Hello all,

First, for the first release of the OSVA project, i start this new clean thread to avoid confusion.
This first post will be used in future to see major projects changes.
The OSVA is an new high performance analyzer that use SAR ADC from Linear-Technology/AD (LTC2380-24).
This project is born to follow up of my previous works done with the LT eval board and an CPLD eval board.
All information about this can be found on this previous post here :
SAR ADC for high performance audio ADC project [LTC2380-24]

So now, after some time of silence i keep you informed about project progress.
That has took more time than expected, time to learn Kicad too (and now Altium at work, Yuck!).
I do that only in spare time an i'm very busy at work right now).

Anyway, i now have finalized the PCB routing and i have ordered it to manufacturer (WEdirekt).
It will be on my desk, ready to start soldering in about ten days now.

From the previous schematics posted, i made several improvements.
I try to list them here :

Low noise regulators for ADC are replaced by LT3042 (as suggested by...).

• I added 2 isolated analog output from PWM signals for external oscillator synchronization (enable coherent FFT).

• The Input buffer LPF include two cutoff frequencies : 38.4kHz and 384kHz by default (they can be customized if required).

• The inputs can be switched to single-ended or differential mode.

• The input buffer is designed to use (at least) one this three buffers :

ADA4945-1 (New FDA OPAMP from AD)
OPA1632 (SOIC8 FDA from Ti, lw noise).
THS4541 (High speed ultra low THD from Ti).

I planed at first time to use the ADA4945 that promised extremely low THD level, but the latest datasheet release
show much worse THD level so i will use preferentially the THH4541.

As this project is fully open source, you can get all project files in it's new GitHub repo here :
OSVA - Open Source Versatile Analyzer


Complete new schematic can be found here (pdf) :
Github AA2380v1.00 pdf file.


Thanks to Kicad, you can also see how it will look like when populated. 🙂



Now, i must order some missing parts to Mouser (a complete bom ready) to ready when i receive the board.

There is some works to be done on others PCBs of the project:
- Front panel control board (leds and rotary encoder)
- AAPSU Power supply board (+5 and +/-Vanalog).
- AA10M08 Digital Logic board (Digital filtering and display interface).

I must also seriously work on CPLD software.
I hope to give others new soon. To be continued...
Regards.

Frex

Why nobody speak about SB34NRX75-6. Most discussion is about SB34NRX75L-8. As I need sealed box then SB34NRX75-6 is much better option because is designed for sealed box (higher QTS).
Any idea for sealed box 2x10" or 1x12" driver?

​

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Hi
A friend ask me for a cheap buffer for class D chip which recommended a buffer because of low impedance of the power amp ips. i decide to by the cheap XH-A902 dual opamp pcb on aliexpress..i expect that the opamp is fake and not a real one.

XH-A902

i try to find a schematic but i found nothing and did reverse engineering. it is single supply.
input( R-GND-L) is left side if the power connector is on the buttom. output is R-L mirrored and on a 3 pin connector.
ground from signal in and signal out is decoupled with a 1µF ceramic (yellow in the middle of the 3 caps).

the opmap was checked over the quiecent current and it is not a NE5532. it draws 4mA...a real suck about 10mA.
according to my short search it could be a RC4558. i dont care...i use my NE5532

can this schematic work?
yes...(i expect not an inverted amp , there is no voltage divider on the non inverted input...?)

i changed the fb resistor to 2k2 and so i get a gain about 1.
i did a short measurement but the low frequencies down from 400Hz get very fast with low value.? why?
i changed the inputcap with a 10µF and the output cap (after opamp and 1k) with 10µf too. this doesn't t help.

any thoughts?

thank you
chris

hi

been a diy audio enthusiast since middle school. then followed to get my degree in electrical engineering . from few months ago started digging through some old stuff and reconnected with my old DIY audio passion. bough a few vacuum tube old radio and a reel to reel tape player. also am reviving my old equaliser and a turn table and a transistor amplifier. changing alot of electrolytics for now. and addapting some cheap electronics one can buy from ebay/aliexpress, but finding also problems

Hi everyone , I am here after reading many many hours long different posts, that helped me in various repairs (or improvements) !

The last one to date is an improvement on the THD of Rotel RA 840 BX 4 , made after the repair led to one channel being hotter than the other, which I found out to be a common trait of Rotel’s from that age …

That led me to Ange’s post with a schematic to improve the RA 820 THD ,

https://www.diyaudio.com/community/...l-amp-thd-by-20db.275171/page-57#post-7846182 ,

which in turn led to my video Login to view embedded media
I made another one on the repair that I will soon post, where I highlight somewhat why some of this amps fail due to heat… Ange’s cure reduces that greatly😊

Looking forward lots of other mods and repairs.

Cheerios

Eric

Ps: I will soon share my repair findings on Alesis powered MKII that I couldn’t find on internet, but that are now repaired, I fixed the power supply and publish also some minor improvements to the amplifier section of that twin amp 😊

Hi All,

Brand new XT4273 - 22.5792M AT, XT4274 - 24.576M. Datasheets provided with individual specs on both 10 XTAL sets.



Please PM.

Regards,
VS

Hi all
Musing a different project to the one I've currently got on the boil. I'm on the lookout for a typical HiFi seperate sized enclosure / chassis / project box. Been looking at broken power amps on ebay and even old Sky boxes to gut and reuse. Where do you guys get your enclosures from? Bearing in mind I'm in the UK and am perpetually skint!

Cheers guys 👍🏻

Hi,

New here! I’ve been into audio for a long time now and my upgrade path has been very pleasing. I’ve been sceptical about many upgrades I’ve done including cables, switches, fuses and other stuff. The main thing about this hobby is that I’m listening first and see if it’s an improvement or not. Different is not always better. So still trying to learn and stay open minded and now I would like to learn and have more information about crossover filters. I will post soon about that.

Thx!

Hello,

After some help sourcing parts please. Have bought the PCB from the Signal Transfer Company and require to source the parts for the switch banks. The information supplied with the PCB lists (I think) Signal Transfer Company's own part numbers and state that only they can supply. I have Emailed Douglas and he said that this would be altered. In the meantime, I need to obtain the manufacturer and their part numbers so that I can approach them directly for supply of same. Would appreciate any pointers you may be able to give on this.

Thank you


Neil

I did I gave away the old analog scope that I had for almost 20 years when I moved.
So when it came time to re-set up my bench I looked at the modern scopes, and it's amazing
to see what even a new digital budget scope can do as compared to an older analog scope.

So if you are looking for a scope you may want to take a look at the new digital scopes.

But I will say if you have an older analog scope now you may want to hang on to it
if you have room for it since they are fun to play with for oscilloscope music etc.

Hello Everyone how are you. The seller of the Lampucera dac kit I bought yesterday has suggested buying other things to improve things like a opamp he sells 🙂. He is saying he can put everything in one package to save on postage 😀. He is a salesman trying to get more money which is a good thing if your buying something good. What do you think of this op amp.

https://www.ebay.com/itm/186781815445

Hi everyone!
My name is Mario. Main field of interest is recording classical guitar and enjoying listening to music mostly with headphones. Now things decided on their own to have achange, I will now therefor start building a audiophile room with two single seat chairs, one of them being the more comfortable one. The double seaters are long gone, i lost the right amount of weight.

All i have to start with area pair of old 80s/90s sony 3 way loudspeakers, a jvc old wooden amp (with wired wires, not yet wireless), another big sony tower amp rack and a dayton 15 inch refenence subwoofer. I plan on doing something from scratch though and i will use some of the equipment of my father either for salvaging or experimenting at the very begining... Room treatement, enclosures....Being new to this, i have a somehow long way in front of me, it will take some months.

I have to confess, i have been watching way to much asian SQ car video content on youtube recently. These guys dont joke arround i tell you. They are not affraid to do the craziest A pillar mounted tweeters, from dynaudio E110 to satori tw29 with flanges big the size of bear's cheeks. If they can use satori tw29 espresso cup plates or scanspeak R2904 anti tank mines in cars, time has come to let me try them at home first and make it a win/win situation and see if they that good and worth the hassle for car use. I have accumulated some love for satori drivers and hard dome materials recently, but i am afraid to use beryllium in a car, so down in the basement will the toxicity go for the beginning. So here we have it, i have pre-selected my tweeters, and the size of the chairs.

