New Build
This will be the third time I have built this amp section so I know it works fine, and is normally very quiet.
I normally don't use a choke but did this time.
But if I ground R1 the amp hums/Buzz very loud along with some whooshy noise.
I tried grounding C2 directly like I have seen done and the amp hums exponentially louder until shut off.
The amp works without this grounded at all as long as the negative feedback is connected.

Test I have done:
All preamp tubes removed, No change.
Preamp section disconnected from amp section no change.
Phase inverter tube removed, hum & buzz gone. Just a normal low hiss
Changed Inverter tube to one I know works, no change.
Grounds test (several points) show less than 1 ohm all the way to the power outlet.
I don't have a scope, but my meter shows less than 2 volts of AC at the power caps. B+ 473
Plugged another amp with the same amp circuit to the same power outlet, with no issue.


Other symptoms:
When turned off the speaker takes a bit to stop making sound (can't remember if that's normal)
The power caps instantly drain almost completely at shutoff. Normally it takes a couple of minutes with a drain resistor attached.

I have had one of these amps for a while and have just finished replacing most of the aged components.

I have though never found a circuit diagram for it on line or seen anything much from other owners.

Anyone have or had one in the past or worked on one?

Hi,

I have been designing.my 2way bass reflex speakers and now they are complete, Proud moment for me 🙂😉, I have checked the frequency response which seems to be ok, however removing all these biases I like them when they play music.
I am stuck at one point here on my winISD model, where it shows me Cone Excursion exceeds limits from 59Hz to 145Hz over full signal power of my amplifier @40Watt. I am paranoid on this as I fear that may damage my dayton speakers at this level. The cone excursion starts to exceed from 10watts of power.
I am attaching the graphs from winISD and need your inputs and opinion how to limit the excursion as I am stuck in the situation. Also I will appreciate any other design inputs good or bad on improving the design.

Thanks folks and look to have your support, help are welcome.!!!!!!

Regards

Cleaning up the mess...

I was going through a box of semis and found a tube of Toshiba 2SC5200N. I needed one for a SLB power supply project, but for some reason bought a tube of 25. 24 remain.

$2 each + ship. Or $40 for all 24 + ship.

Suppose one constructing one integrated amplifier to keep it understandable lets say one P3A and one DOZ preamp
Integrated amplifier no one is messing up between amplifier and preamplifier
so there is one coupling capacitor / DC blocking capacitor in the output of the DOZ and one more in the input of the P3A
can we remove one capacitor ?
only one capcitor between the two devices should be enough
any ideas ?

Anybody ever tried cloning this amplifier? I am planning to make a PCB.
Is the schematic correct?
Will it work perfectly after implementation or do I have to change anything? Also, will it make any trouble if I eliminate the servo circuit from the amp?

Due to unavailability of some transistors, I want use 2SC2073/2SA940 pairs throughout the whole design and 2SC5200/2SA1943 for the output pairs.

Waiting for expert's suggestion. Thnx in advance!!

The easy little kit
Notes-------------------------------------
Ebay link:
(link 1) Two board *stereo* kit TDA7293 Parallel from HappyShop
(link 2) Two board *stereo* kit TDA7293 Parallel from Min9988
(link 3) One board mono TDA7293 Parallel from Happyshop
(link 4) One board mono TDA7293 Parallel from Fly-XY

Power circuit:
Fortunately, the kit came with 220uF power caps for the amp board, which is perfect for clear sound and cool running of TDA7293. This setup with 220uF (or 330uF) power caps assumes that there will be larger power supply capacitance (a real power supply board).

Voltage:
If you push for quality, the Antek AN-3222 transformer is low priced, drops only 2v @13a and has ideal specs for use with TDA7293. If you push for power instead, AN-4228 is about max. However, 25+25vac dual secondaries transformer is typical and that's what I'm using.


Cap values:
I'm changing the 47uF bootstrap cap to 100uF to assist low bass (valid range 68uF to 100uF).

I will omit the 10uF Mute cap (location is right side of the board, near speaker jack) for zero delay.

A highly effective power circuit upgrade is shown at post#30.

Instead of the 22uF FB-shunt cap (which is far too small), I'm using a 680uF 16v cap paralleled with a 0.47uF electrolytic cap for good treble. I'm also using a 1n4007 antiparallel pair as safety clipper to restrict this big cap's discharge to 0.65v. Photo is at post#29

The 105, 1uF box cap is your input cap, but there's other fun options to use, such as 4.7uF (or smaller) Elna Cerafine paralleled with a tiny polyester (to DIY your own low cost blackgate), etc. . . Try some variety and choose which you like.


Resistor values:
The leftmost 22K resistor is Input Load. Valid range is from 15k to 28k. A difference in value can alter the midrange loudness. If you don't need the adjustable feature shown in the schematic with 100kVR||39k, then just use a simple 22k or 25k resistor for input load.

The gain divider is the factory standard 22K/680R and although this will work, I disagree with bad performance that generic values cause. Instead, I would like to use 27K/730R for great quality. If you want quality results, the feedback resistor and the feedback-shunt resistor(s), MUST be placed underneath the board, close to the FB-Shunt cap. The feedback resistor is installed from pin14 to pin2. The feedback shunt resistor(s) are installed from pin2 to FB-shunt cap. It fits easily and shown at post#24.
The above is new text and new schematic. Previously, there had been some problem getting sufficient gain; however, a just-right gain divider setting with resistors direct (not inserted to pcb), and a power circuit update was the combination that got this little amp up to high fidelity.
See assembly photos starting at post#24

It does use a power board:
Due to the power circuit mods for power filtering at the amp board (in the photo attachments at Post#30) we didn't need a CRC type power board, so here's a simpler edition.
(5x3300u caps per rail and a pair of prefab bridge rectifiers is similar but easier.)

See also Bob's power supply

Yes, new content that uses the schematic (above) starts at post#24--previous discussion might not be applicable to the new schematic, so you will probably want to skip ahead to post 24.

