Hi all,

I'm quite out of touch regarding diagnosing faults in CD players - I was never that good at it anyway. However, I recently was given a Sony x779es player, beautiful condition, and it seems an awful waste not to try to fix it at least. The laser sled is KSS272A which of course is unobtainium. The unit looks completely original inside, and doesn't look molested in any way. No caps are swollen, although I did look at some surface mount electrolytics on the motor board itself and they were very high ESR, so I changed them out for new ones.

Of course its not reading CDs. It takes the disc in, the laser head moves up and down to focus, I can see the faint red laser beam, it does the reflective surface check and will spin up the CD. Then after a quite short spin, maybe 5-7s, it stops and the display reads "0".

From reading around, this means that the focusing is working, the laser is not dead, and the motor etc is probably OK. The sled moves on magnetic rails, everything moves very freely, and the head is moving right to the end of its travel to the centre of the disc. I don't think its mechanical at this stage. The fact that maybe the laser is OK, and the fault is elsewhere gives me some hope that perhaps this one can be brought back from the dead.

I think I have read every thread on this player on this site - most of which end with no resolution as you'd imagine. All say not to touch the focus gain/tracking etc on the laser head and the total power output is automatically controlled as far as I can see. Because its not reading, I don't think I can get an eye pattern, so its just that little bit tougher.

Could anyone give me any pointers to start into this?

Many thanks for reading so far!!

Hi everyone. Longtime lurker, first post here.
I’ve always loved the Tc9fd-18. 2 weeks ago on randomly on Facebook MP a guy is selling new old stock TC9 very cheap, so naturally I bought a box of 45pcs. 😎

I have in mind a straight array using 24 pieces each side. I plan to use dsp to attenuate/shade, add various amounts of delay, and low-pass the drivers based on the wavelength/line length ratio. I have a dsp box with 24 output channels, and am exploring amp boards from China or 12ch zone amps to have 24 channels of amplification.

My room has 7’ ceilings, so the array will cover 94% of the height.

Right now I’m trying to understand what issues might come from a delay-curved cbt array going floor to ceiling vs going infinite line/no delay.

the nice part is I’ll have the ability to adjust delay/attenuation/roll off pretty finely once it’s all assembled.

I’d love to hear any tips or cautionary tales anyone has or has seen for tc9 line arrays.

Unrelated but im putting danish oil on my current project: open baffle H frame with grs18-pt woofers. Then im going to get started on this array. hoping to do the CNC this summer and the wiring this fall and winter.

I have a DDC which uses a range of WIMA MKS Polyester, electrolytic and a few PP capacitors. WIMA in general, I've always found can be bettered more often than not - question for the group, what generally is the best more accurate capacitor type for digital audio circuits, is the MKS the best it gets for noise, stability, DA, ESR etc. Could or would it make sense to consider other types where space permits?

Looking at MKS caps around the power section, inputs, and more. Would be great to get some thoughts on this. Thanks!

One of my Parasound A21's developed a problem and, without a schematic, I'm not confident in fixing it...nor do I want to send it back to CA.

Problem description: Amp turns on okay, with the "P" lighting normally. However, the two blue power lights do not change intensity, nor does the relay click. Nothing seems burned so it appears to be simple component failure.

Does anyone have an A21 schematic? Suggestions?

I am Building a Pass Labs Aleph 5 clone and I bought some used capacitors for the PSU from local ads.

They are 2200uF to 5800uF, with voltage rating ranging from 100V to 400V. I know I only need 63V capacitors but effort trying to get used 63V, >10000uF capacitors was futile, so I jumped onto getting these uniformly sized high voltage capacitors when these appeared on the local ads, at a very reasonable price. Beggar can’t be chooser.

I will be equipping myself with power supplies and general voltmeter and ammeter to reform these capacitors. I intend to reform them to 80% of their rated voltage and that should be more than enough for my usage.

Q1) Is there a need to reform them to 100% of the rated voltage do that they are fully “reformed”, even if I will be using them for less than 63Vdc?

But before I reform them, I would like to test if the capacitor is still good, to avoid any mishap during reform, as well as testing them after reform.

From what I gather, I need to test capacitance, ESR, leakage current of the capacitors to determine if they are still useable. I have multimeters and I am buying a DSO and a signal generator. From the YouTube video that I watched, I would need a LCR meter, ESR meter and a leakage current meter.

Q2) Please could you recommend a meter that can do all three? I do not repair electronic equipment for living, but I do attempt to repair simple household appliances, strictly hobby purpose and my budget is <USD200 for the meter(s)

Thank you!

p/s: I have training in electronic engineering 35 years ago, but only worked on system level for most part of my career, I haven’t forgotten my basics and I am fully aware of the dangers of dealing with high voltage but that is about all.

This thread is dedicated to a new 125W amp, about to be born at Aspen.
This will use bipolar output devices, with two matched pairs. Some of the brochure information is attached, and I will add to this in the next few weeks.

Beginnings

I walked into my workshop a year ago and surveyed the inventory. Hmmm. Too many bipolar transistors; small drivers (C4793 and A1837), and large outputs (C5200 and A1943). I resolved that I would design an amp using bipolars again - like the AKSA, Lifeforce, and Soraya - so that I would use these excellent semis before I fell off the twig.

Evolution

I examined my hit rate with amp designs. The early bipolars were very successful, particularly the AKSA, the Lifeforce, and the Soraya - and since that I have been able to refine my front end and VAS stages quite a bit more. So, I thought that I would use a singleton input, a buffered VAS, and a hybrid CCS/bootstrap. Yes, that would do it.......

