Hi folks,
I recently purchased this receiver for parts (no audio output) at a local pc recycle store. Luckily cleaning out the switches brought the amp back to working order, except for a rather loud thump when I turn on the receiver. Would replacing the factory ceramic capacitor (C1001) with a polypropylene film snubber capacitor reduce the thump? Or is the thump more common on amps of this vintage? Photos of the factory capacitor, and schematic attached. The service manual is too large to upload here. It can be found on hifiengine. I’ve attached screenshots pertaining to C1001 from the service manual and schematic. Thanks.

I listened to this Lyngdorf inwall setup this weekend and it was huge, wide and high but some people commented the lack of depth? I liked it!





I another system was Perlisten an wow, it it was nice sounding. Smooth and detailed.

Hi guys!
First build with my own mic, speaker build and dats v3. I am doubting whether or not i have done everything correctly

I measured in rew with an UMIK-1 calibrated and with the distance of a meter from the tweeter level for both measurements. It didnt look to good on the REW measurements of the ScanSpeak woofer, until i applied 1/6 of an octave of smoothing. Is it too much?

Tweeter was easy and looked very smooth

I then imported into xsim and have some trouble with making the woofer not being all that smooth. I now use a graph that make the woofer look better, than it probably is. Am i wrong for doing this?

I guess my question is. Do you guys see any problems with my measurements or crossover design. I have probably made some blunders that i am not aware of.

I have posted the measurements of the frequency respones and impedances below.

I have been in the process of researching and preparing to build an automatic measurement table for a while as making a large number of measurements manually is no fun and very time consuming.

I came across a great website I thought had everything I needed laid out and documented.
http://nicholasmart.in/measurement_platform/

I started getting together all the things I would need and came across a stumbling block. The software exe to have ARTA communicate with the Tic controller is not on the website and the author did not respond to my message or another request posted on another forum that seems to be discussing the same thing.

https://www.audiosciencereview.com/...ar-measurements-using-arta.14282/#post-438440

I started looking at coding it myself and quickly realised it would take me a long and frustrating time if I tried. Fortunately @Tom Kamphuys agreed to help me out with his coding skills, the reason this software works and is available here is due to almost solely to Tom's work.

He has created a github page where the source code is available. At this time the exe is not there but is attached to this post in a zip archive with a basic readme file to explain it.
https://github.com/TomKamphuys/Arta_Tic

This software was created to control a Tic stepper motor controller from Pololu via the ticcmd command line utility. ARTA sends commands to the turntable driver exe which interprets and passes the correct commands to ticcmd.

I have chosen to use the Tic 36v4 as it has the maximum current capacity (4.0A without extra cooling) and a NEMA 23 stepper with a 2.8A maximum current rating. These are probably overkill in most circumstances but I wanted to have the option to move heavier loads. In theory if the friction can be kept low enough these components can move more than 100Kg in the configuration I am building.

My setup will use two 600mm pre cut red oak circular table tops with ball castors in between. The red oak was chosen as it was stiff, solid and on special for on $10 AUD each.
The gearing will be a 360 tooth GT2 main pulley mounted to the table top underside with a 20 tooth pulley on the stepper with a closed loop GT2 belt. Very similar to that in the above measurement platform article. Underneath there will be a pine base frame to aid in stability with levelling feet.



The pulley I have designed contains a 1" bearing that fits a 1" OD Aluminium tube piece used as a centre pin. I wanted to make this solid and low friction so the large bearing and tube seemed to fit the bill. I will make the pulley STL available once I have printed and tested it to make sure it works.



I have made a prototype without gears that functions as intended. I was able to make a 0 to 180 (10 degree increments) set of test measurements with ARTA on my laptop that took only a few minutes to complete.

@jcga was keen to update his existing ARTA turntable with a different motor and driver. He has also been able to use the software to move his table successfully, so I thought it worth making a thread to post the code in case this is useful to others.

TLDR Is there any audible preference/difference noticeable between the two tracks in either (or both if you prefer) of the two folders marked 'Digital' and 'Analogue'. There are two MP3 files in each.

There is also a poll attached where you are allowed a single choice out of seven options. Read the choices carefully before voting. They are:

1/ I prefer Digital Recorder A
2/ I prefer Digital Recorder B
3/ I prefer Analogue Recorder A
4/ I prefer Analogue Recorder B
5/ I prefer the Digital over the Analogue
6/ I Prefer the Analogue over the Digital
7/ I can not really discern any difference

If you can not tell much difference between models but suspect you might prefer Analogue over Digital or vice versa then there are options for that in the poll.

---------------------------------------------------------------------------------------

I thought it might be interesting to do a comparison between two Minidisc recorders, the MDS-JE480 which was one of the last models that Sony produced, a model that was firmly in the 'budget' category. The other is an MDS-JB920 which is an older model but much more of a heavyweight and dare I say more audiophile oriented. The budget MDS-JE480 does however sport one of the last (and best) developments of the ATRAC compression system 'ATRAC3 DSDP Type S' while the MDS JB-920 uses an earlier version of ATRAC. The later ATRAC versions were needed for the inclusion of LP2 and LP4 recording modes which doubled and quadrupled recording time available per disc, a very useful feature and one the MDS-JB920 lacks.

The actual MDS-JB920 used here is one I was fortunate to obtain a few months back. It has that classic early generation quality feel to it, it's a real heavyweight and offers very high build quality throughout. Unlike the MDS-JE480 which majors on using SMD components, this one uses mostly normal sized through hole parts.

https://www.diyaudio.com/community/...ttle-conundrum-at-the-end-of-the-post.405949/

The MDS-JE480 I have owned from new and this picture is from the web. It is much more a lightweight budget model but it is nicely finished and very feature rich and of course having that very desirable ATRAC3 Type S encoding system.



The recordings were made as follows. A Micromega Stage 2 CD player was used as the source and this was fed optically (TOSLINK) into both players for recording. The normal analogue output of each player was then captured and recorded for the comparison. For completeness another set of files was made using the analogue inputs on the recorders which adds the recorders own A/D convertor into the chain.

(for those familiar with the Micromega it has as only a coax digital output as standard but I modified this player years ago to add a TOSLINK output as well)

The recordings were captured using Audacity on a Dell Mobile Precision Workstation and the levels have been equalised. The raw files were converted to 320kbps MP3 to allow a reasonable file size which allows them to be attached to the forum.

I have labelled the players simply as 'Player A' and 'Player B' so you do not know which is which, however to avoid possible confusion Player A in one folder is the same as Player A in the other.

There are three zipped folders attached.

The folder called 'Digital' contains the two files recorded using the TOSLINK input, one for the MDS-JE480 and one for the MDS-JB920.

The folder called 'Analogue' contains the same two recordings but these were made using the analogue inputs to the recorders and so have the recorders own A/D conversion in the chain.

The third folder called 'Micromega' contains the same test track but this is directly recorded/sampled into Audacity with no recorder in the chain. So this can be thought of as a 'reference' and was taken from the RCA outputs of the Micromega. The Micromega Stage 2 uses dual Bitstream DAC's and had a very high reputation for sound quality back in the day.