Super new at this guys. I pulled apart the crossover and upgrading components. The tweeter had a 4uf 200vdc and I am replacing with 3.9uf 100vdc. Is there any problems with doing so when it comes to VDC. And what's the difference in vdc with tweeters

Hi,
I need for a line stage 2SA1175/2SC2785. What is the best replacement I can buy ? I need about 100pcs/each.
Many thanks
Dieter

Intended to learn simulation, this amplifier schematic comes up. Yes, it's a modification from some schematic around internet. I did use Micro Cap 12 to simulate. The simulation result looks like output power = 21.1W (RMS) and THD is about 0.02% when D1/D2 being 1N4749. The quiescent current for each output transistor is about 975mA, if my simulation is not so wrong.

There is a significant question to be asked here: is this safe to use +/- 19VDC or even +/- 21VDC for NE5532A for listening? because according to NE5532A specification from TI, its absolute power supply is +/- 19VDC.

Is this Class-A BJT amplifier schematic worth a tryout? Do you think there is a better schematic to try? Under consideration of utilizing NE5532A for voltage gain and DC servo, and SC5200/SA1943 as output transistors. BTW, for learning purpose I already used KiCAD 6 to get a PCB layout and routed, about 2.5"x7", not send out for PCB sample manufacturing yet. I know there are so many DIY experienced people around here, that's the reason I am asking. Don't laugh at me.

Wood has gotten ridiculously expensive if you are forced to buy at end user stores. At the same time the quality you get has gone down. At least where I live. Ply wood has large chunks missing in the surface that have been fixed and hollow spots. Noting you can put wax on or clear coat. Fiber board is rough as sand paper, in the past at least one side was fine sanded from the factory. MDF is often so bend, you have to re shape it for weeks until you can use it.
I have an alternative, that may be interesting for some DIYS guys here.
Since I have a low priced circular saw with a long guide rail for cutting perfectly straight lines, I have started to use old furniture and panels from all kinds of sources for my builds. I collect clean, usable material, cut of the unusable excess and store it.

Lately for example I got 12 doors from an old living room closet wall in different sizes, veneered in wonderful cocobolo. With some careful planing how to cut, I will build a large subwoofer from it.
If you ask, there are always people which are happy to get old furniture or left over building material picked up, as they may have to pay otherwise for it.
Recently I bought a table saw in a close out for 105€, which is perfect for smaller cut's which are more complicated with the guide rail.
It has paid for it self in short time, as I do not have to drive to the hardware store that often anymore.
There is one problem I want to address: Used panels may have screws or nails hidden, which can ruin a saw blade. If you are in DIYS you probably have an electronic line finder. I use it in the metal setting to check before I cut.

Seems like the amp shouldn't power down until the heat sink is pretty warm or even hot to the touch. Any tips?

I have some equipment with a bog standard LCD 16x2.
I built one system up and noticed in one part of the software the display corrupts.
So I checked solder joints etc and it seemed fine.
So removed display and fitted a new one which worked fine.
So bad display ?
I wanted to see if it was software timing problem so soldered bad display into a new pcb.
Now it works fine in the new pcb !

So had a serious look at my software timings and they are all above what spec suggests.

Not sure where to go next ? unless it was a bad solder joint that looked ok ?

A year ago i bought this amp as defective on one channel.
I repaired it and then it has been on my shelf for a while.
Now i will need an amp to drive 2 fronts and 2 rear speakers in my RV (camper)
i will probably use a portable sub together with my setup.
My idea is something like 2 pairs of infinity kappa and a tube sub.
I will not destroy my interior with a big subwoofer.
Question sell the Harman and buy something newer and better sounding or keep it?

Pelle

Hi

have some problems with my vfet,suddenly it lost all power, can hear faint sound when volume to max, same level in both speakers.

it´s not the source or preamp, using them with my f6 now.

i measure the power into the output stages be 33.somthing volt , shouldn't that be 36volt, can this be the meanwell power supply is gone bad

Andreas

Hi folks!


Does anybody have the schematic of Pink Triangle's THE PIP or the PIP 2 ?

I remember listening to the PIP2 a long time ago and found it very good - a phantastic battery powered amplifier with a very unusual look.
I also remember a HifiNews article rewieing this item vaguely ( it consists a transconductance amplifier and passive riaa).
It seems for what reason ever PT discarded the product early, it was no great succes (which does not say anything about sound quality).

Any deeper knowledge ?

greetings
Klaus

Hi all

Some hesitation on adding to the pile of Sony V-Fet threads. So this is aimed at logging MY refurbishment of a Sony TA-5650.

(My TA-4650 thread is https://www.diyaudio.com/forums/solid-state/376634-sony-ta-4650-fet-thread.html that didn't actually go so well)

First of all lets get some resources out of the way (just in case)

Service manual: best copy by far I've found is at hifiengine although others exist they are resolutely monochrome 🙁
Service bulletins: yes! most important is the 'dutch' one as it details mods to bias and component changes made to enhance longevity (Has ANYONE seen that in English?)
Circuit operation: see "Sony TA-4650 new circuit operation" for a how it works document that broadly applies

Other links:
https://www.diyaudio.com/forums/solid-state/311612-sony-ta-5650-restoration-doc-breaths-life.html
What I hope this thread will mimic 🙂

So here goes, as usual I haven't finished this project yet so its not a tale of, "this is how you" it's recorded live 😀

I find it very useful to step away from the project and document it.

I have *TWO* Sony TA-5650 amps and one set of working power transistors
Serial 601467 - marked as 601518 internally
Serial 602370 - marked as 300378 internally

602370 has Grey Elna Caps fitted rather than blue Nichicon ones, as a side note, it is also missing a positive power rail, at least without Vfets

To me it looks like 602370 went back at some point and got a new serial (?!?) Unless someone knows what the internal numbers actually mean anyway...

601467 is cleaner, as both of these are 'pre-loved' maybe it's been serviced, I couldn't tell you. Anyway I'm going with 601467 from here in. A decision that would have been best made BEFORE I robbed the output board for the TA-4650 project.

Can I just say I hate wire wrapping. I really hate wire wrapping.

