Amateur level status person here...

Just picked up a non-working Luxman LX-104 stuck in protection.

Have verified that it will come out of protection if I disconnect R channel from protection board.
Found negative rail voltage floating on output of R channel (present on Base and Emitter of all outputs of R, but not L channel).
Pulled R channel outputs and tested on a cheap and cheerful small ebay component tester. All seem to test fine.
No fuses blown and current draw at rail fuses is nominal.
Have done an in-circuit test of all other small signal transistors and have found no shorts. But, I can't really access the ones on the "Main Drive" daughter boards as seen in the attached schematic.

So I thought, if it's possible, that I would like to power it up (even at 1/4 or 1/2 power via Variac) with the outputs removed to run some left to right channel voltage comparisons to see if I could identify where the errant voltage is coming from?

There is I assume also the possibility that the outputs are faulty and just not showing the fault at low voltage? And if this is the case I should see no voltage at the B and E pads with the outputs removed?

So, can someone tell me if the amp can be powered up sans outputs?
Or so I need to solder in some temp components to make it stable?

Thanks in advance.

PS, the numbers in red are the voltages I took when I realized what was going on.
Q514 is a 2sc1845 also attached to the heatsink near the outputs.

1" thick pieces of MDF, Free for pick up in Newbury Park, Cal 91320, many pieces approx 28"x 30", many pieces approx 48"x 20".

I have been away from the tube amp world for a few years. I am going to build a 1624T Supro syle amp with 12AX7 pres and EL84 power tubes. The amps were built using 6973 which I can get NOS but pretty costly, around $100 each. Am I making a mistake by using EL84s?
I have in mind to use a vintage greenback 12" speaker which is 8 ohms. I also have a Webber alnico 12" I could try also.

Two questions.
Is there any good reason to use the typical 5Y3 or can I just use diodes?

Do you have any recomendations for the PT and OT?

I will keep one hand in my pocket...lol

Billy

I have a pair of bose 802 unloaded cabs and would like to fit some large speakers in. I have already cut the baffle out on one and ready to fit a new plywood baffle. The question is 2x10 would be my prefered choice but it would be a real tight fit, but possible or 1x10 or 2x8 thoughts please. I do have a pair of subs so bottom end isnt everything.

Anyone have real world experience with this driver? Seems as though its the ferrite version of the N314T (same diaphragm)?

It looks like its only downfall is it falls off abruptly @ 13k…… could this be eq’d or would adding a (super) tweeter be necessary?

Hi everyone,

Does anyone has an updated list of NOS DAC ICs that are currently in production and are not sigma-delta?

The ones that I am aware about are:
PCM56U
AD1851RZ
AD1856RZ
AD1866RZ
I can't find PCM56 chips of the K and J version and devices from AD in the J version.

I'm currently testing an AD1866RZ and it sounds much better than most consumer audio equipment sigma-delta DACs. I can't describe, but for me multibit NOS DACs seem to sound more detailed and natural than sigma-delta, specially in the lower and higher frequencies, but this is only my opinion, in fact most newer OS DACs clearly outperform resistor ladder DACs in terms of measured specifications, maybe I have some hearing or psychoacustic problem(s).

Well going back to the NOS chips, which one from this list sounds the best? I'm more inclined to give the PCM56U a try, maybe in current output configuration? What do you think? 🤔
The PCM56 needs a deglitcher? Or is it only required for single chip stereo applications?
Any suggestions?
The PCM56U sounds better than the AD1866?

All the Best,
Danny

John Gosling, the keyboard player with the Kinks 1970-78 has died at age 75.

https://www.msn.com/en-gb/entertain...ar&cvid=78df1fa7b88648cabd0d350998b011fe&ei=8

I'm dangerously overdue for a revamped back up system; I just use old JBOD among two xeon PCs, though both have ECC RAM. I'm so badly overdue for new storage hardware it's terrifying!!!! But I've got to be sure to buy what I need most to protect my data.

Capacity wise, total data is ~ 350 gig, but I will eventually want to not only do hundreds more uncompressed CD track rips but also dozens rips of TV episodes and rare movies from DVDs (though rarely from not BDs). Those videos I'd be saving as MKV files, not much larger ISO files. The good news is that I mostly watch (re-watch) lots of vintage stuff, and when I do buy more movies I do so on BDs, which are less likely than DVDs to get hit with bit rot. Thus, I'd be less inclined to rip (with RedFox) and back them up. So for for these back ups, should each RAIDed HDD drive be 5 or 7TB?

My plan is to have a multi drive DAS in my living room and bedroom. My internet connection is via my iPhone's wifi so I have no router that could have been otherwise used with two NAS instead. So for every monthly backup session, I'd have to grab the bedroom DAS, bring it to the living room DAS and use my PC's Windows Explorer to share and/or update any document, videos, music files between them via USB.

But got to make sure I don't trip during trips! It would have helped if at least Qnap or Synology made at least one DAS with a safety handle! Why not a case like this? https://www.silverstonetek.com/en/product/info/server-nas/CS01-HS/

AND how best to protect data from however unlikely bit errors?? My data is my life. Qnap and Synology use btrfs, zfs or other non-Windows file management systems offering powerful bit error prevention and self-healing between RAIDed drives. But the learning curves of those file systems-let alone the initial building of them-are way more for the enthusiasts than newbie laypeople like me, and I don't want to get stuck with hardware/software that's a nuisance to learn, use and maintain.

