Hello from Geeece i am Interested to restore a Brionvega Radio fonografo

Hi i'm John from Greece and its me first post. I already have build the Pete Millett's NuHybrid headphone amp and now i'm intending to build another project from pmillett. Greetings !!!!

Hello folks;

I wonder what is you favorite best looking preamplifier, amplifier or player from outside.

Here is my favorite enclosure;


🙂

The series notch filter is used for eliminating/reducing impedance peak at resonant frequency of any drivers. However, since the frequency response curve of most drivers provided by manufacturers still can be roll-off smoothly at the low frequency side, why do we need to eliminate that impedance peak due to resonance? Please help recall my memory.

Also, most of modern speakers tend to have crossover points at lower frequencies compared to those loudspeakers in the 1980s. For instance, the modern 3-way speakers have 200Hz and 2kHz while the 80s speakers had 450Hz and 4.5kHz crossovers. However, I found some of those modern speakers haven’t had any (series) notch filter to handle the impedance peak at resonance anymore. So, does it mean some designers ignore that impedance spike? In all, is the imp. peak/resonance really matter?

Hello. I had the good fortune of purchasing 8 CSS WR125STR drivers. Problem is: I can't find a data sheet with the T/S parameters . . . anywhere.
I even e-mailed CSS, but even they said they don't have them. I know you've designed a lot of cabinets with these drivers. Does anyone have a PDF they can post or send me?

If someone has a pair of boards assembled or not let me know. Need another set to go balanced

In celebration of the launch of the new Aleph J Zen Mod edition, I'm offering up 1 fully built PSU and 2 power supply PCB kits to Aleph Jzm builders.

24 May 2024 - UPDATE - I found the pre-built PSU in my stash that I was looking for. I'm adding that to the raffle prizes!
#1 GRAND Prize - Choice of Fully built stereo Supply, 2 Rectifier snubber PCBs, 2 bridges - OR pass this to the next winner and go for one of the other PCB setups
#2 & #3 - Choice of one of the 3 PSU board kits below. I'll include bridges. If you get the stereo PSU I'll include Panasonic 0R47 Resistors.

Of course, anyone is welcome to enter, but it would be ideal if these boards went to new builders looking to get started with their first First Watt project.

Winners have the choice of 3 power supply styles from my stash:

For a single donut stereo build: 1x "New original" F5 dual rail decoupled power supply board and 2 rectifier / snubber boards. This is the Power Supply shown in the brilliant build guide by @ItsAllInMyHead

If you're considering a dual mono or monobloc build, there are 2 additional options available.
For monoblocs: 2x V8 CRCRC power supply boards, 2x CL-60/AC Cap boards, and 4 rectifier / snubber boards
For 2 donut dual-mono build: 1x W12 CRCRC power supply boards, 2x CL-60/AC Cap boards, and 4 rectifier / snubber boards

Rules:
To be eligible you must be committed to using this on AJzm amp build
Must built by end of 2024 (I don't want the boards sitting in drawers)
I’ll cover shipping within the USA. Outside USA I'll cover shipping up to $10 USD. I'll ask you to cover any additional cost.
I’ll keep entry open until 12 noon Eastern time on Monday 03 June 2024. From there, I’ll take the last post that contains all entrant names, randomize with random.org, and the top 3 spots will be the winners. Spot #1 will be the Grand Prize winner. I’ll post the screenshot - it’ll be the winners' responsibility to pm me with their shipping info.

I have a Grounded Grid preamp. The board is from Analog Metric in Hong Kong. When checking the voltages without tubes the voltages are substantially higher than specified.

HT is 16,9V. It is supposed to be 12,6V
+200V is 236v
-200V is 238V

All components seem to be the correct ones (I have however not measured them).

Is this big difference to be expected, or is something wrong?

Hello DIY'ers, I've been an avid reader of this forum for many years and finally decided to sign up!

I'm into designing my own speakers for both commercial and diy use from the likes of atlasharmonic (formerly Atlas and Hurd) and thespeakerproject.com.

Only here to read what people are building and comment from time to time.

Thanks for having me!

Cheers,
Atlas.

Exciting news! The diyAudio store is now the exclusive distributor for limited quantities of LSK170 and LSJ74 JFETs from Linear Systems.

Watch the announcement from Linear Systems on YouTube!

Please post any questions you have in this thread. We'll be posting information shortly about the difference between the grades. Depending on your application, different grades may be the most suitable.

A comment from Nelson on grades:

Nelson Pass said:

The B through D and most of the A would not be a problem for the ACA, and a slight adjustment would allow down to the 2.5 mA figure without problems. Most of my projects would want a B or C grade as most desirable, but it’s not a big deal.

Click to expand...

Has anyone integrated a Clone Note LDR attenuator into their Salas DCG3 preamp?

Newbie here. I just picked up a pair of Tannoy Mercury M1's for free. The owner said the woofer was dead on one and I thought it would make a suitable first DIY audio repair. I connected it and the woofer wasn't dead but was sounding like a tweeter. Opened it and sure enough someone had connected the tweeter wires to the woofer and vice versa (maybe when they were adding polyfil to the cabinets). Checked the tweeter with a 1.5 voltage battery and it was definitely dead. I had an old pair of Gennexa (optimus) Pro X7s in the basement with tweeters that looked almost the same (both speakers are 8 ohm though the Gennexa's are 89 db sensitivity and the Tannoys are 87 db). After fashioning a new mounting plate for the tweeter out of fibre board, I connected the tweeter and was pleasantly surprised that I couldn't hear a discernable difference between the two speakers. What I'm wondering though is whether the original tweeter might be salvagable and how difficult/expensive it would be to fix it? Thanks.

Is it possible to measure the response of a woofer, or of a complete system, as can be done with a UMIK-1, but with an imm-6, and using REW?

Hello everyone,

I am working on developing an automotive class AB amplifier and I need some help with designing a DC-DC converter. I want to convert 12V from the car battery to ±35V symmetric with minimal ripple.