When learning about car audio in the last five months i saw people doing RCA cables themselves not only because of the custom length needed but because of the sheer number of cables in a DSP active setup where things could go wrong, so mitigation of possible problems was an absolute must for the SQ guys. In home audio i thought that quality off the shelf cables will do the trick but no, i saw a guy on youtube talking about cables worth 4 figures in US dollars and i thought i might do better though with less money like i used to lifehack the way to my home studio some years ago. I might try to fabricate wireless copper cables. I have a bad ground in my house that would need a bigger hole to be drilled, arround 2 meters deep that im not willling to do, also i have a microwave just above the room i plan to use for my audiophile venture. Wireless copper wire could definitely help eliminate all the crazy audiophile interference issues i might come across that dont even appear in cars, in a 12V alternated current environment with (perhaps) not so well shielded speaker wires. I have come across this website when looking for drivers that are used in cars too, it was about time to have my own account here.

Thank you and hi again!

Promise is a promise.
After too long I finally got around to making new speakers.
The project is still a test for now. Hence the use of materials. Crossover is still 1.0 version for now. The units are still new.
I used the SB 15OB350 for the bass and the Sonido FC SWR 096 for the FR.
The sound is very good right from the start. Maybe I caught the frequency cut quite well.
A few more pictures:

The most linear stage for large voltage swings - Lender's Circuit

In my (already older) book from the magazine "Audio Amateur", title "Power Amp Projects" I have found the project from ERNO BORBELY "The 60W MOSFET POWER AMPLIFIER" On page 76 (column 2), I read - quotation -

=================================================================
The most linear stage for large voltage swings is the grounded base or common base amplifier. Unfortunately interfacing his stage with others is not easy because of biasing problems.
Lender (ref2) presents the most elegant solution to this problem. I have come across. His circuit has a differential input stage and a current mirror transfers the bal. output back to the single-ended output.
==================================================================

so as an ref advice (ref 2) to very interest Motorola article from Mr. R. Lender
"Power Amplifier with darlingon output stage"
Motorola Inc., Geneva, Switzerland,
7.9.1974 internal report (July 9. or Sep. 7 - I don't know)

This article I want to have. No PDF file about this I find online (on the web).
Who knows, where I can download this original article from Motorola ?
Also of interest for me are books and additional articles of Mr. R. Lender

This voltage gain stage topology you can find in several designs, e. g.
http://www.davidsaudio.com/assets/images/autogen/a_ampzilla_sch.jpg (ampzilla)
or JBL stage power amplifier 6290
http://www.jblpro.com/catalog/general/technicallibrary.aspx?CatID=20&Run=1
and many other
This topology is a transitional form between folded cascode version (one stage voltage gain amp) and normal version (two gain stage voltage amp). I think, in the orig. article there are to read more about the calculation basics because it was written for development departments

Thank you very much for your advices

P.S. Online about this I have found only the follow:
http://www.tubecad.com/march2001/page25.html (I think, Linder is faulty name and Lender the right one)
http://www.tubecad.com/2004/blog0001.htm
www.tubecad.com/march2001/2001_03.pdf (page 25)

I'm looking for a midrange planar to replace my Coral Beta 10s, which I use in a three way open baffle setup. Midrange and tweeter (Aurum Cantus AMT 2560 / Harwood AM25.2AMT) are powered by a 7W 300B amp, woofer (Acoustic Elegance dipole) by an ancient Krell amp. Crossover points are ~300Hz and 6.5kHz, 12 dB/oct.

I'm looking for a midrange driver of about 95 dB/W/m sensitivity to match the tweeter (and the 300B amp). I just found these on the Radian website:

https://radianaudio.com/products/lm10n-wide-band-planar-ribbon-transducer
https://cdn.shopify.com/s/files/1/0111/0324/0254/files/LM10n-datasheet-v2.pdf?v=1666125534

Has anyone heard these? I was rather impressed by the sensitivity, which for my application looks like a very useable 94dB/W/m. Any dipole alternatives to these planars which can be used between 300 Hz and ~4-6 kHz? I would like to try a planar or a ribbon midrange driver, as I feel that would better match my AMT tweeter.

Pre-announcement: I am a China fan, and my English is not very good. All English is supported by the translator. I am deeply sorry if u can't understand and have any ambiguity.


Disclaimer:

1: This is a geek production, and the final test conclusion after our production is that it can hardly be used as a standard resistor and its performance is poor. Unless you use a special packaging method: airtight packaging.

2: Its production process maybe full of environmental bad factors. This amateur production is not for environmentalists. Please watch it according to your local cultural habits, legal provisions and administrative system.

A long time ago, I heard the myth of PIO capacitor and Allen Bradley (this is often simply called AB in China) carbon composition resistor. They are not the most perfect representatives of audio fidelity, but they have occupied a considerable market in historical audio manufacturing based on their cheapness and universality, so that it has become a fashion and habit. I have some PIO and CC on hand as samples, but they still can't satisfy me.

1: The CC produced later used the sintering process, just like clay pencil lead. After mixing graphite raw materials and clay, it was pressed and molded and sent to a high-temperature furnace for graphitization, forming a solid whole. This process typically has ideal resistance performance in CC-hard structure, low water absorption, low voltage coefficient (in CC family series), good durability and drift rate. But the question is, what is the purpose of this resistor? I want him to give me a special distortion. If you do it well, where will my distortion go?

2: Since the later CC is invariably a sintering process, I don't know enough about the most traditional organic bonding process. What I want to do is: Can I build a process different from the normal CC and form a resistor, which can not only help me realize the fun of "home DIY", but also be used in some unique and strange places? I don't want EE to criticize me here. "This resistor is too bad, it doesn't apply to audio." I know this clearly. I need it, I'll do it-that's my purpose. Fortunately, based on the knowledge given by various network platforms and enthusiastic netizens, I successfully manufactured a "junk" resistor-"gold" carbon resistor. The following is the production process.

For sale ,
Two Mirand Audio A1 amp modules .
In perfect working order and very good sounding .
200 euro + shipping
If you need more info just ask .

I am wanting to lower my crossover point for M & T . The factory points are 385 & 5k. I don't like the 5k crossover point as directivity is bad in these which surely doesn't help when trying to EQ. There is a USB service port on the plate amp. I know it uses Analog devices 64 bit dsp engine but would be nice to just do it thru existing dsp with software etc.. The plate amp is Pascal. 500-500-150. Dynaudio surely doesn't want me doing this so no help. If I can't find a way to get into the existing dsp Any ideas how to get into that dsp system to change settings ? Below is the issue. The design is poor for 9' listening distance in non treated room. I run direct in using AES3 .

for example this driver is not sold in US:

https://en.toutlehautparleur.com/catalog/product/view/id/36539

can i still get it from TLHP ?

i would need 80 of them. LOL

Hello all,
I've been in the mood to change up my analog setup a bit lately. I have been using an Aikido phono stage with lundahl step up transformers. I have thought about building a new phono pre, and have decided on the Vacuum State RTP3C.

I just have a couple of questions about it. Has anyone built/heard this unit? I know it's extremely subjective, but if anyone has heard it, could they describe the sound of it? Also is there anything I need to know about building this particular circuit? It seems pretty straight forward, but I just wanted to seek the expertise of someone who has possibly gone down this particular path before. I appreciate any help, thanks. Hope to hear from you soon.

Hello everyone, I am about to embark on my second speaker build project and will be looking to share my experiences and gain from the experiences of others. My primary focus will be on the crossover. I'm looking forward to learning lots.

What should I do to let ngspice know where to search for component libraries? I have created a file in my /home/user directory named .spiceinit. Can I use it to defined paths for component searches?

a friend of mine aquired this old piece. plays nice but we could not figure out how to save a radio station.

we did try:
1. tune a station
2. press memory
3. choose a number
4. press memory again with no result

i did also delete the stations from a number that i did want to use for a save.

any ideas?

Why are these available? Years ago I mistakingly ordered a couple of sets and can see no purpose other than offering up a chance to make a big mistake? That said, faston connectors fit the otherwise dangerous male pins on the cord which is coming in handy at the moment as I troubleshoot a piece of gear but is there a valid argument for their existence that I'm not aware of?

Hi,

I am a newbie in DIY Audio. I have a background in electrical engineering and am a musician.

I am currently designing my first speaker. It will be a stereo (dual driver) full-range setup with two Mark Audio Pluvia 7.2 HDs.

