Hi folks!
I am resuming electronics as a hobby, after + 20 years without practicing. I have some vintage equipment that has been idle for a long time. Taking advantage of a little more free time due to the pandemic, I will restore 2 amplifiers, 1 pre amp, 1 receiver, and I want to use good components (I know they will never become hi-ends, but I want to do the best upgrade possible, using common sense and appropriate cost-benefit components). Well, my question is, what better internal signal cable can I use? That is immune to noise, that carries the most complete signal possible from end to end? What have you been using for that?
In Brazil it seems that we don't have many options, for example, this seems to be the best available:

Cabo Automacao KMP AF AWG 2x18 - D&D Componentes Eletronicos

am I on the right track as to the type of line cable? what do friends recommend?

Sorry for my humble English, thanks for the comments.

Hi


I need the schematic for the above mentioned amplifier. Can someone help, please.


Thanks

I have used several times the AD-1955 demo board like that from the photo by post #9 about
http://www.diyaudio.com/forums/digital-line-level/135650-ad1955-evaluation-board-schematics.html
and the photo URL
http://www.diyaudio.com/forums/attachment.php?postid=1315495&stamp=1191364151

Unfortunately the AD-1955 demo board is since several years no longer available

This board is much more better than the DAC Yulong DAH1 (DAH-1)
to find about this weblinks:
YULONG DAH1 MARK DAC /Pre amp/headphone amps : hi-end headphone amplifier
Yulong DAC DAH1 Mark headphone amp - Head-Fi: Covering Headphones, Earphones and Portable Audio
and the attached photos

The main disadvantage of Yulong's DAH1 (DAH-1) are the very hot voltage regulators (with the small heatsinks). I have this problem solved by screwing this voltage regulators on the inside of the alu housing (no longer there are this hot spots on the PCB). This work was very unpleasant and time consuming.

I want to have similar evaluation board than that one with AD1955.
Which type could be an adequately substitution (same sonic quality)?

Hi,

For an audio amplifier that needs lets say 10A average (hence 14.1A peak), can it be run on a 10A SMPS without going into protection during those peaks?

Thanks and Regards,
WonderfulAudio

Pearl 2 12v at output and no offset control

EDIT: Supply problem is fixed, but I've still got 12v on my outputs and no bias control on both channels.



Forgive me if this has been covered, but I couldn't find anything in my search.
I just finished a Pearl 2 build, along with the power supply Wayne provided an example of in the build document.
The power supply itself outputs the proper voltage when not connected to the Pearl 2 boards, but once connected it reads as approx -55v on the negative supply and approx 15v on the positive. I can also measure 12v on the outputs, the pot having no effect.
The VR on the - side does output -24v as it should, but obviously the + supply does not.
Any insight would be appreciated. Thanks.

Hi ,

Was looking at the design document for this preamp by Andrew. looking at the non-inverting class-a opamp schematics, it seems like there is a missing link where R1 should be connected to the link between the emitter and collector, similar to how it's connected in the inverted schematics.

can someone confirm that, please?

UNIVERSITY SOUND Model MC8a 8" Fullrange Speaker pair in 100% working condition. Built by ElectroVoice. Both speakers have been treated with several 50/50 coats of a special formulated vintage violin varnish (no poly, pvc, 100% organic) to preserve cones and have phase plugs installed. One cone was damaged, but has been repaired, see pictures. They play and sound fantastic.

Cabinets not included. These are fantastic in OB w/ Eminence 15" woofer. Use a small EL84 tube amp and a 50 W subwoofer amp w/ crossover and they will sing. Speakers were recently treated and need 100 hrs break in to fully bloom. There are other tweeks that could be done to frame/baskets. I will be happy to share with purchaser.

Asking $75 plus Shipping.

My cat put a little dent in one of my Alpair 10p, I bought a replacement and now have one extra just sitting around. If anyone has a single let me know.


Thanks

Help needed. I wish to build crossovers for Volt BM2208 and Scanspeak D2905/95000 to approximate the SM108 design. If anyone has the instruction manual/diagrams, I would be happy to make a contribution.

The Intellectual People Podcast - Tom Christiansen of Neurochrome

Please be sure to watch, like and subscribe to the YouTube Channel!

High-end audio design & PCB layout with Tom Christiansen, Neurochrome & TCA | Part 1 - YouTube

Salas Simplistic NJFET RIAA Phono Stage. With outboard PS, w/Salas Shunt regulator. Designed for Med output MC. HQ parts, Gold RCAs, Shunt volume control. Scratch built on perf board. A generic chassis, but great sounding.

A few pictures are fuzzy.

No hum, 100% operational.

Asking $200 plus shipping.

AR XA-AB T-bar. Excellent Cond. $75.00
AR XA-AB Spring set. $25.00

New Custom made German Turntable platter bearing. 1.5" X .279" SS shaft to fit 1.5" thick platter. High Tensile Bronze bearing well w/ SS ball bearing. This was custom made in a set of six at $175.00 each, 20 yrs ago. I estimate to have new ones built now would cost $250.00. Last one I have. $125.00

PayPal plus shipping.

Does anyone have some good schematics of direct coupled preamp? As for direct coupled output, will you need some type of servo feedback to keep output at 0V?

Hi. A friend is in need of a super tweeter for an infinity Kappa 9.
The numbers on the back of it are
902-2645B and 572TNL
If anybody has one, please get in touch.
Thanks.

Hello,


For the past several months I have been slowly learning and developing a two way speaker using the RS150P-8A and XT25TG30-04. Many of you on this forum helped me get my measurement issues resolved and my technique up to par and I am very grateful.

I would like to start a discussion on the recent attempts I have made in crossover design using VituixCAD. It is an amazing software but... "with great power comes great (complexity)". I now have a full set of 180 hor and ver measurements loaded and can report on my first full sim attempt using this software.

I have attached images that show the VituixCad Sim, the circuit design and the real world measurement results.

It looks like I have some small variations between the sim and the real-life result. Should I expect better agreement? If so where should I look to resolve the issues? One area in the back of my mind is the setting of mic distance in the REW measurements...

While measuring I used the on axis measurement to use as the distance/timing reference. Would I have better results if I readjusted the timing to say...30-40deg? It would be more of an average of the source distance.

