Does anyone have a pic of this area or a schematic ?

Or knows if the transistors are in the correct locations ?

Someone has worked in this before and amp is in protection so wanted to make sure these transistors are in correct locations

Hybrid better than SE vacuum tube amp. ?

Look my simple design in testing phase

Hybrid Amplifier by Andrea Ciuffoli

This is a teardown of an Alps motorized potentiometer. It's a 50k Alps blue velvet motorized potentiometer that I've had sitting around for a while.

Recently, I built the Salas DCB1 with a 10k Alps RK27 pot for volume control. Rather than spending $45 on a 10k motorized unit, I just wanted to modify the existing pot into a motorized one. To see if this was possible, I began digging through the interwebs for a motorized pot teardown and found very little info - let's change that.

I made sure to take plenty of photos for those looking to do similar modifications to their potentiometers. I'll be swapping out the 50k with the 10k unit tomorrow, so I'll likely document that too.

DETAILS:

1. The first order of business is bending the four metal tabs out to release the motor unit from the pot. I used a flat head screwdriver to gently pry each side of the motor case off.

2. Once the motor is off, you need to remove the central plastic gear and two mounting screws. This is probably the hardest part as there is a metal tab/disc thing that holds the gear in place. Once this tab is off, the gear slides off pretty easily. Remove the screws next and we're off:

3. The rest is pretty straight forward; you are essentially left with an "un-motorized" potentiometer (Albeit with a long shaft stick out of the back!). Since this is a dual pot, there are two blue shells that separate to reveal the "wafers" inside, among other things.

4. After everything is pulled apart, you can see that adding a 10k potentiometer should be as simple as replacing the short shaft of the non motorized unit with the longer shaft. Put it all back together and you've got yourself a motorized potentiometer with a new resistance.


PICTURES:
(In the order they were discussed above)

1. Motor Removal






2. Gear and screws removal




3. Potentiometer insides





4. Individual pieces & Putting it together (TBC...)


Here's a link to the full-resolution album with more pictures: https://imgur.com/a/b6gYy

How's that for a first post?? 😛

I am in search for 10k log pot with best price / perfomance ratio. So far I found Alps RK27 "the blue" for 17 EUR, TKD CP2 -601 for 35 EUR and Noble for 45 EUR.


It seems that in this price category, Alps rates very high for what you get for money or I am wrong?😕

On the web there isn't find any information.
Maybe one of the member know this power amplifier or at least the brand - thank you for advices.

These headphones are looking for a new owner. (Current owner shown below). Yes, they are that big.
Can you guess what they are? If you can, they are yours for shipping costs. Should be under $16 in the USA.

I'm looking for Aikido Octal pcb or kit, either stereo or dual mono,

Regards

I am using this integra 817xd, seems to be in very good and works ok except that it produces crackling, intermittently, mostly on slow music. And as it was released in 1988, I suppose it should be now recapped, don't know what performance it might be holding back. Values and numbers of all parts are clearly visible, I need to find what parts to get as I think part to part replacement would not be available for this old amplifier. Haven't attached the pics for power section which has large capacitors and look good, thought first get through this tricky part. I am thinking about getting all the parts first and then take out the boards in one go for replacement. Will be uploading more pictures, might get some cheap endoscope camera to identify all the parts without opening the boards.

So where to start?

Guys, i found some interesting design notes on the internet while looking some class D amps.

https://www.infineon.com/dgdl/irs20965spbf.pdf?fileId=5546d462533600a4015356761d8b279b
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d46269e1c019016a4a5a8fa04a9b
Both chips are PWM input and capable of driving IGBTs. Last chip should allow us to draw current directly from AC without violating isolation hazards.

All the power supply we need is some tiny isolated 2-3€ switching DC to DC converter for the chip. Everything else will be connected directly to rectified AC, ground will be neutral, floating design, some diodes here and there, some zeners to make sure, some bootstrap, few resistors, nothing serious.

In order to isolate speaker for safety reasons or go "tube", we could build up multiple chips to create conditions for centertapped transformer.

PRO thing is that we loose that bulky high-expensive transformer from the powersupply and use 2 diodes only for RECT. There will be only 2 diode sound on the speaker.

Can be made all digital too. Analog only in speaker cables.

So my point is that all this costs nothing and should be researched into.

Approx size could be 15x15cm for PWM.

A very attractive and fancy design, suitable for 2022. Super green too 🙂, maybe sound close to tubes. You can put it into ur pocket, take a walk to friends house and easily compare amps.

To style it up, use this box to build it into.

https://img1.etsystatic.com/000/0/5624852/il_fullxfull.150654955.jpg
Also, can be used as a battery powered amp with a boost converter, for headphones.

Is someone interested on designing it ?

I have two TDA1541A R1 DAC IC's for sale.
Used.
Both are known to work. They are surplus to my requirements.

I am happy to sell them separately.
£30 each or £55 for the pair.
Plus postage. Within the UK £3. 1st class Signed for.
I will have to enquire for overseas postage.

Payment via PayPal preferred or Bank Transfer.

I'm trying to understand how the tone stack of my Fender Pro Jnr amp works and I'd like some help in understanding this part of the circuit. It's placed between the C1 coupling cap and the volume/tone controls. It seems to be a L-pad attenuator with a parallel cap added, so does it attenuate the signal above or below a certain frequency maybe? I've searched alot but can't seem to find this exact circuit. Thank you.

See updated prices later in thread.

I find the FE206EN a bit lacking when it comes to treble.

well this didnt turn out to be much, apart from being filthy dirty and one of the leads had come off the volume control
it looks a bit black in the middle but its just a shaddow from the sponge protection on the filter caps

so repaired that, cleaned it all up, set the idle current back to 4mv on both channels (right was 0.5) and, well thats it im affraid.

sounds ok, no where as good as the creek i just repaired though.
It could realy do with a loudness function as the bass is almost non existant at low levels.

I presume it used to have a remote as it has a motor control for the volume
good sound though, if a little uninspiring.