Andy

Hello everyone. I found a Project Phono Box mm/mc phono preamplifier at a garage sale, the model that is powered by an external 16v AC source.
Since I already have an IFI ZEN Phono, I want to experiment with modifying the Project towards the Actidamp II, just to see how it sounds.
I have found the thread of said modification, but when I look at the circuit board I see that as IC it has TL 071 CP.
I have searched for information and I see that this integrated is not dual.
How could they use it as a dual IC? Or is there a dual version of the TL 071?
Since I haven't bought the transformer yet, I haven't been able to test it, I don't know if it's working.
Another question. Is it convenient to spend time in the modification towards the Actidamp?
According to what I have read, it would be the original scheme of the designer.
Greetings.

Want a giant-slayer amplifier for short money? NAD built the 2600A and its twin the 2700 THX in large numbers. You can find one, maybe with some minor fault that reduces its price to beer-money territory.

This circuit does a lot of things right, right from the factory:

• degenerated IPS
• IPS loaded by a current mirror
• IPS doesn't directly drive either the VAS transistor or the miller cap. It's lightly loaded.
• triple EF output stage
• generous stability margins. (We need this when the OPS rails boost from 54V to 92V when the "power envelope" kicks in, that creates a blip in the output. That blip should settle and stabilize in less than 500nS, healthy stability margins allow this.)

It doesn't sound bad stock. From the factory this is similar to Doug Self's "blameless" amplifier, doing almost as well as anyone knows how to with single-pole loopgain roll-off.

But can we do better? Can we improve its distortion performance by 20db? Will it kill Krells and mince Macs? You know it 🙂


Step 1: This amp comes with a built in preamp, a couple of JRC opamps that implement both the bridging switch and the front-panel volume knobs.

Even a 5532 is better than these opamps. Better yet, just remove R121 and R123 and jumper over them to defeat the preamp and run the "lab input" (aka "THX input") straight into the power amp section. Aaah that's better.

Deleting the bridging support is no sacrifice, as there's NO earthly reason to bridge this amp. With 92V rails, this amp is marginal for a 4-ohm load before bridging -- you're reaching deep into the SOA of the outputs to drive 4 ohms at anything near full rail voltage. Bridging it just makes this worse: 8 ohms becomes equally marginal and 4 ohms suicidal. Just don't.

Step 2:

With a few substitutions, we can convert the factory circuit to TPC compensation. With two-pole roll-off in the loopgain, we can reach >55db of feedback in the audio band, instead of the ~35db we get with the factory circuit. See comments 5-7 and 22.

A word of caution, these PCBs have a very thin copper film. I often use the dremel to gently remove solder mask and clear off some copper, but that doesn't work well for the NAD -- the bit goes right through the copper to the fiberglass! :-C Ah well. If this was the kind of amp whose build quality audiophiles crow about, we wouldn't be hacking it up would we?

Step 3:

Adjust the input network and NFB network for reduced distortion and improved DC balance, see comment #9.


Step 4:

Add filtering on the +18V rail, and improve the IPS current source with an LED; see comment #15.


EDIT: First attachment is the stock circuit. Please ignore the 2nd attachment, which is an older rev of this mod. The "latest and greatest" circuit is in comment #22. Cheers!

I’ve never seen such a big ribbon driver before, nor one with such an extended frequency response. On paper it looks like and option of something close to a FAST system. Of course, there are no THD measurements and I can’t find anyone using them (the pdf is marked preliminary). Are there obvious trade offs with ribbons tweeters trying to go this low?

LM8K - Wide Band Planar Ribbon Transducer - Radian Audio


Brian

Hi all,

I have two potted (epoxy filled) and shielded (Iron can) O-Core Transformers for sale. Both are brand new, and unused.

Originally purchased from James Transformer for a project that never happened....such is the way it goes sometimes.

Transformer Spec:

VA: 50

Pri: 240v
Sec1: 0-18v
Sec2: 0-18v
Sec3: 0-18v
Sec4: 0-18v

Premium quality transformers. Both tested and working.

£65 ea, or £115 the pair. Inc postage in the UK.

Hi all,

I bought a minimum order of these caps but don't need them all. I have 3 of each value and once they are gone, they are gone.

WEET WMH Pure Aluminum Foil and Film caps were chosen to replace some metalized PP caps in my speakers.

These are genuine alternatives to Jantzen Alumen-Z but at a lower cost.

All items are genuine imports from the factory.

Caps:

WMH Aluminum Foil and Polypropylene Film 6.8uF 100V +/-3% 23x85 Axial RoHS

£55 EACH

WMH Aluminum Foil and Polypropylene Film 8.2uF 100V +/-3% 25x85 Axial RoHS

£60 EACH

Price includes postage within the UK.

Will ship anywhere, but please ask for a postage quote.

https://ibb.co/445WddQ

Needing help matching 10" woofer in Ohm FRS 15 , I have set of Ohm FRS 15 with one woofer went bad . The size of the woofer 10 inch . I probably have to change both woofers to be a match . The deisgn uses 10 woofer and one paper cone tweeter only . I'm hoping to get input in this matter to help me getting as close as i can to the orginal sound .

A friend of me have problems with read in TOC. His version uses a KSS-212A.

In the present service-manual is mentioned the KSS-210A - go to
https://elektrotanya.com/nad_514.pdf/download.html

Is the version with KSS-212A a later series and exist therefore a second service manual resp. an additional supplement ?
On the web I don't find any information.

Under
http://vasiltech.narod.ru/CD-Player-DAC-Transport.htm
both types listed.

Thanks for an advice.

What would cause these caps to bow like this ?

Is it from abuse or to low of an ohm load ?

This amp has no output.There is no rail to rail oscillation on the output FETs.I see a square wave on the output of the Lm211 and pin one of the IRS chip.

Using the ground tap of the 7812 regulator vcc voltage looks ok for the chip.I install a new on but no change.

Any suggestions?

I've been running one of the original Cyrus 'pre' amps for many years. Today I found that when the volume level was adjusted one of the motorised pots inside would not settle. It just keeps jittering the motor, like it's constantly seeking a value but can't reach it.

I tried swapping the pots on the PCB for each channel, but the problem channel remained the same, so I do not think the pot itself is the problem, rather the driver circuit.

Does anyone have a schematic? Or know how the volume pot system works?

It seems to me each is a dual pot used for balanced signals. When the level is adjusted I think the circuit seeks a set value on the pots becasue I can see them overshoot slightly and move back again. Or maybe one of the wipers on each dual pot if used for position feedback and the other for the signal?