Anyway. I had good enough agreement to begin work on a new version of the crossover. (images labeled "New Crossover Candidate")I have the sim and circuit images below. Comments are more than welcome.

And thank you so much again for all your help!

Best Regards,
J.

I would like to clarify something about the semiconductors for the SSE build. I have read that the semiconductors are not necessary if a rectifier tube will be used, such as an 5AR4 or GZ-34 tube. Is that true? If so, does that mean the chapter regarding semiconductors (from the assembly manual) can be skipped, and parts D1, D2, U10, and U20 can be left off the board entirely?

Next question. If a rectifier tube WILL be used is it ok to install the semiconductors? Or will that cause problems?

Thanks in advance!

Hi to all. I have to repair my beloved Rowland Research Model 3 Monaural. Has failed the pilot module (black box resin) and I do not know how to fix it. Can anyone help me? Thanks.

I have this old Ar-es-1 turntable in great condition. I never changed the tone and would like comments on it`s negative and pluses. Also is there any tonearm that would fit without alteration?

Hi all, I was wondering if the smart people on this forum would be kind enough to give me a tip or two where to look for a solution to what I'm trying to do with regards to monitoring?

I've decided to go ahead and finally start learning about mastering on the practical level (I've had a bit more than enough theory for a start). I'm kind of confused as to what to use for my monitoring solution, specifically for the routing and crossover setup. My main system is a PMC MB2S XBD stereo pair with the standard tri-amped Bryston electronics. It's a good start and I got it at a cheap enough price. However, because I don't do surround sound, film, or classical music, I don't really need bass to be stereo, and the size of my room prevents it from being useful anyways (roughly 5x4.5 meters, and 3.4 meters high, brick with joists). The current electronics are tri-amped with the bryston/pmc line-level electronic crossover that has three bands. The XBDs are driven by the same band as the 12" drivers of the MB2S. I'll be most interested in learning about how to work with electronic music, so I'd much rather prefer a setup where the MB2S are tri-amped, and then the two XBDs run different parts of the bass spectrum, essentially extending the setup to 5 bands, with the lowest two being mono. I'd probably move the XBDs to from under the MB2Ss to where ever the modes like to have them the most, and run them at an SPL that's high enough to have comfortable grasp of what's going on in the bass region without being annoying to me or people in my neighborhood.

I currently don't have a capable preamp to use with this system, and I'm not even sure I should get a single stereo preamp. I think I should go with a digital crossover of some sort. I also don't have source selection (and I have roughly 6 different stereo sources to select from), so it would probably be best to use a digital input of some sort as well. At this point an analog preamp seems to be a bad idea.

I'd also like to have a secondary monitoring system that is bi-amped or tri-amped, plus possibly a center plus two surrounds. At that point I'm looking at 8 outputs for the PMCs and 4-6 outputs for the secondary monitors and at least 3 outputs for the surround system, totalling at 17 outputs. I have looked around, but I haven't found anything really that would be able to support this kind of output arrangement, other than doing everything on a Windows PC with an audio interface and VST plugins. I would like to avoid that, since Windows isn't "always on", and I don't want glitches disabling my system. However, it also seems that there isn't a standard racked system that has this many outputs and which can do (even modest) FIR convolution based room correction, which I think would be a good idea at least in order to get acquainted to how they work and what abilities they have (I'm doing this to learn after all). If you know of something, please do let me know. I'm sure it would save me a lot of tinkering. One option would be to use a box that can speak AVB, so I can hook up external ADC and DAC via Ethernet.

I am also not sure what to use for the monitoring settings remote. I would like to have a few loudness presets, as well as be able to pad the level of the lowest frequencies (for example, booming bass is extremely annoying in amateur youtube videos which just don't have a handle on that, so I'd like to be able to flip it off). A volume knob would be great too, and a monitor selector. I guess if I'm using some sort of open DSP box, then that could take care of it all, but I don't know of one that can take some sort of remote like that, either via serial input or via ethernet or some other solution. (the idea here is to listen to everything through the main monitors at all times for now, so that I can learn their behavior)

Finally, I am not sure what sort of filters I should be looking for when setting up the crossover. Should I be using normal Linkwitz-Riley second-order filters for the top 3 bands? Some sort of linear filter? Should I be using very steep filters for the bottom two bands? Those are the first ideas I've had, but I appreciate they might be very wrong.


So to sum it up, I'm looking for:
- dsp box (or multiple boxes)
- has multiple kinds of filters available for setting up crossovers, including linear filters
- can do FIR convolution for room correction (even if in separate outboard box), big plus if I can download the FIR kernels and upload my own
- able to handle 17+ outputs (a single pair of speakers is up to 5 bands, with two of these being mono, totalling at 8 XLR outputs)
- ability to use digital remote that can be used to change volume, switch routings, and switch settings of dsp elements (e.g. filter on/off). I am able to build a control panel that talks serial or ethernet myself.
- ability to use AVB or similar for I/O is a big plus
- best if it's fully independent hardware, able to work without a computer

I would appreciate any and all tips. Thanks a lot!

Hello,

I have a Velodyne ULD-15 that recently started with a repeated ticking sound through the driver. Other than the ticking, it still works as it should. As I have three of these units, I tried swapping out the cabinet and observed the same issue. I then tried the original cabinet with a different amp and it works without the ticking. I'm guessing I have a capacitor that is discharging and as such creating the ticking.

A visual inspection of the boards show nothing out of the ordinary. Is it worth grabbing an ESR meter and going through all the caps? Or is it possible that there is something else causing this? Suggestions?

Thanks a bunch,
Mike

For sale here is a pair of Nord One Rev D buffer boards with Sparkos op amps. Unused due to going in a different direction. Asking £400.

SOLD.

Hey guys,
I am planning to use one of these CD with the PHL 3491 10" coaxial driver. One very known dealer i am in contact with states that the HD1050 fits very well and he is selling kits with them. But of course i want to get the maximum out of my built and if investing 200€ in better CD can help i wont step back. The measurements of the 1095 look indeed significantly better.


My question is: does anybody know the exit angle of the HD1050? Or if the NSD1095N fits to the PHL 3491? Or if bot CD have the same exit angle?