Has anyone integrated a Clone Note LDR attenuator into their Salas DCG3 preamp?

hi all main bearing has alot of grey grease in there - the whole shaft covered - i thought it was supposed to be thin oil?

Hi again!

Going through some of the old school amplifiers I have accumulated over the years, and I still have a Hifonics Boltar VIII, A few years back I posted on this forum looking for the connectors. I did contact Steve at Zed who would sell me a used set for $100, not worth that to me so I will probably remove the connectors and replace them with something else or solder wires directly to the board.

While exchanging emails with Steve, I started to discuss the updates/upgrades for this amplifier. It is a service he offers for a reasonable charge, but it is more that I want to spend on it. Unfortunately, he has no support for DIY types. It would have been great if he sold a parts kit and instructions.

So, first question is- Anyone else know the details of the upgrade process? Replacing the capacitors is pretty obvious, but he also mentions modifying the power supply (drive circuit, and regulation). He also mentioned those upgrades in this post: https://www.diyaudio.com/community/threads/hifonics-boltar-viii.367163/

Second question is- even though I think this amplifier works, there are two resistors that look to be "crunchy". One is labeled R14, the other (right next to it) I can't read. My thought is to remove them, and measure but that may not be accurate considering their appearance. Anyone know what this is supposed to be?

Also would love some schematics, if they are out there.

Thanks!

I have never encountered one of these before, but I got an A600.2 that has a red light only. Both rails are present, no shorted output transistors on either channel. I did notice one channel has 150mV of DC offset, whereas the other one is more like 13mv.

Maybe this is why the red light is stuck on, not sure.

Anyone have a schematic? thanks.

Hello!

I have a question. We discuss very often the pros and cons of fixed vs self-bias for output stages. But I do not see often hybrid bias, where self-bias and fixed bias are combined, into something like this:

What are the drawbacks of this approach? I can understand that it is a bit more complex, even when the current source is replaced by a resistor. But I can see a big advantage, which is reducing the power dissipation of the bias component, while still retaining some of the self-bias advantages. Using a CCS instead of the bias resistor makes it even better.
I'm sure it is used somewhere, but not very often. Any ideas?
Regards,
Jose

Hello! I am new here, I am a student and i am learning electronics repair

I would like to share with you my project - Internet radio with touch screen and stations web management system


See it on youtube:
Login to view embedded media
It is very easy to build using only 3 components: Login to view embedded media
My YouTube channel contains various versions, including one with SPDIF Hi-Fi output:
https://www.youtube.com/@arielhhhhh

Article about the internet radio:
https://www.hackster.io/news/build-your-...59513be786

Software, documentation and enclosure 3D print files:
Internet_Radio

Build it yourself option:
https://www.tindie.com/products/33913/

I joined in 2012 but never posted. Now I have more time to work on my hobby. I have DW loudspeakers now since 1977, had those replaced under warranty in 1980. And with some maintenance they lasted until 1999 when I took them apart after several cells had died. I now own a pair of Martin Logan ESL. Since the Dayton-Wright site is no longer functional, I thought I'd post an analysis of how the loudspeaker developed over time and all the engineering decisions Mike told me about. So these posts are on the Martin Logan users forum.
I used have amplification on the cheap by using two bridged Hafler amps. In the mid 80s I designed my own amp for them, which served me well and i still have it running today into conventional speakers today. Back in those days we did not have WiFi so the amp has no protection against that kind of local high power ingress. The caps are all tired now, so its time for a rebuild.
Here is a picture of a dual mono amp with power supply shoehorned into a Hafler DH100 case, but using 6 output devices per channel.
Anyhow I had to post here before I could post an answer to someone that just bought a non functional DW speaker recently.

Greetings

I recently bought a Denon POA 2800 Power Amp and am in need of 4 each 2SK215 & 2SL78 in addition to 2SB1328 & 2SD2004 would be grateful if someone could let me know.

Thanks in advance.

John

Does anybody have any idea who makes these radio's, and where am i likely to obtain a single drive CD mechanism complete to suit this radio?. I've looked high and low, with no luck. I have sent emails, with no reply. There are millions of these cars made all over the world. One would think that a couple of the sites i looked at had heaps and heaps of mechanisms, but none the same as these. I have three to repair, so far, and they are quite easy if you could ever get one of the CD drive mechanisms. Somebody obviously makes these radio's, but it appears to be a big secret, for some reason. I got one reply from one manufacturer, who makes these units for just about everything else, but Hyundai iLoads. They have to exist, it's just a matter of perhaps somebody out there who has fixed one of these before now. Another problem with these radio's, which is the standard radio in these cars, is the four screws that hold the bottom circuit board, come loose real easy, and maybe short something out, not quite shore, but, if you ever buy a new one, the first thing to do is take the top cover off, remove the CD drive unit, and tighten those four screws. Any help in purchasing a couple of these drives would be greatly appreciated. Thanks, and i love this new site, as i am fascinated with this stuff now and have been for a while, after a few mistakes that is. Cheers, Wal.

HI All.

I understand that Aurum Cantus made changes to this tweeter a couple of years ago.

Does anyone know what changes they made? I can't find any info for the specs of the old vs new version.

Thanks!

Hi everyone. From an academic sense, I know very little about power amplifiers and circuits. I have learned a great deal about amplifiers from YouTube and the DIY audio community. To gain some understanding of the fundamental construction of a transistor amplifier, I have collected some circuit diagrams related to amplifiers from the internet and some sketches from the PCB. what I have learned or what experience I have gathered, or, you may say, stolen, 🙂 which I wish to implement on my own designed PCB. This ambition led me to create this schematic. In order to create the amplifier, I would like to ask that you provide some valuable advice and constructive criticism prior to routing the PCB.

🙂
Thanks
OPU

Hi. Anybody still have a pair of Peerless 831727's?