(for anyone keen eyed I have double checked the files because you will notice a difference in compressed file sizes between players A and B in each folder and how they seemingly switch positions between the two folders. Why that happens I have no idea but it comes out that way when I repeated the process as a check. The uncompressed sizes are identical between all five files)

Bose 901 upgrade

Working all my life in hi fi and professional audio a few years ago I wondered what would happen if I replaced the internal wiring of a pair of 901’s for far better-quality wires. So, I bought myself a set of Bose 901 series 3 with the original equalizer. I allready had good results listening to 16 awg multi stranded silver plated speakercable; van den Hull snowline. So, I removed all the wire wrap cables and soldered the new cable from driver to driver. Use a 75-watt soldering iron minimum since the silver-plated cable draws a lot of heat away. And don’t be afraid to drill an extra hole to route the new wire from one chamber tot the other. Finally, I replaced the speaker connections for gold plated 4 mm female banana jacks.

I also upgraded the equalizer. In the signal path there are 3 10uf electrolytic capacitors in each channel. I replaced them for 10uf MKP. And also replaced all the transistors for new ones.

I can say that the difference in sound reproduction is very big; or to say it better; dramatic. The low end and high end is much better. The dynamic range is much better. The date code on the drivers is 1979; it is unbelievable what these 901’s can do! I am using a 100 watt amplifier and I am listening to high res audio via Qobuz. And I am using a USB to USB audio isolator to connect my PC to my DAC; I bought one via aliexpress for a few euro's.

I was searching online if somebody else had done this before, but I did not find anything sofar. So, I am very curious for anybody who will also perform this upgrade and tell me what you hear!

My amp delivers 25 watts in 8ohms. Will a 5w, 4ohm resistor in parallel with the woofer survive this signal?

I was intrigued by the sound differences between ECC83 tubes of different manufactures, even though on the cathometer they looked about the same, that is why I propose an indirect determination of the vacuum quality in the tubes by measuring anode current at a very low voltage. Worn tubes or with air in them give current values a hundred times higher than normal and smaller differences occur in tubes with different manufacturers, what do you think?

I am building the below amplifier. I have it done with the exception of hooking up a speaker. I measured from the point where the speaker connects to the cap and ground and I have 12vdc on my meter. Shouldn't the caps block the dc voltage? So why do I have 12 vdc there?

Hi,
I am thinking of implementing this 2.1 crossover. It is inspired by the ESP (Rod Elliot) 18dB 2 way crossover.
Please review and let me know your thoughts.
Thanks

I was going to buy a McIntosh MB20. But, I was paused by my friend. He recommended me a new and popular WiiM Pro Plus. The WiiM has numerous positive reviews and it costs half of the MB20. So, I’m hesitating now which one I should buy. I mainly/always play music from YouTube music via iPhone XR. Please advise me.

Sold

For the last 5 years I have been harvesting Sony TC500/500a tape decks for speakers and transformers. I think the time has come to create something from the parts I have accumulated. I have plenty of ideas I would like to explore for the transformers, but I currently have 8 pairs (16 speakers) of Coral holey basket drivers and am wondering what those with far greater knowledge than me would do with them, given the chance. I have looked over the numerous past postings, but could not really find an example of anyone with a large number of drivers. I can certainly produce multiple different speakers, each using one, or two, pairs, but wondered if that would be a waste of a rare opportunity. Thank you in advance.

I have a pair of these (along with 2 other driver pairs that I think were intended for a 3-way speaker) and am trying to find info about them. T/S or other specs would help. They are 6.5 or 7" drivers but other than that I've got nothing. There is little on-line. I've contacted Focal directly but don't expect to get much from them. They have 2 sets of wiring posts almost as if they have dual voice coils - I'll figure that out soon. I'm re-doing the surrounds (foam was shot) and would like to experiment with them in some kind of multi-way box. Thanks a ton for any info you all can provide!

Hi,

Would like to get a copy of NatSink but can't find it. Only found few dead URLs.

Thanks

Well it’s back to my very helpful community … I have Acoustic Elegance woofers going in a two way horn project.

I have reached out over and over and over and just can’t get them to respond to any post sale questions.

Very frustrating.

I would say they do amazing work but will likely never buy from them again - if you can’t take 2 minutes to respond to an email (sent 4 or 5 over a TWO WEEK PERIOD now)…

Very simple question:

The gigantic rubber “gasket” with holes all the way around… how is that normally mounted?

It seems very awkward and I don’t understand how it’s supposed to look when mounted. I drilled wood screws right through… but it looks TERRIBLE.

Am I able to remove that, and use normal gasket / subwoofer mounting pieces so it has a better “finished” look?

Please see pics for where I’m at with this

Thanks in advance

I picked these up for the price of the drive. I've never seen anything like these and they peaked my interest, I was told they were removed from a theatre. The previous owner said they have some weird water bladders inside that are supposed to do some funky science stuff, basically more felt bass. It is a dual opposing bandpass setup, with the water bladders in the sealed chamber. the bladders are supposed to be made of some special vinyl, I can hear water sloshing around when I moved them. We will see how they perform.

There are 5 total units; 4 of the smaller dual 10" models, and 1 larger dual 15" model. 3 of the smaller units are missing the woofers, so just the cabinets. I was immediately drawn to the dual 15" model, the woofers looked stout. A quick test with a voltmeter showed both subs as open. I pulled them out and then noticed they were dvc. They were only wired to one coil, and those were blown, the coils not being used seem to test fine. I'm not sure if they were designed to only use one of the voice coils but I am thinking about just trying it on the 2 good ones. I know they can only be used with half their rated power, whatever that is.

There is virtually nothing out there on these things, but I did find some old thread about an advertisement. It said the 10" model went for around $800, and the 15" model around $1400 (circa 2003-ish). No power handling specs, nothing. The fact that there is nothing out there on them and they went out of biz long ago, makes me question the water bladder tech. Non the less, they should be fun to mess around with. The box is made with 1" birch plywood. I haven't torn into the 10" model yet, but I did ohm them out and they tested ok.

Anyone heard of these?

For the past few months, I have been working on a project to utilize a Raspberry Pi with CamillaDSP in a standalone, fully-digital DSP system. To this end, I have created an add-on board, also known as a "hat", for the Raspberry Pi that allows fully bidirectional SPDIF <-> I2S communication with the Pi. As an advantage to other designs on the market, it also performs sample rate detection, providing the information to the Pi GPIO, and allows full software control of the SPDIF transceiver IC. No resampling of the incoming/outgoing digital audio is required, and it supports all stereo formats from 44.1kHz to 192kHz as tested.

The DSP capability of a modern Raspberry Pi 4 greatly exceeds that of the ADSP/SHARC implementations available. This should open up significant possibilities for much more complex and accurate DSP.

Please read more about the project on the GitHub page:

GitHub - raptorlightning/I2S-Hat: An SPDIF Hat for the Raspberry Pi 2-X for SPDIF Communication

KiCad files, Gerbers, and code are all available for anyone to use for their own build. This post is targeted for an open discussion about the board and implementation. Please let me know if you have any questions or comments about the information on the Git page, or if there is anything I can clarify further.

A quick search here on the site doesn't come up with much .

SMD resistors for audio
from 2007.
Vishay Audio Resistors
from 2008.

So anything new about SMD R's for AUDIO ?