Playing around in WinISD for the first time, I think a vented 30 L (net) enclosure tuned to 50 Hz would work quite well.

Now, I need to decide the diameter of the ports. I was thinking two ports? I really have no idea what I am doing here and help would be appreciated. I am aware that larger ports require longer tubing but they reduce air velocity that might otherwise cause chuffing.

Running at 20W system power (also, not sure if this is a reasonable value or not so this is not fixed or conclusive), anything above 50mm seems to be ok, but again I have no idea.

Thanks in advance,
Arlo

I'm rebuilding an old Zenith stereo console, a 1969 Y960, their highest-end unit at the time.

It includes a turntable with a ceramic cartridge. Because the particular turntable/cartridge is considered quite good, (it's a Zenith 2G Professional Turntable) and is aesthetically awesome, I would like to keep it installed in the console, but I need it to play nice with modern electronics. The original amp/preamp is gone, and I'll be installing new components.

I'm very much a newbie in this area of audio (I'm mainly a speaker building guy), but my research indicates these ceramic cartridges have a high output and require a high impedance input to load them properly. So they don't work with a regular modern phono-stage.

This turntable's cartridge is rated at 350 mV per channel at 1 kHz and was connected to the attached preamplifier circuit, which was designed by Zenith specifically for this turntable.

My questions:

1.) How best can I replicate the original circuit's loading?

2.) Am I right in calculating the input impedance of the preamp at around ~1M ohm? It's been a long time (since high-school), and I find the schematic mildly confusing. The transistors used each have a current gain of 100.

My thought was to attach the turntable to a buffer. Perhaps a simplified B1 with input impedance modified to match the original circuit, then in to a preamp. It doesn't need much gain.

Thoughts please!

*Note: I cut out most of the complicated switch diagrams that get the phono input to the preamp, but included the one section because it shows a 2.2M resistor connected across the turntable's two channels at the output.

Somehow way back in 2011, I went down the "home theater" rabbit hole only to find out that it wasn't so great after all. I never should have given up my 2-channel tube amp in favor of a 5-channel solid state monster. About 10 years later I discovered that I had simply stopped listening to music - period. That's sad. Very sad. I tried listeing to stereo recordings with the solid state amp and preamp, and it just wasn't right. I hated it. Then I remembered why I dumped solid state in 1993 and went all tube.

This time last year, I was between jobs and fed up with trying to listen to the expensive - not cheap - solid state amplifier that I hated. With no job and not wanting to spend any money, I somehow found an inexpensive little Chinese tube amp kit built by XrayTonyB on YouTube:

Login to view embedded media
It looked like a nice little amplifier, and it seemed to perform ok in his tests, especially given the sub-$400 price tag. I found out that the kit had been updated to remove the automatic "loudness" compensation circuit that he spent time removing in the videos. So I bought the kit from China on AliExpress. I hadn't fiddled with electronics since the early 1990's, but with his video tutorials, I figured that I had a decent chance of success. I sold my solid state amp and preamp to pay for the project once it was complete. The build wasn't without trials and tribulations. I first had to learn to use PSUdesigner to determine that changing the resistor in the C-R-C filter could very easily and inexpensively reduce the overvoltage caused by putting 120V from the wall through a 110V power transformer, and without using a bucking transformer. The problems started when I broke a secondary lead from the power transformer and had to do a tiny, tiny repair of that fine wire. Then I broke one of the output transformers the same way without knowing it. A power tube then blew, and I was left very frustrated. With patience and help from a number of forum members here, we found the problem, I fixed the hair-like wires that I broke on the OPT, and I ended up with a very nice sounding little amplifier for only $400. I will never, ever use a solid state amplifier again.

The first build thread is at the link below, with a lot of boring newbie questions, and of course the problems that I caused by breaking those tiny transformer wires.

https://www.diyaudio.com/community/...s-before-i-build-maybe-during-if-i-do.394962/

I spent a great deal of time translating the 67 pages of directions from Chinese to English. My translated instruction manual was available on a Google drive link in the first build thread. I have them if anyone needs them. I don't know if those Google drive links still work.

Why am I doing this same amp kit again? Maybe curiosity killed the cat as the saying goes, but I want to see what happens if I change a few things, like using larger output transformers. I'm really happy with the way the amplifier sounds, and anyone who builds this kit shouldn't hesistate to build it just as it comes in the box. Just be sure to adjust the voltage as I described if you are using USA 120V instead of 110V. It can be done simply by changing the power supply resistor and using the included lower voltage Zener diode as described in my first built thread. Then curiosity sets in ... what would happen if I change this ... or this ... and so on.

Why this particular amplifier? 1) It's a kit so ... no fabrication that I hate, I don't have to spend a bunch of time and effort ordering individual parts, and I only have to replace/upgrade any parts I choose like the OPTs, 2) It's not expensive at $312.81 with shipping and tax included (it was on sale plus I used a promo code), 3) I know that I like the sound because I already built one, 4) The compact left-right footprint is perfect for me, 5) I already built one so there is little chance of me making mistakes this time. I had to raise my confidence by building the first one, breaking it twice, blowing a tube, repairing it, and finally ending up with a great amp. So those all are valid reasons for me, despite the circuit not being "ideal." I know there are other designs available for people who really want to build their own amps from scratch, but I don't want to do that, at least not anytime soon. Maybe someday but not now. In an ideal world I'd find a proven circuit and scratch build a custom pair of EL84 monoblocks. We don't live in a perfect world.

I am not against making simple modifications to this amp, and I would like to look at those before I proceed. Suggestions welcome. However, it is a PCB amp with a very crowded chassis, so modifications have to be limited. I also do not want to seriously alter the sound as I love it the way it is. It sounds "right" to me unlike so many amplifiers. I don't know what makes the amp sound so good, but it does. It gets the timing of the music right, and so many amps get that wrong. I'm not sure how else to put it. I do want to see what bigger better OPTs bring to the table. There also may be parts of the circuit that haven't been properly optimized, so suggestions welcome. I'd like to find a way to use 4 individual bias resistors, but it can't be done on the PCB. I'll have to see if they can be relocated to a terminal strip screwed to the side of the chassis I guess.

I will be using the excellent sounding long-life 6P14P-ER (Russian 6П14П-EP) power tubes and the equally excellent sounding 6N1P-EV (Russian 6Н1П-ЕВ) driver tubes. I already have these tubes. Spec sheets are attached.

The schematic is attached. Values in green are actual values measured in my current amplifier. When I say that modifications must be limited, I mean very seriously limited as there is precious little space inside:




The first step is to change the output transformers to see if bigger better ones will make a significant difference. Their larger size will require leaving off the metal box chassis cover to open up additional room on top. That would leave high voltage exposed, and I wanted a 120VAC power transformer instead of 110VAC anyway, so I had one custom made. It has end bells and wire leads, so there will be nothing dangerous left exposed. Since the output transformers also will be exposed, they also require covers. I prefer the look of end bells rather than boxy square covers, so I made traditional end bells a requirement. I like their "industrial" look. A thread looking at various output transformer options for this build is at the link below:

https://www.diyaudio.com/community/threads/el84-pp-output-transformer-recommendations.405967/

I ordered an inexpensive, small SMD-based stepped attenuator for the volume control that seems to be quite popular. SMD stepped attenuator

This time I'm going to spend a few dollars on known quality power supply caps. The coupling and bypass caps that say "WIMA" on them I would bet are fakes, so I'll spend a few dollars getting genuine ones.

I did the first build in all black because the silver "hurts" my eyes 👀 and this one will be all black too, so I have a lot of paint work to do first. I'll start whenever it quits raining. ⛈️🌩️






If I could relocate the adjustment pots for the two magic eye tubes outside the chassis, I'd be tempted to build the kit with them and just leave them out of the sockets when I don't want them flashing at me. They are purely for entertainment and it's just 2 more tubes to worry about. I don't think I can relocate the pots without a major hassle though. Having to disconnect the amp, remove the bottom, reconnect it upside down, adjust the magic eye pots inside, and then put the amp back in the system is ridiculous. Last time I just plugged the holes for the magic eye tube sockets and left them out. If I'm going to leave them off again, I'd like to find someplace that can fabricate a new top plate without those holes instead of just plugging them. Is there someplace online that does small fabrication jobs like making a new top plate for me? The holes have to be very precise as they have to align with the tube sockets and PCB.