Choosing the power

I have the SAKSA at 85W, and the Maya at 200W. I needed something around 125W, and at this middle power I could use only two matched paired outputs, like the AKSA Nirvana. A superior power supply bridge comprised of UFSR diodes (used in the Maya and SAKSA) has now been added. A more powerful amp would need three or even four matched pairs; that is an expensive and difficult exercise, but matched pairs is practical and a large number of raw devices yield a lot of pairs.

Layout

I have a lot of excellent new cases, built for the SAKSA. I thought a monoblock Titan would be very appealing; you could fit one channel with a 300VA toroid in one box and the thermal dissipation could avoid the expensive heatsink since the box material is single piece 3mm Aluminium.
I created the first pcb, had a few manufactured in Shenzhen, and then slowly stuffed two for my prototype.

Above is the prototype pcb, with the production version being more refined.......

Market Information

This completes my range; from the 85W SAKSA to the 200W Maya. It will be offered very similar to the Maya; monoblock, one large 278x71mm pcb per channel, two independent power supplies each of 52V rails and high speed diodes, and full DC protection for the speakers.

I expect a batch of 30 before Xmas; price is now finalised and will be $USD3k for a complete pair of monoblock pair, plug 'n play. For DIY, the two modules, with heatsinks, will be around $USD1450, mid-price between the SAKSA and the Maya. The surreal presentation, resolution, slam and imaging is stellar, up there with the best high end, and if you have 88dB/watt/meter 8R speakers I can't see any point in using the 200W amplifier.

Thanks for the interest, this Titan is a very good amplifier, I'm quite proud of it.

Cheers,

Hugh

I retired quite some time ago from a career in Radio Tech & Data. In the late 70's I built the Powertran 75W + 75W Linsley Hood amp and drove 2 Bailey TL cabinets. The amp was packed away for the decades and now I'm trying to resuscitate it. Age hasn't been kind to some of the transistors which have been replaced, but I'm now struggling with the power amp boards and achieving the desired AB standing current. The amp goes into oscillation and draws lots of current( if I let it) notwithstanding that before it misbehaves, I can measure about 0.75v as the offset voltage on the output. I wondering if some oldies are still familar with Hood's DC circuitry?
Cheers from the deep south and its Winter.

Many people in DIY mentioned MELF as their top choice for SMD resistors.

MELF are regarded as better than thin film by the manufacturers and the reasons seem to be reliability, durability, long term stability rather than real time electrical performance...
these things are obviously important in audio to some extent, but I doubt normal high precision thin films arent already more than good enough in this regard.

Im sure both are also more than good enough for any audio circuit in terms of electrical performance but I would think flat thin film would have slightly less inductance than cylindrical MELF.

Based on some recent browsing it looks like good quality Susumu RG thin films come in higher tolerance and lower tempco for the same price as MELF too.

MELF fill the gap for higher power precision SMD resistors but unless there are other factors im missing for typical 1/4W needs I dont see any advantage.

Hi all.

Just thought I would post this thread, showing a few internal pics of the Gemsound PA-4505 amp (400 watts -8 ohm / channel). - According to their data anyway...!

I haven't had a good chance to put it through its paces yet, but the power supply seems to be a bit better than the old EXA series.. But I do wonder how you can get "400 Watts" at 8 ohms with less than 63v rails (see photos of power supply caps)..

Sansui transformer C1590XX D521, trying to find a like replacement ?
Power requirements: 120/220/240V
8 wire leads on both sides of single unit with two coils
Original stock number: 15010402

WTB Used Modi 2 that works, no intermittents. Does not have to look good as long as it works.

joedawson at

itv-3.com

cheers

pos

I am looking for a replacement for the J-series tweeter from the Jamo company from the 1980s. Does anyone know a speaker with a similar sound, I really like its sound in electronic music. What type of dome is there? Silk or something else?
Is the dome from Heco Psm 1000? Could it be similar? Their speakers in those years were quite similar.

Hey guys, I am running into an excursion problem when modelling a ported 650 cubic inch enclosure with the Seas Excel W15CY-001 5.5" Magnesium cone woofer.

I seem to hit Xmax at only 12 Watts. Is this normal or am I doing something wrong? I downloaded the data from Loudspeaker Database and imported to WinISD without any modification. I use the Butterworth preset.

Here is a graph at 35 Watts. I have not added any filters.

I have read on a few forums that predating the introduction of the 6as7 (radiomuseum says '35 but the oldest schematic I've found is '38) that many other large, low mu triodes were used as pass tubes or regulators, including the 300b. However I have never seen any of these schematics. Does anyone happen to have one to share? Does anyone have any interesting tid-bits on the development of dedicated regulator tubes?

...and what's the oldest HV DC tube regulated circuit that you're aware of? When did those designs pop up? Were other triodes used multi-purposefully for that role before the 300b? I'd imagine tubes like the 45 would work fairly well. Not that I would use one that way... just, curious...

I just can't seem to successfully search for such a thing, since the internet is so densely populated with hits for any search including "300b."

Hi everyone;

I would like to know if anyone knows how I can see the frequency response of a speaker with 2 or more woofers of different models and different Thiele-small parameters.

They told me that I could calculate the Vb of the box by averaging the Fs, Qts and Vas parameters of all the woofers, and use those averages, and I already did it, but now I want to see the response that the box would have

Hello everyone,

I've recently inherited a pair of Altec Lansing VOTT A7 speakers (with 511B HF horns) and would like to restore them. The previous owner made some modifications, including adding insulation inside the cabinet and moving the HF horn inside. They were originally purchased around 1975.

One speaker works fully, but the other has no sound from the HF horn. Suspecting a bad HF compression driver, I found both drivers labeled 802-8D, but one is marked "Symbiotik." Upon inspection, the diaphragm and voice coil in the working driver (labeled Symbiotik) were easily removed, while the non-working driver’s assembly seemed fixed due to attached terminals. I did not force this assembly apart. Testing showed faint sound from the faulty driver; both drivers read 2-3 Ohms on a multimeter. Swapping the drivers confirmed the crossover is not the issue.