Looking on the Mouser site , two affordable types : Thick and thin film resitors
with prices overlapping each other. So what to choose ?
Seems thin film is the best for audio :
Thin and thick film >> Resistor Guide

But are the fair priced like this one , much different to the more expensive ones ?
RP73PF1E1K0BTDF TE Connectivity / Holsworthy | Mouser
Some datasheets I looked at , don't even give information about what metal they use. The TE says NiCr.

Decades ago at the electronics store there where the green ones , said to be carbon, and the black ones , said to be metal film. Now if you look on Mouser , most look the same and black. Even now at the retail shop , they can sell a cheaper thick film as a thin film because they look the same with minor differences between
manufactors. How can you tell .

Ordering from Mouser seems less risky although you never can be sure whether you received the what you ordered.
Oh and then there are the SMD milf , oops , MELF resistors :
MELF Resistors | Mouser

So what is the best affordable thin film for audio in 2019 ?

For sale Ryan's D3 dac along with all the transformers, low noise power supplies. The D3 and I2S simultaneous boards are tested with the same supplies as listed below. The PCB boards are built using very high quality caps, transistors and other components. The chip is original NOS TDA1541 unused (not a de-soldered one). This is a complete kit all soldered using WBT and ready to be mounted/tested in your own chassis. I will not split this and would like to sell as a kit as whoever buys it will get a highend TDA dac kit. Rcore transformer have been purchased keeping in view the dac build with the right secondary voltage and current consumption.

Expecting $900 including shipping within CONUS. I think the D3 dac board soldered usually is being sold for $699 - https://docs.google.com/forms/d/1ZM...dI3CQEFt1b1iGvBE/viewform?edit_requested=true, and mine is including all the rest of the stuff to make a complete TDA DAC so at my asking price its a steal.

What is included:

Package sale for $749 including shipping within CONUS.
1. Ryan's D3 TDA1541 DAC board + NOS TDA1541A chip
2. Ryan's I2S to Simultaneous
3. PEDJA IV output stage (Someone not interested in this but D3+I2S board PM me and we can work out a deal)

Ping me if someone is interested for the rest of the components as a package or individual.

4. Diyinhk XMOS DSD I2S Dac
5. Salas Clone Ultra BiB positive supply for +26vdc for D3
6. DIY Ultra Low Noise DIY LT3042 for +/-15vdc for PEDJA IV
7. DIY LM317 low noise DIY +5vdc and +3.3vdc for D3/Simultaneous/XMOS
8. Diyinhk LT3042 low noise PSU for +5vdc and +3.3vdc for D3/Simultaneous/XMOS
9. RCORE Transformer rated - 30VA @ 12vac*2 + 9vac*2
10.RCORE Transformer rated - 20VA @ 24vac*1

Or - Honey , did I just made World's first amp biased through little bugs in rails ???


Yup , we had some good time , having fun in Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans - diyAudio thread .

While we were contemplating of various things , mostly how to get PapaSits cheap and in unlimited quantity , we tossed more than few ideas how to make DEF amps - pure or little less pure , using parts we can lay our greedy hands on ... (Antoinel is playing with his own ideas in his own threads but , I'm not so talented to keep up with everything ..... or just too lazy , dunno )

Trying sims with various depletion parts (old stash from Semisouth Was Here era ) , Shaded mosfets , Japanese SITs etc.

More than few sims exchanged , more than few interesting ideas ; I believe few amps can be made ditto from LTSpice sshots shown there .

One of ideas was to keep , by any cost , sources of parts in question non-degenerated , as one of important "details" in Papa's purest DEFiSIT specimen(s) ; however , as zillion of sims showed , there is no way to keep source of any of these parts (or - to be more precise - compound pairs) clean , simply because THD spectra of said combos is simply not satisfactory , and some shaping of part behavior is easiest to do with source resistance , and strategic arrangement of same , regarding output node.

Anyway - anyone interested in all these examples , can read there.

One of real special moments was indra1's finding , brainstorming about biasing issue sans source resistors, that there are interesting Hall effect based chips , intended for current sensing ....... fact of , frankly , I was strictly and utterly ignorant .

So , again , I owe indra1 not just one big Thanks.

As some of you already know - M2 is my fave Papamp; not best one , not best made , not best sounding , not most versatile ...... but schematic of M2 is worthy of square mile big Poster ....... breathtaking example of wit , humor and brilliance . Besides that , it sounds bloody well .

Yup , we also had some special and good time , in F4 Beast Builders thread ..... about another specimen of Papa's enormously rewarding use of quality and fun time ; one of main characteristics of said amp (PL XA25) is non-existence of source resistors in output . That means pure square-law of transfer characteristics of output stage ..... in layman terms - Sparrow's fart is commanding to welding apparatus .
I also have Babelfish XA25 in making , but low on schedule stairs .

So ..... indra1's idea was tempting .... tnx to meine Bruder Generg , I obtained ACS723LLCTR-05AB-T2 chips without too much fuss ..... already done some extensive simming of some possible iterations of M2 and XA25 bstrd

We know that work with big puck mosfets demands not just big heatsinks but also seriously big Cojones ; Mighty Moi , ZM , being jut tinytinytiny version of Papa (as we all are trying to be ) , recanted of pucks , and resorted for usual small bug output parts , already seen in regular M2

OK , 'nuff writing for first post , spell checker in my Firefox is already unconscious , not able to cope with ZMEngrish

edit :

Few lines about intention of experiment:

1. to pursue possibilities of using small bug cased 2SK2145BL Toshiba JFets , of present production , instead of more and more rare Toshiba complementary oldies or always scarce LS JFets ........ in both usual SE configuration and in Papa Borbely's White Cathode Follower transpose in JFet realm ;

1. to make possible usage of Edcor , Jensen and Cinemag xformers of final user's choice ;

3.to pursue possibilities of current sensing in rails , to avoid source resistor in output , further allowing:

4. to pursue changes in OS current capabilities , allowed with unspoiled square law transfer characteristics of mosfets used , enabling significantly enlarged A class envelope (4 Ohms load - A class up to 40-ish Watts , then Klunk! up to 50W , 2 Ohm load -A class up to 20-ish Watts , then clunk up to Wattage you are brave enough to invoke ..... so less Klunk!!-ing in your sound ; also lower THD comparing to regular M2 .



So , 4 or more intentions realized , Mighty ZM fully satisfied .

Am I same as Brave Mickey The Tailor ?


EDIT, TRADE post here : Babelfish M25 , AKA M2 on steroids , AKA M2-XA25 bstrd - kit packages

EDIT: pcbs matched to DiyAudio UMS , final schm and pcb sshot posted in #118, Babelfish M25 , AKA M2 on steroids , AKA M2-XA25 bstrd

Hi there,

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

while I was doing research, I met this website with the toroidal question asked on the forum. I realized later that there was a site related to sound systems. I would like to ask a question about toroidal transformers. i want to use the toroidal transformer with a dc motor. but I don't know how many amps this transformer has. there are only volt values on the label on the transformer. how can I find the ampere value of the toroidal transformer? i want to connect a 24v 5a dc motor to a transformer, does this cause problems?

Sold

SOLD!

While I was building my 300B amps a few years ago, someone suggested to me that I pick up a PSVANE 300B tube to use for testing purposes as I built my amps and was tweaking the power supply so I wouldn't inadvertently damage the more expensive EML meshplates that I picked up from Jac. This turned out to be a useful suggestion, but now that my amps have been completed, I have a single tube laying around that probably has no more than five total hours on it. It ran with a B+ voltage of no more than 400v and its heater never saw voltage above 5.15v DC. It's virtually brand new and works/sounds great. I just don't have a use for it anymore.