Thank you! I will start a thread about my build very soon if someone is interested. It will be named components plus a PHL 4021 and Hypex DSP amps with a layered wood tear shaped enclosing.

Hi.
I have a DAC board from a Tact 2.0 and i would like to use it with a player with coax spdif out.


There is no info about this board and all I know about it is that you can see in the pictures and that it is a digital to analog out which usually sits in a Tact 2.0.
The altera circuit appears to be a programmable but i know nothing about it. Could i skip that Altera and do something so that a coaxial spdif signal could come to that dac circuit?
The 3310 circuit is a digital volume, I think

Hi all, and thanks in advance for any guidance you can give. I just received a Triode VP-300BD tube amp from someone in the US, but it was configured as a 100V unit. Opening it up, I see the 100V transformer leads wired directly to the switch, and there are 120V leads that are not connected. Would switching to 120V be as simple as disconnecting and sealing the 100V leads and then connecting the 120V leads to the power switch? I suppose I would just need to bias the amp after, but is it as easy as that?

Unfortunately the manufacturer is neither providing a manual nor support for this modification. At worst case scenario I have a good step down transformer, but this seems like an easy mod considering the transformer has 120V windings.

Thanks.

iCloud

Hey, is anyone still using a C521BEE?
I know mine is pretty ancient now, but I still like it 🙂
Anyway, for the last number of years it's been very jumpy when playing CD's. It is very susceptible to any movement whatsoever. I've put soft rubber feet under it but even with no movement at all it still seems to skip the odd time with perfect condition CD's.
After a quick search I see it's maybe not the most relaible CD player of all time, but it would be really interesting to know if anyone here had suffered similar problems and managed to cure it 😀

This weekend I have been thinking if it would be possible to design a semi parametric EQ using Tubes.

Variable Frequency and if possible some sort of variable Q.


Also a way to make it work like a lo or hishelf.

Most of the time A gyrator is used but in tubes this get's a little bit difficult.
After some reading I've found a way using a wien bridge in a feedback path.
Problem with tubes is that the output impedance of the amplifier stages is rather high and affects the working of the circuit + gain is most of the times limited.

After some thinking and a good night sleep I came up with the following.




2 pentodes in a differential stage with a current source in the kathodes.
the output used for the feedback circuit is buffered by a DC coupled Kathode follower.
Output impedance of an ecc88 kathode follower is low enough.
Using pentodes gives a little bit more gain.
I simulated this in ltspcice and the results looks promising.
The dual 100k pot has a resistance in series of 10k which defines the minimum frequency.

The 5k1 and 5k6 resistances should theoretically be the same but using these values the gain in the middle position is almost 0db (1X)
Actualy the 5k1 could be trimmed to around 5k2 to be exactly correct.

with a 6k8 resistor to gnd this gives a range of +/-18db.
If a resistance of 10k is inserted in series this wil go to around +/-12db and the Q will be lower.
So inserting a pot of 10k in series makes this like a sort of adjustable Q
Higher Q is possible but make this to high and it will become an oscillator. (around 5k1 the system will oscillate => wien bridge oscillator)

Then you could also leave the cap or the resistor out of the wien bridge circuit to gnd and make it shelve.

It would be possible to make the feedback resistors higher in value but I think noise could become a problem.

For a channel strip you could use 4 circuits of this.
2 ecc88's and 8 ef86's :d but if I remember there are some dual pentodes that exist. Dual triodes like the ecc83 could probably also work.

It's just a rough idea. Don't know if I will ever make something like this but when I searched the internet for a parametric tube EQ there was not much I could find.

Hi guys, I'm designing PCB for F2/F2J and I thought that before I send it for the manufacturing it might be a good idea to add some minimalistic buffer on PCB, like in F6. I would like to try this amp with Soren R2R DAC connected directly but without the output opamps so the DAC output impedance would be quite high and HF roll-off might happen. But in F2(J) there is only single rail 24VDC and it's pretty "dirty". I have measured the input impedance in LTSpice and it's 4k at 1kHz, but maybe my SJEP model is not accurate. BTW the output impedance shows 3 Ohm 😉

Does anyone have an idea of a good minimalist buffer that can work at "dirty" 24VDC? An output decoupling capacitor is not a problem because F2 has one on the input anyway. I have some 2sk170, 2sj74 (GR, BL, V) but they like higher voltages together.

I installed LJM L15D SMD ver3 and connected +-26VDC to the board.The board is not functioning properly.The LED light dims and the sound turns off.My questions a) Is the voltage low because the ad says it is scalabe b)is the board faulty and how to check.
Any help will be greatly appreciated
dvisves

Hi there, looking to upgrade IV/amplification of this dac. dont like the sound( sintetics clear hights, dark midrange without texture,looking for more organic, open ,analogic sound)

as there is 4 chanel dac (actualy 5+1) and i use only two( thinking to simply paralel them (2+2) by paraleling data input and cuting wires from df1704) shoud

any ideas apreciated, thanks 🙂

Anyone have any thoughts own this, worth a punt ?

Magic Pads - EMI RFI Reduction for ICs

While trying to set the bias on any channel the amp starts pulling 8+ amps which puts my power supply into constant current mode. If I cycle the remote signal it returns to normal operation. It's like there are bad spots in the bias pots and when I turn the wiper over them the amp starts drawing current like a latching relay.

Could this be dirty pots or something else?

Notes:
Power supply fets were replaced with 3205's and 47 ohm resistors (this was the initial issue)
Power supply drivers were replaced as well.
Both gain pots have been replaced with 2.2k resistors. One was broken when I got it, I likely broke the other one.

so I've been messing around with my https://www.amazon.com/gp/product/B072KTZ2VC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I swapped the tweeter out with a Sea 27TBFC/G That I had. And it STILL sounded TERRIBLE.

I'm lead to believe the crossover is just no good. So I'm going to go Fully Active with it instead. But I still think the stock tweeter is the weak link in these speakers.

Can anyone reccomend a Good tweeter upgrade ???

