, and Xovers for reasonable price. But the lead time is very long.
My question:....I see crossovers offered in 11 and 15 ohms......But I'm not seeing drivers with this impedance. Do I simply use 4 or 8 ohm drivers with these crossovers and the total impedance is delivered at 11 or 15 ohms? Or do I need to source 11 or 15 ohm drivers.
Thanks in advance!

PENDING. Thanks for looking...

Rega P5 Turntable with TT PSU. I bought this turntable and haven't used it very much since I retired, so I decided to sell it to fund other projects.

Includes original packaging. I will pay shipping costs in the lower 48 states if you meet my asking price of $500.

For my good friend from the Croatian forum, I'm looking for a TDA1541A or two AD1862s. He's finally decided to make a DIY DAC, but we're missing the basics.

Thx

Tortoise perform all of their iconic 1998 album TNT live at the Pitchfork and The Art Institute of Chicago’s Midwinter 2019 for its 21st anniversary.

Interesting to see it performed live, I post at "I Set My Face To The Hillside" Almost a Strange Western Movie Soundtrack.
The music is good background sound when working on Amplifiers, Art and any Activity needing a Ambience.
Live Performance makes for a interesting Watch.

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Hi, I wonder if you guys has any experience with re-taping the outer layer of insulation/protection tape on toroidal transformers, diy-style. What I can read is that it’s usually polyester or mylar tape used.

1. What tape to use, where to get it
2. How the **** to get the tape roll through the hole X times. I mean unrolling the entire length needed is undoable. Is there this tape in very small rolls, or how would one do it?

I have some nice working donuts but tape is falling off. I also have some that I am thinking of cutting away outer layer, re-dip in varnish and re-tape. They have a small gurgling noice that I don’t think is because of to few primary turns but rater bad varnish/slightly vibrating secondaries.

I came across an old A18 amplifier with one defectice channel. After repairing the amp I found that the sound was open and transparent as well as the sound stage wide and in 3D.
As this was with my nearfields I use in the studio I wanted to go on a n adventure to use these for my Orion and designed a PCB so I can build 8 channels.
The beauty of these amp is a high quiescent current and about 30W output without feedback.
You can find the schematic idea on the web.

As I'm planning to build 8 channels and 2 reserve I could order some more if there is interest. The price would be around 7 euro's per channel for the PCB.
2mm FR4 and 2Oz copper.


Do not worry about the 2SJ162 and 2SK1058 as I have plenty NOS parts I only want to sell with the PCB's.

The 78x12 regulator may oscilate when using the indicated 2200u cap on the output. Oscilation disappears when reducing the cap to 47u.

If anyone has them rolling around at home, I'd need 6 pairs.

2SC3519A - 6x
2SA1386A - 6x

PM.

Hello, fellow audiophiles. I'm about to build a two way system using Scan Speak 15W/4531G00 and D2004/602000 speakers, Its my first "serious" speaker project (before that I build Visaton Alto system). So anyways, I had some questions regarding XO design. Plan A was to build somewhat regular LR2 crossover crossing at 3100Hz, but it may be a problem with acoustic centers as distance between speakers is larger than wavelength at that frequency. So plan B was to incorporate ladder delay network. Which option in your opinion is more "legit"?

Good health to all! My name is Vasily. I bought this board on Ali veriya 1.1 resistor 112 on it is marked on 75 ohm instead of 15 ohm as on other boards is this a typo or features of the version of this board? And another question instead of mje15034 what transistor can be put the board is needed to power the DAC. Thank you in advance for your answers..

Hello everyone, My name is Paolo and I’m an enthusiast with non-engineer-level knowledge. I have a CD transport with a Toslink output, and I’d like to create a simple DSP using a Raspberry Pi and an input board like the HiFiBerry DAC+ DSP or an IanCanada board. I want to connect the Raspberry Pi to an external DAC (via USB or coaxial). I’ve tried using MoodeAudio and CamillaDSP with the HiFiBerry DAC+ DSP on the Raspberry Pi, but I can’t get the CD transport to be recognized via SPDIF. So here I am, trying to understand more about it.

Hello, everyone!


I am making a simple DIYMic Pre but have run into with adding phantom power.


The pre is unbalanced but the mic coming in is balanced.

I know that phantom goes into XLR 2 and 3 via resistor, but only pin goes to the circuit input.

What should I do with pin 3?


Schematic:

I builded a DDBH (Back-Loaded Horn with Damp-Duct) for MAOP11.
As a 6-inch back-loaded horn, it is small and has little bass volume, but the Damp-Duct effect produces a solid sound down to 40 Hz.
The addition of the Damp-Duct reduces the disadvantages of the back-loaded horn while maintaining its advantages, and the quality is nice.





[Air-Recording] Wish You Were Here / Kirsti Huke
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[Air-Recording] Peace Piece / Richie Beirach
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