I realized that my setup is now entirely Californian based.
Just bought a modest X2 pre-amp in front of my X600's, so all vintage stuff, but I was surprised how good to me ears this little jewel sounds.
I've had, and maybe some other people too, my paradigm about pre-amps from Pass (and Threshold for that matter), because they weren't designed by Nelson Pass (alone) that they weren't as good as the amps. As it stands now, I was wrong about the Threshold FET Eleven (TEN HL G in USA) and about this X2 too.
Bonus is that I like the three dials on the fascia also and I don't matter standing up to adjust the volume...(yet).
Thanks Wayne.

SOLD please clode the topic

This little 6V6 a fun amp. It's a recent amp from China, but a fun one. It uses Russian 6V6 pentodes in single ended output mode. The transformers allow Ultra Linear wiring if you want to. It weighs about 11 pounds, or around 5 kg.

This originality came with some obscure Chinese 7 pin radio tubes on the inputs, but Poindexter help me swap those out for a lovely matched pair of 6GK5 that he uses in his Musical Machine amp. That meant rewiring to the new pinout and setting new operating points. A nice improvement in gain, channel matching and linearity.

I mostly used this to drive the horns on my Altec A5 VOTT system, where it had plenty of headroom. In recent years it's been driving my Fostex T50RP headphones, which benefit from the extra oomph of a good amp. Very smooth. The amp has a little too much buzz for sensitive headphones, but for speakers, even horns, it was always quiet.

Hate to let it go, but I can't take it with me.

$95 OBO. These usually go for $150 used with original tubes. Count about 14 lbs for shipping from zip code 33901

Not sure which forum this belongs in, could be amplifier, speaker, line level...?

The mission: Use tube amp as full range amplifier, have amplifier2 driven by tube amp with RC low pass filters of at least 2nd order, preferably 4th order. Amp2 is driving a 15" woofer in an OB speaker. Experimentation is required.

Now all logic prevents us from going RC passive filtering past 1st, or perhaps 2nd order. The signal loss is just too much, and each section must handle the loading of the next, etc.

But in this case I have a large signal out of the tube amplifier needing to be attenuated approx 30dB before hitting the inputs of the amp2. The amplifier can drive low impedance values the first stage of the RC filter will present, so I can start off with a low value. I would like to load the tube amp as little as possible tho, so an input impedance of sa 25-50ohms is preferred.

One little challenge which probably limits the number of cascaded sections is my amp2 has input resistance of only 1.8kohms. (The amp uses mixed feedback voltage&current, and to limit offset the input resistance equals the feedback networks resistance to ground).

But I have no notes on cascading RC filters... Cannot find much out on the W-cube either.

Any suggestions for calculating LinkRiley 2nd, 3rd, and 4th cascaded RC filters?

If this venture is promising, I will likely go for a LC version later. I can do inductors at work, if I ever get the time...But right now I just want to get going for the weekends test run.

Thnx

Hello, I need service manual for Threshold S550e
Thanks

gentlemen,

sorry to hijack this thread BUT, it's still about FM.
Years back a member was selling solid state FM modules (tuners and decoders) made by Hershold (sp?). Anyone know if he / them are still around?
I want to try my hand at building a tuner but don't have the time/knowledge nor deep parts bin as the author

Thank You

ne5532 vs. njm5532
How do they stack up? Any input?

Using WINisd and VituixCAD, I've come up with a reliable enclosure size for a woofer box I am building. This speaker project I have is fairly aesthetically driven, however, and I would like the enclosure to be a little bit larger than the results I am getting. Is it possible to suspend the enclosure in an outside enclosure (therefore having the appearance of it being bigger?), or can I dampen the box with a certain material to bring the inner volume back down to my tuned level? Thanks in advance for the help...

I've started the design of my first amp. It is meant to be a small PP stereo amp to drive a set of Klipsch Heresey Speakers (circa 1979).

I plan on using all surplus Russian tubes, 6N23P for the input for their low noise, 6N2P for drivers, and 6P1P for the output tubes.

I've modeled it with Lt-Spice, but am a bit frustrated with a couple of things.

(1) There is a pronounced peak around 7hz. This probably won't matter in the real world with a set of Hammond 1609 transformers. Unless, the system acts like the old BOSE 901 series II systems with the active filter between the line out and in. The amp could end up driving the heck out of the bottom end because of the inefficent speakers. With the feedback I have, this could result in the low frequency sucking up a lot of power.

(2) I had to tweak R6 to get a balance between the two differential drives to the grids of U11 and U12. In theory this should not be required.

The schematic does not take into account the UL taps of the 1609 Transformers since I don't yet know how to model them.

First image is a combined gain plot and schematic from the LTSpice Simulation.

Second image is the schematic in LTSpice.

Comments?

Suggestions?

Thanks.

Steven

Recently, I replaced all of the electrolytic capacitors in one of these fine units. The question is, does anyone have the bias settings information for this amplifier? For that matter, any and all specifications regarding this unit would be welcomed. Thanks in advance.

I'm looking at refurbing some 6th order bandpass subs. The factory
Drivers are proving hard to source as the boxes are over 25 years old...

The Kappa pro 10-lf looks ok in win isd when placed in the same enclosure and porting.
The venue is a basement so it doesn't take a lot of energy to do the job, I have to reuse the cabs that are there..


Who has used these? as I'm having trouble finding a review... No news is good news?

I'd appreciate any comments on this speaker driver.


Cheers

Last year I built a pair of Jeff Bagby's auricle speakers, which use a RAAL 70-20XR and single Satori MW16P midwoofers, and now I'm planning to move the drivers to his tower design, called the Testarossa, which is probably known to some here. I'm making this post because I have a few questions and would like to hear the perspectives of other more experienced speaker builders. Being new to this, I'm being conservative and using a proven design, while at the same time reading all I can so I understand what is really going on with the speaker, ie what each crossover component is contributing, how the cabinet design is affecting the sound, etc. I'm a way off from designing my own speaker, and with the dizzying array of proven designs already out there, not sure if I'll ever make that leap to be honest. But the bug has definitely gotten me.

In any case, for those not familiar, the Testarossa is a small tower using the RAAL and two Satoris rather than one. Still a two way. Besides just getting my rocks off building another speaker (and learning), I have two primary reasons for wanting to do this. First is the increase in sensitivity, since I have a 25w amp, and the second is the benefits of two vs one MW, which I think will increase SPL in my smallish room, while liberating the tweeter a bit due to lower resistance values. I think it will sound better, and more full, and take some of the strain off my amp and improve dynamics a bit.