Never Get Old said:

A year or so down the road, if I decide that I really like this little amplifier, a new circuit board can be had for only $11. I could populate it with the highest quality parts, make minor design changes, and even replace the output tranformers with a higher quality pair, for a price of course. I'll see how I feel about the amplifier a year or so from now.

Click to expand...

And here we are almost 1 year later.

Useful links:
Resistor power calculator: https://www.amplifiedparts.com/tech-articles/resistor-power-rating
Tube bias calculator: https://robrobinette.com/Tube_Bias_Calculator.htm
One of many sellers on AliExpress selling this kit: https://www.aliexpress.us/item/3256802532801472.html

Whenever it quits raining and we get some pleasant weather, I can start the painting. I stripped the silkscreening off of the faceplate last night. It requires a 4 hour soak in acetone and then scrubbing hard with a Scotchbrite pad to get that cleaned off. No other solvent or stripper that I tried last time worked. A soak in acetone does the trick. I do custom decal work, so that's how the printing gets put on the new black paint. After drying, the decals are sealed with multiple layers of satin clear overcoat with multiple wet sandings to get a perfect painted-on look and permanent protection from discoloration.

Selling some IanCanada stuff:

1x RaspberryPi with Gentooplayer license and Diretta License SOLD
1x PurePi. SOLD
1x FifoPiQ7 SOLD
1x SinePi SOLD
1x ReclockPi
1x TransportPi SOLD
1x height adapter SOLD

Price is 35% off from Audiophonics, will offer greater discounts for bundles
Will ship worldwide

Any members have any experience building hush boxes, especially for amp units that have fans at the back? The overall concept is not that hard to figure out but it's the cooling aspect that worries me.

Hello everyone,

I am looking for a type of glue or similar material to bond large components (eg inductors, capacitors..) to the PCB, with the goal of suppressing vibrations.
Ideally something that can come off in case I need to replace any of the components.

Do you folks have any preferred products that you would suggest or any products that you hate and I should stay away from?

Thanks in advance for the responses

I've noticed that some coaxial 2 way speakers have very good performance and come with a proprietary metal back can which is very deep. These back cans come with some sort of polyester fibre fill in them. It looks like the stuff they use in pillows and cushions. I'm sure this is possible to get at an upholstery shop.

Hoping some experienced speaker building enthusiasts can help me. I want to build wooden boxes for these coaxial speakers with the objective of reducing their depth but preserving their sound signature. Hence, I have some questions:-

1. Do I calculate the volumetric area of the back can and preserve that volumetric specification when calculating the box size?
2. Is the volumetric specification important or is it ok for me to exceed the volumetric specification a bit as long as all the speaker boxes are built the same?
3. How do apply the polyester fill and hold it to the back? - I'm thinking of incorporating a wire mesh to hold the fibre to the back surface.
4. I would just incorporate speaker wire terminals at the back of the box, air-tight them with silicon. Is that a good approach?
5. I'd love to achieve a final depth of between 4" to 6". I presume this is enough to accommodate for the woofer driver excursion.

My objective is to use them for home theatre. Building a box that is wider and higher but has less depth will allow me to wall mount the speakers.

Attached is an example of a coaxial speaker and metal back can.

Any input and help will be appreciated. I'm sure fellow members have tried this.

Hello, a year ago I made a post where we tried to diagnose this amplifier without much success. Since then I have gained a little bit more knowledge and an oscilloscope.

Recap of what has happened:
Amplifier suddenly started going into protect, we suspect a loose battery terminal was the cause.

One IRFB7437 MOSFET was shorted (no idea if PSU side or output side, compact amplifier so I can't easily tell)

The driver 27324 also was dead and a resistor on its VDD. Also a few gate resistors were burned up.

After replacing the FET, driver and resistors, it just killed a different FET (because PSU was a battery, aka no current limit)

Middle pin of rectifiers is disconnected.

Info and equipment:
I will be able to diagnose more only during weekends.

PSU is a 12v 5A adapter, but can shut off due to overcurrent around 7-8A.

Multimeter Lovrum T28B

Oscilloscope ZEEWEI DSO1C81

Soldering iron

Current issue:
There was a bad solder joint on the driver, fixed that and now it seems to power on and go into protect properly, without being interrupted by the PSU shutting off, but some component is making a whining noise

The whining noise in question:


Board pics in attachments.

Measurements:
All gate resistors in spec ~4.7ohm

27524 driver: Works, all gates get a solid 25khz square wave

IRFB7437 (same on all of them, scope negative on ground):
Gate:

Drain:

Source: Nothing

I assume it's just the scope bugging out on the Gate measurement.

IRFB4321: nothing, I assume that's the output side which doesn't work because rectifiers middle pin is disconnected.

There is a blown up resistor in the middle of the board, unsure of its function, my guess would be a bleeder resistor, but there is a 2nd one intact.

Hi All,
I was considering replacing the 12BH7 pass tube in the regulator. If I do the math the circuit needs 402Vdc at 39.5ma. The 12BH7 has a 228v drop across it, so 9.006W. It's only rated for 3.5W each plate and both plates run in parallel. Most tubes do less than the single plate rating. So it appears that the 12BH7 is not up to the job. Did I miss something? They use a 6550/6H30 in the newer designs. I'm limited by the available heater current and 9 pin socket, so thinking of replacing it with a EL84 in triode? Sound correct? Not sure of the other changes required?

Newbie here, interested in building analog and digital audio circuits.
Wasn't really into analog for decades until I recently found my Kenwood KP990 turntable broken, and mistakenly purchasing those simple crosley-like player for the replacement.
Devastated at the beginning of how bad it sounded, but started to explore how to make it sound better, which I finally succeeded to, by modifying the player and adopting a circuit example posted here at diyAudio.
A lot of trial and errors during the process, not only to find the best sounding circuit, but also things that are basic such as soldering, which I found to be a sustainable joy for a semi retired guy like me.
Look forward to talking with the community, thanks!

Well , everything explained and shown in technical thread :

Iron Pumpkin(s) and other smaller vegetable animals , but be aware that latest and final iteration of electronic part of package (main difference being JFet buffer instead of Diamond ) is shown in Iron Pumpkin(s) and other smaller vegetable animals, Tips 'n' Tricks thread

on sale are several options :

1. Iron Pumpkin SE (yup , that one being for RCA inputs/outputs) ,consisting of :
-Iron Turtle SE AVC , as assembled and tested unit (two irons on one common pcb ), rotary switch ,50cm flat cable finished, necessary stand-offs
-two pcs of Iron Pumpkin SE mono pcbs (selector, shunt regs , buffer -all that on one pcb) , with all small SMD JFets presoldered , all BC bjt critters , voltage references , BD bjts for reg CCS ,all relays, Philips MKC 1uF caps , selector Lorlin switch with two finished flat cables, all multiturn trimpots , necessary 1-pin sockets for optional Borbely WCF buffer iteration, u22 cap for WCF

price - measly 550E , plus 30E for Paypal , P&P expenses

2. Iron Pumpkin (Bal) (yup , that one being for XLR inputs/outputs , possible combination with RCAs, read threads for that) ; that one consisting of :
-Iron Turtle (Bal) AVC , as assembled and tested unit (one iron on one pcb but two pcbs stacked having same footprint as previous one) , rotary switch,50cm flat cable finished, necessary stand-offs
-two pcs of Iron Pumpkin (Bal) mono pcbs (selector, shunt regs , buffer -all that on one pcb) , with small SMD JFets presoldered , all BC bjt critters , voltage references , BD bjts for reg CCS ,all relays, Philips MKC 1uF caps , selector Lorlin switch with two finished flat cables, all multiturn trimpots , necessary 1-pin sockets for optional Borbely WCF buffer iteration, u22 cap for WCF

price - measly 650E , plus 30E for Paypal , P&P expenses

3.Iron Turtle SE AVC (so no electronics), as assembled and tested unit (two irons on one common pcb) , rotary switch ,50cm flat cable finished, necessary stand-offs

price - measly 450E , plus 30E for Paypal , P&P expenses

4.Iron Turtle (Bal) AVC (so no electronics) , as assembled and tested unit (one iron on one pcb but two pcbs stacked having same footprint as previous one) , rotary switch,50cm flat cable finished, necessary stand-offs