Volume up, you can hear the pot constantly jittering even when the other one stops at position. Shared album - Simon A - Google Photos

I've been eyeing a pair of old Davoli-Krundaal guitar amplifiers from 1964 (schematic attached). This particular auction is selling a pair, missing 2 out of 4 EL504 and both ELL80 phase splitters.
Since these tubes are rather hard to find nowadays I'm thinking of changing the output section in some way.
These are the ideas I'm pondering, in order of preference:

1. (Hopefully) convert these into a pair of monoblocks for music reproduction. This is the only way I could get some use out of them. My main fear is that the OPTs will have a ugly response outside of the guitar frequency range. Then again, they are rated for 60W so they may behave well at lower wattages (I don't need more than 8W of power).
2. Do a proper restoration: try to keep them as stock as possible and only fix what is missing/broken.I may end up replacing just the the ELL80 as it's the hardest tube to find. In the end I'd then have to sell them as I don't play guitar and certainly don't need two of them.
3. Change the output section, keeping them guitar amps. Again, I'd have to sell these later.

Hopefully you guys have some experience with these or similar amplifiers and can advise me on the OPT quality.
Either way, I'll probably have to swap out the EL504s and the ELL80s, so what tubes do you recommend as a replacement? As stated I don't really mind changing the sockets/circuitry.
Bonus points if the suggestion includes Russian sweep tubes that can be had cheaply and in abundance (I always like to buy extra for replacements).

I would like some advice please with my current amp project.
I am building a power amp with the chip LME49830 as driver stage for IRFP240/IRFP9240 mosfet quads, it's going to be used for bi-amping to drive the woofers of my speakers, each speaker has a pair of 9" woofers whose impedance @20-300Hz ranges from 3.5 to 6.0 Ohm
I already have a 1.4KVA transformer with a pair of 0-60VAC secondaries that I would like to use and it will give me rails of approx +-85VDC.
I know that in theory it is OK to feed the LME chip and the mosfets with that high voltage but I am not sure if -even with a very good but passive cooling- it will be safe with the load I intend to drive.

Please advice!

Schematic of the amp

sale for a friend 4 chokes in very good condition, located in Germany.

2X Lundahl LL 2733 700mH / 1A

2X Lundahl LL 1638 4Hy / 400mA

each Choke 55€

pse ask for shipping costs ( DHL with tracking)

Have FUN!

Greetings. Am building a dac with dual 9038pro chips with only usb input. Me and my friend are building it together. The rest of the circuit is pretty much done. We would like to put in an upsampling circuit for the 9038. Does anyone have any ideas on this?

Just curious if anyone has had any experience with the Beyma 15MC500? Looking for a 15" up to approx. 800hz.

Thanks!

I'm working on a Kenwood Super Eleven receiver that came to me with shorted outputs in one channel. As I make my way through the rest of the circuit to see what else may have been damaged, I came to a shorted 2SA1111 driver, Q18 on the attached schematic (haven't checked the 2SC2591 yet). These are long obsolete, which is unfortunate because both have pretty fast transition frequencies--200MHz. So far the best subs I've come up with are 2SA1859A/2SC4883A.

Thoughts?

Hi,

I want to replace the LM324 on my Fosi Audio BT30D with better opamps since I don't like the sound of the 324, and I believe it produces slight audible distortion. Can anyone suggest which opamp that I can use? The Fosi Audio uses 24v power supply.

Thanks

I've mostly been a reader only on the diyAudio forums up to this point, but I'm starting to diving into some more audio projects now and need to get more actively involved in discussion and questions. One of the projects on my to-do list relates to a pair speakers and amplifier that I found at a local estate sale. The speakers are "The Great Horned Heil" from the Horn Shoppe. This is a rear-loaded horn speaker with a ESS Heil Air Motion Transformer (AMT) on top. There is an external set of crossovers which were presumably designed to work with this pairing. The speakers also came with a First Watt F1 amplifier and "The Truth" Preamp. (I've found mixed reviews about The Truth preamp, so I'm going to ignore that component for now.)

Everything seems to work and I'm liking the sound I'm getting from the setup so far. (Although, I'm detecting a small amount of distortion from of the Heil AMT drivers on some recordings... The diaphragm may need to be replaced) I'm still experimenting with speaker placement and which room to put them in.

I understand that the First Watt F1 amplifier is an effective choice for efficient full-range speakers due to its transconductance (current drive) design. While this encourages better bass out of the speakers, I'm still interested in incorporating a powered-subwoofer to see if I can improve the overall performance.

Normally I would start by connecting the amplifier speaker outputs to the "speaker" inputs of the powered subwoofer. I'm worried about doing this with the First Watt F1 amplifier, however. Will the fact that it is a current source design create problems if I attempt to connect a sub in this way? I had found a short statement in a old forum post (via Google search) in which someone suggested that you should never connect this type of amp to a powered subwoofer. There was not enough detail in the post to fully understand the reasons. Could anyone advise me to what my options might be for incorporating a powered subwoofer for this system? Will I be limited to tapping off a line level signal back up the signal chain to a pre-amplifier?

Thanks!

Hello, am using Philips DSP 2500 multimedia speakers. These are 5.1 speakers. I.e . 5 satelite speaker & 1 sub woofer bass reflex.

I am going to create holes in the main enclosure & put all satelite speakers into one place at diff
Can i do this. Wil there be interference or any issues.

This is how the satelite speaker looks.

This is how I want to drill holes & put all 5 speakers in the same enclosure. Will there be problem !

Hi
About two years ago I bought a set THF-51 like so many others on this forum (I think we all know who to blame…).
To start with I needed to figure out what to build wit them. Single ended class A was a given, and based on Ben’s excellent builds I decided to make a common drain choke loaded amp. This out put stage does of course not offer any voltage gain but Rahul’s SCG could be used as a front end for the THF-51 out put stage. But I would also need some way to bias the THF-51 and I would like a low impedance bias supply (seen from the THF-51) to prevent any (high) gate current from messing with the set points. I achieved this by inverting the SCG.

I have not done any simulations on this circuit other than ohms law on a calculator. And measurements are limited to DC work points only. So, you have to make due with a hand drawn schematic. The reason is that I have been on a tight schedule to finish the amplifiers for a DIY loudspeaker event yesterday in Viborg Denmark.