The first question I have centers around which version of the Testarossa I build, the options being a 10" passive radiator (which would be located on the side of the cab), or a ported version, which in my case would be located in the front to lessen boundary issues in my room. It seems the passive version would result in a different response from the MWs, since there is no air exchange, maybe tightening up the response a bit? I'm actually leaning towards the ported version, mostly to save a little $$ but also because I have a decent sub and always will so unless the PR has an obvious advantage I am wondering why I would use it. Jeff did in his own pair, and that counts for a lot in my book, but I don't have the experience to choose like some here.

There are also some details about the cabinets I pan to build that aren't according to the plans, and this is where the experimantation comes in, but maybe that's for another day, but I'll just say it involves mass, which I'm convinced can make a big difference. I come from a world of woodworking and carpentry machines and I've always noticed how much mass just "quiets" things down, and I think a cabinet that's vibrating is causing noise. When you push a piece of stock through a tablesaw, shaper, or planer that weighs a lot there's a smoothness that just can't be had with lighter machines!

Anyway, if anyone has any thoughts it would be helpful, thank you.

Has anybody gave a thought about soldering fumes ? I remember my father said that these fumes are comparable to a "fumes that originate from welding". Welding fumes are super dangerous actually. Companys with a little success are replacing humans with AI welding robots.

Soldering and welding, both are pretty much robotized. It is that dangerous. You can even exhaust it... it does not help... environment backfires everything... EMI effect 😀

Soldering > be it lead free or whatever solder, as soon as metal melts its over, heavy metal molecules will learn to fly, then they will overflow ur system and most important, a brain and after a good years of soldering its gg to ur input and output systems, including brain capability, sound, acoustical perception, everything.

Life will turn from REDish-Green-Bluish color to dark-matrix styled lightly colored lifestyle. It will take time, but everybody will experience it no matter where you live.

So, maybe we should somehow re-think our amplifier assembly and do it environment friendly ?

Why we have SMD at all lol... some say its cost saving and saves space.. i would say that with SMD technology we can use AI to produce more, faster and better cash...

I think i am off the voodoo **** now too...

From my experience as a cigarette smoker, then solder fumes are like 44x more dangerous to ur health system. Does not matter, if u inhale it directly or trought some filters or exhaust it entirely from the room.

And, TIN does make ur head "silently" dizzy, influencing the acoustical perception also.



.

https://www.diyaudio.com/community/...list-for-a-horn-like-this.383020/post-6940892

Says a member has been banned, but as I see it, that member is not banned.

Hi guys.
Stupid thing... I have a wallward transformer (the old kind, no switching PSU) for an inexpensive 1-in-4-out headphone amp that used to have 12VDC output. After I opened it on order to resolder the cable, it suddenly puts out 18VDC. This thing only has 4 diodes and an electrolytic cap! I testet the diodes and all are OK, switched the cap just in case. Any idea whats wrong with it?

Hi all,

When using a source follower to drive an output tube, e.g. tubelab's powerdrive topology, is it ok to mount the MOSFET to the chassis for cooling (insulated of course)? I ask because in Morgan Jones' book he cautions against mounting CCS devices on the chassis due to the loading caused by the capacitive coupling to ground. Interested to know if the same thing applies in follower applications, or isn't an issue due to the bootstrapping effect of the output voltage.

Appreciate your thoughts,

Greg

I'm looking for a midbass horn that can operate in the area of approximately 80-600 Hz. I use a Klipsch K-402 top horn, crossed at 500 Hz at the moment. I would like to match its directivity (90 h x 60 v). I have several JBL 2226 in bass reflex' for the lowest frequencies and use active cross over.

I need some basic information on the cons and pros of different horn profiles for this usage and what people would recommend.

Corner horn is not an option by the way. Free standing only. Having a horn that's a little bigger then K-402 is fine.

Hi everyone,

This is my new 49810/49811 + ThermalTrak Amp intended for low output power (Class-AB/B, <= 60 W). Output stage is driver + emitter follower. I have not put the heatsink for LME and driver (too noisy to do metal work in the midnight).

I changed the thread title.




Anybody ever seen a series V Zeus with a board like this? Pwm. IRFP260M ps fets. Tip142/147 outputs.

I was expecting a ps with BJTs…

This one has a blown channel, mismatched outputs, and mismatched emitter resistors. Should be a straight forward Repair.

Hello,

Recently i was thinking about current drive, high output impedance and tewbs. In the interest of not derailing the question of the thread with why current driving sucks and we want damping and everything was designed with voltage drive in mind and so on, lets just take it as a premise that's what we want to do, hypothetically.

Normally we take the current out of a dac, turn it into a voltage (transimpedance), then amplify it, and so on, to the load it goes.
There are amplifiers that take the line out voltage and output a current, so the current is constant and the voltage varies (transconductance amp).
But what about taking out the middleman, never doing I/V, and using the current straight out of the DAC and just adding some gain with an opamp or whatelse to drive some headphones for example?
I mention opamps just because that's what i tried to build in LTspice, however i couldn't find a configuration that does what i want. In fact havent even really found any circuit for this out there, leading me to believe im embarking on something silly, or that of course the opamp might not be the thing i need for this, despite its many conveniences. In the attachment find the best i managed but it a bit fishy and not sure how to null it without a servo or something, since cant put a DC blocking cap in the loop.


Since this is DIY, i hope you can humour this concept, so in this thread i ask the basic 2 questions:
1. If we want to current drive something (say some headphones), why not start at the source and just add some gain to the current of the DAC, instead of doing I/V and then V/I?
2. If this can be done, how?

Regards,

This amp may actually be a Series VII in a VIII chassis not sure. Says ZEUS -1 on the board, and revision AA. Board is missing ALL TIP102 drivers in the PS/Vari circuitry. This board has no added components nor modifications what-so-ever.

Amp will work but from what I can tell the PS pulses on/off every ~1/4 second. I cannot probe pin #3 of the TL494 very well; especially unwell with a source plugged into RCAs. That source has common ground and good connections case-to-shields.