Perhaps someone else might find a use for it rather than having it collect dust in my basement.

Price: $$$ delivered to your door in the continental US.





This is the circuit that it ran in:

I completely restored my Plush 10560 bass amp, replacing all the electrolytic caps and most carbon comp resistors. Also replaced the death cap and installed a properly grounded 3 prong power cord. I'm the original owner. The amp always had excessive gain. Back in the day, they designed them so zero to 4 was the maximum usable gain setting. Made people think their amps were more powerful then they actually were. Anyway, cutting to the chase... Because this gain from the 12ax7 preamp tubes is so high, I get too much microphonics. Anyone see a problem if I replace the (2) 12ax7 preamp tubes with 12at7's to make the volume control more linear and reduce microphonics?

I've built the DSELF PREAMP v13.01and it works wonderful and now I have a smaller chassis that I'd like to fill. I was looking at this old design, it's actually a 4 band parametric. but I only need 2 bands. I did a bread board test and hooked it up to my Wolverine amp, it actually sounds very good, to my ears.
So before I send the Cad drawing to Fabrication, I was hoping someone here can take a look at the schematic to see if I made any blunders or anything else.
Yes Its old school but I have all the parts.
Thanks all.
Scott

Good evening everyone
I am about to buy one of those alpine underseats subwoofers
Would u please confirm to me if they are authentic and not fake ?
Pictures attached

Hi all,

This is a bit odd, but some years ago I replaced the tray gear and the sled gear B on my VRDS CMK 4.0 equiped Copland CDA-288 MK. II with no problems.
I had taken the tray off and just inserted it again.

Now, on my other CDA-288, I replaced the sled gear B and reassembled, but now, I seem not to be able to turn the big black plastic gear the sits directly under the tray, to accept the tray correctly. It misalings with gear underneath which lifts the lower puck. And it also seems to be hard to push in the tray the last bit of it's way to fully closed.

Can anyone describe to me how to correctly adjust this and align all parts, so sled sits correctly?

Anything else I should know?

Kind regards,
Jacques

These circuits date back to the late ‘90s (below). There are plenty of SMT LDOs with soft start features but I’m not seeing anything in TO-220. I am angling towards using the MIC29152 or MIC2941A for 6V / 750mA, which encompasses two 6922 heaters and some 5V relays running at 4.3V downstream. I’m looking to avoid heavy inrush current. I’m not trying to ramp power over a long interval - even 1 second is more than enough.

In my application power will already be applied, and I am thinking of having a simple SPST “On” switch that toggles the EN pin from ground to open (with the R4/C1 node connected regardless). Is there a snazzier way to accomplish A) the soft start, and B) the turn on, or should I just copy what’s drawn in the ancient Micrel white paper (with R1/R2 corrected of course)? The TI version is almost the same but for an added cap across the upper R in the ADJ network, and the designer assumes an enable voltage separate from the input voltage, which is not the case in my application.

I didn’t bother including the classic LM317 soft start diagram because it has no enable pin.

Go easy on me, I’m not well versed in these circuits.

Hello,

My original plan was to build a second raspberry pi streamer with the Allo Boss (1.2), which I have done before and am quite happy with.

But that was six years ago... there is a new Allo DAC, and then there seems to be a lot of praise for the Khadas Tone Board.

So I am curious to hear your opinions on this project. I already have the following components:

• Raspberry Pi 4
• ESP P05 Linear Power Supply PCB
• A fun vintage case (broken tape "echo chamber")

What do you think? Stick with the Allo Boss, or give the Khadas Tone Board a shot?
-- oh, and just now I came across another candidate, the Innomaker HiFi Pro DAC (sort of a clone of the Katana they say).

Hello Everyone
This is my last hi-end audio-pc/streamer

It iclude:

• Ultra linear low noise Power Unit
• DSD and MQA DAC
• DVD/CD player/mastering Unit
• HD touch screen display
• Integrate temperature control (has one 200mm ultra low noise fan that start only over the set point temp.)
• Metalized Carbon Fiber Chassis
• Complete rear pannel connection, also SD card port port for rapid OS change.
• Windows 11pro/Foobar2000k - monkeymote app remote control (Android/iOS) - wifi USB keypord/pad for playback without internet connection
• 8Gb Ram, 2-16TB SSD memory library - zero noise CPU/Cipset

Retrofuturistic design (Low level WAF)


I use with esternal good DAC that in the second step will be incuted in a second cabinet/chassis


R

Looking for a ~5.5" mid and I see the Faital Pro 6RS140 being spoken highly of. For example, Troels uses it in his Loudspeaker center and raves about it. My problem with this (and other Faital drivers that have been measured) is that it has some fairly high distortion. In this case there appears to be a giant peak at ~1300 Hz as shown in Dickason's review linked below. I realize most of this is 2nd order harmonic (up to 4%), but the 3rd order also clears 1% in this range, which from my understanding should be clearly audible. Is the problem that other drivers are not better here? (Wondering about the SB Acoustics SB15CRC30-4, where the IMD has been measured but I can't find harmonic distortion tests) Or is it that the strong 2nd order harmonics are inoffensive enough and mask the 3rd order for most listeners?

https://audioxpress.com/article/test-bench-faital-pro-6rs140-midwoofer-midrange

This is a Tektronix power supply for two probes with the Tektronix probe interface. One probe is included, the high frequency low capacitance probe P6245, 1.5GHz bandwidth, <1pF tip capacitance. The power supply/amplifier has two independent channels. Each channel has switchable and coarse/fine settable offset. The unit is mains powered and can be set for 110/115V or 220/230V mains. Fully functional. See pics; I have more from sides etc.

Asking € 375. International shipping to most countries is € 33; ask to be sure.

Jan

Hi.
I hope to buy some audio products from Japan, the process seems almost impossible to me. Is there a Japanese member out there who would be willing to lend a hand?
The process would include getting packaging and shipping organised (not doing it yourself as the items could be large). Happy to pay for ones time. Please PM me if interested.
Regards.

2SA1943OTU - (5pcs) / 1pcs=4€
2SC5200OTU - (5pcs) / 1pcs=4€
NJW0281G - (5pcs) / SOLD
NJW0302G - (5pcs) / SOLD
NJW3281G - (3pcs) / 1pcs=3€
NJW1302G - (3pcs) / 1pcs=3€
MJL4281AG - (4pcs) / 1pcs=4,5€
MJL4302AG - (4pcs) / 1pcs=4,5€

I'm sending all over the world
Paymet via PayPal
Shipping on request (tracking, no tracking)

Hi All,

I can find no information about this here or out there on the Internet, so I'm asking if anyone might have some experience here.

I have an Into-Maker DAC (marked "Skylark" on the board) hat based on an ES9038Q2M chip,on a Pi4 running the newest version of Moode. The Pi is powered by a switcher, and the DAC is powered by a linear supply. The jumper enabling the power from the Pi to flow to the DAC is out, separating them, as it is supposed to be. Moode is working fine.

It is playing music and there are things I like about the sound, but it's making a dirty ticking sound at approximately six clicks per second. The noise is constant, no matter what the volume level on Moode is. At low music levels, the ticking is plenty apparent. When I power down the Pi, it stops. Some noise seems to follow the activity of the pi, with short bursts, etc.