Instead, will the right RAID configuration in both DAS boxes and the ECC RAM in both my PCs get me reasonably good error prevention? If yes, which RAID config to use with two to four 5TB or 7 TB HDDs in each DAS? https://www.seagate.com/products/hard-drives/barracuda-hard-drive/

And which Qnap or Synology model DAS?

B1 rev.2 complementary FET, as discussed here :
https://www.diyaudio.com/community/threads/b1-rev-2.301812/

Board is designed by member Mikerodrig27, as posted here in the thread:
https://www.diyaudio.com/community/threads/b1-rev-2.301812/page-20#post-7266237

Resistors are Vishay CT55, Dale CMF60, Dale RN60 in the critical position. 2SK170/2SJ74 matched (to 0.1mA) quad IDSS value 8.3mA, from the highly recommended punkydawg ( eBay seller). Trimmed to a rock steady 0.00V dc on my Fluke multimeter on 300mV range.

58 USD (shipping included, registered + tracking). Shipping from Singapore

A quad of AD1862N-J chips for sale at xx USD ,shipping ( registered + tracking ) is included.
This quad belongs to a friend who bought too many of these chips together with me. We built the Miro AD1862 dac together .
We have no spares anymore after these are gone. They are clean, new.

Paypal FF only please. Check all my past sales records for reference. All buyers know i pack very well and provide proper updates.
Shipping from Singapore.

Hello all,

I am still learning about BJTs principle of operation and came by the concept of quasi saturation and hard saturation.
To better understand the concept I tried simulating emitter follower using popular transistor models.
I am not sure at what I am looking, but would appreciate if someone can explain.
I tried varying collector current of Q1 by changing R2 from 100R to 1K.
Probed collector current of the Q1 and I get kind of wobbly sine wave.

Sim file is in the attachment.

I am looking into building a Hypnotize buffer amp but would also consider on that is for sale completed. My preference would be just the board itself, but they may already be rare. Hoping to add this buffer to an already existing passive pre that I have built.

A better solution has been found. Thanks guys.

Recently aquired two Musical Fidelity X-A50 power amps and want to check them out.
I need a circuit diagram- Can anyone help?

Have searched only to find circuit info on the various clones of this amp, not the original.
Many thanks

It gets worse:

"The malware uses artificial intelligence to make informed decisions and synthesize its capabilities as needed to conduct cyberattacks and continuously morph to avoid detection."

[..]

Using the current early versions of generative AI, EyeSpy is capable of:

1. Selecting its intended victim independently or through a threat actor’s specification.
2. Assessing the target environment, platform, applications and environmental footprint.
3. Identifying optimal vectors to extract information.
4. Writing malware on the fly – for example, if a target is on a specific video conference app, it will compose, test and validate the malware for that app.
5. Executing the attack.
6. Analyzing the QA result.
7. Self-repair and continued attack iteration until it has achieved the attacker’s goals.

Jan

Hive Mind,

What's your favorite 2nd-stage (power) IC for headphone drive (to 16 ohms) in a composite circuit? Will likely use the use the OPA1611 as a first-stage in the composite. The power IC should have at least +/-250mA of drive current and at least +/-12V rails. I want a composite design in order to get super low THD and noise.

I've not checked lead-times, but these are the candidates I've found that meet my criteria, so far.

OPA551
OPA564
LME49600 (this one looks great, and I've had good sonic experience with the old LME National parts, and it won't need as much FB compensation)
TPA6120 (ditto)
BUF634

Another approach would be to parallel some high-performance opamps for 250mA performance. The performance of these opamps is so dang good that I wouldn't need a composite solution. I'm looking at these:

OPA1655 (x3 in parallel)
OPA1622 (x2 in parallel)

Appreciate your time.

DD

I picked up a Perreaux 2150B and working on restoration. Someone desoldered the wires from the Bridging switch to the boards.

I have the service manual, but this wiring is not well detailed. All the photos I can find are from top side of the boards.
I believe the wires go where the inputs attach, but I want to be sure. Hoping someone here may have knowledge of these amplifiers.
If I had photos from the underside, it would be easy to figure out quickly.

Thanks.

I just bought a simple Victor VC2002 generator. It works but the Voltage display seems to be fully out of range. On the front panel it says Vp-p but actually it measures something half of p-p , so a Vmax. But even this value is about 20% wrong. I found an older post with a link to the schematics here (downloadable from Scribd). Unfortunately, the quality is so bad, that I can not identify anything. Does anyone have a better schematics? Or can tell me, which potentiometer is responsible for calibration of the voltage display value?

Hi all,
Here is schematic of my 12au7 pre, it use dual polar hv and an opamp to sense the output node and output current through 2 current mirror (q1,q2 and q7, q8) to set dc offset at output voltage.
You may ask why i make thing so complicated, instead of cap at the input, it can be moved to output so i can get rid of negative hv and opamp servo. But my next stage can have input impedance as low as 10k (common pot value) so i can't use low value capacitor. I want to use capacitor as low as 0.01uf so i can afford hi-end Duelund cap at that position.
With this schematic, it simulate perfectly 0V at output but when i try to change R1 and R19 different value instead of 300R, it no longer work correct, output jump between supplies.
Does anyone have an idea of what's wrong here? Thanks!

SOLD SOLD
One pair of PCM63P chips, with free Miro PCM63 DAC board ( blank)
Circuit design and board info available here:
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-209#post-7049224

The PCM63P chips are bought new. Please refer to pics attached below.