TL494
1. 3.384
2. 3.356
3. 4.61 <-- Had to measuring with Fluke 16 set to max/peak hold as it fluctuates every 1/4 second
4. 0.308
5. 1.479
6. 3.548
7. 0 <-- Black probe connected directly here
8. 14.19
9. 0.2 (Strobes)
10. 0.2 (Strobes)
11. 14.19
12. 13.62
13. 5
14. 5
15. 10.89
16. 6.75

Now, if I plug in something into the RCAs with good common ground the amp stabilizes slightly. As I increase input signal the amp becomes more stable.

Fear the PS FETs getting hammered on/off like this would cause failures.

Resistance between B- and RCA shields is 670ohm. Secondary ground is connected to RCA shields.

If I lower input voltage to about 10vDC, the amp locks into full duty cycle and stabilizes.


Any thoughts why this amp is cycling every 1/4 second at 14.4vDC?

Hey,
I want to build a 3-driver stereo bluetooth speaker with the following components:

2x https://www.soundimports.eu/en/dayton-audio-ps95-8.html
1x https://www.soundimports.eu/en/dayton-audio-e150he-44.html

Is the sub to powerful for the 2 speaker?
Which amp could i use? I only found some that are eather to powerful for the fulrange-driver or to weak for the sub.
What are potential problems I could run into?

Thanks in advance

I would like to say good afternoon but i may have a problem.

I've been working in my brothers shed while he is away. Today i realised i put one of those car subwoofers with a huge magnet next to his Denon platter which is one of the type with the magnetic tape on the rim for speed control. Would this magnet have affected the speed control thing? Its his pride and joy and I cant test it because the deck is locked in the house.

Hoping for a positive outcome, sp

Got an untested Rockford 200DSM with leaking caps on the preamp riser board. Checked the amp for the usual blown mosfets (none), then thoroughly cleaned & recapped the entire amp 100% except for the large power supply caps. Still wasn't getting audio through the preamp board so I replaced the LM833 chips and now have clean audio. I made the rookie mistake of running the amp outside the heatsink for a few minutes on music and ended up blowing a couple outputs on the right channel. Replaced all 6 IRF540 and that channel works fine. I thought the left channel was good, but looking at the outputs with a 50hz tone I'm seeing the following from the two channels, and I'm not sure where to look:

Right channel:


Left channel (at different input voltages):

My TU 8200 DX performed flawlessly for 4 years from the first time I turned it on. I use it daily in my office.

The left channel died due to a tube failure. Now I can't seem to get bias voltage at pin 8 or 1 of the tube. It is correct at the base of the transistor then acts like a short to ground. Each component tests correctly. The tube also only heats up to about 50% of the channel that works but the heater voltage is correct.

Any ideas? It seems like a fairly simple circuit but it has me stumped.

Hi everyone ! I have this soundigital amplifier to repair and at first glance it has damaged final mosfets! The abbreviation of mosfets is C2, what kind of mosfet are they?

Hi,

I have just finished designing my crossover for a three way speaker. Now I want to put the crossover in small box which is availble in the upper side of the midrange enclousre.
It´s dimensions are 30,5cm x 12,2cm x 9cm. There the complete crossover should be placed.
I have 7 coils in my crossover design. Two core coils for bass (red), one core coil and two air coils for midrange (blue) and two air coils for tweeter (green).
I have already read the article about placing coils from troels side:
http://www.troelsgravesen.dk/coils.htm

I am now struggeling placing all the coils in the small box without interacting each other (induction and crossover talk wise).
I have greated two suggestions (see attached pictures). Which one you would use?
Can you give me some suggestions what is the best placement?

The new DIYAudio forum face looks good, by any technical standards, and with a few improvements could be close to perfect.

Then why am I subjectively no longer tempted to open the forum and post? It is not the quality of the current existing content, this followed a down path for years now, it's not the bore of endlessly teaching the basics like the Ohm law, it's not the endlessly seeing the same dusty implementations of 50 years old concepts and circuit topologies, it's not reading again and again the same stupid/wrong advice and being tired of rebuking and streamlining the topics.

It's simply no longer having fun to get involved in what I subjectively perceive as an impersonal and unfriendly virtual environment. Or I am getting too old for this ****. Or I need a new hobby.

One to another, I subjectively find the new forum format annoying, which is a nice way to say I hate it. BTW, I am turned off by the ASR forum as well (same software, I infer).

Hey guys, I recently finished recapping a C370. All the caps on all boards have been replaced. No other components have been touched. All swaps were checked for correct values twice. All solder joints were measured for continuity with other joints on the same trace and also checked to ensure there is no continuity to neighboring traces.

I'm trying to get the unit fired up for the first time since the refresh and the following happens (dim bulb tester used):

- DBT switch is off
- Amplifier power button is in the "on" position
- DBT switch to "on"
- Amp power light turns on, DBT no light
~1.5 secs later
- Amp power light still on, something clicks in amp (sounds like relay), dbt flashes on and immediately shuts off along with another click from amp

The last event repeats about once every second.

I don't dare leave the DBT on for more than two cycles of this since I don't know what's going on.

Is this a result of all the caps being fresh and drawing too much current and setting off a protection circuit? If so, what's the solution - just let it click on and off until it settles down?

Or has something gone terribly wrong?

Hy.

I got audes 75w104-4 AUDES
Some time i heard this in 50L vented box but i dont like that only have huge(5db) 50hz hill.
So now i want tray something deeb and loud.
I but i to may room.
Witch type box? vented or bandpass?

Henri.

I need to rewrap the inductors on my Kicker 06zx750.1 class d monoblock car amp as the shielding on 1 has failed, 2nd doesn’t look too bad to where it would malfunction so I tested it on my cheap-o LCR tester and got a reading of .12mH and .32-.36ohms. Does that seem anywhere near right for this amps inductors?

As far as the inductor itself it seems to be a brown(green on 1side) core that measures 40x23x15mm with what seems to be 10awg magnet wire (waiting for wire gauge feeler) it has 35 turns total, 20 1st wrap, 15 on 2nd wrap.