I've contacted Bill at Great Plains Audio about replacing the diaphragm and re-magnetizing both drivers, but have yet to send them in. Additionally, I'm interested in refinishing the cabinets and would appreciate any advice or tips.

Here are some images for reference: VOTT A7 Album

Thanks,
David

This thread is about the new lineup of 3” dome mids from Bliesma. There’s 4 different versions. Alu/mag, paper, silk and Beryllium. Please feel free to share any thoughts or experience about them. Datasheets for all below:

https://solen.ca/wp-content/uploads/M74A6.pdf

https://solen.ca/wp-content/uploads/M74B6.pdf

https://solen.ca/wp-content/uploads/M74P6.pdf

https://solen.ca/wp-content/uploads/M74S6.pdf

Hello, Greetings from Bali.

Currently on an extended holiday at the moment but hoping to get back to reality by Autumn time.
Just picked up an old set of Klipsch speakers for next to nothing so hoping to rebuild the crossovers when I get back to Europe.
Worked in Engineering for 20 years but the last couple have been in Electronics or Electo-mechanical assembly. I'm here to learn from those with more experience so I can invest wisely in test equipment for a lab to hopefully test and repair audio equipment and to learn about useful resources to accelerate my Learning Initially it will just be a hobby.

Cheers

Paul

Just did some maintenance on one of these classics. Class A preamp, they run warm. After recap, noticed this one is idling even hotter! There are a number of pots, I'd like to check bias settings, I asked Krell about the procedures and targets - and of of course nothing 🙂.. Anyone have suggestions on adjustment targets for this beast? I measured ~60mV across the resistors. The pots in the center control adjust both resistors, unsure the TPs for the pots on the left.

After hearing so much about MiniDSP projects and having gotten my appetite wet by the iDSP from OSD I bought one.
I had a rocky road with the iDSP app initially regarding to to the auto room correct function to generate FIR filters I got it ironed out.
I didn't use the iDSP for subs but instead used it in an expanded implementation with an XO at 300hz to the woofers in my speakers which were already designed as an active system to get better baffle step and LF room correction.
The IDSP is the same board as the Parts Express DSP unit but with 2v out in mono and nice RCA's vs 1/8" jacks. Same software as well.

I decided to try the Mini in my next active XO project and as a first step I substituted it for the iDSP in an already well sorted system.
The result using the panel to configure the Mini was terrible!! The filters had terrible ringing and a huge loss of transparency.
How could this be I asked myself. The iDSP is dirt cheap vs the Mini and the Mini has far fewer features relating to dsp built in to go wrong.

We all know the Mini panel is very basic but allows the more complex FIR filter import through either plugin (Dirac) or 3rd party FIR filter generators

It turns out that the Mini built ins are IIR filters for simplicity vs the FIR based iDSP and it is clearly audibly better with FIR based filters.
Unfortunately to access the much better sounding FIR based adjustments for the Mini we need to spend a bunch more, a WHOLE BUNCH MORE!!
As a baseline the iDSP has dynamics, phase, delay, limiters, Sub harmionic synthesizer, Dynamic bass control, parametric eq plus the XO up to 48db. The iDSP is doing all that via FIR based filters, which makes sense as IIR filters would fall apart with so many complex filters, and does it via the iPhone app and it's only $5 to buy the app vs hundreds for DIRAC or Eclipse Audio's program.

Granted in the grand view of what I have invested into my system several hundred bucks is cheap but having such great sound from a $50 unit has me pissed that it's going to cost and be far more complex of a process.

Hello all. Hoping someone on the forum can help me out with this problem. I recently acquired a SP20E preamp that has nothing but a loud buzz coming from the outputs. I see a couple of potential problems that my/may not be contributing the problem.

1) Appears to be a missing resistor - see photo
2) The the second smaller toroid has two taps tied together 1.9+2.9 but the board input appears to require 9V

Can someone share some insight if the above will have any impact (ie is that resistor location meant to be empty and is the existing toroid acceptable). If these two issues are fine, can you suggest where to look for the cause of the buzz and where to find a schematic. I've reached out to Dan at Tubes4Hifi but not yet received a response. Much appreciated.

Hi everybody

I am new here but not new in audio designs specially for ESL and Tube amplifiers.
My normall interests lie in electrostatic speaker designs in combination with tube amplifiers, all do-it-yourself. All aspects.

John (off Johannes)

[Moderation edit: This thread split from - https://www.diyaudio.com/community/threads/monsoon-speaker-parts.391848/ ]

Thanks woody for the monsoon planars. Since this is already in the right section, i will post the measurements data here.
Lets start with mh-700.

When you want to ship overseas, you keep it strong and impact resistant obviously, but as small and as light as possible. I am soon to send a pair of tweeters across the water. The cost is astronomical as you go up in size and mass. Hmmm... nothing around the right size at home but there is some large cardboard boxes in the basement. This is what happened.
Measure what you need, lay it out and cut it up.
Figure out how you are going to protect the contents on all six sides
Go to work with your box cutter and tape.
The inner box has a pair of Aurum Cantus G3Si tweeters. Top and bottom are the foam board sandwiches and sides use cardboard rolls in the sandwich.
Bon Voyage my precious little ones.

You may also be interested in reading my story on the repair of a Krell KSA250 link below

https://www.diyaudio.com/community/threads/krell-ksa-repair.402617/

After repairing the Krell 250, I proceeded to upgrade the amp which deals with the power supply section. The first one is an easy tweak which all modern audiophile grade amplifier incorporates. This is to bypass the large electrolytic filter capacitors with small value high quality film capacitors. In this case I use 1.0uF 100V polypropylene film cap. Four pieces, one across each of the 68,000uF capacitor.