Working on another Sundown Audio SCV-7500D. Outputs were shorted. Power supply is fine. pulled all the outputs. Working on the driver board. Pulled all the driver IC chips. Powered it up without driver chips installed. I have good drive signal to pad one of the driver chips. Installed new driver chips. Still have good drive into the driver chip. No low side drive out of any of the four driver chips. Haven't checked high side drive. I suspect it isn't there also. I have good 12 volts referenced to negative rail going to the board and on pin 7 of the driver chips. Good plus and minus rails. Good plus and minus 5 volts to drive board. Not in protect. Anyone shed some light on what might be going on?

Announcing a total of 10 Sapphire kits will be available at a cost of $100 each.

The Sapphire desktop headphone amp is a two stage, voltage gain + current gain design, with a 4 transistor diamond buffer typically running open loop as the output stage. Typically about 10 mWpc of class A output, 1-2 Wpc class B output, and a total quiescent dissipation of 6-7 W stereo. The board revision is 14s1. BOM and info attached, or see the Sapphire web page and RJM Audio products page for more information.

The kit consists of a pair of boards and all the parts for the boards. Volume control, chassis hardware, transformer(s), rectifiers, are not included.

Richard

Hi Guys,
I am Liem from Indonesia.
I own Threshold S/300 and recently accidentally I blew one of the fuses (positive rail) after I unplugged the interconect without turning the unit off first.
After I replaced the fuse and turned it on, it blew my speaker.
When I checked the DC voltage of the speaker output terminal, I found 61 Volt output!
I wonder what has caused this problem.
What parts should be checked or replaced?

Thank you for your advice.

Best regards,

Liem

Hi all - first post, long time lurker..

Just wanted to relay my experience of the humble Mission 760i speakers I picked up for £20 for an office system.

They sounded reasonably good to begin with, but nothing special. I also have 751s, and they were leagues ahead.

I began reading higher praise for the speakers the more I dug about online, and decided it might be worth the effort to try to improve them and/or return them to their original spec - they're over 25 years old after all.

I ordered up some Mundorf caps for the crossovers, dug out some old thickish QED speaker cable for the drivers, and bought some cheap carpet underlay for damping the cabinets. I made up some 12 AWG OFC cables to replace the cruddy Richer Sounds stuff I had been using.

The speakers were lined with foam from the factory in a fairly slapdash fashion - it was around 10mm thick and not remarkably dense. Two layers of the underlay were glued in - again slapdash due to my limited craftsmanship & patience - and the damping felt much more substantial. These are ported so I left the stuffing alone; as per the original design.

The cable originally used to connect the drivers was pretty thin - particularly for the tweeter. The caps were the usual in house stuff from Mission - adequate, but basic.
Out it all came and in went the Mundorfs and the QED cable - all larger and a bit unwieldy on the little moulded plastic panel used by Mission. I did my best to make it look worse with my soldering efforts looking like a Terminator's bad hair day, but it all worked after a tweeter solder came loose first attempt.

So how do the Mission's sound now - better, worse or no different?

Truthfully, they sound amazing - much, much better than before. They're on the end of a little Yamaha mini HiFi at the moment - humble gear, but I'm already trying to remember whether the 751s sounded this good when they were in this system briefly a few years ago. Certainly, I think these would be killers hooked up to some more capable amplification.

I'm not sure how much of the improvement is down to the quality of the new caps - perhaps I've just restored them to spec? I tend to believe good caps make some difference, but equally recapping in itself can bring about a big change. The cables I'm sure have improved things, both internally and externally. My instinct is the damping makes a huge difference - it felt so much denser than the foam in situ.

I set out to get a decent sound on a very small budget, and so far I've spent £35 on these speakers so I think I achieved my goal!

Can't wait to get these in a real system..

I have marantz cd67, It is not reading CD disc. Does Not spindle, you can hear laser 3x moving up. It is old laser, so I try to increase laser power on trimmer. And in one point CD start to play, you can switch from track to track. But if you turn of player, and tur ON, it fail again. I buy new replacement VAM1202 mechanism. But same again .... On the new I didn't touch the trimmer, but when randomly pres play, and spin with the finger in same time, if you are lucky it start to play. I watch pattern when start to play, it is 1.2Vp-p, and center is 1.5Vdc. On manual new laser is 1.7Vp-p, and center is 2.5Vdc. On old laser pattern is 0.8-0.9Vp-p and center is the same 1.5V. Servo board need 5V, on the schematic after reg. it is 4R7 and 47u. when new laser tries to spindle voltage fail to 4.6-4.7V, but with old laser voltage fail to 4.2V ( maybe because increased laser power ). Does anyone have an idea?

Hello everyone

I would like to clarify some points with you

I have akabak 3 and 2

Or on two similation on the same design I find two different results

My project and a 4x? being designed

Concerning akabak 3 I put him in 4v source in source to have 2.83v in 2s / 2p on driver

Do I have to put in two sources and how much should I put in value source for 2 driver in series or how much in a single source in 2s / 2p?



I find this akabak 3.0 attachement 1et akabak 2.0 attachement 2

However, in akabak 3.0 when I connect the first 4 two segments of each hp the following segment takes the surface of the 4hp sement that akabak 2.0 does not

Which response curve should I take into account? Akabak3.0 or akabak 2.0

In akabak 2.0 what should i do to connect my first segment to the segment that connects them into one?

cordially, impatiently awaiting your answers


Charly

Hello,


I am really new to all of this stuff and just wanted to repair the blown up speakers that I apparently purchased used...


The driver is 25DT65-6 Ohm. What is a good replacement that does not require anything more than an soldering iron?


I could do more advanced things but I just have not enough of time...



Cheers!

I'm trying to resuscitate an early-60s Bell T-338 reel-to-reel with an integrated RP-320 preamp. In the course of the inspection prior to replacing the electrolytics, I noticed that the heater wiring for the two 12AX7/12AT7 pairs differs from the published schematic.

The heaters are driven by a 24V winding from the main transformer. This feeds a Selenium bridge type rectifier. The output of the rectifier goes to a 4.7Ω resistor, then splits. One leg goes to a 150 mfd cap (one section of a can; all 150mfd caps are in this can), the other to the heater of the first tube. This is where the actual wiring departs from the schematic (both circuits shown in attachments; V1 and V3 are 12AT7, V2 and V4 are 12AX7).