I guess I could just rewrap each core with appropriate length/size/turns of magnet wire and just be done with it, but would like to know what the inductors for this amp are supposed to test as so I can make sure it’s correct. Thx

Hello all,
The amp in my son's car stopped working a while back. We checked the fuses and confirmed that it is getting power. He was going to replace it but we found that you could order a replacement board from Rockville, so that's what we did. We have the amp opened up and the old board removed but before we just slap in the new board I have a question. On each of the long sides of the board there are some tabs that were held down with metal straps to the amp housing. The tabs themselves were not screwed down but they did have a white paste under them. I don't know what these tabs are or what the white paste is but I would like to clean it up and put fresh "paste" down first. It's this some type of heat sync paste or dielectric grease? Any help would be appreciated. I imaging Rockville isn't the only company with this type of design.
Thanks in advance!
Matt

Hello,
for sale a new, never used or installed ACUTEX STR 415 in perfect shape.
160 150 euro+ shipping and Paypal fees.
Best regards
Guglielmo
Italy

Some kind person gave me a pair of Quad988 speakers a few months ago( I had to drive a few hundred miles to collect them). They are now my destination speakers, and hence, I am offering, for free, pick up only, these open baffle projects that got me hooked. No crossovers, I used minidisp.
1. 8”high qts PE buy out woofers and Fountek 2” aluminum full range driver. Mounted in solid cherry OB frames.
2. 6-1/2” PE buy out woofers mounted on a quite complex cherry baffle. Built to be used with 26” Apogee ribbon. Includes rear mounted floor brackets. I sold the Apogee Centaurs from which the ribbons came. Sounds great, if you like open baffle. I put a lot of hours into making these.
3. 4 way open baffle speakers with Dayton N16 tweeter, 3” tang band bamboo full range mid, the same 8” woofer as above, and two 10” GRS subwoofers in a W frame arrangement. This pair was great fun. 3/4” mdf. With baffle covers.
I live 100 miles from anywhere, Andrews NC, but if you are visiting the Smoky Mountains anytime soon, they are on my doorstep.
cheers,
Peter

Did someone here succeed in using a MOTU 8A with a Linux PC? I want to use the MOTU just as an 2 channel audio interface with REW, not for mixing. Preferably with Ubuntu, another Linux or Windows will do as well, as long it runs within VirtualBox.

Please post in thread or message me.
Thanks

Looking for any sizes, but mainly 50 cm^2 sd and 8-16 ohm.

The BMS4550 seems to be a golden standard for 1" based MEHs. Are there any alternatives (with up to double its price)? I really like the Beyma CP755 compression driver, it is a 1.4", so its equivalent would be BMS4554. My next MEH build will use a planar driver for HF, but I still do not want to give up on the classic construction and its higher SPL potential - and I am still undecided whether 1" or 1.4" driver and which one. I think the horn itself can be built in a way that it would work for both dimensions with different 3D printed (or machined) throats.

Short story: Corner line arrays can save space, can eliminate ceiling and front wall reflections, and can be fairly efficient. Using 24 Vifa TC9s, a 3.5" full range driver, a corner floor to ceiling line array was created. The array measures and sounds pretty awesome and achieves the design goals.



Long story: If you read Toole and other research, it says that the reflections that color the sound the most are the ceiling and front wall (the wall behind speakers). Reflections from side walls can add a sense of spaciousness but reflections from the ceiling and floor are perceived as modifying the frequency response.

Horns can be used to prevent ceiling and front wall reflections, but to control reflections at mid frequencies (sub 500 Hz) requires large horns. There are some active threads with folks trying to solve this problem by using cardoid cabinets for woofers, which is a pretty cool way of doing things, but there are problems.

I played with horns for a while and I could get good sound using Altec VOTT mid horns and constant directivity SEOS horns, but the sound was never quite of the peerless variety. The balance of the HF with the rest of the spectrum was never quite right. Horn speakers also tend to be big and occupy a lot of space and this annoyed me. And thus were born some design requirements. The new speaker should:
1. occupy less space,
2. control ceiling and front wall reflections, especially in the lower frequencies (below 500 Hz),
3. have a smooth on-axis response and uniform off-axis response and,
4. be fairly efficient, have low distortion, and have the dynamic headroom to hit 110 db peaks.

Toole kind of gives it away in his book that an ideal floor-to-ceiling line array would solve some of the key issues in sound reproduction in the home (figure 18.3). He describes the Keele CBT array as a practical implementation of an ideal floor-to-ceiling array with perfect drivers.

From here, putting the arrays in the corner was a no-brainer. It would completely get rid of the front wall reflection, and the floor-to-ceiling nature of the array would avoid ceiling reflections also. And I had a room that allowed a corner design.

The next question was the choice of drivers. Keele’s CBT uses a cone and a dome. But his arrays are relatively short. The floor-to-ceiling array would need a lot more drivers, meaning more cost, more wiring, and more worrying about unit to unit consistency.

If a smallish full range driver was to be used, the Vifa TC9 was an obvious choice. It has one of the smoothest frequency responses amongst full range drivers, a low distortion motor, and with Vifa manufacturing it, you could be relatively assured that there would be good unit to unit consistency. There are many designs here on diyAudio that use this driver. The Manzanita OB uses this driver. And many others have used it in their design. Seeing it used in Wesayso’s heroic tower build and other line array builds sealed the deal. Plus the TC9s are relatively cheap and I love cheap 😉.

The construction is relatively straight forward. It’s a three-sided cabinet. The front baffle is as narrow as possible so that the drivers can be as close to the corner as possible. The drivers are flush with the front baffle. I had this design in my mind for at least a year but never got around to building it. Finally, after months of frustration at never finding the time to build the cabinets, I asked my friend John (carpenter) to build the cabinets and wire up the drivers.

John completed the build and the arrays are playing music. They occupy very little space, can go plenty loud, are pretty efficient and very low distortion (each driver is barely moving even at loud levels). Using a single 3.5” driver ensures a uniform off-axis response up to a high frequency, above which the Vifa does start to beam, but it is relatively well controlled. The on-axis response is flattened using DRC software, i.e., automatic room correction. The final result is quite good. Measurements coming up shortly. There is still a long way to go. The EQ is doing a pretty good job, but I think it can be better.

Looking for good used 8" mid/bass pr. for two way ported box. Old Kef, Celestion, Philips, etc or ScanSpeak paper cone (just hate plastic). Recommendations welcomed.

Recently acquired HP330B vacuum tube distortion meter. Since HP part #s from 1950s probably not much help now maybe one of the engineer types on the forum could recommend modern replacements that would work. Meter probably needs to read AC volts up to at least 100kHz (5th harmonic of 20kHz).