The bias is adjusted by a small DC voltage applied at the bottom end of the 1M input resistor.
And here is a photo of the two amplifiers ready for yesterdays DIY event:



Best regards
Simon

I have for sale about 75pcs of NOS TOS K389BL at $14 each. + shipping.

I randomly picked 3 PCs, measured Idss and Vp, the. calculated the Gm. The results are in line with the data sheet. This should verify they are genuine. Both JFETs are very well matched both Idss and Transconductance for all three sample.

Please PM me if interested.
Thank you

Greetings. I have a Mc2500. The amplifier board was badly repaired a long time ago and now has become unusable. I do not know if I'll
be able to salvage the op amps. The rest of the amplifier is however still in good shape. I am making a new amp board myself for both channels
with new components as there aren't any stock available in the company and the used boards on online auction sites, look dubious. I need to
know however, what brand/type of resistors and capacitors did the manufacturer use in those Mc2500 amplifiers. I need to purchase new
components to make the new board but do not want to end up spoiling the original tone of the amp. Also, if I can't salvage the op amp on the board,
what is the best substitute for the original op amp? If someone knows, kindly advise me on this issue. This means a lot. Thank you.

I am taking apart a NAD T750 and it has a vertical volume circuit board that connects directly to the (horizontal) main circuit board. There are two board-to-board connectors to detach and one of these easily pulls up without any manipulation but the other one does not budge. On another forum it was suggested that I tried pulling on what looks like latches on the sides while I pull the board up, but that part of the connector does not seem to move at all. If anyone has come across this type of connector I would appreciate any advice!


:

Hi Guys,

Im doing my first build of a Hiraga 30 Watt class a . I put all components right and checked them all, but appearently my powerstage does not go 1,5 amps current.
I did some measurements, maybe you can give me some direction where to look / what might be wrong?

There is no load, input shortend, and it does amplifie, all be it crooked class B with a lot of distortion. Im puzzled !

Hi,

I have bought a Beresford TC-7210 speaker/amp switch, described here http://www.beresford.me/downloads/TC-7210 speaker selector REV3.pdf

I've been misleaded reading this sentence : " Load Protection circuit design safeguards your amplifier when it is not connected to the speakers" so I figured out that the circuit was designed to insert a resistor between amp's hot and negative binding posts when an amp was not in use. As I'm a curious guy, I cracked the box open only to discover that a 100R/10W wirewound resistor is soldered between hot and neg of each input terminal, thus being connected in parallel to amp outputs permanently...

What would be the effects of such configuration on amp's and speaker's operation ?

Hi all,

Is there any source of such wire as in the title? Small amount is needed.
I understand this is 1/10th of the human hair. It intended to be used for an MC phono cartridge repair.

SOLD_________Looking to either sell or trade for a good quality TPA3255 PCB.

asking 90 shipped lower 48 paypal.

Message for any offers or questions, thanks.

Does anyone have measurements of Vifa (Tympany) D25AG-35-06? Would really appreciate it, if you would share them 🙂 Thanks!

Hello, is this LM1875 PCB design good?

Any advices?

(First time posting)

After 12 years of use one of my crown xls2500 start some problem.when i push the power button amp starts all relays click but no sound on speakers.after about 20 seconds all the bar leds start blinking for 3-4 seconds and relay click ones.then i have sound on speakers and the amp going on for hours without problems.can someone give me advice what causes that?or someone have the same experience with this very popular amp?i have all ready do some troubleshooting desolder all relays and checked then check all relay diodes all ok.capacitors is all new change 2 years a go.thanks for any help.

I built this Tangent Pimeta2 over decade ago:

https://tangentsoft.com/audio/pimeta2/

It has worked fine for years, even surviving many daily road trips and errand runs. Sound quality is first rate!

BATTERY POWER, IEMs and CURRENT DRAW :

I have been using an external battery pack comprised of 10 AA 1.25v NiMH batts. So I have about 13-14 v of power for my PIMETA2. The charge lasts about 7 hours (I built a multi-hue battery health LED ckt for the front of the PIMETA2; this provides very good insight about how the PIMETA2 uses batts).

As an experiment , I recently switched to two 9v alkaline in series (18v).
Music played as normal, perhaps a bit more beefy and dynamic given the extra voltage.
HOWEVER...
My PIMETA2 drained two new Ray-o-Vac 9v alkalines in less than two hours. I noticed this symptom rather quickly: music went from sounding ok to very distorted over the span of only, maybe, two minutes. This is when I checked the batt. LED: Indeed, the PIMETA2's batt indicator was almost not visible anymore (it was beyond hue change--- very dim).
I switched the PIMETA2 off for about a min. Turned it on. Same batts inside. All LEDs green again, but same battery-draining thing happened -- only now after perhaps 5 min of use. Seems as if the 9v battery chemistry was beyond recovery!

All these years of uneventful use, I never wondered/guessed how much current the PIMETA2 draws (idle or playing music thru IEMs) until the two 9v alkaline in series incident.

I measured PIMETA2's current draw at batt terminal with my Fluke 87.

Idle (no input or IEMs plugged in): ____ mA.

Music, normal volume, with JVC IEMs: ___ mA.

I assume this ____ mA is draw NORMAL given that I opted for buffers. (I did bias into class A; my L, R and G channel opamps: all AD825). And I also use this completely passive xfeed board. Modified Linkwitz Crossfeed https://tangentsoft.com/audio/mlxfeed.html

I only use IEMs with this and all my portable headphone amps. I have a 2006 Go-Vibe portable amp that uses a single 9v batt. The GoVibe also has an op-amp ground channel. It draws: only 6-7 mA (idle or with music into IEMs)

Try to guess " ___ mA" based on the info provided above, as well as links to the device -- theory of oper., topology, schematics, BOM, etc -- on the original Tangent website.

Reason for asking: believe it or not, the original designer has no clue about his own creations' specs. And he seems to avoid all queries about such topics. The whole PIMETA project was group-forum effort on the orig Headwize site, so Tangent may genuinely be clueless about many specs.