On the schematic, the 4 tubes are wired in series, with the heaters on each tube in parallel (voltage to pins 4 and 5, out pin 9). The sequence is 12AT7: 150mdf to ground : 12AT7 : 150mfd to ground : 12AX7 : 12AX7 : ground.

The preamp is wired with two tube pairs in series (the two tubes in each pair are in parallel). The heater on each tube is wired in series (in pin 4, out pin 5, pin 9 not used). The sequence is 12AT7/12AT7 : 150 mfd to ground : 150 mfd to ground : 12AX7/12AX7 :ground. Yes, there are two caps in parallel between the two tube pairs.

Since this whole thing is driven by replacing the caps, I'm curious about having two caps in parallel between the two pairs. In particular, I'd like to know if this was a matter of expedience (using the existing component) or if there is a valid reason for using 300mfd instead of some other value. Or more to the point (since the can is being replaced and I can do what I want), should I consider some other value for all three of these caps?

As an aside, the transformer has a 24V .250A winding which is used only to drive these 4 heaters and a separate 6.3V 1.2A winding which is used only to drive the heaters on a 6V4 and 12AU7 and an indicator light. This seems an unusual transformer (at least, I can't find a replacement with 520V, 24V, and 6.3V secondaries). Is there a reason for running the 12AX7 and 12AT7 heaters on DC? Is there a reason for not using one 6.3V source (rectified and/or not) to drive all 6 heaters?

Thanks.

i want load this driver in reflex loading.
which liters and duct do you suggest ?

thank you 😉

I have one of these in the shed as a spare. I haven't fired it up in several years.
Opening it up it looks very repairable as everything seems discrete and lots of space inside the box.
Dual transformers, 10k smoothing caps and big double die transistors 2SC2774 / 2SA1170.
I need a bit of power for my new speakers and as I know nothing about amplifiers I am wondering if these are worth working on.
My online searching finds very little information.
I can take pictures if needed.

Made these a few years ago and I was never really happy with the midrange [ my fault using El-Cheapo drivers] and I'm looking now to rebuild them.
Last XO was a cascaded in the bass with a largish inductor before the 10" woofer in the 20 litre sealed box, wired in series with the dual 8's in parallel. For the Aussies the 8" are old Jaycar woofers I got on clearance, CW-2110.
They have a Qts of ~0.95 and a peaky hump in response right on their Fs at 40hz.
Another fun but cheap project to give to somebody doing me a favour with renovations.
Just looking now at some S/H Vifa drivers on eBay for the midrange. I have some cheap silk dome tweeters suitable for tweaking I intend to use.
Watch this space Pete

I've got a vintage pair of Dunlavy SC-III-A's and an S-I.CC from 2000 that I'm looking at upgrading the crossovers. My problem is that towards the end Dunlavy started recessing their backplates to be incredibly tight-fitting (see picture). Does anyone have any techniques beyond trying to push out from inside the speaker (not practical due to cabinet construction) without marring the finish?

TIA, Mark

Hello DIY Folks,

I bought a Marantz 3800 and noticed that if I turn the volume all the way counterclockwise, I could still hear music from the left speaker, although the volume is really low. This doesn't happen when I move the balance slider to the right speaker.

Could this be a dirty volume pot, or could it be something worse? I'm out of Deoxit and headed to Guitar Center to buy a can for $15 either way.

I'm also going to switch to another preamp just to verify that it's this preamp.

Not really that big of a deal in my mind, because I don't normally listen to music with the volume turn all the way down, just wanted a sanity check.

I thought I'd post about my current hybrid car/home amp project. I purchased this Adcom GFA-4702 several years back. It was missing the power supply chassis and cables but it was a good deal so I picked it up with the intent of building my own power supply. I sat in in my pile of projects 5yrs ago and I finally dug it out today to give it a test using a power supply I had out of a home amp.

The amp board was in nearly immaculate shape except for a repair someone had performed on a ground trace from the 8 pin molex where the front end regulated voltages are routed. It looks like somebody had miswired this connector in the past and toasted about 1 inch of the ground trace. Their repair left a lot to be desired and they covered it in silicone so it looked like hell. I removed all of the silicone and their attempt at a trace repair and repaired the trace properly. No silicone needed with this repair. 😀

Initially I had planned to build up a new switching supply to use with this amp but once I realized I had an old supply out of a home amp in my parts bin that would work it made it hard to spend the $$$ on a switch mode supply.
My homebrew supply works out just about perfectly with both channels of the amp properly biased (60W draw per channel) the power supply sits at about +/- 29V for the unregulated supplies and +/- 33.5V for the regulated front end supply which is just about perfect.

I'm going to set this power supply up to have fuses on each DC rail in addition to the fuse on the AC mains. So it'll have a bit more protection than it did using the original power supply that Adcom used.

I'm driving it temporarily in the picture with an old MP3 player and it sounds great. I've got a friend that is going to strip and powdercoat the chassis for me and I've got the parts on order to build up some original wire harnesses. My plans are to purchase a medium sized chassis off of Ebay to put this power supply in and build up cables about 6 feet in length so the supply can be positioned on the floor with the amplifier up higher.

I'm not 100% certain what I'll use this amplifier for or if I'll even keep it in the end. I could use it as an ultimate garage amp or even try it out in my home stereo if the fan doesn't prove to be too obtrusive. I'd like to try it out on my Acoustats to see how it sounds driving a pair of electrostats. I'll leave the 4702 amplifier itself original (aside from some parts that need replacing) so if I sell it another user could couple it with an original Adcom power supply or drive it from my homebrew AC mains power supply I'm building.

I recently purchased a nice Luxman MQ-70 from Japan. I’m getting to know the amp as I await a quality step down transformer. Unfortunately it did not come with a service manual, so I don’t know how to adjust current / bias and voltage (if applicable). I did see people have posted their versions of a schematic on this forum, thanks for doing that.

Does anyone have a service manual for this amp, or can anyone provide guidance on how to best adjust it? Seems like the innards have a number of variable resistors, and while I partially know my way around electronics, I only know enough to be dangerous. 🙂

Thanks...

any idea why would these transistors being sold with two legs?

1pcs -SemiSouth S30S120 Transistor | eBay

I'm in the market for a new car. This is going to sound weird and maybe ill-advised, but I'm willing to let the quality of the car's factory stereo help determine what car I purchase.