Hello! I have a problem with the t1500 1bdcp amplifier. At low volume there is constant noise after the amplifier warms up. It looks like the problem is in the throttle output ring. it seems to have lost inductance. can you please send me the circuit diagram of this amplifier? I want to replace the ring and throttle, but I don’t know which one. The frequency at which the driver operates disappears; it is not clear why this happens. I checked all the little things, everything is fine. There is a suspicion that the ring on the output choke has lost its inductance due to time and heat. The amp also gets very hot even when not playing.

Hi Forum
It has been over 6 years ago that I build my big 3 way speaker.
"building the best 3-way full range speaker"

Earlier this year we did a big renovation of the living room with attached kitchen and when this was done, I found the speakers a big too massive.
Maybe it is my age and the testosterone is diminishing but the speakers always were big.

So I am starting a new design, with 20% smaller footprint and 30% less volume.
Still a large speaker but a bit better suited to the room.
I will start a different thread on this built.

But..... I want to improve some parts on a design that will borrow a lot of the original as to my ears it is still a fantastic sounding speaker.
In the preparation to this new design I want to simulate better and measure more precise.

So, I bought an Earthworks M23R reference microphone.
This unit has an insane flat curve with a correction file that onlu has +/- 0.16dB of correction.
I designed a new mic stand by combining some parts of existing good available mic stand parts.
The reason not to go with a standard mic stand is the possible reflections the boom and mic-clamp can introduce.
So the ideal speaker measurement setup is kind of a floating microphone with nothing close that can cause reflections,

The parts I used are:

• The main tube of a Gravity MS 23 XLR B Microphone Stand
• K&M 252 Black standard mic stand where the main tube is build out of 3 parts so the vertical pole can go pretty low
• An Adam Hall SDMSB 190 Stereo Bar that gets mounted on the K&M stand by standard 3/8” threaded bolt
• A K&M 21105 Counterweight (that I mount to the mic tube with a rubber door stopper)
• Some bolts, nuts, washers and 4 black electricity tube clamps.

And this is the result:

Amp came in with low ohm light lighting up and barely any power draw. I found Q835 which is an FQP30N06L signs of overheating. I replaced this part with IRFZ44. The low voltage supply will turn on with 1A for 15 seconds. The new IRFz44 gets raging hot. I put a small sync on it for now.

The amp does fully power up but with Q835 overheating its not stable to test much out. Gate looks alright, a +4v square. It could be cleaner but seems to be alright. Drain is very jagged. Looks like a downward 2 steps. I would have expected this to be cleaner. First image is with REM quickly applied. Second image is after about 15 seconds. 10vDiv, 2uS. There is always about 13v on drain.

Gate resistor for Q835 is 47 ohms and absolutely fine.

The 0.1ohm resistor and 33ohm resistor near Q835 are good. All diodes before and after the low transformer are measuring OK.

U802 is measuring:

1: 13.6
2: 0
3: 5.01

OpAmp regulated voltage seems OK at +-14.6v
Any thoughts as to why Q835 is overheating?

Hello,

my friend Oli (Rese66) told me, that some of you might be interested in my current project. So I post some photos and in case of any questions, I will try to answer them. Okay off we go.

What is in the speaker:
1x Faital 18XL2000
1x Faital W8N8-150
1x Beyma TPL150 the Horn only
1x Dayotn AMTPRO4
2x t-amp Quadro 500 DSP

And here some pics of the speaker build. I name the speaker "fatally", because of the Faital speakers and it's enormous output.

I have created a 10W amp (2.5A) in QSpice and I'm preparing to build a prototype on Perfboard.
My question is what should I target for the current across the diodes?
I have attached datasheet screenshot. My interpretation is I'll only need 7mA which seems too low.
Please take a look at the datasheet and advise me if I've got this calculation wrong.
Both hFE and fT are over 270mA and 270MHz respectively.

Also, I have the option to use dual channel. Advisable or superfluous?

Many thanks for reading.

I have viewed several great and very informative posts already here on the site regarding my exact amp. Even have noted some of the exact same issues with mine that I know will need fixing.

My first initial question is my gate resisters on the PWR fets are toast of course as seen on many here already. I noted these are 47 ohm resistors I believe Mr. Perry stated in another post. Mine however are not through hole type like I have seen here but mine are surface mount or where I should say they where really smoked! pretty much all crumbled off the board.

Anyway they said 470 on the tops of them but they are only 47 ohm? and Question 2 is one of the pads on at least 1 of the bad resistors surface mount area looks like it was completely burned off and there is nothing left for me to solder a replacement too? What can I do in this case? Wishing mine where through put at this point. Any and all advise would be great! So R605s left Pad looks the worst out of all of them again not even sure what to do with that flux and dab of solder or?

Now below this text here is from another JL Audio 250/1 amp where they are using surface mount Resistors as well but they say 470 on them is that still a 47ohm resistor or 470ohm? Sorry for the dumb questions new to this repair thing but find it very interesting! And would love to fix my amp. Also the 2 amps are using the same fets for PWR IRFZ44N which I saw in another post Perry suggests replacing with IRF3205s so will be doing that! Thanks for taking time to review this and for any help guys/gals!

8 plastic cases containing film capacitors, driver transistors, output transistors, trimmers, heatsinks, and so on, for sale.

Having given up on buying a decent Thorens turntable at a cost less than a used car I now have my eye on a used AR turntable.

So... is anyone using one? Are they any good?

I understand they have a good suspension system which seems to eliminate any vibrations caused by someone walking on the floor or sound as a result of high speaker levels.

I need help in troubleshooting my denon pma 520 amplifier that started misbehaving recently.A few weeks prior to malfunction
one channel was playing slightly louder than other and it took quite long for the relay to connect.
What i did was to replace old relay but this didnt help . Now the symptoms are ( and were before relay swap)
1. After turning on relay still takes too much time to click
2. after the click amplifier can either:
a) work properly
b) not engaging source selector light , have fixed volume ( quite loud , overdriving my test speakers) and not responding to volume pot or anything else)

turning the cd direct/subsonic/normal selector can temporarily fix the amp ( or spoil if it was working correctly)

I dont know much about electronics but i have multimeter, esd meter and know how to solder so obviously i can change some components like capacitors etc but need instructions/suggestions how to find faulty ones and where to start.