I just got an error message saying the forum couldn't email me because it was not correct. I haven't changed my email address is a million years. Anyway, I confirmed my email as per request, and now the forum thinks I'm a new member, because I don't see my replies. Obviously, I'm not a new member.

jeff

I have all the electronics savvy of your average Amish kindergartner, so bear with me please LOL I'm putting together a homebuilt E-Caller rig to take the place of my 30 year old Johnny Stewart cassette deck outfit (25 pounds & clunky as all getout). It involves a 12 volt 7.2 amp hour battery - inline buss fuse -- Kentiger lHifi Power Amplifier - standard AC wall outlet - connecting to 65W Pyle horn speakers, using 12 gauge speaker wire.

I have the stuff to build the E-caller EXCEPT a power cord from the battery to the Kentiger amplifier. No power cable was supplied with the amp.

Now, I tried a really thin wimpy wire recharging cable from my old Johnny Stewart E-caller, since it had the proper connector to fit the male plug in the amp. So I cut the AC wall outlet prongs off and put the positive and negative alligator clips on the raw end, added the in-line glass fuse, and hooked the whole thing up to the battery. Within 3 seconds the thin wire sizzled and melted from the alligator clips to the fuse housing and would have burst into flames if I hadn't disconnected the clips from the battery. WOW -- SCIENCE!

So... apparently the wire that re-charged my Johnny Stewart tape deck battery was TOO WIMPY?? to do the job?? The glass automotive fuse DID NOT blow, by the way. The amp itself, and the wire from the fuse fitting to the amp itself, were not affected.

I looked online and Kentiger only offers 1 power cable ... it has an AC wall plug - to - 1/8th" female connector. This cable has a circuit breaker built into the cable. Is this what I need to get, and cut off the AC household wall plug and replace it with the red and black alligator clips?

CAN I MAKE MY OWN POWER CABLE (Alligator clips to fuse holder to amp) out of the 12 gauge speaker wire

Or what do you suggest? (besides give up DIY electronics projects; too late for that now, I'm hooked on the smell of ozone and plastic insulation smoke in the morning). THANKS in advance Gordo

Hello digital active speaker friends,

my DEQX PDC-2.6p seazed cooperation a while ago. Repair of this old unit seems to either be impossible to do by myself (no documetation anywhere) or prohibitively expensive by DEQX. Buying a new unit looks out of the question budget wise and buying a used unit would again be old technology.

So I have come to the conclusion to buy a new, more modern xover/DSP.

Features wantes/needed :
Analog Input for phono
Digital Input AES, SPDIF, Toslink, USB (optional), not bluetooth
Streaming and MQA support not necessary
Control by PC over USB port
IIR and FIR filtering
4-Way xover
Internal processing and AD conversion with min. 24Bit/96kHz
Output balanced (preferred) or unbalanced
Budget up to 1,000 €uros incl. taxes and shipping

The above list may not be complete... 😉

One product attracted my interest is the new miniDSP Flex Eight, but this one is missing the ADC and I'd like to have the ADC clocked by the DSP internal DAC clock.

Maybe someone here can recommend a product (with justification please) which meets my needs.

Thanks a lot and kind regards,
Winfried

I am experimenting since quite a time with TPA3055 modules at supply-voltages of 30 Volts and up .
Tired of moifying the power-supply every time for different tests and after several ups and downs I found
that a combination of cheap chinese units gives me a good result for my own purposes of Voltages and
currents with an ample margin for both values :
a 24 or 36V switched PSU with 10 to 20 Amp-rating ( of the type see picture ) is one :

and a boost-converter of 20 amps input current ( again see picture ) is the other.

Both together come to 50 dollars or less and allow for any output voltage and current one might want
to try for ones amp . Lowest voltage is 24 or 36 volts , depending on chosen PSU , and current is limited
by maximum input current of the booster or less if so adjusted on the booster unit. Set both in screened
box to keep radiation locked in and taking power out through a small choke and an equally small
capacitor ( 470uF/100V los esr-type )and you have a stabilized PSU which adapts to whatever you want
at a very low cost , weight and safe to operate as any failure can only result in lower voltages.
Choke and capacitor placed next to the outside wall of screen-box.
Gives 8 to 15 amps depending on freely adjusted output voltage up to 50 volts

As it happens it makes a good low cost PSU to use in a definite amp as well .

Opinions ?

These are "The Stinger" as described in the PDF attached to this thread:
https://www.diyaudio.com/community/threads/woden-design-3-box-designs-babylabs-more.247904/

I purchased these from Dave (aka planet10), and I believe they were built by Chris.
They are made from Baltic Birch in a very nice Rosewood veneer.
Cosmetically very nice except some minor damage to one of the back top corners (can be observed in the photos)

Drivers are Mark Audio Alpair 6.2M.

Asking $300 includes shipping and fees in the US.

In addition,
SINGLE Mark Audio alpair6.2PeN (the driver with EnABL treatment). I believe these were originally around $65/ea, so asking $50 incl. shipping in US.

Hello DAC experts (which I'm not!),

the motivation for this project comes from the fact that I want to drive my active Speakers' balanced inputs with a balanced Preamp Signal.
The Preamp involved is an old, but well working, DSP DAC PreAmp with 3-Way digital x-overs and equalization capability, working with 24Bit/96kHz resolution, on digital and analog inputs. The standard outputs are cinch connections.

A closer look at the main board shows 18 x OP2134 between the AD1853 DAC Outputs and System's cinch Outputs: The first stages do I>V, filtering and unbalancing, next is analog volume control (PGA2310 based, jumpered "off" because I use digital volume), a jumpered 4 level coarse output control (which I won't need), then a buffer stage for an add-on board (which I don't use) and finally buffers for the cinch outputs (which I won't use an longer...).

So I came to the conclusion (maybe naively?) that I could switch off all circuits the above, cut and derive the signals at the DAC chip outputs and feed them into an own I>V, filtering and balanced output stage made up of just two OPA1632 (fully differential OpAmps) per signal. This would reduce the number of OPAs the signal is fed through to just 2 (one I>V & filter, one as balanced buffer) and have the (just perceived?) advantage to keep signals balanced from the DAC chips' outputs to the balanced Speaker inputs without unbalancing and rebalancing on the way...