For my past new vehicles, within months of purchase I've replaced the factory system and installed a new amp, Mini-DSP, speakers, Subwoofer. But I chose to leave the factory system in place because commonly, it's so tied in with the rest of the car (tire pressure, energy reports and gauges, GPS). In my last install, I used the Mini-DSP to try to correct for the factory unit's deficiencies (with mixed results).

In test driving cars, I find the factory systems to be, at most, adequate. And often they fatigue my ears quickly. I just want good or great sound (and loud is good as well - a quiet car noise level always helps immensely as well).

I'm at the age now where I'm a little tired and would just rather buy something that had a great stereo built-in that I could live with happily. I realize that one way to go would be to pay some local shop to install something for me. I'm keeping that in mind, but it would be more expensive than sticking with a great factory system (if such a thing exists).

Lastly, I've tried to research this myself but haven't had great luck. The best I can determine is that car manufacturers don't think a purchaser of a non-luxury car would enjoy quality non-fatiguing sound. Those are out of my range. I suppose something in the 30 grand (but not 40) range is my limit.

Anything come to mind? Maybe I'm asking too much (nothing exists in that price range)? The Mazda 3 seems to get good reviews for the 12 speaker Bose system, but I haven't had a chance to test drive it yet.

Anyone know of good subs for the 2SC3421/2SA1358 series pass regulator transistors?

Thanks.

Conrad heatsinks again...

I sent them an email asking about shipping to sweden,but no answer so I sent another...
Are they still open or?
Where do you guys buy heatsinks for your firstwatt amp?

SOLD
$420 includes shipping in continental USA using USPS. Expect that will be at least $30 due to heavy transformer.

Bought these with the intent to drive LXMini's just like Tom Christiansen's set. In fact, had the pleasure of hosting Tom with his setup. And that sold me on the system. Got all the parts, life happens and got put in the closet. Followed his ordering instructions. So you have all the parts except for input/output connectors and wiring and chassis.

Included:

Modulus-86 Tom Christiansen to build 4 channel amp:

(4) Modulus-86 boards
(1) Power-86
(4) LME49710 (not available any longer)

All the components from Arrow, Digi-Key, Mouser (all are still in shipping boxes)
Antek AS-3222 300VA 22V transformer

Price these out and will be over $550.

Send me private message if you have questions.

Hi can some one please recommend a power supply that will make this amp work at its best Hifimediy T1 ALPS vol pot TK2050 STA510 JANTZEN CAP 2x100W | eBay

Hello all.

So, I decided to build another speaker... 😀

The last open baffle speaker was a (successful) experiment, but some of the parts (Behringer) have failed and we moved to a new house with a bigger/better living room so I'm starting over, building a more "permanent" set.

I'll post more information as I go along, but for now, I'll just give a short overview and some modeling information. (Big thanks to Kimmo Saunisto for publishing such an awesome piece of software!!)

The design is a 3-way open baffle speaker + closed subwoofer (i.e. MTMWWSW) The hope is that the result will have that wonderful open baffle sound but with the option to operate the closed subwoofer in tandem with the open baffle woofer. I am optimistic I may reduce the rear radiation/reflections at the lowest frequencies while still maintaining a relatively high directivity index. The primary design goals are a higher WAF than the old monsters, even better sound, and slightly higher SPL capabilities.

I am re-using the 6.5" midranges (peerless HDS 830883) and 10" woofers (Peerless XLS830452) from the old 4-way speakers but I have purchased some much better 1" tweeters (SBAcustics SB26ADC) and some 15" subwoofers (Dayton RSS390HO) to go along with new replacement DSP/crossovers (Dayton) and slightly more appropriate amplification.

The plan is to use a recently acquired (older) 7 channel Outlaw Audio amp to power the MTM section(s) of the LCR channels with a Crown XLS1002 powering 4 @ 10" for the woofers and I'll keep the Dayton APA150 on the new subwoofers unless it needs more power. 😱

For sale a pair of NEW in box SB17CRC35-4 6" Woven Carbon Fiber Cone Woofer.
Retail price 92€ each
I'm selling the pair for 100€ + shipping

Hello everyone,

I stumbled upon this forum a few days back and found a lot of meaningful information on here so thought I would make an account to share some of my wisdom as well. Hope I can help the community! 🙂

Cheers! 🙂

I am building one of Pete Millett's HV Regulated Power SUpplies, and posted about it, but apparently in the wrong place (i.e. no traffic):

https://www.diyaudio.com/forums/equipment-and-tools/212518-pete-milletts-bench-power-supply.html

As part of the process, I redrew the schematic so that it's like a conventional regulated power supply schematic (mostly so that I could better understand what's going-on), i.e. Pass Tubes, Error Amp, Regulator tubes, top-to-bottom. See attached.

In this form, it looks much simpler and lots easier (at least to my old eyes).

If anybody wants to tinker with the schematic, I can post it here or send via PM.

Also, the original post has questions & comments, particularly about using sweep tube (6AV5GA) pass tubes, so take a look...

Hi all

I purchased a Tang Band W5-1138SMF subwoofer for a project of mine. I proceeded to measure the free air parameters with DATS V3 and I got completely different results from the specs, especially the Fs that registered at 65HZ instead of the advertised in the specs 45HZ. I attach a picture of the measured free air parameters in DATS vs the advertised ones by Tang Band.

Since the speaker was brand new I proceeded to give it a reasonable burn in period and tried again to measure. Again the measurements did not improve with Fs being reported close to 63HZ now, but nowhere near the advertised 45HZ.

For peace of mind I went on and purchased a second similar unit from a different supplier, and guess what! The second brand new speaker also had similar bad results when tested in DATS V3. My set up for DATS V3 is working perfectly since all other speakers I have tested come very close to advertised specs.

So based on my experience on buying two different similar speakers from different suppliers and both measuring bad either (a) Tang Band has very bad quality control, or (b) it lies on the advertised specs to push sales, or (c) it sells at discount the speakers that do not pass quality control to dealers which subsequently sell them to innocent consumers without a reference that they are buying a defective product.

I do not care if (a), (b) or (c) is true, or all of the three, but in any case Tang Band is not a brand I will ever trust again as a consumer. I plan to post a video on youtube to expose their shortcomings as a brand.