Used these briefly, but decided to go in a different direction with the project. 2x JBL 2445J compression drivers (1987 date stamps) with 2x 2380a horns. Drivers are completely functional, and horns have no cracks. I'd prefer to sell these together, but will consider offers for the horns and drivers (in pairs only).

Asking $600, local pickup preferred, but willing to ship.

Onsemi has the complimentary part Spice model but not the KSA1015!
Could you share a copy if you have one?

Cheers

I am trying to find a schematic for my Sansui RG-700 graphic equalizer. I did a Google search and nothing comes up except a four page service manual that does not have any schematics. Can anyone help?

Hi to Everyone !
at least for me one of the objectives of a recording is to be able once played back on a very good system to provide a realistic sensation of the original musical event
I'm obviously talking about pure minimalist recordings with no eq effects and so on
And consequently a system must be able to give back that sensation of listening to something live, perhaps when listened in the dark or blindfolded
I wonder if the movie sound effects which nowadays are recorded with incredible quality are not extremely useful to evaluate this ability
I asked myself this some time ago while watching a DVD whose title I unfortunately don't remember
The scene was inside a laboratory in a control room separated from the actual lab by a safety glass
At a certain point an actor from inside the laboratory rapped the glass with his knuckles
I jumped. It wasn't a reproduced sound. It was a real sound
It felt like a person was inside the television and tapping on the screen. My friend and I heard it several times and we agreed that the sensation was incredibly real.
For the record the chain was $80 Samsung DVD player > Revox b150 > quad esl 63
Since I didn't have much money at the time, I only bought the Samsung DVD which I later found to be quite good even with normal music. Very good indeed actually.
So can high quality sound recordings of real sounds be a good tool for evaluating easily the capabilities of a system instead of music?
I think so. In fact, I'm convinced of it

Hi, this is a pair of Jensen JT-DB-E DI (direct injection) transformers, unused. These are a 12:1 ratio transformer designed for stepping down line level for input to microphone preamps. One (on the right) has some tarnish from sitting open on a shelf. I don’t have mounting brackets but they would not be hard to make.

Specs/info here:

https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-db-e.pdf

Max input signal level is 22dBU (10V), however they can be used with higher signal levels (eg power amps) with additional attenuation as in this app note:

https://www.jensen-transformers.com/wp-content/uploads/2014/08/as008.pdf

Price for the pair: AUD250 (PayID/EFT) shipped in AU, EUR167 (SEPA/Wise) or EUR179 (Paypal) shipped to EU. Other locations please enquire (FYI not a great deal for USA due to high cost of international shipping).

Thanks, let me know if any questions 🙂

[SOLD] For Sale - Used Edcor XPWR008-120 power transformer.
PRI 120V
SEC 600V 200ma, 6.3V 4A, 5V 3A

$95 , free shipping

SOLD : Used Edcor CXPP-25MS-8K 23% Screen output transformer pair
25W 8K primary, 4,8,16 Ohms secondary

$150, free shipping

Hi,
I am a new member, name is Rob. Live in a small time in central Kentucky. Known for Bourbon and horses. My 2 strictly two channel (no HT) set up is:

Tidal ---(cat 6)--->NAD CSI ---(coax)--->RME ADI-2 FS dac/pre ---(rca)--->2wpc 45 tube amp --->(mogami cables)---> Heresy IV's

Small room (16'x15' converted bedroom upstairs), listen at low volume levels - mostly acoustic guitar, instrumentals, vocals. Interested in adding a subwoofer someday. Limited knowledge, limited experience and even more limited budget. I do love listening to music though. A lot. It's my number one (maybe only one) past-time.

Some of my new found artists whose music is outstandingly recorded: Pat Matheny, Bill Frissel, Martin Tallstrom. Always searching Tidal for supremely recorded albums. I can listen to most any music, and have...as long as it is recorded well.

Glad to be here and learn from the experts.

Gang,
I have a real good customer who bought a system from me back in 1994. Napoleon 300B driving TRIO horns, CEC huge transport and so forth. He upgraded his system 2 weeks ago to a Triton Silver 300B amps, Tempest Silver Preamp and so forth.

He is moving the Napoleon's into his home office with some DeVore speakers and wants to bring the CEC transport down to spin CDs. I know tried to convince him, but heck the transport probably cost him $17,500. It's nice I have used them at CES shows way back.

Anyway so he wants my Pelham DAC (71A Directly Heated triodes, differential NOS, optically isolated USB, transformer coupled and isolated digital) but with a BNC SPDIF input. Luckily the Pelham USB board is a module, so I can remove that module and sub in an SPDIF and change the back panel and be done.

So this is basically a 16/44.1 system, I have designed the following ones so far and wondering if the time and effort is really worth it:

1) Have a bunch of CS8412s so I came up with a slave using a (have a bunch of these as well) Valprey Fisher VCXO I have at 2.8224Mhz really low jitter 100ppm pull. VCXO DPLL 74HC590A, 74HC86 to create the DATA+ and DATA-.
1a) Use a TentLabs 11.2896Mhz VCXO same as above, possible reclock with 74HC175 dump the 74HC86.
2) CS8412 Master Mode, Crystek 22.5792Mhz VCXO DPLL reclock (SCLK, WCLK, DATA+/DATA-) using a 74HC175, Q0- to D0 divide by 2 ->DPLL CS8412 MCLK into DPLL.
3) CS8412 Slave, Crystek 22.5792Mhz VCXO divide by 2 split into DPLL and ->74HC590A create SCLK, WCLK, possible reclock as well. Use 74HC86 all 4 to create and time SCLK, WCLK, DATA+/DATA-.
4) Punt go with WM8804 live with 50ps of jitter take output into 74HC86 all 4 to create and time SCLK, WCLK, DATA+/DATA-. Use a TXC low jitter 11.2896Mhz crystal.