After reading AD1853 & OPA1632 vendor application documents and looking at other available I>V/Buffering solutions, I have basically merged two app note schematics into one circuit concept which (I think!) does what's needed.

Here is the AD1853 application from the datasheet:


This is "my" circuit adaptation with OPA1632:


Now I would be very grateful for feedback and input on this, especially on the values chosen for I>V, filtering and buffering, no matter if that's all OK or not OK 😉

Thanks a lot for reading all this.
Best Regards,
Winfried

Hello, everyone,
I'd like to know if anyone has used the 6-24 crossover pass to enter with a stereo signal and exit with frequencies above 100 Hz still with a stereo signal and with frequencies below 100 Hz with a mono signal going to the subwoofer amp. Use the 6-24 to sum the left and right channels and output in mono without losing audio quality.
Thanks in advance to everyone for any suggestions.
Cheers
Giubos

I have a pair of Tannoy Comet 10 speakers (made in Canada a while ago). Two years ago I upgrade the original Vifa Tweeters for a pair of Fostex FT17H horn Tweeter with great success ... ie, High frequency are very good now with no distortion. The bass is so so, not sure of that but I think that there is nothing that cut the frequency going to the woofer witch may cause distortion in the low frequency woofer, the only have a capacitor acting as a high pass filter. I'm using a small subwoofer made by Energy with a 8 inch woofer. So my bass is good, the high are good but I'm missing medium frequency to my taste.
Since I'm on a very tight budget, I want to add a mid range and I found this mid compression tweeter at low cost : https://www.skaraudio.com/products/pd1-x-1-inch-horn-driver but they are design for car audio, PA and Monitor system. The specs are exactly what I need, ie, 100 Watts RMS, 110db (wow) 550 Hz - 6,000 Hz but I'm not convince that the quality will be there, what do think ?
I would add this low cost 3 way crossover witch have the specs I need : https://www.ebay.ca/itm/321510819685?epid=1400372746&hash=item4adb89c765:g:rgIAAOSwxH1UBzqV
Thank you for your input.

I haven't heard about this CD Changer. Who can upload schematics and internal images ?

https://nakamichicaraudio.com/pages/history
https://www.soundandvision.com/content/ultra-rare-find-nakamichi-dragon-cd-changer
https://skyfiaudio.com/products/nakamichi-dragon-flagship-cd-player-and-dac-super-rare-colectable

Completed an amp Works great except one channel is louder. My easy fix would be some sort of balance control Where does one find a channel adjustable stereo pot?

SOLD Thinning out collection selling batch of 6 6SU7GT tubes and 2 6SU7 tubes for $175. Premium vintage tubes includes:
Two TungSol 6SU7 tubes appear to be, and test as NOS
Two Military Sylvania 6SL7WGT new in original boxes
Two Sylvania 6SL7 Brown base tubes, appear and test as NOS
One RCA and one Delco (probably RCA manufactured) look the same with the round plates used test good around 50 where 32 is passing on TV7D/U.
Shipping only within the US should be around $
NO Paypal accepted, please don't ask for it. Will accept check or MO. Price is $SOLD

A friend of mine asked me to fix his old Philips AH684 FM receiver / amplifier. It had crackling pots and switches. So I took everything apart, disassembled the pots and switches and cleaned them. I also re-capped the tone control board.


After assembly I wanted to check the bias of the 'main amp drive unit'. Although I have several versions of the service manual I was unable to find the testpoints. Due to my lack of knowledge and experience I am also not able to determine the test points by going through the circuit diagrams. I hope that someone can help me out:

i find it to be quite useful in its simplicity

https://www.soundton.com/

Marco puts it through the paces: Login to view embedded media

A cute animation showing boiling electrons off of a hot filament, in context of starting a fluorescent lamp.
Login to view embedded media I never knew electrons had arms and legs and eyes.
But wait! The Mercury ions have caps and clubs to "direct traffic"! Later they get over-energetic!

If you like Closed Captioning, this one is bad. The phosphor is checked for "sickness". And instead of "she is", "Jesus"! Must be voice recognition on a voice the system has trouble with.

I have an Sumo Polaris III amp which my brother gave me that was having issues.
While the case and the board within say Sumo III the contents visually are unlike any of the Polaris 310 images I've seen posted in this forum. It seems like a later move (based on the IC dates 9640) to combine the two boards on in the 310 into a single board. There is no stenciling on the rear of the case. That along with the socketed 741s and some odd resister mod on 2 of the MOSFETS makes me wonder if this was a prototype or some early build of the rev.

After looking at the schematic for the 310 they appear to be a similar design based on 240/9240 MOSFETs with 741opamps providing a servo loop for DC offset.
Have you or anyone else with Sumo experience seen or worked on a this variant of the Sumo Polaris III? .

I have bought a pair of tang Band W8-2145 for use in my kitchen with a Single ended tube amp.
The ceiling is tilted at 45 degrees and I intend to insert them in the ceiling( infinite baffle?).
Will these speakers work tilted at this angle or will the internal parts "hang down" or be unbalanced?

​

SOLD


This is a I2S to simultaneous mode TDA1541 dac board designed by Miro. I have built a few boards, sold a couple of them and i am only keeping one board for my own system. This is last spare completed board i have to sell since i have completed my adventure, and keeping one set for myself in my system . It is built with care and high quality parts, tested to work with stability. Your own PSU and i2s source is required to complete this DAC for it to sing.

The 14 decoupling caps for the TDA1541 chip are WIMA MKP10. Decoupling caps for the psu are KEMET MKP, and electrolytics are mainly Nichicon FG for the DAC section and ELNA Bipolar for the op amp IV. Resistors used are Vishay, including the zero ohm jumpers and the IV resistors is DALE RN60. Logic chips are decoupled with high quality Kemet SMD x7r capacitors.

This dac is designed by Miro and more info can be found here :
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-268#post-7159210

Miro also designed the PSU for this dac (not included in this sale):
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-268#post-7159234
Please study the power supply requirement carefully if you intend to use your own psu design.