Does this issue sound familiar to anyone? Could it be some kind of ground problem, even though there's no humming? The whole thing is simply plugged together with commercial cables and is not contained in a case. I've used other DACs with this and similar setups with no issues of this kind. I actually have two of these DACs, and they both have this issue, even though the other one is pretty well contained in a metal case. It would be great to get this fixed or else determine that this is a flaw in the devices. I did find they are no longer listed on eBay, FWIW. Any help. as always, would be greatly appreciated.

Cheers.

Does anyone have experience with this driver? I have just found some up for sale on eBay but haven’t heard of anyone using them or seen them for sale before.

https://www.ebay.com.au/itm/2354861...lgAa3NhR5i&var=&widget_ver=artemis&media=COPY

I wanted to make a short 2 way line array with them combined with a 8 inch woofer and was wondering how they might compare to other 2 inch drivers on the market, the power handling looks good.

I have had this idea for a decade and I have prior art and signed NDA's dating back over a decade, I am now making it public to prevent any one company from trying to patent the concept and either do nothing with it as they are making so much $$$ selling the existing garbage, or make it so expensive most people never benefit from it.
I hope the above sparks some more research into the exciting audio applications for Aerogels and allow the public to benefit from the tech at affordable prices... It might be another 5 to 10 years before mainstream production of this tech comes to market but some niche high end companies should be able to start much sooner.

I have been researching advanced prosthetic limbs for 16 years (one of my twin sons was born without a right arm) and it led me to Prof Ray Baughnan and his astonishing Aerogels Login to view embedded media
Back in 2005 they solved the electrical conductivity issue Login to view embedded media and this carbon Aerogel makes has countless disruptive applications, loudspeakers are the least important but still massive! There are countless applications within audio and there is still a lot of R&D to refine the connection methods but the medical sector has already successfully connected individual human nerves to the sensors and Aerogel artificial muscles for direct "mind control" from the brain to the prosthetic limb, astonishing.
There are others with prior art for carbon nano tech loudspeakers but so far they are all missing the real end game (3)... Here are a few starters to kick off some brainstorming:

(1) Replacing conventional voice coils wire and electrical connections: Aerogel yarn which is highly conductive, almost mass less and it does not increase in temperature when passing the current / voltages required to energise a loudspeaker.
(2) Aerogel artificial muscles can replace the entire electromagnetic motor: A conventional dome/cone/ribbon etc can be connected to an Aerogel "motor and suspension" which is directly powered by the amplifier, the Aerogel can expand / contract up to 20,000 times a second (20,000Hz) and does so in a perfectly "pistonic" fashion ie the CSD plot is FLAT!
(3) The end game... An tiny battery powered chip amp powering the perfect loudspeaker as Peter Walker described back in the 1070's... " A mass-less sphere pulsating in perfect time to the electrical signal" This can of course be scaled from in ear devices, mobile phones / lap tops to loudspeakers and live sound PA... You will need a strong "bird cage" surrounding the Aerogel sphere so the "good old roadies" can still through the PA into the lorry!

Hope the above is of interest!
Cheers
A.

What 8" drivers are best suited to build a home (not car's) subwoofer, either in sealed or tuned box, not very large.

If someone already knows of a whole project, with box and all, even better.

Hi there.

Anyone knows the correct bias setting for this amplifier?

Thanks.

Kind regards
JCT

https://www.diyaudio.com/community/threads/fostex-fe206en-or-dayton-ps220-8.323208/#post-6803633
Following up on the Dayton PS220 project above. Special thanks to Curt from Speaker Design Works and his Singularities.
I was wanting some more highs, but not overpowering. Ended up using the Vifa ¾" tweeter(now Peerless by Tymphany). Integrating a front tweeter with the full range, not easy. After discussions with Curt, decided to go with a rear firing tweeter for ambient fill, air, not wanting harsh.
Full range without a crossover. For the tweeter I originally went a 1st order at 10K, using the Dayton film and foil, 0.47uF x 4. It did very little, few cymbals, muted, disappointing. Added a ClarityCap CSA 1.5uF, total 3.8uF, crossover 5.9K, about as low I would go with 1st order and the Vifa ¾".
Now with air, ambience, no phase issues. Additional volume is there, not overpowering. For this, less is more. Too much would have been too much.
Joseph

Im having trouble determining a set in stone answer for this with the search when it comes to power amps, and ive already made some poor decisions through making assumptions.

If im running signal into a single ended line stage, then from that into a single ended power stage, is my assumption that that phase will invert in each stage, and hit the drivers correctly with no need for follower stages or phase inverters accurate?

Are these old stock resistors any good for Pass Aleph J mosfet bias resistor.

It's for an ultralinear 813/FU-13 SE with 850 Vdc plate and 100 ma primary current. The test OPT is an original series and flawed 5K:8 Hammond 1628SE using the 4 ohm tap to reflect a higher plate load. Does anyone have a recommendation for a proper high impedance SE OPT with UL taps that can take power? Softone's 9K OPT is close but doesn't have the current rating. Hammond has a 6.5K opt that just squeaks in but the tube really shines with 10k, breaking 35 watts into 8 ohms with very low 1 watt distortion. Worst case a newer 1628SEA run be off the 4 ohm tap but the preference is for a proper 8 ohm OPT ratio. Thoughts? Preferably something that doesn't cost like a used car.
Thanks.

Over the last week or so I have been working on my 1995 Wadia 16 CD player that stopped working back in 2007 and has been languishing up in my attic for more than 7 years. It worked fine for 12 years then suddenly crapped out. I opened it up back then and poked around, but without the prospect for obtaining any kind of dealer or factory support (Wadia was in and out of being a viable company for years), I quickly abandoned my effort. I remember being really pi$$ed off that a $7000 CD player was essentially junk because some tweaky high end "company" knew how to design, but wasn't so interested in the business aspects of running a company; a hobby run amok. If it hadn't weighed 45 lbs. and was in outwardly mint condition, I might have thrown it out in the trash along with a case of Budweiser to ease the pain of the garbageman.

To make a long story short, the 16 is back up and running perfectly. There were a couple of minor issues including a dirty laser, but nothing that was a show stopper. Troubleshooting analog is one thing, but with the advent of microprocessors and FPGA's, modern electronic equipment is becoming more and more non-user serviceable. Thankfully all of this was in good shape, along with the transport, even after 7 years of zero to 100+ degrees F and wide humidity swings.

I think a lot can be said of Wadia's attention to detail when compares the Teac VRDS servo PCB to the Wadia PCB. The Teac isn't even close.

In the end, the last thing that needed to be done was re-solder the servo board digital output shielded cable that runs to the Wadia digital IO board. I broke it loose at the servo board end when I unwisely attemped to remove the bottom chassis plate which has the servo board mounted to it. You get to the servo board from the top. Since I had no idea where it was soldered to I figured I'd email Wadia last Friday and ask them if they had schematics and assembly drawings for the 16. Based on what I've read here in the DYI forums and elsewhere, I wasn't expecting even a reply from them, but it took little effort to at least try.

Wouldn't you know it, they not only replied, but sent me PDF's of all the schematics and drawings they had on the 16! Now that's customer service!