I attached a link to short youtube video showing the issue.
Login to view embedded media

Hey I am looking for a replacement for sw 180n75 mosfet 1 fet failed amp went into protect when removed it turned on normal. I can't seem to find it.

I have a Marantz 250M here from the original owner who says it worked fine until he put it in a new system and the speaker leads were shorted blowing one channel.

He had it worked on, but it is still not working. I think it was checked out but not completed.

I have the schematic. Does anyone know the story behind these Motorola SJ2519/sj2520 output devices?
Are they simply beta selected?
The beta range is listed for many of the transistors.

This is a nice looking piece, however it is a rather unusual design. Seems it does not tolerate a shorted output even though it has protection.

Pete B.

While going through my project bits, I came across some nice, Seas drivers.

I have no idea what I bought them for or what I could use them for. They’re not really full-range drivers, my current interest, and they’re 15ohms, so semi-custom.

Anyone know what they might be worth?

For sale stereo kitt, price 44€
LM4780TA with PCB with supply and stereo potentiometer bare PCB, also the connectors are included.
Alps Pot and relay aren't supplied, relay is used to bypass Pot.
Tracked shipment to European union
Skematics sended together with articles.
Payment by PP
If you enjoy this kind of stuff maybe check my offers related:
https://www.ebay.de/usr/dialedinmusic?_trksid=p4429486.m3561.l2559

LM3875TF stereo set for sale, price 75€, if you wish with heatsinks the price is 106€ solid walnut is included,check pictures..
I also offer this in mono channel and a full diy kitt, if you want to check take a look on the link.
LM3875TF genuine amplifier IC's assembled on Enig PCB's put together with high quality parts: Allen bradley carbon resistors,
Nichicon electrolytic, Evox mkt's and Murata ceramic caps with bare supply, pre-amplifier and Potentiometer PCB,the supply
connector is included.Pre-amplifier and Potentiometer are also Enig PCB's.
Alps stereo Potentiometer and relay aren't supplied, relay is used to bypass Pot.
Stereo amplifier 56 watts rms good for Hifi stereo system or amplified speaker.
Tracked shipment to European union
Skematics sended together with articles.
Payment by PP
If you enjoy this kind of stuff check my stuff related:
https://www.ebay.de/usr/dialedinmusic?_trksid=p4429486.m3561.l2559

It was suggested that it might be worthwhile posting my experience as a Guinea Pig 😉, but first a BIG THANKS to all who have made this project possible! The level of professionalism and dedication exhibited should be an example to other companies, especially those in the retail segment.

So far my build is moving along nicely, pic to follow, but I wanted to mention a couple of things that I have discovered. First off, though I am using Kester solder w/ rosin, I still prefer the look of the finished product more when flux has been added. In general I'm finding that the less flux the better, it is still a PIA to clean off.

For those who are having difficulties getting some components to line up nicely, things like LEDs, Jumpers etc. I find that putting the slightest touch of solder on 1 hole, heating it and inserting a leg, with LEDs obviously the long leg, till it is properly aligned, solder the other hole then touching up the first joint.

What has everyone come up with for filling the tiny spaces you see in these pictures?

I have been just filling it with putty but the issue is that sometimes the stain doesn't quite take right in that area.
I am considering mixing the putty with some of the stain to hopefully blend it buuutttt, that might just double stain that particular area and make it way worse.

I've quite a few 2w Kiwames and the following Charcroft Z foils & Mills resistors:

1 off 47K
4 off 1K2
2 off 15R
4 off 150R

Mills:
4 off 0R56
4 off 0R47

£10 each for the Foils and £2 each for the Kiwames, £5 each for the Mills. Free UK postage. PM me for Kiwame values, I've boxes full

Kiwames are mostly new, foils & Mills have been soldered

Hi,

Only just joined and apart from my introduction this is my first post.

Hoping someone can help me out here.
My beloved Marantz PM7200 has developed a problem, occasionally when turning on I will get no sound from one or both of the channels, the only way to fix it is to turn the volume up to max and wiggle it about a bit and then the sound comes crashing in. It's usually fine after that.
It's a random fault and I can go weeks without it happening and then it will happen regularly before behaving itself again.
I've had it from new (so at least 20 years old), any pointers would be helpful, I don't think it's the protection circuit problem but I'm happy to be corrected (I've used some contact cleaner on all the switchs, dials etc. but doesn't seem to have improved things)

Thanks,

Hi

I am trying to identify the part number for the switching(PWM) IC used in the SMPS power supply for this amp. (photo attached). Some one who repair this power supply earlier has intentionally erased the part number. Please assist.

Thanks

Hi, glad to be a member of the forum. Have loved and tinkered with Hifi for about 40 years now and no signs of stopping yet.

My current setup is a Michell Tecnodec with modified Rega Arm, Graham Slee Phono Stage, Marantz PM7200 and Dali Menuet speakers. Sounds perfect in my (not too big) front room.
I also can't resist buying up Hifi and Audio bits and pieces whenever I see them (Boot fairs, etc.) and spend many happy Sunday afternoons restoring them (just need to start selling them afterwards as running out of space)!!

Hello all, I've been a long time observer into this forum. I have a basic background and have been planning a project with my 1995 f150 radio, which I will undoubtedly need some sort of advice down the line.

Most speaker drivers have symmetrical Fs impedance peak but there are drivers (woofers and also tweeters) that have asymmetrical Fs impedance peak, which looks 'strange' intuitively if you saw many raw driver Fs impedances. What is the source of this and what are the realworld consequences (mainly audibility) of such an impedance? Thinking mainly about woofers where tipically using the drivers at it's Fs.

Examples of asymmetrical Fs peak:

https://sbacoustics.com/product/6in-sb17nrx2c35-8-norex/


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

Good evening good people.