I have a bunch of these custom made SPDIF input transformers I had made 2000 for SPDIF data to 24/96. That is why I kind of like the CS8412, plus it's 5V which seems to work better for the NOS thing.

Thoughts before I pull the plug? Thanks in advance!
Gordon

Messing about with mongrel floor-standers . . . I found the bass response to be a little boxy. The ports were tuned to 60Hz - a little high in my experience.
I extended the ports (42Hz) using the bodies of washing-up liquid bottles. These are made from 1mm, flexible plastic. Does the flexibility of the plastic have a detrimental effect on their performance?
The boxiness is cured but I'm disappointed in the overall bass response.

The cabinet is 30 litres - an environment in which 98% of 6.5" woofers would thrive.

G'day everyone,

I am currently working on a Sanyo DCA 200 amp. I'm comfortable ordering replacement capacitors but have never worked on transistors before. I want to replace the 4 main output stage units but am a bit unsure how to go about getting suitable equivalents.

The transistors are marked:

1. SANYO B514D 91
2. SANYO B514D 91
3. SANYO D330D 60
4. SANYO D330D 60

From what I can figure out, 1&2 are PNP types and 3&4 are NPN types.

I usually use DigiKey to ship here in Australia so if they stock something that would be good.

If anyone can help me I'd appreciate it.
Cheers

Hi,
I am a new member, I have a background in Physics and I got interested in Acoustics by trying to improve the sound quality of my living spaces..

I've built a number of kits ranging from your ACA kit to a couple Transcendent Audio kits ie Masterpiece 300B Preamplifier and Son of the Beast and a few Heathkits when I was a teen in the 70's. I'm looking for some advice on which amplifier the F5 or F6 would be a good match with the 300b Masterpiece Preamp that I love? The Masterpiece has all the warmth and lush mid-range I need so I'd want the to build the one that is more detailed and precise of the two. I'm currently using an early B&K ST140 that I recently rebuilt and modified. It's not the best match for the Masterpiece Preamp. The ACA is better but not enough power. I'm using that in a small bedroom system with a pair of small 92 db efficient speakers and I love the sound. Can't seem to find any subjective comparisons of the F5 vs F6 to make a decision. Any input on which would be a better match?

Hi guys,
I have a CA-35 Beard Pre-amp that i want to recap and upgrade all caps to higher grade like Mundorf Evo or Supreme. I also plan to upgrade all of ECC81/82/83 to Tele nos tubes ( 1960s). Would it be wise to do so ?

I tried to find the preamp schematic online but could not find any detailed schematic at all. Most of them are just general schematic without notation of capacitor specs ( fara /voltage). Most of capacitors inside the pre were washed out that i can barely see their specs.

Would it be possible for anyone here to help me out? Really appreciate!

Do subwoofer headphones sound better? What technology is inside? I am looking at this wireless headphone https://www.comtar.com/product/hi-fi-headphones/ , do you have any other recommendations?

Regards,

Getting back to my P3 after a lengthy hiatus, had a few SMD 0805 to do, working with new tweezers managed to lose 2 !!!! On the plus side the 2 that I did today are quite a bit better than the first 4.

Here is my project of simply to realize Feedforward Error Correction Amp
(A+B).
The most iportant in this project was:
The Amp must be very cheap and with better sound than the "famous"
"Gain Clown" 😀
Here is a schematic:

There are two schematic for phono preamp, which one can I should chose?
Thanks.

So I bought this piece of gear thinking I might like to hear the contemporary preamp to my X150.5. Well, at first thought it was fun and had incredible dynamic range. After a few days of listening, I felt I lost something. Something pleasing.
Then plugged the Susy iron pre back in and, well never had the urge to put the X2.5 back. Instead I've opened the hood. I first and foremost would like to understand the topology..fets on the input? I don't need to be spoon fed. A reference to an article would be preferred. But some topology I noticed Is this similar to zenpre? And what function? And DC blockers in and out? Possibly early tech of a resistive ladder volume control? What smd resistors were used? My ear is keen on resistors in the signal path . My iron pre has Vishay thin foil input voltage divider and that change was was night and day in my rig with new alps exercised with deoxit to get them to read even close. I want to like this pre but I'm struggling.. any suggestions? The money guy in me wants to pass it on. But. I have a hard time with that. A schematic would be really helpful. Awe. Nobody wants to be benched for a better player...

Hello,
I've been working as an electronics technician for 15 years and privately repair pretty much everything electronic that is broken.

Today I bought a pair of the EV speakers mentioned in the title. In perfect shape, like new. Very rare here, imported from Germany. I had only a minute of listening, but I think these are really good. The datasheet shows some impressive polar diagrams and acceptable FR. A googled image is in the attachment. Mine were updated with a speakon connector and wheels (which I will remove). Together with my bass horns, it should make an enjoyable 3 way horn loaded system - until I have my new more compact midbass horns and new tops finished.

I would definitely like to own a pair of A7s, but these are not available at sane prices here. I thing the EVs come close to the concept of the A7, with some compromises and maybe better dispersion.

Hello!
I have managed to get ahold of a Sunfire Cinema Grand 200x5 with one broken channel that I would like to try and fix.
The power supply is working and all channels except rear right is working properly. I know this is a complex design and no schematics that matches the actual PCB is available.

After visual inspection I noticed at burnt area and that someone had tried to repair it. I cleaned it up and replaced the resistors with proper values.
After that i have a wave form! Much closer to fixing this already!





I would really appreciate some comments on the distortion. Is this crossover distortion? Should I look toward faulty transistor or could this be caused by bad caps?
I would like to probe this with the scope to look for the problem but without a schematic I'm a bit out of my comfort zone 🙂

Attaching the schematic. It's accurate enough to get an idea, but the components IDs are not the same as on the actual pcb.