A while ago, I got similar results from Krell, so I also have complete schematics on the KRC preamp and the MDA 500 amps if anyone needs them.

Regards,
Doug

Is it possible to make a inwall line source dome tweeter array in a long waveguide?


F ex with Seas 27TDFC which have low fs.
Norwegian living rooms are 240 cm high and with 16 tweeters the line could be around 180 cm. C/C will be 112 mm and crossover maybe 1000-1200 Hz due to the waveguide and the number of drivers?

https://www.seas.no/index.php?optio...fc&catid=45:seas-prestige-tweeters&Itemid=462

Hi there,
Forgive my noob question but I am playing around in VITUIXCAD and in the all-pass filter there are multiple options for shape.

I'm trying to linearize the phase of a tweeter that is part of a PC based active crossover system if that helps. I've put in a passive high pass filter for the tweeter because I'm afraid EQ APO will bug out and destroy my tweeters. Let me know if there's a better way for this.

E.g:
1st order,
2nd order,
1st order phase linearization,
2nd order phase linearization,
LR phase linearization,
Bessel phase linearization,
Butterworth phase linearization.

When looking at EQ APO there is only an option for Fc and Q for the All-pass. Can someone help me understand which one of these will EQ APO apply? I'm guessing either 2nd order or 2nd order phase linearization.

Thank you!

Hello everyone!

I'm working on a project which I want to add an audio amplifier, I already have the tda1558q but I need more power. I'm looking for an amplifier around 30W. I want 4 channels so I can add 2 dual channel amplifiers. Does anyone have a recommendation of a chip that is good or anything?

What is better sound for 1K-20K range - old school Fostex ACR FT7RP+FS21RP or Mundorf AMT AMT29 ?

Hello. I just completed a +/- 15V super regulator using the board from the diy store and all parts from Mouser. I'm giving it +/-20V from my bench supply. Both regulators seem to work fine. However, I'm getting oscillations on both outputs. I'm not sure where to start troubleshooting. Can someone point me in the right direction please? Scope shots are of both outputs across a 100 0hm load.

I've tried a couple of these DC/DC supply boards and so far my testing hasn't been quite up to par. I've added a decent amount of filtering (47uF 1k resistor into another 22uF cap) and it reduced the noise by a lot but I can still hear it especially if I use compressor after the preamp stages.

Is the idea of DC/DC for a high voltage preamp supply (200VDC), just not practical?

I posted this on another forum I belong to with no feedback so far so though I would try here.

I have several 816 tubes to test but cannot find the proper test settings for my 612. In trying to roll my own I've come up with what I think are some of the settings.
A (1?) - B 4 - C (7?) - D 1 - E Not used(?) - F 9 - Fil Cont 4 - Comments - Use black grid cap

I found a Phillips exchange guide from 1965 that says the 816 can be replaced with an 866A which I do have the settings for. In looking at the spec sheets for the two I can see they are very similar(to me at least). The settings are similar to my original 816 settings attempt except for C.
The settings are A2 - B4 - C30 - D1 - E not used - F9 Fil Cont 4
Does anyone have any input on trying the settings for the 866A? C seems to be the only one really far off from my stab at it.
I just acquired a pair of WE 259a and a single WE 244a. Neither are in my settings list!

I think I ready need instruction on how to figure out my own test settings.

Thank you in advance for any help.

Hi,

I finished my latest build based on the schematic of Doug>
Doug Circuits
unfortunately the tremolo wasn't working in a periodic way, so I used an OPAMP based LFO.

I reused a cheap transistor cabinet, which was initially loaded with two 6"speakers. I changed the chassis, the speaker, the baffle and the grill cloth.
Now it is loaded with a 10" greenback.

I also made some changes in the schematic to have one half of the 12ax7 as a preamp stage. With the input jacks it's possible to select between EF86, 12ax7, both in parallel or the 12ax7 in series with the EF86.
This last configuration has quite some gain!

Here some pictures:







cheers,
Thomas.

I used TNY267 IC in my SMPS without connecting load the output is coming. but when i connect a load it's not working (it comes like ON and OFF). when i check PWM of the IC it shows fluctuating not constant signal. but i change the IC then also the same thing is coming so problem is not with a IC. only the signal is not coming properly. here i attached the circuit also tell me some tips.

Hello fellow techs i need help so I recently got a punch P1000-1bd on a trade so it would power on but had strange waveforms almost like multiple waves amplitudes picked up at same time. After looking closely I found R9 30ohm 2/3 watt resistor had broke a lead so I replaced it with a 30ohm 5 watt resistor I had on hand and now the amp powers on and power supply waveforms look great.

When measuring between rectifiers I get 53.3vdc @2.18Amps on the lab P.S. there's no DC offset and with signals injected there's no audio. So after probing the output section with the scope I found that half of the output section appears to be wonky from what I'm used to seeing.

So highside A & lowside A looks how I would assume it should however
highside B & lowside B looks off. I believe im getting voltage were there shouldn't be and it looks like it's picking up 2 frequencies on the same waveform.
I added pics of the resistor R9 that broke and of the waveforms from the output section labeled as above.

Any help would be greatly appreciated this amp circuit is a new one for me and I can't find a service manual thanks for reading.

This a fork inspired by a post by @hifijim following his inspired thread on measurements that matter, except we all got into the weeds for the first 10 pages...all about impedance traces...

So to clear the air, I thought we could play the Impedance plot game:

Rules:
Maximum 2 sweeps per graph.
Phase is included, but if graphs get too busy, I can remove them.
1 Logarithmic Y scale MUST be included (allows one to view high and low values simultaneously)
A zoomed in trace may be requested (optional)
No red/green traces please (for our red/green colour impaired friends)

Winners:
Correctly guesses the reason for the difference between the two traces. Close enough is good enough...

GOLDENEYE award- correctly understands the difference between the two traces.

SCIENTIFIC COMMUNICATOR AWARD - explains why, in lay terms, for the differences, so that we can all follow along.
eg. "This trace is a of a subwoofer, because of the peak in the graph is at a low frequency ie. 23Hz. Is it a very high peak, because... . The double peaks and the saddle in between them at 38 Hz suggests that this is.... The discontinuity at ~170Hz suggests either... however we need more information on the..."

I'll be adding to this this list as I collect more. Please feel free to add your own for the diyAudio brains trust to help solve your impedance plot problems... Remember, the only way to learn is to make mistakes. So feel free to have a go!

First up:


GOLDENEYE! for @PKAudio's post. How did he do it? Any Scientific Communicators among us?
previous Leading scorer: @stv, partially correct on both traces. very close- please try again!

ITEM 2:


GOLDENEYE award to @mbrennwa . Yes, correct on all counts. But why only possibly in a sealed box? Was there any doubt? And why/why not? What happens when one omits damping?

ITEM 3: courtesy @Hörnli



ITEM 4: same product, different samples.



2nd graph courtesy of John Krutke

ITEM 5: Coming up....

PS. Once you win a prize, please go to the end of the line and wait for other people have a go. Better yet, post your own confusing/tricky plots for us to play/learn from....