I'm trying to repair a GK mb112 amplifier. As far as I can tell, the power amp (Icepower 50asx2 btl) is dead. On the manufacturer's website they sell for 77$ in bulk and 152$ a single unit. 152$ is too expensive. It's basically the price of a new TC electronic BAM 200. Since they sell in bulk for 77$, maybe it's possible to find them selling for around a 100$. Do you know somewhere where they sell them at a reasonable price ?

I would like to measure my cassette deck when I get it restored with new belts, and probably checking the turntable too at some point, and thought I would ask where to find a suitable smart-phone app that can do it, if such exists.

Found these two apps on Google Play Store:
https://play.google.com/store/apps/details?id=com.AM.AM.RPMSpeed&hl=en_US
https://play.google.com/store/apps/details?id=com.vinylrpm&hl=en_US

But these seem to be aimed at turntables only, can one use any of these for cassette deck measurements, or do anyone know of an app that can specifically measure cassette deck W&F ?

I assume the measurements have to be done in conjunction with a prerecorded calibration cassette / vinyl.

Thanks

ps. some links to useful SW etc.
The latest version 8 of the WFGUI program by Alex Freed, ANT Audio
http://www.ant-audio.co.uk/index.php?cat=post&qry=library
http://www.ant-audio.co.uk/Tape_Recording/Service/wfgui_8.zip

edit: BTW sources for calibration cassettes and vinyls would be good too, of course Ebay have a lot of stuff as usually but not sure of the quality so recommendations are welcome.

46 - Sylvania in original box £65
46 - Sylvania in original box £65
46 - Sylvania in original box £65
46 - Sylvania in original box £65

Postage at cost. I don't post to Italy, China, Singapore. Possibly other Asian countries as well. Japan is OK.

I have created an account some times ago, but never posted anything until today. However, I have been reading/searching the forum often and I have learned a lot. It is a great place, thank you.

8 2sj74 and 8 2sk170 original jfets from punkydawgs for sale

Hi all,

I have a few 90s Kenwood active crossovers meant for car use and they have an interesting IC(s) right at the input to cancel out common mode noise.

They are given different names in different models and googling the part numbers doesn’t turn anything up.

They can be found in the service manuals for these two:

https://ia902301.us.archive.org/20/items/manual_KEC300_SM_KENWOOD_EN/KEC300_SM_KENWOOD_EN.pdf

Page 9, given as IC1 “lNH-02080”

And for this model

https://ia902308.us.archive.org/32/items/manual_KEC301_SM_KENWOOD_EN/KEC301_SM_KENWOOD_EN.pdf


Page 6, given as IC2 “NH384”

Anyone heard of these, why these rather than the other types of op amp (upc4570) used in these crossovers?

Hi,

My wish is to fully simulate speaker with VituixCAD before buying any of the components and building physical cabinets.
Project in details:
-Bookshelf form
-Passive crossover
-2-way with only 5,5 C 1,5 CP coax driver
-Bass reflex 5-10L of internal volume. Manufacturer gives 8L or 9L as recommended in its documentation, quick sim with WinISD also gives "ok" results in 5+ liters range
-Narrow baffle with massive edge radius, 50mm or similar. Only to fit the driver and then some more for rounding/beveling

I already invested some generous two-digit hours of time in understanding some of the Vituix tools, but... Unfortunately it is a tremendously complex software comparable to the collection of the scientific calculators but still with no clear workflow how to actually simulate the speaker in digital form before starting the physical process.

What I did:
1. Took the freely available measurement files in picture format from dibirama.it. I assume they are made on large baffle, 2pi space, 1000mm at 0 degrees H and V.
2. Made FRD and ZMA files with "SPL Trace" tool in Vituix.
3. Simulated Baffle Step Loss with "Diffraction" tool, opened FRD file from my trace, then exported FRD files with 10 degree steps. All the steps above for both drivers - tweeter and woofer.
4. In "Drivers" tab created 2 drivers and opened bunch of FRD files and ZMA file. Everything seems to look ok.
5. Started to play with crossover, manufacturer suggested as a starting point.

This is what I got with dibirama.it SPL and impedance data AND manufacturer suggested crossover:

dibirama.it data with tuned values of manufacturer crossover:

The same with manufacturer data AND manufacturer crossover values:

I do not worry much about the 100Hz range simulation, as the vented box behavior is pretty much clear to me. Also, I have made all the simulations in the virtual 1m distance, because I think the manufacturer and dibirama.it measured at the same distance.

Below are manufacturer polar diagram of separate tweeter and woofer:


It seems dibirama.it + manufacturer crossover is even better than the manufacturer data alone.

I do believe, that manufacturers make their data by cherry-picking their drivers for measurement or/and simply by painting them to look more beautiful, but my questions are:
-Does the driver look listenable from my simulations?
-If not - what could be reasonable crossover for this driver?
and most importantly:
-Are my simulation steps right?

Here is manufacturer data of the completed speaker with their suggested crossover. All the ripples are in 2-3dB range, but my simulation shows closer to 5-6dB, a pretty big difference:


It is a pretty expensive experiment to do in physical form, as drivers and crossover components will be at least 250-300EUR, I want to make sure it will not disappoint me. There are not many projects with this driver, and also I am scared of crossovers with ridiculous amounts of components (15+...).

Thank you for your thoughts

I find the Heath AA-32 a pleasant little amplifier perfect for a office or den.
It is small and simple, gives off moderate heat and in my experience they are long lived and reliable.
Although simple and modest in design and measured performance I find the AA-32 produces a utterly pleasant musical experience when called on to fill in the acoustic spaces in ones den or office with pleasant background sounds to work by. While the output quad of NOS 6GW8 tubes with many hours on them still produces a acceptable amount of output power at moderate distortion they have now lost about half their emissions. One can see the writing on the wall for this set of tubes. So what to do as for me the prices of a set of NOS 6GW8 tubes just does not compute.