Price is $110USD, covering also the registered shipping worldwide from Singapore.
I have sold and delivered almost 20 items successfully to Europe, UK and US with zero problems.
My preferred transaction would be PAYPAL FF only. For members who are unable accept this mode of payment would have to skip this deal, i am sorry.

I will always be happy to buy Miro a coffee as usual, for his generous sharing.

Orion GT420 missing rectifiers and a transistor in the power supply section. I could not find service manual.
Any help would be vastly appreciated.

Hi! What will change if you increase the supply voltage of the op-amp after the DAC to 12 volts?

Does anyone know the name of this style of LED? Any guesses on who makes something like that today? I'm not totally sure, but I believe It's 20w and most likely a high current, low voltage type

Selling for parts , no speaker box, parts include
Dynaudio esotar t300d pair
Morel supreme carbon 636 2 pairs
Crossover
Mounting plate

Asking 2700 USD PayPal plus shipping

Looking for an audio grade toroidal transformer with goss band and screen idealy made by Canterbury Windings or similar. 240V primary 22V 0 22V or 2 x 22V secondary windings. UK only.

See below :


Impossible to paste the said link in the blue zone - as it is feasible on other website offering the same facility. Why ?

If I use the code to insert the link, it works, but it's not very user friendly...

Can you tell me more ? Thanks! 😉

T

Hi
I'm a complete novice when it comes to this stuff so go easy on the nooB!

Speakers: Mission m64i
Problem: one blown mid bass driver LF-M049, 8ohm, 168mm OD, 140mm cutout.

I am having great difficulty finding a replacement because the baffle cutout diameter is 140mm, which is slightly too small for the normal 6.5" driver options. There's no info available for this driver using the search term LF-M049 as per the sticker on the magnet. It looks just like a regular Monacor driver, but they don't have one that's the right size for the baffle cutout.

However I've found a Peerless driver - SBS-160F35AL01-04 - this fits but I don't know if it is the right spec.

What sensitivity should I be using? Most of the woofers seem to be around 84-09 dB but these Peerless ones are 78.7 dB. So I haven't the foggiest if they would sound ok and match the crossovers.

Like I day - completely ignorant about this stuff! But am an engineer (mech) and love getting into new stuff, so feel free to educate me.

Any guidance on what to go for in terms of audio specs would be greatly appreciated. I'd replace both drivers obviously.

Amp is a Cyrus III with PSX.

Hi ... I have a Goldmund VSR-V2 preamp. Spec sheet says output stage impedance < 10 ohms and corrected output impedance ~ 330 ohms.
I'll be driving an advertised total 2012 ohm load not including any added residual load which might be substantial as it will be driving 6 amplifiers, but are all short IC's.
If 10 ohm I should be Ok. Not sure what to do if it will not take load.
Would appreciate you guys help.
Zene

Second thread from the novice ACA Mini builder.

This time I have a question about the supercaps for positions C6. The BOM says "SUPERCAP 1F, 2.7V OR GREATER". My Completion Kit has two blue caps labeled "2.7V3.3F". [See photo.] Are these OK? Does the "OR GREATER" refer to the capacitance? I don't want to solder these in until I know.



I read that film capacitors have no polarity, so I assume I can solder these red ones (1 uF) into C1 without worrying about their orientation.



Finally, a progress report. My new soldering iron is working well, and I've got the board to the stage you can see below. I learned how to desolder after I noticed that the small transistors don't face the same way for the left and right channels. I just assumed, wrongly, that they'd be symmetrical.



I am having loads of fun with this project. If it works and sounds good when I'm all done, I'll be grinning from ear to ear!

https://en.aliexpress.com/item/1005001302655864.html
Hello. Not so long ago I received this board I bought without being entirely sure whether I'd be able to power it properly or not. I was attracted by it's price, power and neatness of the PCB. I knew that I would need a dual AC power supply (2 AC waveforms with a 180 degree phase shift) and assumed that I'd somehow manage to power it using two of my transformers. Well, it seems that I won't be able to use one of them since the rectified voltage that I would get from it after rectifying and smoothing exceeds 50V, which is way beyond the maximum value the STK chip supports (max. +- 40V min +- 30V). The other transformer, on the other hand, has a secondary providing 28v. The rectified and smoothed DC voltage would be approximately 38.4 V assuming a voltage drop of 0.6V of each diode in the rectifying bridge. (28/0.707 - 2*0.6) The seller/designer recommends +- 37V. I intend to get +- 38.4 V from a single secondary.
Here are my questions:
Has anyone managed to successfully power this kind of Sanyo chips (STK family) using a transformer with a single secondary?
Would it greatly impact it's performance in a negative way?
Would it actually present some danger to the speakers?

Seen this in a thrift store. I don't think it is for audio.
Anyone know what this is used for?

Hi all,
As i had to open it for some reason, I took a few pics and thought I would share them if useful to anyone.
This is the non "Plus" version of PA7.

Hey guys, I wondered if anyone could give me any tips or insights of what've done so far. I need to know the following:
1- Is there anything wrong with my circuit?
2- How to connect XL60? Pin 3 and 6 together? Only pin 3? Or only pin 6?
([Warn] : Found some components Pins floating, suggest placing No Connect Flag on the Pins : U2.2,U2.6,U3.2,U3.6)
3- Wanted as well to know, recommended Power Rating for the Resistors
4- PCB Design: Anything I should have done in a different manner?