Hi all. I like to think I’m not totally incompetent but I am totally new to vintage amps.
I purchased an akai 1020 in really great condition. All that was needed were new led bulbs which I did. When it arrived only the right channel was working but I quickly figured out a blown fuse was the culprit.
Everything seems in order but to be safe I bought some contact cleaner and she’s really nice and clean. No pops, crackles, etc. I’m not an electrical engineer though and have struggled with a good chunk of the terminology. I think I’ve read every single available post on this model though. I’ve only visually inspected the caps but they’re all in good visual condition. I know an amp of this age should be re-capped, it’s definitely something I intend to do.

My struggles relate to balance and current adjustments though. The service manual says to balance each side to 40 mA but no matter what I try, both channels are only at 24. If I move the potentiometer to the max each way, it will go down to 23 and up to 25.

And when I try to set the DC balance, the advice is to to set each point to half of supply voltage , but I’ve no idea what that figure is, at the risk of sounding very dumb, is that 230v or just the voltage the rail is pulling from the mains?

I did say I wasn’t an electrical engineer so again, I’m sorry if I sound stupid.

I do want to get it looked at properly by an expert but given lockdown, it’s not possible.

Apart from not knowing what the values should be or how to get there, the amp sounds genuinely lovely. I’ve got it paired with a set of wharfedale Denton 80th anniversary speakers. They are rated from 20-100 watts so the amp does just scrape in there in terms of minimum power recommended but it does a great job.

Thanks in advance to anyone who can help.

Ryan

I'm considering buying this kit from Madisound with the pre-built cabinets. In discussing this with them, their cabinet is unbraced. They claim it's not needed, which I find hard to believe given the size of the cabinet.

1. How should I brace these if I buy them from Madisound? For example, put a rod at the midpoint of the height, add some sort of mass loading panels on the midpoints of the sidewalls, etc.

2. Have the cabinets built custom with bracing instead?

Hey Folks,

After installing a new solar array last year. I have been keenly aware that the system runs at an average of 365 VDC. Seems like that would be perfect to run a pair of EL84's or even 6L6's in PP. Granted I would still need to get the filament voltage. But geeks are always going to be geekin! I am going to build something up for my garage to take advantage of this situation that seems to be crying out to me...LOL

Hi i would like to mod my Nikko NA-500. I am open to every ideas. But i want to start with changing caps. I need your help with choosing which caps and how should i change them?(my hands can change a capacitor, but can't choose the right cap)

Thanks.
Nazim.

This is the link to schematics.
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Hi.
Does someone use this combo:
Amp: Wondom IRS2250
Power: Hypex SMPS 400A400.


I don't find proper information how to connect these...



Help anyone?
Thx

Classe lovers and techs,
I've a P-401 amp vintage 1995 and she's having an issue. When I power her on, the red light flashes for about 3-5 seconds and then it flashed green meaning not going to start up. It's supposed to turn solid green meaning all is well, send me a signal.
I'm looking for a technician who can ru n diagnostics and repair my sweet beast. I love in Northern CA, so the closer the better.
Anyone know anyone?
Thanks,
JD

I recently acquired an original Dynaco ST-70 power amp and PAS-2 preamp. I've been checking them out, downloading docs, checking the tubes, etc.

I'm starting to think that EICO did a better job of documentation than Dynaco did. My docs on my EICO ST70 seem much more clear.

Is there any documentation on the above Dynaco amps where the schematics actually label the tubes, and layout diagrams indicate which tube is which? Just because I can do it the hard way, I don't think it excuses that documentation.

-- KW

Hi folks, been using my HB daily with some nice Klipsch 150 Watt Towers. I've always had a strange issue with it though. Every time I power it up, there is static coming from the right speaker for about 20 seconds. It starts off faint, then gets pretty loud before trailing off and fading completely.

I'm guessing due to this behavior that it involves a capacitor in some way. I have the soft start circuit added to the amp too. Another issue is that it was blowing fuses every now and then on start up. I've since switched to a slightly higher value fuse and it hasn't done it since.

Can anybody suggest a place to start looking, maybe the across the line cap? There is a bit of a strange wiring with that cap since the softstart circuit needed to be wired bypassing the switch pad.

I "got retired" last year, so plunged back into thermionics. Have made some shocking discoveries in the recesses of closets, under guest room beds, back of closets, etc. Like going to an estate sale, but the Dearly Departed was me...

One big surprise was an untouched Bogen DB-130 Mono amp, the original Unnecessarily Complex tube amp. Apparently dates from circa 1955.

Uses 6AV5GA power tubes with a 6CG7 voltage regulator and final driver.
Plus the usual chorus line of 12AX7s and a 12AU7 for the phone stage.

WHAT TO DO? I am totally flummoxed by this one.

I DO have a Mono LP dedicated system (currently using a PhonoDude phono preamp and 300B/417A TubeLab power amp), so I COULD actually use this amp in a restored condition.

Some options:

(a) Sell on eBay untouched.

(b) scrounge tubes (think I have them all), bring-up slowly on Variac & hope the power caps reform (ie don't spew), then reappraise. Then, for example:

(c) recap the power supply; just finished doing this on an old battered QUAD 303 closet find, worked great without any other alterations.

(d) rewire an input bypassing the phono stage and tone controls, use as power amp.

(e) re-use the iron and sockets for a screen drive 6AV5GA P-P amp. Haven't studied this option, but I'm guessing it could be done within the confines of the chassis.

(f) Sell on eBay as working amp...

The build quality is spectacular, so it pains me to think about dissecting it, but I'm afraid it's merely an example of 1950's peak tube amp complexity, and doesn't promise to do any one thing very well (which is why they continue to be quite cheap; super clean working DB-230s (6V6s) are going for say $200 now.

PLUS, it is VERY crowded under there. I reckon that a full-on restoration would take a man-month.

PS have a pile of 6AV5GAs. Running them in the shop in a heavily modified TubeLab Simple SE at 23W dissipation.

PPS did just upgrade to a nice LCR, so I could take a sweep of the components to see if there are any clunkers...

All opinions appreciated.