I have an Ian FifoPi in one system fed with an Andrea Mori entry level clock. (TWTMC-PPG). Obviously this has its own psu, doesn't get power from the Fifo. The other crystal is a Crysyek. The fifo will still select the correct clock for a given frequency family as designed.

Does the Kali work in the same way?. So I can remove a crystal and replace with a Mori clock. I understand there may be a couple small smd caps to remove also if using an oscillator and not a standalone smd clock. I have a couple of new clocks from Andrea and a Kali to play with.!

I came across this super simple tube-based shunt "regulator" circuit which I think is pretty cool. For use with line amps requiring a clean 15-30 ma supply. It's simplicity gets me wanting to try it using a DC Link for the final 220uf capacitor. The ability to trim the voltage is appealing to me as well as choke input, although I'd trim it then replace the trimmer with a resistor. Also not needing heatsinks, IC regulator chips, etc... is appealing.

Looking at the circuit below it doesn't seem to be a "regulator" at all as it has no solid reference voltage, it floats with mains variation. Is it more like a simple ripple-canceling shunt? Or is it indeed regulating the 2-4 volt drift my house mains might experience? For line amps I'm not really too concerned about the 2-4 volts my house mains may vary, ripple cancelation is more important.

I have a few questions (this is one reason I need to learn spice this year):

1) Is it too simple? (whatever that means) to be a reliable circuit.
2) What effect does the mu of the shunt tube have on the operation of this circuit?
3) I've never seen a 6SN7 used this way, I thought it was a "voltage triode" not a "power triode".
4) The vertical deflection dual triodes 6BX7 and 6BL7 are base-compatible with 6SN7 (6BX7 10u; 6BL7 15u) and considered "power triodes". Would those be more reliable long term? Do I need to have 20u? Would more amplification factor be even better?
5) Is the 2k5 trimming voltage or current?

Discussions about class D audio amplifiers from Connexelectronic

Hello all,
I have recently acquired an olive Snaxo 2-4 that has been reconfigured for use with Linn Keilidhs. I would like to return it to original so I can use it with SBLs.

Is anyone able to advise on component values or have a schematic to share? A good picture of an SBL version would be really useful as well.

Below are some pictures of mine along with values of capacitors currently installed.

Thanks in advance

Martin



Dropbox - HF with values.jpg

Dropbox - LF with values.jpg

Dropbox - LF.jpg

Dropbox - HF detail 1.jpg

Dropbox - HF detail 2.jpg

Hi!

I'm currently deciding what to do with all the fuse holders installed in the case of an old amp I'm repurposing. How do you best fuse an analog power amp with transformer-based power supplies?

There's two independent power supplies, one for each stereo channel, delivering 2x +-50Vdc @ 5A. Obviously, one slow-blow fuse will be placed on the primary of each transformer. That leaves me with 4 fuse holders 🙂

Option 1: Fuse the amp output, in the signal path

Pro: Best possible protection for speakers
Con: Amplifier not really protected against malfunction
Con: The fuse, being essentially a temperature(current)-dependent resistor, will introduce distortion

Option 2: Fuse each of the positive and negative rails, right after the main power supply capacitors

Pro: Protect amp and speakers against malfunction
Con: Bypass capacitors on amp board can still discharge into speakers during malfunction
Con: When a fuse blows, one power rail will disappear, but the amp might continue with just the other rail. This would make the amp clip either positive or negative half-waves. A surefire way to kill speakers. Am I mistaken or is this a real concern?

Option 3: Fuse GND, right after the main power supply capacitors

Pro: Similar to option 2, but would alleviate the concern regarding disappearing rails. They'd both disappear at once.
Con: No protection should I ever run the amp in bridged mode

Option ?: Something else?

I'd love to hear your thoughts. Thanks!

1. original amplifier circuit.
2. after a little tweak Apex ax2022 -)

Seems like it should work? What are your thoughts?

Hi guys,
I am searching for a simple digital panel meter like these:

Blue DC0-500V LCD Digital Volt Panel Meter/Voltmeter New - UK seller | eBay

LED Digital Voltage Meter Voltmeter Panel DC 4.5~30V Small Mini Blue Portable | eBay

Digital-Panelmeter PM438 Panel-Meter PM438 | eBay

They are probably all based on the same chipset anyway.
The thing is, I want to measure a few volts negative to the power supply ground. I believe these panel meters have floating inputs, so should be possible, but I cannot find any information on the negative common mode for the input.
Any of you have experience with these and/or know the allowed input CM?

Edit: some descriptions say something like: power supply 3-12V - must be galvanically isolated from measurement voltage. But that does not say anything about allowed CM range for the measurement input.

tia,

Jan

104 db / watt

400 W AES

copper demodulation ring

https://www.eighteensound.it/en/products/lf-driver/8-0/8/8nm610 8ohm
does it get any better ?

looking to cover about 250 hz to 1 khz

here is what it looks like inside:

Login to view embedded media

Hi,

I'm looking for a matched pair of SJDP120R085, and I would like to swap it with a pair of 2SJ27 (it's not a Typo, it's Yamaha 2SJ27 and not Sony 2SJ28) that I have.

Take note that there are no known design using these 300W Yamaha P-channel SITs, and their characteristics vary a lot (I have come across 16 pieces of these, they measure very different). So, they're probably not for everyone, but if you're familiar with SITs and want to know how a genuine 300W P-SIT sounds, 2SJ27 doesn't show up very often.

Attached is a picture of the SIT (marked 5 and 9 in the photo), as well as their measurements.

Please send me a PM if interested.

Hi everyone.

I bought a Hana SL a few weeks ago, but I'm having some issues, with IGD in particular. I've tried all the various printed protractors (which have worked well in the past), but no luck this time. So, I was wondering if anyone has one of these for sale, or even if I could possibly borrow for a small fee etc? I'm based in Berkshire, UK. Thanks!

Chris

Edit: One of these popped up on ebay so I went for it. I was surprised how far out of alignment I was, as I thought Conrad Hoffman's arc protractor scaled correctly and on high-quality photo paper would be fairly accurate. The SL is sounding fantastic now and the IGD has reduced significantly. Now just to dial in the azimuth...