Thanks in advance

The new FreeCAD version 0.21 is out, this is a powerful 3D parametric CAD.
https://www.freecad.org/

Odd question but I'm hoping someone may have experience to guide my tuning.

I've built a set of EL34 monoblocks which I'm steadily refining, mainly tuning the feedback for best response and the input stages for optimum values per the loadlines. By the book I'm aiming for minimum distortion across the board. OK cool, makes sense... but it sucks some of the magic out of the soundstage depth and width.

Does it sound better, objectively? Yes. Does it sound better subjectively? Ehhh... I'd like to get a better balance between the frequency response and pleasant room-filling depth you get when it's close but not quite right.

Detail, tone, and extension in high and low is fairly consistent so I'm happy with that, now I'm just fine tuning the final character - which is mainly the imaging and holographic qualities.

So the question is: rather than chasing minimum distortion in all categories, which distortion should we "allow" or focus on? We all hear about the even harmonics being the "good" ones, so do I allow a few % of 2nd on my loadline calcs? 4th? Etc.

My first iteration was poorly optimized for the output load, had too much feedback, was borderline unstable, and was cathode biased- but had some impressive depth when listening. I'm trying to get it back to that depth but without the faults.

Has anyone built them that care to share construction ideas and pictures?

I have for sale two td15h+ Apollo subwoofers/mid bass there in gloss black 17” cubes made from 25mm mdf stuffed with lambs wool to give a a of roughly .6
They also come with a inuke 3000 with silent fan mod which gives them roughly 750w each

The cabinets have a nice finish but have a few chips and scratches from kids
The chips I’m sure can be touched up with some
Gloss black touch up paint to look great in the room again
Binding posts are on the bottom so they can face the room or the wall

They also come with grills but the lugs have been snapped off I can supply new lugs but they need the old lugs to be drilled out and new ones glued in again

These are super clean 15” that can play up to 500hz easy so amazing for music
Can be put in bigger enclosures or eqd in these small enclosures which are nice and compact

( note one driver has a earlier foam surround the other has a neoprene surround as bought at different times this doesn’t effect bass frequencies )

£700 for the pair with inuke

There heavy so collection only from post code TW17 shepperton U.K.
unless you want to arrange a pallet or something

SOLD SOLD SOLD

Spare set of Miro PCM63 DAC for sale. i2s inputs on board.
Circuit design and board info available here:
https://www.diyaudio.com/community/...s-input-nos-r-2r.354078/page-209#post-7049224
You need a PSU and I2s source and a pair of single op amp for this DAC to function. Look at the info in the thread to see the PSU requirements.

Board fully populated with good quality caps eg. Panasonic FC for digital , Nichicon Fine Gold for all the analog circuit, Kemet ceramic bypass smd for the glue logic chips, Epcos film bypass caps for all the decoupling electrolytics , low noise non-magnetic resistors, good quality Nextron IC sockets etc. Packed with good parts.

The PCM63P chips are bought new for this project and used for a few months for this board. I have attached the pics of the chips when it arrived to show the legs before i inserted them onto the board. Pins of new chips need to be bent inward slightly in order be socketed, which i hope the pic can show (i am not great at taking pics).

Again, to remind you that I will not be providing the IV op amp.

Price is $180USD, covering also the registered shipping worldwide from Singapore.
I have sold and delivered almost 20 items successfully to Europe, UK and US with zero problems.
My preferred transaction would be PAYPAL FF only. For members who are unable accept this mode of payment would have to skip this deal, i am sorry.

I will always be happy to buy Miro a coffee as usual, for his generous sharing.

Hello everyone!
I have CD player ATOLL CD 200 first generation. The player is upgrated with better capacitors, sockets etc. I bought it like this from Germany.
The sound is beautiful, the job is very well done. It outperforms the new Atoll CD200 signature.
Unfortunately few days ago a strange noise appear in the right channel. The left channel is clean.The quality of the sound is not affected in any way, but in the low passages of the music the noise can be heard,
Here is a link where it can be heard :

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I connected external DAC to the coaxial exit. Everything works fine, no noise.
I need help where might be the problem.

I used four PMT-2040N1625AL01-04 to make a small soundbar.



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Hi all,

I have a bit of a head scratcher with channel tracking and the attached, very simple circuit.

I have an issue with a low input level of the DAC I use for my TV and made a very simple gainstage based on a standard OPAMP non-inverting circuit. It works very well, gain is at x3 (9db). This then goes into an ESP P97 preamp as indicated.

The problem I have is that there is a large channel imbalance when using the pot to adjust the level, but, when the pot is at max (zero resistance), the channels are perfectly balanced. So, perfect balance with no resistance, imbalance with any other setting.

I did speak with Rod at ESP and he stated it must be the load resistors are not matched, everything else being rulled out as the channels are balanced with no resistance (i.e. max setting). But, they are matched?

I thought to ask you guys here, I ask Rod too many questions (!)

FS: A pair of the 2016 First Watt push pull Sony Vfet amp kits. The pairs of 2SK82 and 2SJ28 are matched and graded by papa himself, all 4 are KE-33 rank.


(from the pdf) - The amplifier delivers 15 watts into 8 ohms and 20 watts into 4 ohms. The open loop gain is about 36 dB without a load, and 35 dB with an 8 ohm load, and the closed loop gain is 16 dB. The output impedance is 0.18 ohms, a damping factor of 45.