My first tact was to switch the outputs with the available and low cost NOS PCL86, the same tube with 13V heaters. Searching for a available small and affordable filament transformer that would fit under the chassis to provide the 13V for the 4 PCL86 proved harder than I expected. There is little space under the AA-32 chassis. I did find a 7V 10VA (6.3V+7V=13.3V) unit from Amgis part number XF-10224 that is 23.5mm thick and should just fit under the chassis however there seems the be a minimum order of 10 pieces for a total cost of over $250 and a 26 week lead time. If anyone knows of a source of this transformer or a replacement that can be ordered in singles let me know as this is still a possible way to go.

As part of my preparation for changing the output tubes I figured to audit the passive parts in the output stage. The result was there were almost no resistors and few capacitors that were still within the original specification. Resistor value drift of 30% was all over the amplifier's power section and it is testament to a robust and forgiving design that the amplifier still sounded and measured close to the specifications of the unit when new. It did seem clear that any tube replacement would need to involve replacement of almost all the power sections resistors and capacitors. Given all the parts had to be removed and replaced I figured 4 new sockets were in order. Can you see where this is going?

Now looking at rebuilding the output section from scratch why stick to 6GW8 tubes? How about replacing the original design with a new design using other tubes. Yes it would no longer be original a valid concern but nether will it be original with a extra power transformer stuffed under the chaise.

Looking around what I had on hand I came up with a bunch of Russian 6F5P, a power pentode and low level triode combo designed for the TV industry as a vertical sweep amplifier.
These have a max plate and screen voltage of 250V close enough to the 290 and 280 the AA-32 runs at. When considering sweep tubes, ratings can often be pushed in audio amplifier service in my experience. The 6GW8 data sheet lists S=10.5 and the 6F5P data sheet has S=7 suggesting the 6F5P would lack some gain, a possible issue as the simple drive circuits in the AA-32 are pretty limited in both voltage swing and gain.
Peak plate current @ a=75V g1=0V is listed on the data sheet curves for the 6GW8 at about 107mA.
Looking as the 6F5P peak current is shown as.. well plate current is not show as it is off the charts high @ over 200mA and this is with only g2=170V? What would happen with g2=250V or more? The 6F5P it seems is a sweep tube with a very sensitive screen not at all like the 6GW8 and clearly dropping it into a AA-32 like circuit will not go well. Add in the triode in the 6F5P has a u= 70 VS the 6GW8 triode u=100. With lower gain and limited drive into a pentode needing higher bias voltage and more drive the 6F5P seemed doomed.

Having owned a utracer for some years I have leaned the data sheet tells only a very limited story about a tube. There are many more operation conditions for a tube than what is listed on the data sheet that can be of interest if you do not mind straying off the beaten path.
So I ran some curves on the 6F5P and the 6GW8 looking at peak plate current VS screen voltage and found that the 6F5P hit the same g1=0V peak plate current at g2=100V as the 6GW8 hit at g2=280V. So the 6F5P can deliver the same peak plate current as the 6GW8 with only 100V of screen voltage. Hmmm.
Next I ran the 6F5P plate current VS the g1 voltage with a=300V g2=100V.
The 6F5P result for a=30mA was a g1=-9V the exact same g1=-9V for a=30mA as a 6GW8 with a screen voltage of about 280V.
With the same peak plate current and the same bias voltages suggests a 6F5P with a screen voltage of 100V has almost the same characteristics as a 6GW8 at a screen of about 280V.
I build up a spice simulation of the current AA-32 circuit and a new version using the 6F5P with a screen of 100V both using a 290V plate voltage. The result was both versions driven with the same drive voltage delivered the same power output into a spice model of the AA-32 output transformer with about the same THD. This was fun to see.
Now lets see of we can replace the driver stage with 6F5P triodes u=70 VS the u=100 of the 6GW8. I was hopeful as the 6F5P triode has S= 7 to a low S=1.6 of the 6GW8 and triode realizable gain is influenced by S as well as u. The AA-32 input stage gain simulated out at 33.208dB @2.14% THD and my version with the 6F5P triode resulted in a gain of 34.717dB @0.75% THD with no feedback. Looking good.
As the 6F5P triode has high S there was no need to bias it separately like the original AA-32 for the split load phase splitter so I lost the blocking capacitor and grid leak resistor between the gain stage and the splitter of the AA-32 design saving a few parts, improving the low frequency phase margin and dropping THD.


So the 6F5P version came out with a gain 1dB less and lower in THD. Very workable with a caveat. The 6F5P due to sensitivity of screen voltage changes would need some sort of screen voltage stabilization circuit in operation to set the screen voltage and so the operating point.
Below I have attached the spice circuit diagrams for both the original AA-32 and the 6F5P version.
For me the jury is out on how I will deal with my aging AA-32 output tubes.
The above may be useful for others that have a unit they would like to put back into service that uses the 6GW8 or anyone who wants a nice simple good performing amplifier based on the 6F5P.

https://www.kartesian-acoustic.com/copie-de-monitoring-studio

Even better this one - what a bargain at 980€ !!

https://www.kartesian-acoustic.com/copie-de-wom120-vms-3

Are we in heaven now or in hell 🙂

THD 0.0001%
Easy Project with good performance

I got to hear that T25S sounds very good and wanted to try myself. I like waveguided tweeters so I started making experiments and this is the 1st version that measures reasonably ok. WG is quite shallow, 20mm, with overall diameter ~160mm. WG was 3D printed, low quality, so it may cause some irregularities. In this stage it is just about finding the direction. I do not use any advanced methods to design WG.
Distortion measurements is excellent. FR irregularities ~9kHz somewhat copies native tweeter FR measurements.

And as I have 18W/8542-10 around, I tried to measure it as well to model 2way crossover. This looks definitely good.