Hi there,

I know most PA speakers now use DSP. But if I was to include a good DSP, like MiniDSP into my speaker, it would double the cost of my amplifier/signal path.

Im going to use an IcePower amplifier coating around £100, and as far as I understand the cheapest MiniDSP module is about the same cost...?

The thing is, I only need a few notches of EQ. Can it be done with a passive EQ setup? Is this something one can buy?

Thank you!

Hi all,
I have a question about upgrading
Nad 2700 amp.
Where can I get power Capacitors replacements for this old amp?
Power Capacitors 2 x 10000uf – 80v
Power Capacitors 2 x 10000uf – 120v

I found this upgrade kit (which I would probably get) containing
35 Nichicon audio capacitors KZ, FG, FW, KW but power Capacitors are not included.
Any directions or general thoughts about my plan (should or should not) would be highly appreciated.
BTW, The reason for the upgrade is that It makes some dearty sound from the speakers like bad contact sound from time to time. Do you think changing the Capacitors of a 30 years old amp might solve it?

My speakers are martin logan source.


Thanks

Hi, I bought a used 8000p and find the right channel sometimes drops in volume for a short time before returning. It seems worse right after being powered on, once warmed up after about 5-10min it seems to stabilise and not have this issue any longer. I have been testing this by joining the left/right inputs together so they play the same source (in mono). I measured the bias as and found the left channel was almost zero and right a bit higher than expected. Both about 25mV now. I can’t see any overheated components or other damage (the right side +12V dropper resistor PCB through hole is a bit brown on one leg but not bad). Any ideas welcome as to what it could be!

Hello, how can I conduct a test on a PX25 tube with a TV-7D/U tester?
The tube chart contains test data for a CV1040 (which is identical to the PX25) but I can't figure out where and how to place the tube.
Do I need a special adapter for the European B4 it to fit into the UX4 base?
Any help would be appreciated.

I finally found a better power supply transformer match for my endlessly fiddly little DIY linestage/preamp project. Only 5V too high in this case.

But maybe it isn't really too high, taking into account the load presented by a 12AU7 after it warms up and starts to conduct? It sure would be nice if this is gonna be OK now that I have the hum issues worked out.

Specs say max. 300V on the plate.

Downstream of the 100K feed resistors on plate pins 1 & 6, at power-on with cold filaments, for a short time I have 305V.

Quickly drops to around 90V as filaments warm up.

Do the tube specs refer to plate voltage after idle conduction starts? Thus the second uncertainty: if that's supposed to be the unloaded value post-dropping-resistor, is 5V over still acceptable for a few seconds before filament warmup?

Once again, thanks in advance for all of y'all's lovely input on this. 🙂

Per a marketing email this morning, ESS Labs have a one-day sale on the large Heil AMT at $120/ea, limit 2, using discount code ILOVEESS. If you've been thinking about a pair of them, now's the time to jump.

Bill

Question on TL594.

Pins 9&10 go to the amp's PS drivers, but pins 8&11 are connected to ground. Shouldn't 8&11 be connected to +12?


Someone modified the PS drive circuit of this amp. IRF3205 in the PS, PNP/NPN PS drivers. I dont see the drivers connected to +12v either. Both 8&11, and driver transistors are connected on the same trace with a PINK/PURPLE wire soldered back to Ground terminal. I think thats wrong.


Also this amp is using large un-synced TO247 rectifiers instead of the a square & round ones usually found in these amps. The two large square rectifiers are in-tact, but usually these amps have a smaller round one. Photos next.

Board has been repaired before. Looks poor to me. Board condition is poor. Notice heat under transformer. Heat under PS fets. Lots of broken via/pads. I may just move the purple wire and return to owner if that 'works'.

I’ve built a (Deacy-style) guitar amp from the output stage of an 18v 1.5w portable radio (Hacker Democrat Rp34). I’m powering it using a 5v/2.4a powerbank and USB buck booster module set to 18v. I also have a Range Master treble booster in the guitar signal line that can be swicthed in or bypassed. See attached diagram.

The amp is quite noise free when the guitar is silent but when you play notes on the strings behind every note you hear a sympathetic fizzing, fuzzing buzz. This buzz decreases in volume when I touch the inductors on the buck booster while playing. And it goes completely when the guitar strings are silenced.

With the treble booster engaged a loud squealing noise is added in, which seems to be triggered by the lightest of touches on the guitat string and sometimes it will continue to squeal even when the strings are silent.

I’ve tried powering the amp using a 12v DC wall supply the sound is a lot cleaner (compared to the buck booster also at 12v). I am fairly certain that the buck booster module is responsible for the noise and I think I need to filter the power coming from it.

1. I’ve read that a Pi filter - capacitor-inductor-capacitor - might be what I need but despite some research my very limited knowledge of electronics is holding me back. Could anybody recommend a very general starting point for the values of these components? [powerbank is 5v/2.4a, buck booster is 3w max output set to 18v, amp is 18v 1.5w going into a 16ohm speaker]


2. Also I've read somewhere that Pi filters are "not suitable for varying loads" - an amp is a varying load, isn't it? The same website recommends an L section filter "as its output voltage do not vary largely with load current.” Is that correct, should I actually be making one of these instead?

3. Am I missing something else?

I have gotten a pair of LT12 "Wolverine" speakers for basically postage. They work but the main cones are shot.
I have found one speaker parts dealer in Australia list the recone kit as being available from a US supplier.
Yet I have yet to find any dealer who lists or has access to any parts for these speakers.
I can't even get a dealer to help me find an equivalent 12" kit (I can salvage the "wizzer" cones) using the information I have about the voice coil, spider, etc., for the speaker.
These are nice speakers to work with and I can't believe there is no way to get them reconed
any idea would be great

A little smoke and a blown fuse, low B-

I built a TSE 300B for my adult son a couple of years ago. He and his girlfriend seem to have a habit of turning it on and off without waiting for it to cool off. (I replaced the fuse once before.) He says before it stopped working, he smelled something and then it blew a fuse. The amp has a CL-90 in it, but I’m thinking the quick on-off-on was the cause of the problem.

I replaced the fuse and put in the tubes and started it up; one of the bias meters went to zero while the other was pinned and then the fuse blew.