Hi
I've done some calculations and think they're right, I want to build a 5v 5A power supply. So my parts are a 230v toroidal with 2 12v 6.6A secondary outs. I'll only be using one at the moment. so the 12v 6.6a goes into a rectifier then 2 4700uf caps and a 1uf ceramic cap all parallel, then a 5v 5a regulator then the same caps again then a 1k resistor for bleed.
are my calculations way out or should this give me a decent linear supply?
another question is what awg wire can handle 7-5 amps? is 22 too low? what about 18? i keep reading things and can never get a definitive answer.

Good morning,

Selling my analog set-up:

EMT TSD 15, full rebuilt by François (Ana Mighty Sound), sounds lovely. François measured all specs that I sent to Dave Slagle in order to wind a couple of his SUT up.
SUT IS SOLD


(Tonearm is also for sale SME 309 MAGNESIUM, complete with original box: 1500 eur) SOLD

Contact me with your best offer,
Thanks

Should you buy a commercial speaker with a ferrofluid tweeter or not? I read lots of cases where the ferrofluid corrupts with age and I don't fancy taking on the problem of cleaning and replacing ferrofluid in a tweeter.

I have a pair of early Wharfedale speakers Program 30D-6 and I have no idea if the tweeter has ferrofluid in it or not - can't find any info. I was thinking of buying a later pair, like the Diamond 9.1, but the tweeters do have ferrofluid in them and I'm concerned that this will degrade with age.

Given that ferrofluid deteriorates over time, should one simply stay well away from tweeters containing it?

Got a Cambridge 851W in for repair from a friend. It goes directly into Protection mode when switched from Standby to On.
LED flashes 4 times indicating DC on output, but no DC to measure on output relay contacts...
Seems to be a fault in the Cambridge CAP5 protection system (quick search on Google indicates that this CAP5 system is highly unstable).
Anyone??
Thanks in advance

Hi diyAudio,

I have Parasound HCA2200II and recently had issues that started with the cracking sound on Right Channel. I removed any speaker due to high probability of damaging the speaker.
When I am verifying the schematic which I have, I found that the R225 is measuring 20K ohms instead of 47K.
Bias resistors are railed voltage at +/-77V on the Right Channel while Left is around 25mV.

I am inclining that there is/are bad components on the driver board.

I also noticed sparkling on the R217 on the PCB trace when powered-up but this is gone now. I've checked the Q201-202 and Q203, they looked okay when compared with Left Channel.

I am attaching the schematic I found in the web.

Thank you in advance for the help.

Up for sale is an excellent condition Panasonic DP-UB9000P1K w/ upgraded power supply + DAC modification + custom furutech power cable. Free shipping.

details of the modification here:
https://www.audiogon.com/listings/l...er-modification-blu-ray-dvd-universal-players

Has anyone conducted experiments with R2R resistor values?

I would like to get a lower output impedance without compromising the sound.

I saw 7.5 and 15 kOhm on the Internet. I also found that there is no sound above 3 kOhm.

Hello,

I am trying to save this classic passive subwoofer.

RH Labs SB-3p with Pyle 12” W12C600-F

I will refoam the speaker.

The crossover needs help. The coils are disconnected.

I believe this is a 1 way crossover with L-pad.

Can anyone help me solder the resistors back where they belong?

I’m hoping the pros here will be able to take one look at this set up and point to the solution.

Thanks a bunch,
Dane

Photos of terminal board, driver, and circuit attached.

https://photos.app.goo.gl/78repHM1zyMQZPK46
https://photos.app.goo.gl/6Lv23wxFGVpmBJcy5
https://photos.app.goo.gl/2Fu5QMjvmtqWjtYw9

Hi
I would like to try building a DAC using an R2R Ladder board, you can get them on Aliexpress and Audiophonics. the one I'm looking at has bck/lrck/data/gnd inputs.
My question is should the iancanada reclocker fifopi Q7 be connected to the output side or the DAC board side? I was thinking of having a transportpi mk2 on the output and a recieverpi pro 2 on the DAC board. But where should the clocks sit?
cheers

Hey guys was wondering if anybody knew anything about this preamp and the name of the plug for the power supply
Cheers

As of 3/30/24 I have 8 transformer seats available to give away. I will update this post as they are snagged up. I'm offering up a free 3D printed seat for interested persons as long as shipping label is sent to me. 2 quantity limit per person please. Works with both 300VA and 400VA Antek transformers (or similar dimensions).

I can ship these to anyone interested as long as you pay for shipping by sending me a shipping label. To make it slightly more enticing, I'll also include a few other fun 3D printed parts you can use in builds in the shipment. Please PM me for details on how to create a shipping label. The goal is to give these away with no monetary transaction required, just a shipping label PDF and I'll pack it all up and send it out. Please let me know if you plan to use this with a 4U or 3U chassis and I will tailor the 3D print design I send respectively. They technically can be used for either option, but each print can be set up for the ideal use (still modifiable for other chassis with a careful Xacto knife cut).



----------------------------------------------------------------------------------------------------------------------------------------------------------------------
Here's the "funny" transformer seat I used to horizontally mount an Antek 300/400VA over the "lip up" on a Modushop 4U chassis. For "Version 2" I've added a second slot to use for 3U chassis so you can pick how close you want the transformer to be to the front panel. There are two options as there are two slots. I suggest you use supports to "plug" the slots with support structure, then simply use an Exacto Knife, or similar, to remove whichever slot you intend to use. This ensures the part overhanging the lip has minimal sag.

The part was designed to be printed with the "compliant and squishy" TPU material (thermal polyurethane). However, PLA (much harder) could be used with the included rubber gasket that transformers come with as an interface between the transformer and the seat.

I designed this to allow "lip up" orientation while keeping the transformer as close to the front panel as possible by simply raising the
bottom of the transformer up ~10mm off the pate using the seat. If you install the bottom perforated plate "lip down", then there's no need for this part, but you still could use it for whatever reason you may have.

Attached are both *.STL and *.3MF files. You could use a "fab print house", however, I'd suggest finding a buddy (or buddies buddy) with a 3D printer, or use a Makerspace near where you live. Feel free to reach out to me with questions or suggestions. I'm open to feedback on how to improve and will keep the files attached to this message up to date with the latest revision.

Here's a link to see it in use (my first ever Firstwatt design build): https://www.diyaudio.com/community/threads/firstwatt-aleph-j-zen-mod-edition.410644/








Here's the start of a print in TPU, just after first bottom layers have finished and the "gyroid" 15% infill has started. Note that I blocked support for the inner most slot but left support for the outter most slot. This ensures if you choose to use the inner most slot (for a 3U chassis), the outer most slot essentially does not exist as you leave the support structure in place. The whole purpose is to avoid a 'floppy' overhang off the plate and therefore still provide some 'support' even though that portion of the 'seat' is cantilevered in free space.