The area were the bad repair had happend, that I cleaned up is marked in yellow. Before this the wave form had no positive cycle. 🙂

Any input that could nudge me in the right direction would be greately appriciated!

Best regards,
Daniel Elvin

I would like to ask how to adjust the voltage of Krell FPB and KAV 250A to 110V

I probably wouldn't use 110V as the FPB requires 4000-6000W to reach its capabilities.
But I need to know it.

If you have these two machines (110V), can you turn them on and take a look?
Many thanks!

What I can do is give the original factory information to those in need.

Jef

IMG_20210108_171719.jpg - Google Drive

hey guys its a google drive link but i basicly had this unknown 18inch driver that needed a repair ti the tinsil leads and finaly did a box for it the box was aimed at 13 cubic feet to be tuned at 35hz it sounds alot diferent to my other ported boxes as this one has an internal l port and doesnt seem to a wide a bass frequency as my others but its running at 90hx off a electronic crossover and have a good 600watt to feed it

but need to move things around a bit because halfway its makeing my cd in my luxman cd player jump

I started my project of a 3-way sound system and TRYING to achieve the best possible audio quality is my first project. I have already bought the tweeters and the midrange and now I have some doubts when choosing a woofer that would fit perfectly into the my project. Some old and experienced sound people in my state talk about dry woofers instead of rubberized ones for the following reasons:
1 - Frequency Response: Dry Cone: Dry cone woofers generally have a wider frequency response, covering both mid and low frequencies. This is important for 3-way systems where the woofer needs to integrate well with the midrange driver. Rubberized Cone (Subwoofer): Subwoofers with rubberized cones are optimized for very low frequencies and do not do as well in the mid frequencies. They are designed to move large volumes of air and produce deep bass, but can lose clarity in the midrange frequencies.
2 - Rigidity and Control: Dry Cone: These cones generally have a better transient response, which means they can respond more quickly to changes in the audio signal. This results in a more accurate and detailed sound. Rubberized Cone: Although rubberized cones are good for preventing distortion at high volumes, they can be less rigid, which can affect the accuracy of sound reproduction in the midrange.
3 - Integration with Crossover: Dry Cone: The more balanced nature of dry cone woofers makes it easier to integrate with the midrange and tweeters in the crossover, providing a smoother transition between drivers. Rubberized Cone: Integration can be more challenging due to the more limited frequency response, requiring specific crossover adjustments to avoid gaps or unwanted overlap.
I said that I had chosen a rubberized midranger and even so they mentioned the dry cone woofer again and recommended the following woofers: JBL Selenium 10PW5
JBL Selenium 8PW5
Oversound 8G300

I've been using speakers for 40 years and now I'm in a country with a different voltage
My major is in large systems
Hundreds of pairs were used on post-1991 products. The speakers are dynaudio acoustics m4, M3A
My English is not good....so I use a translator....

I live in Taiwan now and there is no service here. And we need to spend twice the price to buy it...so I'm here to ask some questions

Wanted to Introduce myself. I'm just coming back into my audiophile stage again. I have a pair of efe (ed frias designed mtm) that I love, I also have the bookshelf speaker he gave the design for years ago. And old bolder cables mensa dac and a tube preamp someone built. No idea what it is since I brought it second hand. Thinking about getting all these pieces up and running again. I need a new amp so toying with making one, either a solid state of a tube amp.

So I picked up one of the vtv purifi amps to run my teo EFE (ef frias Mtm) designed speaker. Model t-22 carbon fiber. Sensitivity is 90 db, 8 ohms 30 to 200 watts.
Anyway looking for recommendations on a tube preamp and a dac. I listen to music mainly from amazon prime. Budget is around 2500 total.
I am always after the giant killers. Before I had a custom built tube preamp (sorry brought it second hand so don't know what it was) too long ago lol and the dac I used to have was the mensa by bolder cables. Loved that set up.
Thanks
Dan

Hello, I'm currently building a chip amp based amplifier and want to try measuring distortion with my Scarlett 2i2 gen 4 sound card. I've seen some protection circuits and posts about earlier generation 2i2 but there are still some things I do not fully understand, and I'd hate to blow up my sound card.

First I want to ask about protection. I guess there are 3 things I need to consider:

1. Amplifier power rails touching line in or line out.
   • I use 60V center tapped to power my chips. From what I understand I can use 2x 3.3v zener diodes to protect from this. Could someone elaborate on this? Why does the 1k resistor take up the load?
2. Level too high on line in
   • I'll use a simple voltage divider for this so it becomes <1Vrms for my measurement.
3. DC on line in.
   • First off, isn't line in already AC coupled? and if not, what capacitor should I choose so it doesn't affect my measurements? Should I also put one on line out?

Here's a picture of how I think it should look:


Another thing I wonder about is the balanced inputs and outputs. The user guide says:




Does this mean that I can choose whatever and it detects what I'm using? If I use a TRS jack, should I if so ground the right channel so the sound card thinks I'm using mono? I'd prefer using mono for simplicity. In this thread https://www.diyaudio.com/community/...r-measurements-whats-next.301166/post-4963930 @wintermute says that it's important for 2i2 gen 1 to atleast output balanced audio, but I'm not sure if it's the same with gen 4.

So, for my protection circuit, Could I simply add another pair of 3v3 zener + 1kR to the inverted output as well going into the linked bal->SE converter, and output that into my amplifier and keep the rest of the protection circuit same if using balanced output?


Last thing, why shouldn't I use speaker out - for line in ground? I know for certain amplifiers the speaker - is not ground, but if it's not ground how do I get accurate/any measurements by putting line in ground on line out ground instead? Since speaker + is referenced to speaker - and not line out gnd? This does not make any sense to me.