Included are everything in the photos, the 2 amp boards, the 2 pairs of Vfets, the other fets, the mica insulators, the aluminium mounting brackets, mounting screws, power supply, as well as some mica goop not in the photos... The boards have been stuffed with everything except the fets and Vfets. These must be completed, tested and adjusted.

I have had some expensive repair bills for my car that were very unexpected and this project that I have had on the shelf must go to help me cover some of the costs....

Please make me an offer via private message.

Thanks

Which HT should be suitable for 4 ways speaker system?
8878T01 300Hz
JBL 2450 300-12k/20k around
??? 12k/20k around-6k around
JBL 076 6k above

the question is which HF is better for this range, from 12k/20k-6k?
someone say RCF ND350
Faital HF108/108R/108D
JBL 2420 second hand
or others......
I think the throad should be 1 inch no doubt.

The HF should have good curve in that range, most important it should sounds musical.

Many thanks for your advise, thanks in advance.

Hi all!

After couple of years of reading this forum (a lot), I finally got to design my first chipamp PCB.

I'm a total amateur, surely there are errors in my design, but where should I go, if not here? 😉

I'm using LM4766, because:
1) is was available, while 3886 was not,
2) I don't need much power for starters,
3) I couldn't find any sensible 4766 pcb, so I thought that maybe I'll give it a shot.

I'm worried about a couple of things:
1) grounding (what else, really? 😀 )
2) overall layout or schematic bugs,
3) ...maybe crosstalk issues? Wrong feedback coupling?

The design is based on the TI reference design, but I have used a lot of information from Circuitbasics, Neurochrome... I looked everywhere basically.

As I mentioned before, I'm an amateur - though I understand electricity and basic physics, I lack proper PhD Master Blaster Engineering educaton.

Thanks in advance, you all are awesome and I hope I'll learn some of electronics engineering myself, as much as it is possible for a hobbyist.
What do you think?

Hi all.

Just purchased an fx audio 502e-l class d amp for the grand total of 19.99 including shipping from ebay in the u.k

Pairing it with an fx audio tube 03 pre amp. For a budget build 🙂.

Just wondered if anyone had bothered to modify one before. Noticed from looking at pics of the board it has a surface mount ne5332 op amp on there which could be swapped out easily enough and potentially upgradeable capacitors.

I have built the Pensils with MA-CHR-70A/3. Very pleased and after the extended run-in added the 'Holey Brace' 🙂

Now moved them to my library (small, near-field) and have a placement problem. They need to be lifted 300mm off the floor to clear some obstacles (don't ask ).
As they are designed for floor standing what are the ramifications of being lifted ?
If I add a plywood (sand-filled ?) box-stand will this help in continuing the front baffle to floor level ?

Thanks,
bob

A nice Pair of Lundahl LL1943, 1:16 and 1:32:
300$ + 20$ shipping

So, if you don't want to pay more for a couple pair of RCA jacks the entire rest of your build....
YET you don't want oriental ripp-off junk....
But JUST want something electrically sound, good quality, reasonable cost....

What do YOU go for????

TIA

Greg

Removed

My almost-5 year old 2912 left channel has developed a strange digital 'squeal' that's coming from a specific spot bottom left section of the speaker. Somewhat ignorable when playing stuff but still unacceptable given the quality of these speakers overall.

Trying to record it with a phone .. you can hear it clearly https://recorder.google.com/share/57968ffd-d5b6-49a2-af4b-9387dc51fec4 increasing in volume when mic is close, but the digital squeal nature of the sound is somewhat lost. Best I can describe it is that an old PC of mine long ago piped noises my harddrive made into the soundcard output (fun). Somewhat uneven noises.

How does an analog speaker even create this noise?

More importantly, anyone know if this is an easy fix (I'm not super skilled but I can replace a cap or two.)?

I have been receiving a lot of emails asking about the availability of the Buffalo SE-Pro28/38 and associated parts.

While I am winding down Twisted Pear Audio, I am thinking of making a limited run of Buffalo Kits, if there is interest. This would be pre-order, and would have options for the Buffalo DAC, Tridents, Mercury output stages and power supplies.

Thoughts?

Hi! So I think I've searched enough that this isn't duplicate

Going to me more Howie Didit, than my usual ramblings, but there you are. "If only one CD-Z is saved it will have been worth it"

So Teac's CD-Z500 (or CD-Z 5000) nice player frankly with two times TDA1541A = one for each channel

Best of all it has a discrete 'doing all the CD stuff' board and a 'doing all the audio stuff' board (technically there is some clock handshaking betwixt the two but meh

FIRST OF ALL ok it has TDA1541A's in parallel - if you need a moment to yourself after hearing that, take a shower & wipe your self off before reading on

This is just for fun OK? no one died

Typically I didn't take any photos of the outside but armed with this very websites version of the truth (special mention to Pedja Rogic) I did the standard version one mods replace all electrolytics and add decoupling caps for the TDA1541A's as suggested

And you know what?

It's become my daily. Pretty sure I own at least one CD player that is technically better but I turn this on, it makes music and I like it

Yes output op amps came along: SIL yes, thanks for that Teac,

TBH it gas been a few years since I 'did' the first one. but see pics

more to come from the last iteration FYI

Andy

I’m looking to repair my amp but cant find where to buy parts for it
Im looking for transistors and gate resistors
Amp turns on but no sound

i can make pcb copies from good pictures/photos, pdf templates etc. using the tracing method (provided the dimensions are known so i can scale them properly).
If there are interesting templates and there are enough interested parties, I would be happy to take a look at them!
best regards

Attached is the board of the tube-tester µtracer 3 that I copied 😎

Hi,


I'm working on a replacement preamp and amp for an old B&O. See this post https://www.diyaudio.com/forums/class-d/342430-beomaster-refit-controversial-6.html


I have a TPA3116 based board from Aliexpress, XH-M569, this board had some bad noise issues from an unnecessary opamp on the input, I removed this as suggested elsewhere and now it has acceptably low noise.