This thread is a follow-on to my thread last year on getting TDA1521 to play nicely in parallel with lower gain. In short, it wouldn't cooperate so I decided to switch the design over to TDA7294. Yesterday we got the first in-a-box prototype up and running. Here's a pic to whet your appetite :



Probably the most unusual thing about this amp is its power supply, a hybrid of linear (a standard toroid) with a high powered buck regulator. The reason the power supply isn't an off-the-shelf switching brick is because I wanted to avoid common-mode noise which comes as standard with such a choice. I did much of the development work on the buck regulator last year but its still not quite optimized - you may note the buck regulator's output inductor isn't tied down to the PCB because its very much a work in progress. Some of the back story to the PSU is told in last year's thread. I've attached the amp board schematic, there's nothing much out of the ordinary there except perhaps for it being a single rail design and the provision for an external bank of supply rail caps. This prototype has about 85,000uF of rail capacitance per channel by virtue of its two out-board cap banks. Having a buck reg means the soft start is built in so with this amp there can't be such a thing as too much rail capacitance.... 😎

(More to come later)

Hi, what you guys use as insulators for transistors on heatsink ..
Is Mica better then Silicone ( Google says. as W/m-K , some silicone has 1.1 and Mica 0.5. )
Are these good from old power supplies. .?.

I am building a speaker with curved sides using a couple layers of bendable 3/8" birch ply (wiggleboard).

Question #1: What glue is best under tension to attach the bent sides to the skeleton frame? There will be front, back, and 5 pieces horizontal crosspieces, all 3/4" ply. I was planning to use titebond 3 along each skeleton edge to attach to the bent ply, and some screws down each end to hold in place while it dried.

Q#2: for the second layer, i intend to coat the entire first bent panel with glue, and then wrap the second panel. Is the same titebond 3 a good choice for this as well?

Increasing distance to the source of sound can, of course, attenuate SPL. e.g. a doubling of the distance might lose 6dB depending on the environment.

However, I've frequently seen this principle applied to subwoofers in small rooms, and I'm not sure this is correct - certainly it doesn't seem to tally with my past experience. I presume this is because at low frequencies, the room's modes start to dominate; the louder areas are more random and may not even be nearer the subwoofers. Even with multiple distributed subwoofers, the peaks and troughs may be less pronounced but the aim is for more evenness throughout the room.

Am I correct in my belief that listening distance in a small room (say in the order of 5m/15feet square) is largely unimportant, or should I still factor in some distance attenuation when choosing what SPL to design for?

Thanks,
Kev

Hi, does anyone know the bias current for this power amp?
One channel is not hot, the other is very hot

I recently picked up this integrated amp and am planning a full restore. I know the SM is available to download, but taking a shot to see if someone has an original with the bigger fold out pages they don't need anymore.

If anyone has one of these they don't need at a reasonable price please let me know. Thanks!

Hello, I am from Tehran
My setup includes:
Jamo c109
dussun v8i
teac ud301
imac
pcocc speaker cable
diy occ interconnect

I am looking for information to make TDA1541 over sampling with usb to i2s input

I am making plans to bring the plasma tweeters to BAF! I already have a friend in SF who can bring a helium bottle.

I have a number of 'smoldering' questions:

• where will it take place
• need a pair of fast (planar) speakers to provide mids and lows (x-over is at 1kHz) to go with them
• need an amp to drive said fast speakers (gosh. who might have that, I wonder 😏 @Nelson Pass )
• need a good quality music source - either digital or analog as my x-over accepts both

I know it's way early for a venue to be chosen, but I am itching to go!

Tony

Hello there,

I would like to measure the THD, Frequency response, Output Level etc of a preamp and DI that I have made with the help of an Oscilloscope.
Please can you help me how to do it?

Thank you very much.
George

I have a friend that runs a photography class and uses these power supply timers dark room lighting. Apparently they’re quite important to him and he has had some failures of the power supplies. I’ve seen that many others have as well. It looks like the common part to fail is a little switching triac, a solid state relay.




He knows that I am into electronics and that I etch my own boards. he asked if I could build him some new boards for his power supplies using a different device since they are no longer available. You can get them from for China for fairly cheaply, but he knows other photographers that have gone this route and the devices from China are pretty poor I guess. So he was hoping I could redesign it. I see no reason to redesign it, just put in a suitable part. My thought is that they are failing because they use such a pathetically small heat sink for the device. I’m trying to figure out the exact load on these power supplies. I was hoping to get some of the lighting back to my house, but it would require removing the lighting from the dark rooms, which she was hoping not to do. Regardless, it is ready for 12 A at 250 Vac, I would think it would benefit from heat sink bigger than this.



At first, I was thinking a standard physical relay, but if the load was immediate, the arching on the contacts would not be great. so I’m back to a solid state. I’m thinking about just getting pretty much exact same device from a different company rated for either the same or more current and mounting it to an appropriate heat sink. There is plenty of room in the power supply case for a substantial heat sink. I don’t want to mount it to the case of the heat sink since it has line voltage, but it’s easy enough to isolate the heat sink from the rest of the chassis.

Similar to this
https://www.digikey.com/en/products...nduYfIIAt9b30ioSpvswMA3aq_YbhqdRoCQPsQAvD_BwE

But being $37 I was hoping to find something a bit less expensive. We were hoping to repair a total of 15 to 20 of these power supplies that are used between him and a couple of his other photography friends. so kind of just reaching out to see if maybe anybody is familiar with these types of devices and can point me in the right direction.

Thank you,
Dan

Looking to source original/real AD1862s times two. If I can find them I'm considering a build of Miro1360's DAC.

Regards,
Dan

Hi all:

I recently came across a Nakamichi Sound Space 12 sub and satellites. I want to test the sub to see if it works. However, it has a 12v DC jack on the rear to get it turn on, and I don't have a receiver or any other component with a 12V trigger jack function.

What's the easiest safe way to trigger that thing to turn on? I've read that you can't go beyond a certain current limit on a trigger circuit, or you could damage the components.

Let's assume I have extremely little understanding of electronics.

hello all just acquired a yamaha b-2 no sound. i am trying to sell it as i dont have a tech near me i am including a 1000w step down transofmer i wish i could get it fixed but no knowledge nor techs in my area of florida. will ship. turns on. im in the florida panhandle area. looking to break even at $500 for all.