I took it apart and looked at the circuit board and didn’t see any problems.

Next, with only the rectifier tube and the 5842’s in place I got a B+ of over 400 and a B- of 170 and then after a minute some smoke. This time I checked and the solder around R25(36K, 3W) was burned off.

Am I correct in assuming that the problem is the low B- and that the either D2 or D3 (FRED’s) are bad?

Any suggestions on how to troubleshoot?

Thanks, Jacques

I'm currently building a DG300B and want to use relays to change between three output options: 4 ohm OPT secondary, 8 ohm OPT secondary to binding posts, 8 ohm OPT secondary to an XLR headphone jack.

The amp is rated at 10W. Would a 2A signal relay be sufficient, assuming the output would never be switched while the amp was outputting?

From what I've read, higher power relays have issues due to needing a minimum load current to keep the contacts clean, whereas signal relays avoid this issue?

Hello!

I'm building an analog stereo amp that can be switched to bridged mode. i.e. a 4-channel amp with a switch on the back. Each channel shall have it's own DC offset speaker protection, so I'm looking at 2x stereo protection boards.

This protection board I'm looking at. They state "Stereo module for 2 channels. (not bridged because GND common)". I'm going to copy the shown wiring diagrams here:



This leaves me confused. It would force me to buy 4 instead of 2 boards. Why is the bridged setup different? Bridged amps share a power supply, so they share GND on the power input and speaker output anyway. I just don't use GND as a speaker output, that's all.

I'm assuming the module measures DC between D+/D- and G+/G-, and has the relays switch D+ and G+. In bridged mode, the speaker would plug in between D+ and G+. If one of the amps blows, a DC offset may appear between either D+/D-, or G+/G-, triggering the protection module and breaking the connection to the speakers.

So what's up with only using half the module in a bridged setup?

Thanks a lot!

I'm preparing to DIY build a Line Array pair of speakers, being convinced with:

- their cylindrical dispersion
- more efficient with distance vs point source
- multiple drivers equal less cone excursions needed - huge argument IMO
- better heat dissipation with multiple voice coils vs one larger driver

Now, I want to use about eight, full range drivers with no crossovers and ideally no sub. Inspiration came from Grandinote Mach designs. Of course, there are many other LA models, but most use crossovers - I prefer to avoid them.

Perhaps only the top one driver or top two drivers could be mounted in an open baffle? - something to consider later.

I need help in choosing the right drivers.
Goals are:
(1) bass going to 40 Hz, but if it will be 50 Hz , hmm maybe i can live with that
(2) best as possible transients, microdynamics, the lowest distortion
(3) more pistonic

As its usually the case in audio, goals 1 and 2 are hard to have together so as 2 and 3.

For 40hz bass i will most likely need eight larger drivers? 8 inch, 6.5 inch?
What if the Line Array will be positioned in room corners forming a type of horn? Very wide baffle gives +6 db, while a quarter volume of space should improve low freq. by approx 9dB, right?

Can it be done with 5 or 4 inch drivers?

Transients.
Here is a good presentation by founder of german Gauder Akustik
YouTube

Since accelaration = Force / mass.... i'd love to have very low moving mass.
Some smaller drivers have like 2-6 grams moving mass which would be excellent.
However, they are made of paper bamboo or aluminum.

The guy from Gauder is saying that ceramic drivers are superior in terms of impulse response to all other cone materials. However, ceramics/alum have a resonance peak at 7kHz and i dont want to use crossovers to avoid that peak.

My main questions is: are ceramic cones in general better in terms of speed, transients even when they weight 20-30 grams vs smaller 2-5 grams paper cones?

Or maybe carbon fiber drivers will strike a good balance of all these qualities?
For example:
Dayton Audio CF120-4 4-1/2" ? it has freq resp. 50-15khz and mass 6.8gram

How about Tang Band W3-2141 3-1/2" Paper Cone? Cone mass only 2 grams
resp 75-20khz.
Price is similar about 30 bucks.

Your input greatly appreciated!

Let’s say spec calls for 2.08A. If I get a transformer they produces 2.08A even, is that fine, or should I leave some buffer? Get slightly bigger than what I need?

I wasn't sure where to post this one.

Before the idea was a thought I always liked that Les Paul design. Every stage of the making looks perfect. Very cool Login to view embedded media Login to view embedded media

Hi. I'm dealing with a Pionner SA 408 amp. I want to recap it, bias it and so on. I've attached the schematic.

Almost all electrolytics were Elna caps (dark blue ones, they label says (RE)). The main power filtering were Nichicon and the small ones were also Nichicon.

Here a pic of the main board (preamp & amp section):




And here a pic of the phono preamp (right) and power supply section (not complete):


This is my recap so far:

C53 & C54 Nichicon UPW. These are the two big power filtering ones

C49, C51, C52, C53 & C56 Panasonic FC. All these caps are near the big power supply ones except C51, which is in the phono preamp section.

C1, C2, C11, C12, C46, C47, C31 & C32. All of them were electros. Since they are small values (220nf, 1uf, 2.2uf & 3.3uf), I put film caps there.

In the remain positions I've put Elna Silmic II

For what I know, there's some debate about what is in the signal path and what's not. Since it's not that clear, I made my best based on my little knowledge. But I might be wrong about some positions, please let me know if should do some changes.

There are plenty of ceramic capacitors all around. Should I change some of them for another type of cap? There are lot of small ones (47pf, 68pf, 100pf, etc), but there are also some big ones (47nf). I've never come across any information regarding these, so I'm kind of lost here.

I started a thread a couple years ago when I wanted to recap the phono preamp only. Some very nice users gave me advices about what to do. But I got a bit overwhelmed and realize that I needed to learn more. Some advices were regarding the value of some input/output caps. It turns out that these caps are pretty small in this unit. Is it true? Here the thread I meant:

https://www.diyaudio.com/community/threads/pioneer-sa-408-recap-phono-preamp.339995/#post-5846574

About the biasing:

I've dealt with a few amps of this era and all of them had trimmers to set the idle current and to center the voltage at the output. All of them were class AB. In this amp there are not trimmers whatsoever. There are not big caps at the output as well, so I guess this is a different design. Any ideas about what can I do?

I really appreciate any help. Just trying to learn 🙂

Cheers!