I am trying to hook it up to an NE5532 based preamp, aliexpress XH-A901, but it has a terrible whine noise, which is not dependent on volume. I have tried several power supplies an configurations, running both amps on same power and separate power.



Both the preamp and the amp have single line inputs, would it be possible to convert the preamp output to balanced? Would this help with the noise?



Can anyone help with how to eliminate this constant whine noise?


Thanks,


Theo

Does anyone have a schematic for a Mark Bass Little Marcus (miller) bass amp?

Hello


Anyone have the the Scott 121C schematic?

Thank you

Aldovan

Hello Guys,
i am back here again looking for you advice, and opinion, i have ordered this diy amp board from ebay,from here, it is still on the way, so i dont have it yeat, i am looking for a schematic, because the seller did not provide a clear schematic, just this fuzzy one i had attached. Please tell me what you believe about this board.

It is without tubes, and transformers.

Thank you guys !

Hi,

The schematics are below.

I wired. Black to power/hot and White to neutral. Mains here are 123VAC.
Green/yellow to ground. Green Green per schematic.
I ASSUME yellow black (center tap) and yellow to 5Y3 per schematic.

I have two questions. Is the yellow 5V correct?
If I want higher voltage should I use the grey wire on the primary based on 123VAC mains?

Thanks,

Billy

Looking to try a Subbu DAC. I live in TN.

Like many people here, I have some leftover parts from my car audio days, including two 12" woofers. At the time of my infliction I was a reader of Richard Clark and David Navone's Autosound 2000 newsletter. They eventually began selling parts for projects modeled after their multi-winning Buick Grand National. After some discussion with them, I purchased their Membrain resistive panels which included the ANN "Aperiodic Normalization Network" to help modify the circuit. (In my vehicle at the time: wow.)

Of course now I want to DIY a pair of cabinets for home subs using the same parts.

I know that the original design included specifications saying the box should be as small as possible, with the "membrain" directly behind the woofer. The woofer is technically inside the vehicle and the membrain is open to the trunk area. The description also mentioned to keep the back wave from the membrain (further will read as membrane) from getting into the car interior and affecting the front wave from the woofer.

FFWD to today and I'm reading about open baffle speakers and open baffle woofers. I'm wondering how effective a woofer would be if the rear panel of a speaker box were moved forward to be within an inch of the woofer, had the membrane mounted to it, then letting the membrane see the rest of the box (to eliminate at least some back wave) and leave it open.

I've seen mention of WinISD around these parts so I'll test that software to see if it can even render what I'm thinking.

The membrane and the ANN were custom made for each speaker back in the day so I've no doubt they will work together well. I'm just curious if creating an open-baffle aperiodic woofer with a five-sided box is worth the effort.

Am I missing something? (likely!)

Does anyone have experience building this kit?

Trans-10

If so, comments? Impressions?

Measurements

As a preview/teaser, I would like to present some measurements of my system. It comprises of bandpass subwoofers, basshorns and mid-high horns. It looks like a 3-way but it is a 4 way. A Minidsp 8x10HD is the heart of the system. The amplification for subwoofers and basshorns is solid-state, the mid and high portions of the BMS 4592ND drivers are fed with a signal from low power tube amps. The midrange and tweeters are as such biamped, by the way.

I have applied acoustic treatment in the form of a mix of basstraps, diffusion and absorption. The room measures 5.28m by 4.15m with half open rear wall to dining room and kitchen. Total length of room is 8.6m. Listening position is about 1.2m from rear wall (the rear wall that matters is 5.28m from the front. To the left of me the room extends, to my back and to the right I have the mentioned rear wall. So my room is not very symmetrical.

About the measurements: these are taken from the listening position, only one measurement. All screenshots are taken from this measurement, exept the subwoofer measurement., where the mic was placed very close to the port of the subwoofer. The subwoofers have also been included in the total system measurement, so the measurement range is plm 20hz-20khz.

I tried to place the mic as close to the "middle line" between the speakers as possible, at the listening position. The speakers are on their usual/quasi optimal position. I must note that I am not yet finished dialling in the system after the latest upgrade of my system. Also, I am just starting to understand how to measure loudspeakers well, so please take the measurements with a grain of salt. I may have made errors, but nevertheless I guess it is entertaining enough 🙄.

At a later stage in this thread, I will show some more details about the system, the build of the 3D printed horns and especially explain about the choices I made over time to create this system as it is now.

I hope the horn afficionados (and of course all others who build speakers) like my effort 🙂 it is by all means not perfect, but it is a very musical sounding system I dare say.

Edit: the SPL/phase graph is total system output with subwoofers included

Hi! I have not much experience with DSP-s yet, so i ask. As we know, on same dB levels low frequencies are less audible than high frequencies. Can this be solved with pragrammable DSP so that i adjust the DSP graph so that on low frequencies the amplifier would give more power to driver, than on high frequencies? Is this an average DSP's standard feature or only some "high-tech" DSP-s could handle that?
Are there any other options than DSP to handle this phenomen?