Greetings!

I am restoring an old speaker from England - a Mordaunt Short Signifer. circa 1980.

I am looking for a replacement tweeter/s. The original is described as an Isophon 25mm soft dome, and there have been references to this being some sort of Isophon KK10/8 possibly but that is not verified. Have reached out to Lockwood in England - but they no longer have the spares.

I was hoping someone would know of or have you come across a possible replacement for this tweeter, or where some stock of it might still be available?

One tweeter is not making any sound, but the mid and bottom end are excellent, and soundstage and transparency are very very good. Wide and easy soundstage. Timbe of piano and guitar and voice are well reproduced even with one tweeter MIA.

Any other information would be welcome.

Many many thanks

Jay Mendoza (Sydney)

Here to learn. Thanks!

Best,
Daniel

Attached are the files for the TMOQ 834P Preamp, released for the benefit of the public. Includes BOM and schematic for the main board, tube power supply and SS Power supply in various flavors.

Also attached is the original version of Thorsten's "The very much non-definitive EAR 834P Modification Guide"

Feel free to use this thread to document your builds.

Some threads for reference:

End Of Life Phonostage / The Last Phonocorrector - Romy The Cat's Thread

EAR 834P Modification Guide 834PTF - Romy The Cat

LencoHeaven 834P TRLH Thread - Lencoheaven

Original 834 Douk Board Thread - Lencoheaven


“The earth cannot move without music. The earth moves in a certain rhythm, a certain sound, a certain note. When the music stops the earth will stop and everything upon it will die.”
― Sun Ra, Space is the Place

hi i need help selecting loudspeakers for my newly aquired behringer europwer pmp2000 powered mixer , i have been loong and cant seem to find loudspeakers to fit the spec of this mixer
so on the mixer it says it can handle 225watts at 8ohms per side
or 350watts at 4 ohms

i was told that i need to find a loudspeaker that is rated at either 175watts 4 ohms or 125 watts 8 ohms is this correct

any body that has used this mixer any help on recommended speakers would be violently appreciated James

So, I would like to build a simple, or not so simple damp ducted voigt pipe speaker enclosure. Good combination of uncomplicated design, and hopefully good sound.

Now my question. For given design, say one done for a specific speaker, fostex xyz for hypothetical example. How much flexability is there in substituting different drivers? I have no desire to become a speaker design expert, but what are the critical speaker parameters that go 8nto the design of a voight pipe etc.?

I would like to start out with a modest driver, with the hope that an upgrade would be possible that would work with the original design.

Most of the folded horn orvoight pipe info articles go into way more detail than I am willing to invest in at this time. General, overview types of web sites or articles are not readily found.

Roger

Up for sale is a Pearl 3 power supply that has been in use for many months in a prototype build. This one uses the split bobbin transformer.

IT WILL NOT FIT IN THE 1U HEIGHT CHASSIS!!!!! It is too tall.

If you’re planning to use an alternate chassis to the 1U Pearl 3 chassis from Modushop that has taller internal height, this one is for you.

$35 + shipping. Figure $10 shipping in USA.

SALE PENDING

Found a pair of these in a storage box, can't find the datasheet for this exact model but they are used in ceiling fans. The manufacturer's site just mentions "Metallized Polypropylene or Polyester film", but which one is it no one knows 😎 Probably equivalent to CBBs. I have been using oil-immersed motor-runs for a long time, they sound good for power supply filtering but are rather large. Interested to hear if anyone used these boxed types and if they sound good, because they would make for a more compact design - or am I losing my time on them.

Series' page on the manufacturer's site

Mainly because every twenty minutes I have to get up out of my chair and either turn the record over or go to the shelf and pick something else

Hello!
Anyone has used car part restorer (Bumper black) to clean rhs junk off on the drive units?

Thanks!

Just wanted to say hey. I got attracted to the group by a very intriguing thread on building a tube amp - thanks guys! I also will probably be looking to build some other stuff like Dacs and streamers. but first i want to start by building the whammy headphone amp.

So i found this passive bass treble board on Aliexpress that seems somewhat decent imo

https://a.aliexpress.com/_oFtNCp8

İ am thinking of using it between the preamp and the power amp section of a diy tube amp
İ have a few questions about it tho

What would be the cons of using a passive board over a active one

İn the description of the board it says that the output gain is 0.5 which is half of input gain would that be a huge loss and does it mean it outputs %50 less sound than the input

Thanks in advance,

I have been gathering a lot of very important info from all the discussions here and I would love to start being able to write a few comments myself. I am from CZ, I studied architecture in France and I live in Canada. I am currently designing my first speaker build, since this will cost me a lot of time I decided to go fairly high end, specially in the cabinet design. I will be using CNC trans laminated wood to achieve curved forms and I am looking for some advice on driver selection.

Experts please guide me!
I have 2 Nos of PULSE 24-28 Volt 17-20 Amp SMPS power supply unit
Can I use this For Any Class A amplifier?
i.e : Pass lab/Jean Hiraga 30 W or another Class A
For Symetrical Power supply cant both use together?
Thanks

I've been an audio enthusiast as long as I can remember, and I am excited to start a journey restoring a set of Altec Lansing A7 VOTT speakers! I'm also a fan of BIC America home theater speakers.

College professor and audio enthusiast in south MS.

Hi, I am moving my audio system (which includes a Raspberry Pi 3 running Moode, a SMSL DAC, connected to the local WIFI) to a new home.

All was working fine.

In the new place I connected the RB to an external monitor and keyboard to configure the connection through the new WIFI. However, soon after logging into moode the video signal is lost. If I'm fast I can manage to run a command, but then it's gone. This has happened with three different monitors, with different cables. Any clue about what might be happening?