Hi everyone
New member here. I own an old Philips Laboratory series AH578 power amp. I have been desperately trying to find a service manual or at least the schematic for this amp to no avail. Even Philips customer support can't help me. I stumbled across one post by EchoWars who said he had the schematic for this amp. Unfortunately, being a new member, I can not pm him.
Would anyone have a copy of this that they would be willing to scan and email me? I am the original owner of this amp( purchased in 1978) and it has sentimental value to me plus I think it is a great amp. I would like to be able to fix it even though I am but a hobbiest. Thank's
Don

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SOLD: Omega Speaker Systems Customshop 8 HO Monitors

anyone make something like this ?
omega website mentions 200hz...………………

"Stop scrolling and check out these sweet monitors now on sale at the Omega Store. Feast your eyes on the Vintage 8 High Output Monitors finished in curly fumed oak. This absolutely stunning pair features two of our very own 8 inch full range drivers in our high output configuration. What does that mean? It's a no compromise design by which you enjoy all the accuracy and holographic midrange of a full range driver with an identical (sans the whizzer) driver cutoff at 200hz for added bass and dynamics. The bottom-ported design reinforces low end even further for a speaker that's perfect for whatever music you throw at it. It's all you could ever want. Plus, these speakers deliver very high efficiency so you can make them sing with only a few watts. The cabinet for these monitors was modeled after classic speakers like the JBL L100 and fits perfectly in these Deer Creak Audio stands (included). Did we mention they're hand made right here in the USA? We're blowing them out this weekend at a low introductory price. Don't miss your chance on these! Order today! Link in the bio."


200hz seems a squeak low for baffle step, but I remember an old Klipsch pdf where a heresy was taken off floor (wall / corner ?) and placed on stands, bass below 200hz really nose-dived...…………….

picture below is from their custom shop.

Who can upload a schematic of this pre-pre ?
A slight popping is audible without playing a record - dependent of the position of power supply lead (connection cable) to the pre-pre.
Thank you very much.

Graham Slee Projects Era Gold Phono Stage and Elevator EXP Step-Up [English]
Graham Slee Elevator EXP Pre Amplifier - Analogue Seduction
era gold mkv graham slee + elevator mk III mc - DISQUANTIQUE
MachOne classics - einfach Stereo! | Graham Slee ELEVATOR EXP

Anyone have a sub for the RCA 1A15 transistor on the FEB of an early Threshold 400a?

I'd like to stick with the TO39 case.

I've found:
2N5666S and 2N5667S but both are $25 to $30 each.
There is also the RCA 1A09 which would work .... but the min. order is 400.

Thanks for any help.

Eric M.

Where to buy 0.3mm steel lamination for output transformer core in Europe?

Hello
I need some help with a Chinese tube amp that I’m using for one of my turntable setups
It’s a el34A type amp
When nothing is playing, I hear soMe noise in my speakers, it does not sound like a 60hz buzz, or I don’t think it is. I just tried some other tubes in it and still has the same noise
I have meters and a scope, not very handy with my scope, have it for setups input gain for car amps.
What steps and how do I accomplish these steps to track down the source of this noise.
Also one other problem I’m having is that the left speaker channel is not as loud as the right channel. And it’s the same no matter if I’m playing the turntable or cd inputs.
Here’s a photo of the amp, later today I’ll flip it over and remove the bottom plate and take photos of the inside
Thanks for any and all help
P.S. I’m a newbie with doing this type of stuff so please try to dump it down for me lol

I start this thread because I want to make sure I'm giving my First Watt J2 a fair chance to compete with a few other amps. Cause so far, it's not sounding good to me...

This has nothing to do with measurements -- only a listening evaluation where I keep the source and the speakers constant. The variable is power amps.
Speakers: Tannoy V12
Source: iphone 5s
All amplifiers have been warmed up for 2 hours. The switch from amp-to-amp takes about 30 sec, thanks to phenix connectors.

Let's say I have 5 amplifiers and I want to figure out which ones sound best to my ears.

Is it fair to evaluate good amplifiers from an iphone 5s, as the source of music material?

Hi All,

I will use a SMPS300R 36-0-36V to power an amp.
It has two grounds separated by a ground loop breaker (see attached schematics).
Which one has to be connected to the mains earth and which one to the star ground on the metallic chassis?
Thanks,

Jacques

Looking in EU for a good quality interface, if possible with support for DOP over SPDIF. If you have a project you want to sell PM me.

I wanted to start a thread on this topic. I'm curious if people know of software that can keep two or more streams very tightly synchronized. I do not mean "multiroom streaming" - that just needs to be approximately synchronized, e.g. below 1 second difference. I am talking about 1 millisecond (!) or less difference between the playback on two or more clients.

Why have such a strict requirement for synchronicity? For example, it is to send audio separately to playback systems in the left speaker and the right speaker. In order for the stereo image to stay in the middle and not wander from side to side, the time difference must stay well below 1 msec.

Another reason I am asking is that I just made some changes to the Gstreamer based app I wrote and that I use to stream audio around my home. I now seem to be able to stream to multiple clients and keep the stereo image centered. This means that I will be able to build two completely self-contained, independent active speakers and deploy them as a left+right pair anywhere in my home, with just an AC mains connection/plug and no other external wiring.

If there is enough interest in this from others I will be happy to share my app with everyone. It's a much improved version of my GSASysCon app that I first described a few years ago. It can stream and implement DSP on the clients. Add multichannel DACs at the clients and you have a streaming, DSP crossover audio system that can be reconfigured at will. In the past, it has been the documentation that has prevented me from releasing versions as I make improvements because it is very tedious and complicated to explain everything in sufficient detail. It would be great if I could get some "testers" signed up to do some test runs and give me feedback on everything.

NOTE: when I say "app" I do not mean something that you install on your phone. This is a Linux based bash script with a Gstreamer backend doing all the heavy lifting. You must be able to have multiple Linux computers (R-Pi 3 or 4 or similar, minimum) and DACs to implement this system. Experience setting up and maintaining headless systems and using SSH is useful.

Hi everyone,

I am trying and failing to make a layout for a diode that can take both vertical TO-220 and horizontal like 1n4007 diodes. I've seen people do it on boards, but can't find an existing layout or come up with an easy way to do that. It is basically keeping one square pad and make a duplicate further away for the second round pad on the layout. Any suggestions?