Important things to note :
1. If you intend to have no capacitor at the output, it is advisable to have a dc protection board as explained in the post:
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-285#post-7187720
2. Tested with JLSounds i2s card, i have trimmed the TDA1541 offsets to be null and very stable. Any changes to the board, including inserting different op amp and different TDA1541 chip will require adjustments again. Please do check and do necessary adjustments by following the instructions by Miro. You will need to explore this on your own, with your i2s source connected.
3. All components, including the TDA1541A and the OPA627 chip are new and needless to say genuine, which is only used for the testing of this DAC.

The whole board, with shipping worldwide included is priced at US$250. Members who bought and received my items know that i pack my items with utmost care to prevent possible damages. PayPal available.

Saving Laser Life by Amplifying the Photodiode´s Current?

I tried to swap a sharp LT022MC Laserdiode in a Sony BU-1 transport with no success.
Besides aligning the biggest problem is that replacement diodes on the market are junk. Bought 28 of them, 26 were defective.
I will try a replacement with a contemporary Rohm diode, but this can be only done with experinced help, see this thread:

Dead Laser Pickups - why not replacing the Diode only?

Now, another idea:
Voltage p-p of the eyepattern in early Sony players (as well as many others) was 1.2V.
The ones I own are between 1V and 0.8V after 30 years

To save laser live: Why not putting the output down close to threshold current
and amplifying the current of the photodiodes before it is sent to the RF-Amp?
Threshold curent and operating current are close but in my case it looks like
I can halve syepattern´s p-p close to 0.5V before the player fails

Would this save laser live? I have read somewhere that running a laser
in it´s lower emitting limit could be harmful as well -
but I do not recall the source in the moment as well as its credibility...
I also do not know if beam divergence is influenced by this.
But for the moment, a good idea to follow?

All the best,
Sal

I am looking for used hashimoto MC HM-7 or HM-X transformers. If you want to sell,
please let me know. I am located in Slovenia.

Thanks.

TPA3116 Dual Board Questions

Hi all,
I've been lurking here for a few weeks. I've finally got a few questions that I'm not too sure about. I purchased this board: 2*100W TPA3116 D2 Dual Channel Digital Audio Amplifier Board 12V-24V for Arduino

Regarding the upgrades; can I use the components suggested here or are there other requirements since this is a dual chip board?

TPA3116D2 Boards - diyAudio

Which swap would give me the best bang for the buck?

Also, does anyone have a schematic for this dual chip board?

Thanks!

I'd like to know what is the best thermal adhesive in terms of bonding and thermal conductivity regardless of electric conduction.I don't care if it conducts electricity, I just need it to be as strong bonding and thermally conductive as possible.

Got to experience some seriously insane planar speaker action last week. Check out these systems.

Hi everyone .
I have been trying for some time to create an alarm clock combined with a reader ( with infinite loop function) to listen to white noise for the duration of the night in the room.
you can understand that the reader must switch off at a pre-established time to make room for the alarm clock which must sound at a specific time.
the only simple way I've found to do it, is to use an ipad alarm clock and a bluetooth app that puts the cd or dvd player in standby through a relay.
there are many products on the net but I can't find the right one that works with the programmed time, do you know the bluetooth app and pcb relay?

Hi to Everyone
Some manufacturers have used horns with conventional drivers with great results from what i understand and listened in some occasions
I refer to Avantgarde and Acapella in particular
Fwiu they have used off the shelf drivers like Audax and Dynaudio and exalted their performance using a properly designed and built horns
I wonder if anyone has tried for instance an off the shelf horn with a dome tweeter and what the result
Thanks a lot
Gino

For sale is my Nelson Pass designed Sony VFET power amplifier. The VFET's and boards were bought from the DIYAudio store in 2017.

I've used a dual mono supply with Antek 18v transformers and generic Pass PSU boards, also from DIYAudio. The case has been used for a few projects and has some scratches, in particular on the top, but this can easily be replaced with a new one from Modushop. The heat sinks have also been drilled a few times to support different Nelson Pass boards, not that you can see this unless looking through the fins.

I used a Modushop 4U case which weighs a ton with these transformers inside, therefore this is collection only from Solihull (B94 postcode) UK, or I can deliver within a 20 mile radius. Having never seen one for sale I am not sure how to price it, so I will start at £795 and see if there's any interest.

Hello,

I got gifted a 6" full range paper cone rated 20Wrms, but as it's a bare element it needs a cabinet.

Now I don't know much about this topic so I thought I'd ask all the people who do know what I should build 🙂

I'm looking for a design that is:
Simple to put together
Cheap
Doesn't sound like total crap
Preferably no larger than a meter in any dimension.

This is for a mono system I'm working on, it's going to be living on a desk in the corner of my living room and playing music. The mids are the most important, followed by bass. If I feel it's lacking in highs I'll add a tweeter later. This is not ment to be the highest of fi systems ever created, I just don't want it to be bad.

Thanks for any help!

I’m rebuilding an 8K amp .
The outputs are drivers survived .

The only damage I see is the power supply fets and drivers .

All the gate resistors for the fets are within tolorance I checked them at room temp I did not hear them nor cool them to see if the drifted out of tolorance .

Wondering is it a good practice to replace the gate resistors when replacing the fets and drivers ?

Also is there anything else that should be replaced when I’m in there in the power supply section since some parts get stressed when the fets blow .

I’m asking this since this amp is going back into a competition vehicle and need it to be reliable.

Here's what I came up with using my JVC QL-50 and Pioneer tonearm. I had to get creative on arm length because it was not a PL-41 arm. Got it to align fine with the Turntable Basics mirror.

I've been away for a few years, wasn't sure if I'd be back. My wife has no interest at all in hifi and doesn't like the equipment in the house.
She don't like my old shovel either!
So I've gone back to my workshop, I can play music on my PA and tinker with my bikes. I even started building stuff again. There's no cure for diy hifi addiction. I shook off Harry, but can't beat this one

What's the general preference between solid state and tube power supplies?

I've been building power supplies recently, and for some reason I prefer a tube rectifier like 5U4 for the 2a3 output stage. But paradoxically I prefer a solid state PSU for the 10Y driver stage with Wolfspeed 1200V Schottly diodes. The same diodes on the output stage sound flat and lifeless. I've tried this a few times with the same results. I'm not complaining though it does mean 2 supplies. Any thoughts welcome.

What are your preferences, and why?