HELP - I desperately need the Bruel & Kjaer 2123/2133 Service Manual. I have searched the Internet, but no joy. Can anyone help, please ?

I have been having a blast with the SB Acoustics x Solen Fully-Assembled and Tested Sasandu Tx (TeXtreme) loudspeakers.

My review will go up soon! I think it's the longest and most in-depth loudspeaker review I have ever written!

john

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I have a couple Bash subwoofer amps that I would like to get up and running. They both seem to have failed from the typical problems associated with the SMPS power supplies. I have replaced the FET's and anything else burnt, but I have hit a wall. On the power input side what seems to be an inrush current limiting thermistor has failed and I cannot identify the component. The markings are DSP 104. Also the PDC board has what looks to be a failed diode. Unfortunatley the silkscreen is double marked so I cannot determine the proper direction. The diode is d11 in the upper right corner. It can be seen burned and black. Please have a look at the pictures.

I am looking to design some subwoofers that match in style my Duntech Crown Prince speakers. I am looking for true Infra sub sub's. something that will cover the 16hz to 40hz range at the very most. I have a pile of some very interesting drivers i want to use. More details on those later...but...When designing an ELF type system. sealed box, EQ'd response. How do you size the cabinet? does it matter over such a narrow range and if you are applying EQ?

the drivers I have are 10" drivers designed for open air use and have a high-ish Fs. again more details later. but...lets talk about the cabinet theory for now. I want to use 6 drivers per column per side. My Duntechs are nearly 7' tall and narrow so i want to match the look. maybe 12-14" wide at the face. 7' tall and maybe 12-14" deep and I am wondering if i should use one large open column or divide it into equal spaces for each driver. How do you calculate such a box??

Hello,

I'm planning to upgrade the power supply of my subwoofer amp. Long story short, i made a mistake by purchasing the wrong kind of psu and now i ended up with selectable output voltage (25v/35v/45v) dual rail halfbridge smps that i can't return.
It's working without a problem, but just using/loading one of the two rail makes me uncomfortable.
The last time i use/load one of dual something like class d amp (using one of the two channel of tpa3116d2) ended up on blown amp and burnt speaker.

btw, i use tda7498e class d amp wich requires single rail supply, 36v is the upper limit.

I have a plan on how am i going to do this, i also (i think) already have reverse engineered it, but i'm not quite sure yet.

so, here's the smps.

and this is the schematic of the smps that i reverse engineered and drawn on easyeda.


Before i proceed with my plan, i need an input on the schematic.
is it right/correct? is there anything that i got it wrong?

Thanks.

ps: sorry if my english is bad, since it's not my first language.

-

Hello guys,
About half a year ago I decided to design my own high performance headphone amplifier. The idea came more from some kind of engineering challenge rather than serious need - my O2 was probably more than enough.
My designs considerations were pretty simple:

• Challenge myself and check what lowest distortion can I archive
• Decent power with ability to drive almost any headphones
• Near zero output impedance
• Safe for headphones, no DC at output and stability in any conditions
• Relatively cheap and easy to build - no unobtainable, expensive or exotic parts

After a bit of reading, tinkering and simulations I settled with composite amplifier architecture. I've considered lot of solutions including discrete buffer, LME49600, numerous models of opamps, ADSL line drivers. Every solution had its pros and cons like price, stability, output impedance, DC characteristics, output power, minimum load resistance, complexity, power dissipation limit, temperature and so on.

Finally I decided to nest already very good TPA6120A2 inside feedback loop of another operational amplifier. At this time I'm using OPA1602 but want to experiment with something else like OPA1652 or OPA1656. Especially the last one seems promising but first I need better test equipment to analyze such small distortion levels.
TPA6120A2 is almost perfect candidate apart from one thing - stability. It is current feedback operational amplifier and its stability is not so easy to tame. High attention must be paid to minimize stray capacitances at PCB.

Apart from that TI recommends at least 10 ohms of series output resistance. But this means rather high output impedance. I tried to address this issue in two ways - complex feedback, post output resistor or output inductor.

At this time I'm using ~300nH air core inductor at output. TPA6120A2 seems happy with it and output impedance is very low, about 10 miliohms. There is downside tho. Such inductors are hard to get off the shelf so I had to hand wound them. Inductors with other that air cores probably would introduce high distortions.

But there is another way. PCB can be configured to take feedback post resistor/inductor. This configuration is not so popular way of isolating capacitive load from amplifier while maintaining low output impedance. I haven't tried it yet but possibility of omitting inductor is very promising.

For power supply good, old LM317 and LM337 regulators are used with half wave rectifier. Board can be powered by AC-AC wall wart or transformer. Those wall warts are cheap and easy to use as there is no contact with potentially dangerous mains wiring.

Instead of using more common voltage divider to set output voltage I decided to use zener diodes. Dynamic resistance of zener diode is lower than required resistor which should result in lower output noise. By default 13V zeners yields about +/- 14.5V at output with less than 10mV difference between negative and positive rails.
Cadj capacitors are of course present. There are two LEDs at both rails. Besides being indicators they run at relatively high current, providing constant load to regulators which keeps low output impedance of power supply.

Whole PCB was designed in free and open source software - KiCad. Simulations were done in LTspice.

3D render, real photo taken before mounting my ugly hand wound inductors and schematics could be found in attachment.

What are my plans for future?