The aim of four stage amplifiers was to offload the gain profile of the LTP to an assistant second gain stage before the main stage, the requirement of the assistant second gain stage was that it was to have virtually no distortion of its own and have a substantially lower gain than the LTP. With the A70 the second stage is coupled to the main gain stage almost as a current mirror, while SANSUI uses self cancelling. Here's my rendition of what SANSUI was aiming for https://www.pcbway.com/project/shar...audio_power_amplifier_a_rebirth_4a7881e9.html, while for reference is the A70. Are these better than the 3 stage Morpheus? https://www.diyaudio.com/community/threads/morpheus-ultra-low-thd.406485

Could someone tell me what Ge's these are/who/where they were made?
And hopefully what the values written mean too?
Background:
I have two spare Ge transistors (plus some resistors) given to me in bags by the bloke who modified the Dunlop FuzzFace JH-2 i bought 13yrs ago. The Ge's that were and are still in it are a NKT275 and a B175.
Could someone tell me what these SPARE Ge's (see pics)are/where were these manufactured, and what the values mean? (see pcs).
Q1 and 2 obviously each Transistors' place, but I think 'L' = leakage or gain?
The markings on each spare Ge ive written on the note (see pic).
The Ge's that were and are still in it see pics.
1st pic is spare Q1,
2nd pic is spare Q2
3rd pic is the values of these spare Ge's, or maybe the spare resistors i was given.
4th pic is the engravings on each of the two spare Ge's,
5th pic is underside of spare Ge's (both the same),
6th pic is top of spare Ge (see 4th pic for engravings),
7th pic is the Ge's that were in it when i bought it (1x NKT275, 1 x B175),
8th pic are values written on inside FzFce base plate for Ge's NKT275, B175 i assume.
Thanks.

Like it says on the tin.

Been looking at all kinds of transistors from bog standard BJT to RF HEMT. From my understanding, configurations like darlington, sziklai (can never remember the spelling of that), and composit amplifiers allow you to mix and match properties of different semiconductors in order to get better overall functionality. Is it worth looking into this further, or should I just stick with one set of transistors? If it is worth it, I would really appreciate some part recommendations. While I understand there's a few gold standard parts (Toshiba transistors for example) I'm sure there are a lot of others out there that may not be as prevalent because they are not used typically for audio, but can still perform as well if not better.

what is the purpose of C2 in the following example (b)
.... (snip from https://www.nutsvolts.com/magazine/article/op-amp-cookbook)

Hi everyone, have an issue with my crown 5002vz. Upon power up channel 1 signal light is stuck on and odep is off. Channel two is in normal state.

I open d top lid and the ch1 DC/LF light indicator is on along with with d stand by.

Once in a while when it put it on both channels come in to normal state and plays well. But sometimes channel one doesnt click in

Did anyone ever encounter a problem like this? And does anyone know what could be the issue.

One guy told me it could be the output modules started to get defective, corrosion. I know these crown 5002 n 5000 output modules are susceptible to corrosion. But this particular one the output modules are clean.

So if anyone has any idea what could be to issue, please let know TIA

~~~~K20

Today I replaced the origina 1:1 interstage transformers in my Audionote Kits DAC 4.1 with a couple of 80% Nickel cores custom build by David Slagle (Intact Audio).
The upgraded transformers are a bit bigger than the original ones, but I was able to make them fit quite easily.

The results are quite impressive in terms of wider/deeper sound stage, more clarity in particular on the top end where the DAC 4.1 with the original 1:1 transformers sounded a bit edgy and fuzzy, and in general the music sounds more fluid.

I am really happy with them and I would suggest the same upgrade to all the owners of an Audionote Kits DAC, together with replacing the coupling capacitors with Duelund CAST PIO Cu/Sn.

My next upgrade will be replacing the AN1865 DAC board with a AN1862 one.

im thinking of buying a digitech g300 mosfet guitar amp---technology by hafler--- for my home music system, but i dont know anything about this amp.....would a guitar amp suitable for home audio??it has 1/4 " plugs on back...could these be converted to rca type plugs? input imp. is 100k ohms. input sens. is 600mv for 150 w @ 8 ohms. im not sure if this info is vital or not! anywho, any feedback is welcome!! thanks ..shallenn

Hello, I have been searching to no avail online to answer a question about impedance wiring, crossovers, and amp load. What I have are some very old 70's PA/Musician speakers that I use both for music on solid state amps and my guitar tube amp as well. These old Peavey speakers had a passive crossover that I am working to redesign and things have become a bit too complicated for me. Originally 2x 15 inch 8 ohm woofers in parallel back to the crossover (so 4ohm), 2x 45-ohm horns in parallel back to the crossover (so 22.5ohm) and 2x piezo tweeters which don't have an ohm rating back to the crossover. It's not a good design, and the tweeters im going a different route with which will match the woofers impedance, and I ended up putting in a single 4-ohm woofer instead of 2-8ohm's. I am also making different cabinets. Each bank of parallel speakers has its own signal coming from the crossover, and the negative terminal just daisy chains around all of the speakers. To me it appears that each bank of speakers effectively parallels all the speakers at the crossover. (All passive crossover design's are this way). Does that not mean they are all paralleled? I read in a few forums that speaker banks at the crossover do not parallel and the amp will see them individually so 4+22.5+4 instead of whatever the 5 speakers would be paralleled together. Is this true? can someone clarify how this makes any sense?

Now for the nitty gritty, 4+22.5+4???? okay so I have also read if you are mismatching impedance that you should use similar impedances. Well, those are definitely not similar impedances. The crossover says (4-ohm) on it but I think this (22.5ohm) may have been damaging my old Randall tube amp. Is this safe to run? What can be done? I don't want to wire resistors in parallel to drop the horn bank more, wasting power and heat, I would rather just completely buy new ones that are rated correctly. They sound decent and I have used them for 25 years on solid state amps with zero problems, but the math makes zero sense to me. So to go a bit further on my impedance question, for simplicity lets say my speakers are all 4 ohm 4+4+4 in each cabinet. Say I connect both cabinet's to left and right channels to my solid state amp. Does that mean my amp is then powering all these banks of 4-ohm speakers? would the two 4-ohm cabinets not also make paralleling and make both cabs 2-ohm total now? Its all very confusing to me. I really don't understand how the crossover which wires 3 parallel speaker banks in parallel doesn't do paralleling. I hope someone can help me I am confused. Thank you all!

Working on a split RIAA networks eq, I used this old spreadsheet of mine.
I couldn't find on the net (not even here) any formula which keeps into account the effect of the input impedance of the stage following a network. This calculator does.
I work with LibreOffice. The .zip file here attached contains both the original .ods spreadsheet and its translation into a .xls.
I wish to share it, perhaps it can be useful for some of you.

Stuff just went up on eBay. Decent deals on these unused components... ok, the Dolby DP564 is used.

This 38Q2M DAC use a ES9038Q2M , a OCXO with phase noise on 10HZ down to -108dBC/Hz ,much better than CCHD-950 or CCHD-575

4CH I/V , and 2CH LPF out

Hi, I'm new to building speakers and recently decided to make a new box for the subwoofer for the existing 2.1 speakers(JBL creature III). The old subwoofer driver had torn its surrounds and therefore decided to make new one.I am not making something very loud but rather flat sounding. I went for dayton ND140 5.25" 4 ohm driver (https://www.daytonaudio.com/product/57/nd140-4-5-1-4-aluminum-cone-midbass-driver-4-ohm) in a vented box. The driver is rated for 40watts (although my amp can do max of 15 watts), 4mm Xmax, 20mm peak to peak. The manufacturer recommends 1cu ft box with F3 of 34hz (parts express says 0.75cu ft with F3 41hz) but when I was designing the enclosure in winisd , it showed that the speaker was already hitting Xmax at 15 watt in a 0.75cu ft box. Increasing box size only makes it worse. I came across several reviews where the driver was put into 1cu ft boxes and worked flawlessly but i couldn't figure out how was it working for them if its already way beyond its xmax limit. Could someone please help me with this.