Proud owner here, as of last week. I threw them up onto a pair of table leg stands, just to be sure they're OK after shipping, as a Saturday morning effort. They are.

I'm quite happy with the sound. Now, I need to mount them on an OB design of some sort. Any assistance would be much appreciated!

I was casually thinking I might replicate Decware's "Betsy" design and would like to understand why the "barrel" shape works. Caintuck Audio, the originator of the Betsy, also offers "tombstone" style baffle boards with parallel sides.

Lucky for me, there's a Washington state surplus store very near to where I live, which has tables, desks and other MDF based bench-tops at very inexpensive prices. My plan is to pick something up and start cutting. If I'm lucky, there'll be two of something I could cut into a Betsy, or something with parallel sides I can simply trim to height.

The typical desk or workbench top laminate - my worry is how to get a clean edged, say, 16" circular cut in something that may be 2" thick. I like the standing mass of a baffle like that, but I dread trying to make such a cutout with something like a Sawzall. The Decware speaker mounting is flush with the baffle surface - looks really nice - However I assume the only way to do that is with a router...

Hopefully I'll be choosing a couple of hunks of material to work with this coming week. I could have got a pair of matching 6' diameter 2" thick tables - which would have easily yielded a pair of Decware style Betsy Baffles - for $5 each. I couldnt have lifted them atop my Subaru forrester if I wanted to. What practical width should I be setting my sights on for this 15" and its free air of ~50 Hz?

Thanks!

I’ve ordered my Pluvia 7.2 HD drivers and came across an interesting speaker design. Does the design seem viable? Has anyone built it?

In most of the new cars many of the displays and controls have been moved to a large touch screen and the traditional items removed. In the Telsa Cybertruck that has been taken to an extreme and except for a few things on the steering wheel everything has been moved to the large display. Here is a picture:

https://www.motortrend.com/reviews/2024-tesla-cybertruck-foundation-series-interior-review/photos/

Instead of being able to control things like heater, air conditioner, radio, etc., with a single button and motion you now have to first manipulate several steps on the touch screen to get to the item you want to change.

So are the new designs for the better, or do they in some way compromise safety?

Hi folks!

I am fooling around with Altec speakers, and trying to run the 808 8a + 511b horns with 416a / b style woofers. At the present time I do not have any questions regarding the HPF and horn correction circuit; I am hoping for some basic design input in the spirit of "look this direction".

At the encouragement of an engineer friend, I am learning to use LTspice. The following screenshot shows the Z19 / Altec Model 19 LPF. Top models use TS parameters associated with the 416Z (0.567 mH VC inductance / 11.6ohm series resistance) -- bottom models use the 416B (2.5mH / 6.5ohm series resistance).

In both screenshots, the bottom model represents the LPF circuit with the intended 8 ohm woofer. My intent is to create a model for a 16 ohm woofer which corresponds to the frequency filter response with the 8 ohm woofer.

First model, with matching crossover values:


With matching XO values, I get:
Top: 416 Z (16 ohm nominal): -6db @ 1.130 kHz
Bottom: 416 B (8 ohm nominal): -6db @ 1.330 kHz

With capacitor value doubled and inductor halved for the 16 ohm nominal speaker, I get this:


Top: 416 Z (16 ohm nominal): -6db @ 1.180 kHz
Bottom: 416 B (8 ohm nominal): -6db @ 1.330 kHz (unchanged)

I realize that I am a newbie and generally speaker crossovers are regarded as EXTREMELY complex, so I am not looking for a silver bullet. Does anyone have some math or anecdotal suggestions? What could I try next?

EDIT to add: I realize I am only using two parameters to define an inductor and there must be significantly more sophisticated ways to do this, and I'm learning as I go!

Hi everyone!
I am an audio enthusiast, and this last year I have been getting more and more into this world, specifically in box design. I don't have many tools to measure different things, such as the Thiele-Small parameters, which I was able to measure on my own with a circuit I made. But over time, I have realized that I need more tools to be able to reach the objectives I want, such as a calibration microphone. The problem is that I do not dedicate myself to this, nor do I plan to do so, at least not for the next few years, so I am not going to buy tools as expensive as a UMIK-1 or UMIK-2, or the Dayton Audio DATS V3 , since I don't have the ability to buy things at that price either.

My question is if there are cheaper options, specifically for the calibration microphone, I would like to have one. And if someone recommends other tools that could be useful to me, and that are not very expensive, I would appreciate it.

Hello,
Following Bonsai constructive comments and advises,

Ref.:

1. https://www.diyaudio.com/community/...as-a-small-sizzling-sound.411503/post-7659500
2. https://www.diyaudio.com/community/...as-a-small-sizzling-sound.411503/post-7660158

I redesigned my DIY Amplifier PCB. This is the same schematics as threads :

• A Lateral MOSFET Power Amplifier Design (second try)
• My DIY Amplifier has a small sizzling sound

with the HBR resistor added, and a totally new traces strategy.

• I removed all tests points except TP3, now renamed TP1
• I moved the DC Servo closer to the IPS.
• I made Rails connectors closer to each other.
• The BIAS Spreader is closer to the VAS
• I minimized the ground loop area at the IPS
• I passed the +Rails and -Rails in folder view with their respective own ground traces under them, on the other side of the PCB
• I kept the Signal ground return track close to the feedback track to minimize the possible ground loop, I also kept it without nothing connected to it.
• I added the 4.7 Ohms HBR resistor, close to the input.
• I put the speaker output at the very end of the traces.

I'd like to share the schematics and the new PCB captures for your comments. I am very open to any comments or advises from every ones...

My bests regards and, thanks in advance...
P.S.: Schematic attached below in PDF format.

01-Ground Components Side highlighted



02-Ground Solder Side highlighted



03-Rails Traces over respective grounds (grounds highlighted)



04-Ground Loop Area



05-Silkscreen on top

06-Silkscreen and Ground Loop Area

07-3D View-Top

08-3D View- Iso