• Learn CAD software to design enclosure and order it at CNC workshop
• Acquire/build equipment allowing me to measure true performance of amplifier (aiming <-130 dB THD)
• Adding micro controller (probably STM32) used for monitoring amplifier - temperatures, DC offset, failure, relay control and etc.
• Maybe bigger version with XLR input, preamp output, switchable gain and Alps RK27 volume control?

I built Electra-Print's passive preamp using a pair of their PVA-2n audio transformers, following their circuit design, but with two switchable inputs and no subwoofer output:

Electra-Print.com PVA Passive Audio Pre-Amplifier
You Can DIY! Passive Preamp: Transformer Implemented | audioXpress

I used a Galaxy 1U 124mm x 170mm Alu case from diyaudiostore.com with customized drill holes for an ALPS 10k pot and a DPDT on-on toggle switch on the front panel, and three sets of RCA jacks on the back panel. I drilled out a few of the vents on the bottom panel to accommodate mounting screws for the trafos.

With the PVA-2n based passive preamp replacing a Schiit SYS passive preamp (10k audio taper pot with switchable inputs), my system sounds amazing. My perception is that digital sources (a Sony CDP-302 and a RaspberryPi with a AD1868 DAC HAT card) sound much cleaner, with more instrument detail and better levels (frequency response). Listening fatigue I experienced with the CDP-302 completely disappeared last night, and albums with challenging levels to my ears, like U2's The Joshua Tree, suddenly sound way better balanced. I much prefer the sound of this preamp to my Korg NuTube B1 as well.

The only real downside was sourcing parts from multiple vendors and the cost of the customized case. Being my first build completely from scratch, I'm satisfied with how it turned out. Hope you enjoy the pictures.

I have two unused new / old stock Focal 6K412L bass-midrange drivers. Bought for a project long ago and since abandoned.
These are 165mm (6.5 in) drivers with gorgeous yellow kevlar cones in cast frames. Still in the original boxes. See pics below.
Nice for 2 way or 3 way with subwoofer.

$25 each or $40 for the pair + shipping from Chicago, IL, USA

Weight in original boxes is 60 oz = 3.5 lbs = 1.7 kg each.
Weight for two in a shipping box with extra padding is expected to be about 9 lbs.

One speaker will fit in a USPS Medium Flat Rate Priority Box and cost $17.10 to ship anywhere in the continental US. Unfortunately two speakers will not fit into the large flat rate box so using USPS Priority Mail would be two boxes.

Price with USPS Ground Advantage for both speakers together is expected to be about $24.40 or less within the continental US.
Will take Paypal, Venmo, or Zelle.

Hi All,

I have 4 new capacitors for sale, EPCOS 47000 uF / 100 V (PN# B41456B9479M000), 5 mOhm, 12000 h. Bought from Digi-Key.

Any capacitor test can be made if required.

Anyone interested please PM.

Regards,
VS

I just finished refurbishing this Teac A-4070 (plays forward and reverse). I have refurbed and built from scratch quite a bit of gear. This was my most difficult project yet. I bought it in March for $20 not working, power up only. I ended up replacing all of the electrolytic caps, some of the film caps, some transistors and all 4 heads.
I used NOS Nortronics for the playback heads and was very lucking in finding NOS Teac record/erase heads. It seemed like every time I fixed something another problem popped up. It had hot chassis issues that went away when I removed the extra wiring etc. associated with using different voltages. I will never be used outside of the US now anyway. It cleaned up nicely and more importantly sounds fantastic now hooked up in my main system.

So my stash was invaded by a 4 y/o 3' tall white male perp. Managed to drop one of the ACA's and bent the back panel. Fins and front panel perfect. I purchased another back panel with the intentions of making it right but have lost interest. Both ACA's are V1.18 and were working fine before the ransacking but I believe the bent one lost a wire solder to the back panel. To be safe I would assume that both need a good going over as I have not tested either since putting them on the shelf a few months ago.

$350 plus 25 shipping includes both ACA's with power supplies and extra back cover and the SMPS filters. You might have to do some work but you're in at less than half price from the new kits. I will post some pics shortly but if you want specific pics PM me. These are all silver faced units.

The ACP+ kit is SOLD...should power up but in the mayhem the ground plane bolts/nuts, power supply and volume knob were lost. I'm still looking for those items but the kid is pleading the fifth. It does have the ground plane. I also have 3 complete SMPS filters that go with it.

I also have two Galaxy 1U enclosures new in the box. SOLD One 230mm x 170mm with 10mm front and one 230mm x 170mm with 10mm silver front. $50 each shipped.

Pics below.

Be careful ordering things that ship via UPS this week, looks like a possible strike Aug 1st.
https://finance.yahoo.com/news/ups-...-tuesday-billions-are-at-stake-165811027.html

Anyone have a schematic for this amp ?

So here I am in Torino, Piemont, for a one-day trip with the family. Got there at 10 in the morning, and until now, I have seen h&m, COS, Zara (and another one not worth being mentione), and had a bowl of something inspired by japanese kitchen.
According to maps, I haven’t moved fuether than 4 minutes from the starting point.
So much for holidays.

I have several of these old stock 6N30P-DR tubes, made early 1980s and in new, unused condition. I’m looking for $100 per tube. Payment per USPS money order and shipping is on you from Central Illinois, 61821.

There is lot of discussion going on about soundstage, but i found almost no actual information in that thread.

Here is a good test of your soundstage. Please play 3rd track on annie lennox album 'bare' and report back if you hear your 2 channel audio to circle around your head.