Thanks,

David

Would someone please clarify, in a push-pull tube amplifier, two pairs of power tubes operate in opposition of phase.
The audio signal is applied to two power tubes—one with a positive polarity and the other with a negative polarity.
One pushes the speaker cone the other pulls it.
In a SET amplifier does one tube only push the cone forwards and backwards or only forwards?

Many thanks
EZ

Hey guys, noob alert!

I've bought a cheap used TEAC SW-P200 subwoofer and it works just fine for my use case... apart from the damned auto standby feature!

There's no way to turn it off or change the sensitivity of it so I'm stuck with the sub working great while there's enough "oomph" in the signal (like listening to music or action scenes/games) but as soon as the content gets quiet it turns off after about a minute.
It turns back on as soon as "something" happens, like an explosion, but its annoying and the poor relay switch has to continuously tick-tack every few minutes...

Unfortunately there's no way for me to increase the signal level at the source so probably the easiest way would be to just remove the relay and bridge the contacts but if possible I'd prefer to keep it as is and make it more "sensitive" to the incoming signal or increase the shutoff time

I cant find any service manuals or schemes online for this model and honestly even if I did I still wouldn't understand what I'm looking at without some help 😆 I've opened the back and there are 2 PCBs connected by a flat cable, the main one where all the main electronics live and a smaller one where the LFE IN and volume knob are connected.

What do you think? Is it possible just by looking at some photos for you guys to figure out how the standby circuit works and help me find what can be replaced? Hopefully a resistor or something like that!

Thanks a lot!

hello from northern ireland

Hello friends of sound transducers,

My milling machine is hungry, and so are my ears, so I would like to build some loudspeakers for my living room. I have already filled out the following questionnaire:

-How much money can be spent (per piece/total - with/without cabinet)
approx. 300€ without cabinet

-How big is the room?
20 square meters

-How can the speakers be set up? (a small sketch with location, furniture and listening position is very helpful)
Approximately square room, stereo system / TV set against one wall, sofa opposite against the other wall. Speakers to the left/right of the stereo system. From the sofa, the windows are on the left wall, the entrance door to the living room is on the right wall.

-Do you want floorstanding speakers, compact speakers, wall speakers or something else?
I had imagined something like the LS from the 60/70s, in terms of appearance. For example, L100 or Beovox 2400 and similar.

-How big can the speakers be?
(HxWxD approx. 600x350x400)

-Is a subwoofer available? (if yes, please describe in detail)
No

-Which amplifier will be used?
Onkyo A8820

-What do you want to listen to through the speakers?
Rock, metal, hip-hop, movies

-How loud should it be?
Higher room volume, there are songs that you have to feel

-How low should the speakers go (Hz)?
As low as possible

-Is great importance attached to neutrality?
Hm, I would like to feel the bass in my diaphragm, clear voice reproduction, defined highs

-Is there anything in particular that is important (full range, sub-sat combination, closed construction, number of ways, manufacturer, active speaker, horn, etc.)?
I'm not sure. I once read that a closed system would have advantages in terms of bass reproduction as I want it, but I also read that it depends more on the drivers. I was thinking of 2 ways, but I'm happy to be proven wrong. I think I would be tempted by 10 or even 12 inches.

I have measuring equipment and software for evaluation.

I hope that you can give me any suggestions.
Thank you very much in advance.

Cheers,
Frederik

I built a whammy a while ago and it worked fine and sounded great. A few days ago I lost one side of the headphones - one side blown due to about 16v dc!
Any ideas?

hi i am looking for a great pa system that will work for a blues band playing to about 150 people indoors , i dont have much of a clue about pa's so any help much appreciated

Looking for a BASH 300s plate amp. Parts express used to sell them but they have been discontinued. Before I try and cobble something else into place, I thought I would check and see if anyone had one. Would be interested working or not

I want my phone that I use for field recording data storage out of the ground equation. Also external power feed for long recording sessions.

• I have a working recording system using an OTG cable between the ADC and the phone.
• In order not to drain the phone from power feeding the ADC, I have made an y-split cable to connect a IKEA USB battery bank - it works good.

Now, introducing a USB isolator with possibility for power feeding downlink device.

• Using an ordinary USB-A to USB-micro (phone), the phone is charging from a battery bank (an other IKEA unit)
• Using an OTG cable, the phone is not charged.
• In none of the two cases above with the isolator do I get any signal transferred. The phone app says in both cases: "No USB recording device detected".

Units involved are:

• Isolator: https://www.altor.co/products/test-equipment/usb-isolator
• ADC: Cosmos
• Software: USB Audio Recorder Pro 1.61.0
• Phone: Mi A2 lite (Android 10)

I have tried most variants in which order the different things (units, power units, cables...) are started up and connected to each other.

I have tried the Isolator between an RME Digiface and a Mac Mini - it works and sound OK. (perhaps even an improvement actually..)


Why? Any hints or suggestions or obvious errors made? What could be the problem?

Thanks in advance...

//

Hello there. I am trying to add a compensation circuit very similar to the one explained here to a tube preamplifier based on a simple E88CC common cathode stage + cathode follower.


I am adding the compensation circuit between the balance and volume control. The thing is that I have high frequency attenuation.


Please see attachments.




If if bypass the balance control, the frequency response looks as it should in the LTspice simulation.


I believe this is an impedance mismatch problem but I cannot move the circuit after the cathode follower cause it works together with the volume control which is at the input.
NOTES: I dont want to move the volume after the cathode follower and also don't want to add another potentiometer for the compensation.
I also cannot use a four gang volume potentiometer.

I tried changing the balance pot value to a lower 10k, which seems to cure the problem but input impedance drops way too much to load sources properly.

Any ideas? THANK YOU!