price - measly 550E , plus 30E for Paypal , P&P expenses

5. Iron Pumpkin SE electronics ( so no AVC in package ) (yup , that one being for RCA inputs/outputs) ; that one consisting of :
-two pcs of Iron Pumpkin SE mono pcbs (selector, shunt regs , buffer -all that on one pcb) , with all small SMD JFets presoldered , all BC bjt critters , voltage references , BD bjts for reg CCS ,all relays, Philips MKC 1uF caps , selector Lorlin switch with two finished flat cables, all multiturn trimpots , necessary 1-pin sockets for optional Borbely WCF buffer iteration, u22 cap for WCF

price - measly 130E , plus 20E for Paypal , P&P expenses


6. Iron Pumpkin (Bal) electronics ( so no AVC in package)(yup , that one being for XLR inputs/outputs , possible combination with RCAs, read thread for that) ; that one consisting of :
-two pcs of Iron Pumpkin (Bal) mono pcbs (selector, shunt regs , buffer -all that on one pcb) , with small SMD JFets presoldered , all BC bjt critters , voltage references , BD bjts for reg CCS ,all relays, Philips MKC 1uF caps , selector Lorlin switch with two finished flat cables, all multiturn trimpots , necessary 1-pin sockets for optional Borbely WCF buffer iteration, u22 cap for WCF

price - measly 160E , plus 20E for Paypal , P&P expenses

for all technical questions , visit linked threads
for other questions - ask here or in PM

considering prices from other vendors of AVC thingies , I believe this is pretty good bang for the buck

shipping time from 1 to 4 weeks ......... sometimes things need to flow from Germany or China ......

and yes case/chassis needed : regular width , minimum 3HE ........ even if , with some care , it can be squeezed in proper 2HE case

in both cases 350mm deep case is good to have , from various reasons ..... one of them being - necessary distance between small Donut to rest of preamp

Greetings in Amplifier Land. I am in need for some I believe DEC or IDEC AP4U Relays there is one per Driver/Amplifier Board I'm open to possible Substitutes if there any available.

Thank every Body!

I'm working on an old Philips EL6425 and would like some advice. This is my first PP amp and I haven't come across phase inverters before , and this one seems out of the ordinary. It is an LTP (I think) , but there is a negative voltage on the cathode resistor R27 (marked as -3 voltage ), around -40v . Also the second grid on pin2 is grounded without an AC coupling capacitor , and there is a diode and resistor connected to the input which is explained in the manual by "GR3 in the grid circuit of B5 improves the RC time of coupling capacitor C18 and leak resistor R26 so that when Grid 7 of B5 becomes too far negative this charge can leak away faster through GR3"The diode GR3 has a negative voltage (marked -2) on it , which is about -3 volts.
I want to put a Master Volume control before the Phase Inverter , so my questions are ...can I do so while still leaving the existing PI as it is without interfering with the function of G3 ? Should I replace the PI altogether ? I'm trying to keep the amp fairly original where I can , but maybe it doesn't make a great deal of difference here , and having the MV in this position is probably more important to me . Any help much appreciated.

I bought these IT to Thomas Mayer gapped for 10mA SE connected Alt Q 4.5:1.

I guess if I connect Alt Q 4.5:1 the max. Primary DC current is 10mA, but what about if I use other connections? or doesn't matter because all connection are max. gapped for 10mA?

Gentlemen,

I own Sonido SWR 096 AlNiCo speakers. I'm thinking of making a Karlsonator case.

I have no idea how to choose a case. Which type to take (0.53, 8, 12 or 15)? Size? How to calculate whether the units are suitable for Karlsonator and for which type.

Im asking for help.

Orders are now open for Abbado III NOS DACs - DM me and be sure to mention your preferred payment method (Wise or Paypal) and location so I can quote you inclusive of fees and shipping. Abbado III is based on Abbado II architecturally but also includes an aspect of Celibidache's design hence is perhaps best seen as the merging of Celibidache and Abbado themes. Its DAC supply rails regulated by discrete transistors fed from IR LED voltage references but has a lower noise floor owing to the use of more paralleled TDA1545 DAC chips (24) and improved dynamics from a plug-in filter module which in stock form is 9th order (11th order by request). There is also the option to include an analog volume control to allow direct drive of a poweramp in systems with only digital sources. Use of an analog volume control beats a digital one in terms of SNR at lower listening levels. The physical footprint remains the same as Abbado II albeit slightly taller at 100mm * 70mm *24mm high - the fixing hole positions have moved though. We are using a 4 layer PCB and the DAC requires a single power rail of 9V at 270mA. Design wise, it's non-oversampling (i.e. there is no digital filter on-board) and the input format is I2S (three signal wire) at 44k1/16bits active within a 32bit frame. BCK is required to be 64fs (2.82MHz at 44k1 sample rate), MCK isn't required. Output is nominally 1.5VRMS with a 6dB gain reduction option on-board and a limited range of overall gain from a multi-turn trimmer. The gain reduction comes in handy when you want to use a pair of Abbados to create balanced outputs, the balanced output level can be kept the same as when unbalanced. In this configuration, the trimmer allows interchannel matching of output levels. Our I2S splitter board provides the functionality to run a pair of Abbados in balanced mode.

Preferred payment method is via Wise which typically adds a 2% fee. Our receiving currency is CNY, alternatively USD or Euro. PayPal may also be used, in USD but will attract higher fees, 5.5%.

Price for Abbado III built and tested, 9th order filter, with volume control : 1320RMB
11th order filter option : +120RMB
Omit volume control : -140RMB

Shipping is in addition and depends on your location and speed of service. Courier (FedEx, TNT, DHL) typically takes 8 - 10 days and e-packet four to eight weeks. Not all locations can be serviced by e-packet though.



FAQs

What else is needed to turn Abbado III into a fully operational DAC?

First, you'll need a well regulated low noise power supply of 9V rated at 270mA or higher. An LM317-based board set to the correct voltage will suffice if you already have an unregulated supply (like a typical wall-wart). The LM317 will need adequate heatsinking. I don't recommend switching supplies due to issues with common-mode noise, its very hard to filter out. That disrecommendation doesn't apply though when both the DAC and amp are within the same box as in our example below, in that case the CM noise isn't a worry. We have a suitable LM317-based board which takes in an AC feed from a mains transformer at 18V and down-regulates with a buck converter prior to the linear regulator. The use of the buck means it runs cool as the linear regulator is operated with just enough voltage drop to ensure good line rejection.

Second - you may need a digital interface card. I say 'may' because some digital sources produce I2S directly (like Raspberry Pi, dedicated SDcard players) but most sources will either output USB (like a PC or laptop) or S/PDIF coax (a CD or DVD player) or Toslink. We can supply a card for interfacing one (or more) of those sources to Abbado's I2S input. A CM6631A-based card for USB input is the premium choice as it operates under 'async USB' and offers up to 192k sample rates. However in stock form it isn't suitable because at 44.1kHz it outputs a 128fs BCK - when we supply such cards we upgrade the firmware for you to support a standard 64fs BCK. Async USB has the lowest jitter however given it operates under high-speed USB it needs a fairly expensive isolator to protect your DAC and amp from common-mode noise. A TE7022-based interface has the advantage of only needing a $5 full-speed USB isolator while still offering up to 96k sample rates and is normally cheaper than a CM6631A board. For S/PDIF inputs, the board we recommend handles both coax (two inputs) and Toslink. Further, it has a switched I2S input - this can accept I2S from the USB source. A single pole switch acts as source selector, cycling through the inputs. An OLED screen is an option to indicate the selected input. This board needs a 5-12V supply, so it is fine being run direct from the DAC's 9V rail.

Third you'll be wanting some output sockets, typically RCAs so you can connect your finished DAC to your amp or preamp. We can supply these and we also have a PCB to mount them to make outputting Abbado to your system easier. XLRs would be the recommended way to output in balanced mode.

Lastly, and this is obviously optional for a DIYer, is a case. We haven't supplied cases in the past because they're so heavy (i.e. expensive to ship).

USB CM6631A card examples : https://www.aliexpress.com/item/32874113831.html www.aliexpress.com/item/1005004083748180.html
TE7022 interface example : https://www.aliexpress.com/item/1005005388553366.html
USB isolator, full speed : https://www.aliexpress.com/item/1005001369085297.html
USB isolator, high speed : https://www.aliexpress.com/item/1005001379930133.html
Multi-input S/PDIF card : https://www.aliexpress.com/item/1005002923079600.html
Coax/Toslink S/PDIF card : https://www.aliexpress.com/item/1005002772984954.html


What's supplied with the DAC?

The inputs and outputs of Abbado use Molex type 2510 4pin connectors which mate with a shell containing crimp-terminated wires. We supply those wires pre-crimped with shells along with the DAC. If you buy an input board through us we'll also provide the I2S cable ready-made to suit that board. If you buy our PCB mounted RCAs we'll include the 4 wire cable to interface to that.

What, if anything, is unique about Abbado's design?

Commercial NOS DACs typically have minimal filtering after the DAC chip itself whereas Abbado has a steep (9th or 11th order) low-pass passive filter afterwards. By strongly attenuating the NOS image frequencies this LC filter improves dynamics and makes the aural picture more clearly delineated with acoustic instruments having a well defined position in space. Passive filters like this are extremely difficult to implement using off-the-shelf inductors as no commercially available ones have sufficiently close tolerance. So Abbado's inductors are custom, hand-wound using gapped ferrite P14 cores. Having a passive filter prior to any active analog stage means the downstream discrete buffer stage no longer 'sees' a step waveform out of the DAC chip, rather a continuous signal. The volume control option uses the lowest resistance ALPS pot available (5k) so as to add the least extra noise, its driven directly from the I/V resistor which is only possible because of the substantial output current from the array of TDA1545s. Abbado's DAC chips are 'multibit' but they're not strictly speaking 'R2R' as internally they use no resistors. Instead, capacitors are used as elements in the DAC which have their charge constantly refreshed (similar to the DRAM in your computer) to compensate for any drift. By paralleling 24 of these devices and running them at higher current levels than typically used, the noise floor is considerably lower than with a single chip - this translates in practice to a 'warmer' sound where the acoustic ambience captured on a recording is more easily perceived. In order to achieve retrieval of these low-level ambience cues, the DACs' power rails need to be extremely clean and this is achieved through use of a pair of discrete series regulators fed from an IR LED derived reference voltage.

The development of Abbado III has taken place over several years and it builds on and improves prior designs, most particularly it draws its heritage from Celibidache. While Celibidache used an array of 20 TDA1387s, Abbado swapped the DAC chips to TDA1545 because each chip has a 3dB improvement in SNR compared to TDA1387. Thus Celi's already black background has been darkened further. Celi used a pair of current sources to 'steer' the current into the I/V resistor whereas on Abbado I've been able to delete one of those CCSs with the aim of further lowering the noise. The last improvement over Celibidache has been made in the output stage - its now fully discrete whereas Celi used a very low noise opamp. The discrete nature of the output stage seems to contribute a more relaxed sound, particularly in the higher frequencies.

Abbado III is well-suited to the creation of a convenient 'all-in-one' box - aka a 'DAC-AMP' using its volume control option. Here's a picture of an Abbado (green PCB bottom right), minus filter to reveal the DAC array, in such a configuration. There are two power supplies - a 24V SMPSU top left for the amps (our own monoAMPs) and a hybrid linear-buck for the Abbado DAC. The input board (yellow colour bottom left) supports USB, Bluetooth and S/PDIF - switching of sources is done with a push-button on the front panel with LEDs for indication.

Selling a Tube DEM clock board, made by Abbas Audio.

Adjustment between 490khz and 1.2mhz, to feed the DEM clock circuit on the TDA1540/TDA1541 DAC ICs

Power transformer, Tube rectifier EAA91 and output tube EF180 or 6S3P

New and unused (ordered 2 and only needed one in the end)

SOLD

Seeing as there isn't a thread in Pass Labs for this wonderful little amp, I thought I'd start one.

I have all the key parts. In fact, the circuit is identical to the Delite, except the actual transistor. I will be building this soon.

Mike, what's in store for part 2?

Hi everyone,

I'm hoping to fix my KEF 107 Kube.

I found a link to the KEF 107 KUBE schematic on HiFiEngine, but unfortunately, I cannot access it as they no longer take in new registration. I was wondering if anyone on the forum has the schematic diagram for this model and would be willing to share it.

https://www.hifiengine.com/manual_library/kef/model-1072.shtml

Any help would be greatly appreciated!

There is a 2 way mono crossover diagram. In the lower part, the output stage is responsible for generating a bass boost when turning the volume knob (like tone compensation)
The problem is that both channels are not synchronous. The HF channel is quieter with the same potentiometer position.
How can this be compensated and both channels synchronized?
Attached file for microcap

Hi, cleaning after years of building amplifiers output and power transformers, new or barely used.

I have tube output Hammond make : 1645 (x2), brand new, 1650R (x2) barely used 50-100 hours

Edcor: cxpp25-5k, 2x used 200 hours.
and power transformer : XPR002 720V x1 used 10 hours

Any one have a couple ring radiators of some kind or should I just buy them from an online retailer?
Not sure if it's annoying or helpful to ask on here first or not?

First post is actually post #4 under
https://www.diyaudio.com/forums/solid-state/340058-accuphase-300s.html#post6095754
maybe the moderation can filed this post and the post #6 in this topic.

Simple circuits to reduce noise of common LM78xx voltage regulators.



Updates:
1. Turns out that LM7805 doesn't start up reliable in this configuration, and thread name difficult to change. It happens if 5 * Iq rules is broken, so there is another version:



2. Basic concept, that helps to understand role of a regulator as "pass element"


Some test results with 3v3 and 5v6 zeners:


Scale is referenced to 3 nV-rms at -140 dB line.
So the best performance I've got so far using lm7805 & 5v6, about 7 nV-rms. It's interesting, as I know that 5.6V zener noisier than 3v3, but high dynamic resistance of 3v3 (70 Ohms vs 5 Ohms) limits the gain of bjt. Option may be to use 2 bjt or some OPA, if I decide to push noise down.

MarkAudio Alpair 12P seems to be a perfect full range.
Have you any thoughts or experience of this driver?

Hi:

The Government of Canada posted this thorough review of media longevity. I have thousands of optical discs but I never paid much attention to this topic. Lasted updated in 2020.

After a quick search I didn't find this on the forum, so posted it below. Apologies if it's redundant.

dizmayed

https://www.canada.ca/en/conservati...tute-notes/longevity-recordable-cds-dvds.html

Hi guys,

I have for sale a reclock pi + fifo pi q3 and u.fl cables(x4)

I am from the EU.

The price is 100€ + shipping.

Let me know if you are intrested.

I thought I would share some measurements of this Tymphany/Peerless DFM-2535-R00-08 1.4" voice coil, 1" exit titanium compression driver with ferrite magnet

Here's the spec sheet, retrieved 01/08/2024 shows the response in a Plane Wave Tube @0.283V:


As well as in a horn:


N.B. The left vertical axis denotes 2.83V/1m ("with LTH102 test horn")... A web search shows... is this the FaitalPRO LTH102 horn ?

Since Tymphany don’t make their own horns (AFAIK), I mounted it onto a SB Audience H225 , a 225mm square 90x70 degree constant directivity horn.

It needs four M6 x 16mm bolts to mount directly only the horn- no modifications or adaptor required:



Now we measure at 0.5m (to reduce reflections in from floor/ceiling) but plot for 1m (-6dB) in the "standard" 25dB/decade aspect ratio, from 600Hz to 40KHz:



Here are the polar measurements, taken in 10 degree steps, in both the Horizontal and Vertical axis from 0-90 degrees.
This is with a gentle 1V RMS drive level so measurements could be taken down to 500Hz, but SPL plotted for 1m.
The gating is 4ms, so the frequency resolution is approximated below 1KHz.






Here's the polar response, with 1dB demarcations.





Next we use software DSP to flatten with on-axis frequency response and insert a filter for acoustic LR4 1KHz:

86dB@1m seems to be a walk in the park- all harmonics below noise floor of this room:





Here is 96dB , this time with crossover for 800Hz (see post 17)






STRETCH GOAL:
106dB/m

Edit:
01/08/2024 - tidied up. B&W for some, colors for others!

Hi all,

I recently refunded a gentleman who purchased this kit. He's had a health diagnosis that means HiFi is no longer a priority and this became a project he was no longer going to pursue

Unused PCB and Unused NOS/Brand New Valves, £365 Inc shipping.

Valves: 2X Colmore PCC88s and 1x PS VANE gold pin ECC83.

Hi All,

Here is my development on microcontroller-based "smart" soft-start / protection, or, I would say, amplifier control board (see attached).

Let's use this thread for discussions on firmware-driven boards - no matter what the PIC is, I believe, exchanging experiences will be useful for everyone interested.

Cheers,
Valery

P.S. My firmware and gerbers are available on request 😉

Fusion world or ethnic music is kinda under the radar. I know there is bunch of streams for world music but you have to dig deep to find something good and free time is scarce.

Here I will post some I found and enjoy, please fell free to put any kind of your local or not so well known music that you find worth to share.
So, Orange Blossom for start

Orange Blossom - Black box HD Live - YouTube

With all the recent talk about unipivots and such, has no one ever considered knocking off a magnet stabilized string pivot like the Schroeder? I have been considering a DIY arm just to add a mono cartridge to my TT. This implementation "looks" fairly simple Assuming you have a source of wood and carbon fibre, the only things slightly out of the ordinary are the neodium magnets, which are fairly ubiquitous on the web.

See pics and a review of the Schroeder's stuff at his website: http://www.schroeder-tonarme.de/

Mike

Both devices are brand new, never used, in original packaging! Prices are in CAD.

Key Digital 8x8 Video Matrix Switcher with Audio distribution system - KD-HD8X8BT - $450 CAD

8 inputs to 8 outputs HDBT/HDMI/DVI via single CAT6/STP.

Key Digital 8x8 Video Matrix Switcher with built in Compass Control - KD-HD8X8Lite - $850 CAD

8 inputs to 8 outputs HDBT/HDMI via single CAT6/STP.

I’m currently working on a Luxman L-31 amplifier but doubting my choice on a transistor substitution. Lots of people replace the 2SA836 and 2SC1345 transistors with BC560 and BC550 transistors. But for Q201 and Q202 the VCE exceeds the maximum VCE the BC560 can safely handle.

Without checking the further specs I picked two KSA992 transistors out of my stock and used those. The amplifier works fine but I suddenly realized the KSA992 has a maximum current of 50mA while the 2SA836 has a maximum current of 100mA.

My transistor calculation skills are practically gone after 30 years so I tried simulating the circuit in Falstad circuit simulator. That resulted in a maximum emitter current of ~2.9mA in Q201 and ~1.9mA in Q202. Those values feel a bit low to my idea.

Can someone explain, or advise me a website with a decent explanation, how I can calculate the current in a differential pair like this?

Hello,

going forward from this post: https://www.head-fi.org/threads/what-is-this-in-theory-unseen-absorber.975948/

i wanna 3D print/design something better looking and possibly easier tuneable

The greatest advantage of full-range speakers, in my opinion, is their ability to extend vocal fortissimo naturally.

General multiway speakers (with LCR networks) often fail to reproduce the same open and extended vocals as full-range speakers.

Even high-end multiway speakers can sometimes make fortissimo passages sound compressed.





I asked ChatGPT a question

[QUESTION]

Why do multiway speakers (with LCR network) have poor vocal fortissimo extension compared to full-range speakers?


[ANSWER]

Multiway speakers with an LCR network (inductor-capacitor-resistor) often have poorer vocal fortissimo extension compared to full-range speakers due to several factors related to crossover design, phase issues, and driver limitations. Here’s why:

### 1. Crossover-Induced Energy Loss & Damping
- Multiway speakers rely on crossovers to split frequencies among drivers. These passive LCR networks introduce energy losses due to component resistance and impedance mismatches, reducing transient response and dynamic range.
- Inductors in the midrange and woofer circuits can limit the rise time of transients, making fortissimo passages sound less explosive.
- Some crossovers over-damp the midrange, making vocals sound compressed compared to full-range speakers.

### 2. Phase Shift & Time Alignment Issues
- Crossovers introduce phase shifts, especially around crossover points, which can cause destructive interference and loss of coherence in loud vocal peaks.
- In a full-range speaker, the entire signal comes from a single driver, avoiding phase misalignment that can soften high-energy transients.

### 3. Driver Interaction & Compression
- In multiway speakers, multiple drivers (midrange & tweeter) attempt to reproduce vocal harmonics, but integration issues can cause cancellation effects or uneven dispersion at high SPLs.
- Multiway drivers often have different efficiency levels, leading to uneven power handling during loud peaks.
- Some midrange drivers have limited excursion, causing dynamic compression at high SPLs, whereas full-range drivers are designed to handle the entire vocal range without a handoff.

### 4. Cohesion & Direct Radiator Effect
- Full-range drivers radiate sound from a single point, ensuring phase coherence and direct radiating energy, leading to a more natural projection of vocal intensity.
- Multiway systems introduce lobing effects (interference between separated drivers), which can reduce perceived vocal presence at high volumes.

### 5. LCR Network Damping Effects
- The impedance of a crossover network interacts with the amplifier’s output impedance, sometimes reducing the damping factor and affecting transient sharpness.
- In contrast, full-range drivers typically run with minimal or no crossover components, allowing for direct amplifier-to-driver coupling and faster transient response.

### Why Full-Range Speakers Perform Better in Vocal Fortissimo
- No crossover-induced phase shifts or energy losses.
- A single diaphragm handling the entire frequency range ensures better coherence.
- Direct coupling to the amplifier maximizes transient response.
- No multi-driver interference or lobing effects.

This is why single-driver, full-range speakers are often preferred for vocal reproduction, especially in high-dynamic passages like operatic or live performances.

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

[ Air-Recording ]
"Danny Boy - Jacinta" listened to with 1.5” full-range (1.5 USD) and Bluetooth Amplifier (6.5 USD)

Login to view embedded media

Hi, I wanted to share with you a nice video of a guy that built a 2 way box implementing the filtering using an ESP32, I found the approach very interesting, and also the video is entertaining :
YouTube
Have a nice day ... at home ...

Hello everyone, my name is Artur, I’m a computer engineer from Brazil, right now I’m employed at the O&G industry, but i still find time on my weekends to use my computer and electronics skills on personal projects, mainly focused on audio diy projects. Right now I just finished assembling a network audio streamer, and I’m looking forward to find new challenges here on this forum!
Cheers!

Hey!

Just wanted to introduce myself. Recently started researching chipamps to use in another project of mine.
Always loved audio, never given much thought on how to make my "own" circuits. Coming mainly from digital electronic designs.

Goal was just to get something "decent" to drive a speaker, of course, as it often happens, it can escalate and now I want to learn more about audio design!

EDIT: (many years later...)

Putting a couple amazing links here in the top so members can better find them;

Mike Barney's page, which in my opinion is the best single SP-10 page out there -
https://sites.google.com/site/mpbarneysources/sp-10-mk2-pro

A great rebuild thread on AK -
https://audiokarma.org/forums/index.php?threads/technics-sp-10mkii-restoring-an-icon.900468/

JP's storefront -
https://fidelisanalog.com


Amazing SP-10 content here -

https://www.theanalogdept.com/sp10-gal.html





(The funny widgets are the motor hub fixing plates)

No, you are not seeing double.

This is my newest and most ambitious project yet - Technics SP-10Mk2A. Neither have a PSU, but that's not a difficult thing. Happily, both are operational, I tested them today with a friend's PSU. One has a fiddly main switch. Both are in sorrier cosmetic shape than I thought. That may prove an issue, only time will tell.

So will I make one good one from the ashes of two? I have no idea yet. Of course, having two at the end of this is always more attractive of an option. I do, however, think I may make one black, that would look quite sharp.

On the to-do list -

Re-cap the main board.
Build PSU
Adjust main board and switches as needed.
Figure out if I have one good table or two.
Build plinth(s).
Address cosmetic issues.
Determine if I can get a long armwand for my Graham, or just get a 10.5" Jelco.
Etc...



So let's get started --



Like I mentioned, both tables are operative, the biggest concerns (other than the need to build PSUs for both) is purely cosmetic.

So let's look at the tables as I received them. These photos intentionally are showing all the warts as ugly as possible.


The prettier one. Not bad generally, but the marring and corrosion is all on the 'close' side of the table where it will be seen.


The text can be re-filled. the corrosion is fairly shallow.






A couple of nicks in the black paint. No big deal.


Marring on the paint, no corrosion.


Inside the brake section is very clean, and there is plenty of friction material (felt) on the band.


I have no idea if this is a lot of wear or not on the hub. I thought it worth a photo, to see if anybody can compare.


The platter of the prettier one.


A bit of corrosion, nothing severe at all.


The stock platter mat had something glued to it. I have no idea hot to get a hard adhesive residue removed from rubber...

New and looking to build Open Baffle speakers. Also a new combo listening / video

Hi, I'm Henk, have very little experience with electronics, but would like some input on a fairly small problem I'm having with one of my power supplies.

I’m looking forward to using diyAudio as a resource and interacting with members.

Does anyone recognise this horn model - it is roughly 12-12,5" opening for a 1.4 inch driver.


Oneminde

Hi. I got a small amp with 12 V trigger in (3.3 or 5V will not do) and a Raspberry Pi 4B with a dac hat and running camilladsp and a USB gadget mode, UAC. Works well enough so that I want to make use of the 12 V trigger. The problem is that I'm a newbie with low level electronics, although I have some basic understanding on how things work. I have also assembled diy duplos (Hypex NC400 kits) and they work well. I asked ChatGPT, but it gave conflicting answers. I need a human confirmation so that I won't fry my devices.

I now know that the 12 V and 3.3 V rails on the Pi have good current output so that they can easily handle trigger signal through a step-up converter (that I have) and some other small components. However those rails cannot be controlled with software, they are always on. The togglable GPIO pins supply 3.3 V, but very little current. Less than 20 mA I think. The AI gave two possible solutions.
1) A relay: 5V -> relay -> step-up -> amp, control relay by a GPIO pin. I don't have such relay, but there should be RPi/Arduino compatible relays available everywhere.
2) Using an NPN transistor or a MOSFET. I happen to have a small electronics kit that came with TO-92 (?) packaged NPN transistors that are labeled as "PN2222". AI says they're good. Print on the actual component says "2N 2222A -1726". The guide goes like this:

• transistor emitter to ground
• 5V supply pin to transistor collector
• 10 kOhm resistor between transistor base and ground
• selected GPIO pin to transistor base through 1 kOhm resistor, this is the programmatically controlled pin for toggling on/off
• ground to step-up converter in-
• transistor collector to step-up converter in+
• when GPIO pin is high (3.3 V), it should allow current flow to the step-up converter and produce me 12 V trigger (when voltage is adjusted correctly).

I'm quite confused, doesn't the current flow from 5 V rail to the step-up converter at all times or is the transistor shorting it to ground? Either way it looks funny to me, so I started checking from other sources. First I checked transistor pinout and BANG, the AI gave conflicting description on how the pins are set on a TO-92 transistor. Can anyone confirm if the above description of the schema is good? And describe how the pins on a transistor are? I happen to have this small tester, that gave the following result:

This result conflicts with what the AI was telling for legs. With the flat side of the transistor facing me (down in the pic), the legs should be from left to right: EBC, right? It's difficult to see in the pic, but that's how they go into the testers numbered slots. Anyway I see the letters NPN, so it's correct type?

Low power consumption is a requirement, because I'm on USB 2 power budget and I got other devices to connect too. At this point I feel like the relay would be a better idea, but I kind of hoped to make with stuff that I already have. What say you?

PS. I'm also developing UI with a small OLED screen and a rotary encoder, but this trigger is higher on my priority.

FS: Four (4) Hammond Transformers, 100-238V PRIM, 24V SEC, 50VA, 2Kg each. It has a multiple voltage PRIM (100V to 238V), 4 wires (Blk, Brw, Red, Yel) and one green wire that was connected to gnd, possibly shield, and one single 24V secondary, 50VA rating. They are probably 24V control voltage transformers, used in various industrial control system.
These transformers are like new.

Open to offer

Payment by EMT within Canada without fee, for the US Paypal 3.5% fee (or use F&F)

Thanks for looking

OFF --> going to metal recycling...

SB

I am going to build a pair of Open Baffle speakers . My tweeter is ESS Heil AMT 1 . I am trying to deicide on which one of these 5 woofers too use . SB Audience Bianco -150b350 , Goldwood 215/4 or 8 ohm , Goldwood 212/8 and Lii Song W15 . If anyone has used these send me a comment on using them . Please do not send me opions if you have not personally used any of these speakers . The Goldwood specs. look great and the price is the best. Thanks for any info.

Take this 2-minute test of the audibility of EQ errors and distortion when driven by clicks and pops.

The attached file contains four 30-second segments of an impulse with a 10Hz repetition rate. To that, I have added at a 0.5Hz repetition rate:

(1) Time 0-30s: EQ +3dB at 20KHz
(2) Time 30-60s: EQ +3dB at 200KHz
(3) Time 60-90s: 2KHz sine at 1%
(4) Time 90-120s: 2KHz sine at 0.01%

(1) and (3) calibrate the listener's expectations.

(2) is representative of the +1 error in phono pre-amps with non-inverting active EQ and no correction.

(4) is a proxy for distortion.

In all cases, the small difference is switched on and off at a 0.5Hz rate. You are listening for a small change every second.

The impulse is a challenging waveform due to its flat frequency spectrum and high peak-to-average. The software-generated waveforms are perfectly bandwidth-limited to 20KHz.
Ed

A basic power amplifier delivering more than 16 Watt.
An amplifier that could be before D.Self published his Blameless.
The THD distortion is moderate, but the harmonics are interesting. Mostly 2nd harmonic.
Enjoy this simple amp!

Hello!

Recently I saw in internet that someone build MTM Cabinet using this speakers:

2x Scan Speak Illuminator WU18 https://www.scan-speak.dk/datasheet/pdf/18wu-8741t00.pdf

1x Seas tweeter https://www.seas.no/images/stories/excel/pdfdataheet/e0011_t25cf002_millennium_datasheet.pdf

I managed to download some photos to show to you and to discus with you.
What is your opinion? Do You think that they will match and sound very good, or just basic?

Also I dont have schemes of the box and filters, but it would be interested first of all to see what do you suggest me to do - should I change to the classic MTM Seas project from 2000 year? --> https://deskfi.ru/products/akustika-na-dinamikah-seas-odin-mk3

A while back, I built the RJM phono preamp. The result can be seen here. It's been working great, but I started noticing an externally audible ringing sound a while back. As in, nothing coming through the speakers, it's actually coming from the amplifier itself. I troubleshat it, and couldn't find anything obviously wrong. From memory, I reflowed all the solder joints in the power supply section, as it was all I could really think to do at the time. Admittedly, I'm still fairly new at this sort of thing, so the odds that I missed something, even obvious, are high. It finally got bad enough that I could track it down, and it's coming from the RECTIFIER tube! Whatever was ringing got bad enough and loose enough inside that I was able to tap the tube to make it stop. I figured it was a faulty tube, and swapped in a new one. It's doing the same thing (though not as loose yet).

I took a video:
Login to view embedded media
Camera is close so you can easily hear the noise coming from the tube. Toward the end, you hear me tap the tube, and the sound stops. Really, I think it disrupts whatever is resonating, and it has to build back up to be audible again.

Any suggestions for what might be causing the ringing would be appreciated. I'm stumped.

The PhL-100 offers three inputs: one for MM cartridge and two Line inputs. It includes also a Headphone amplifier.

The article was presented in Audioxpress (Feb 2022), it is posted online and you can read it here:

https://audioxpress.com/article/you...quality-mm-phono-line-and-headphone-amplifier

I have a few PCBs (as shown in the Photo) for the construction of the PhL-100 preamplifier.
The price for one PCB is 55 Euros (shipping is included).

If you are interested, send me a message.

As of 8 September 2022 I have no more chips. See post #92 for details of how to buy in quantity for a group buy or to pick up as the supplier for happy diyaudio ears.
-----
After running a couple of group buys it seems silly to make people line up and wait, so I've been ordering a couple dozen AD1862N at a time. Same pricing as the group buys, without the wait.

AD1865N-J are $27 each, limit 2. No further 1865s, build an 1862 DAC 🙂
AD1862N are $49 per pair, limit 2 pairs = 4 chips

Often I have DAC and PSU 1 boards in stock, add $3 per board.

Shipping is per order:
US shipping $14, which is insured (ie, I'm responsible until it hits your mailbox)

EU, Oz, NZ, JP, IL, IN shipping $22, which is insured to most, but not all places. The post has been good with no losses and I've built up a reserve from the shipping fees so I'll personally insure to EU, Oz, NZ, JP, IL, and many other destinations.

Payment via Paypal in US$ or €, or € bank transfer @ Wise. I try to ship within 1 business day of payment and will send you tracking info once the package is on the way.

Cheers-
Ed

In the absence of a manufacturer's recommendation is there a way to determine optimum bias adjustment settings?