Hi

I've an old Audio Innovations Series 500 that seems to have gone wrong. I've replaced the four EL84s and three ECC83s and am waiting to get my hands on a pair of ecc88s to complete the valve upgrade programme.

However, I was surprised to find that replacing the 84s had no effect as I'd previously thought that they were shot. I'm wondering if there is some other failed component inside it. I have the schematics but I'm not very experienced with tube amps - just love the sound - and would like to ask if there's anything in particular I should check first. I read somewhere that a particular capacitor goes and that leads to tube failure but cannot remember the details..

Symptoms are as follows:

• 
  Humming (well it's allways done that a little bit, I guess there is a bad earth in there somewhere).
  Very very low output which distorts if you turn the volume up all the way, but stays quiet.
  Phono stage is dead quiet, no output at all.

I guess the first thing would be to test the output from the tape loop. This will provide some indicator for the phono stage.

Can anyone suggest the sorts of things I should look for? What typically fails in these amps? I can post the schematics if it would help.

Thanks

JonB

Hi, this morning I found a Sony CDP-30 CD-player on a fleamarket. Couldn't resist for €2,50. I want to compare it to some of my Philips players. It had been in the rain. I dried it, and when I came home I opened the case to let any damp escape. I dried it carefully with a hairdrier, not too close.
To my amazement, it came to life when I hooked it up. It wouldn't read a cd and did not spin. After I cleaned the lense, however, it does read the disk and spins. It reads the index very quickly and the display is functional and shows the disk content. So, there's actually not much wrong with it, I think.

It plays the disk, but makes a scraping noise that sounds like the spindle is not turning freely. Any suggestions?

I've been having problems for a while with a DIY power amp I've been partly responsible for building.

It's a good amp so I want to get it right. Currently NOT working.

The current spate of problems started when I lost a channel. When I picked it up to take it to my desk to start investigations I noticed it had burnt my wood floor it had got so hot.

So as part of repairing the obviously blown components (some resistors) I decided to upgrade the heatsinking by fitting a big plate of 1050 aluminium suspended between the steel chassis floor and the PCB.

I bolted the transistors down to the aluminium heat sink. Turned it on, it fizzed, popped and smoked a bit. So that wasn't ideal. The fuse had blown so probably ok.

I started again with a new board and new components as I didn't want to have to keep fixing up a board which had burnt-out once already. I thought a brand new board with brand new components would solve all my problems.

Got it all reassembled with new everything except the power supply. Turned it on, same thing, pop fizz, smoke, blown fuse.

I suspect both my boards are ok.

So the difference between when it did work and now it does not work is the way I've attached the transistors to the heat sink and I'm wondering if I've made a crucial error. I'm a general engineer rather than an electronics specialist so what I don't know about electrical engineering makes quite a long list!

In the past the transistors have been bolted to the steel amplifier case with some blue sheet between the transistor and the steel. It's worked like that for a couple of years.

With the new heat sink plate suspended inside the chassis the transistors have CPU heatsink paste instead of the blue sheet I used before.

Could it be that the blue sheet was some sort of electrical insulator which was stopping the transistors shorting on the chassis or is the difference between blue sheet and CPU paste irrelevant to my problem.

Could it be the power supply which has blown? It's the only other part not changed.

Jan Didden's Linear Audio was a great forum for different audio authors to write and get published, however Linear Audio basically ended in 2017, I already have all the volumes but I cant stop thinking "now what?", where will the authors continue with their work? I dont believe that the JAES compares to what Linear Audio used to be which is closer to what the old Wireless World magazine used to be.

Hello,

I'm rather new to this forum, so first off I'd like to say how informative you've all been during my days as purely a browser, rather than the fledgling member I am now 🙂 .


OK, down to the nitty gritty.

There is a pair of 15" JBL Speakers that I'm looking into buying, they go by the name JBL2226HPL. Problem is I can't find too much information on them, I understand the 2226H is quite a revered speaker round these parts, but I'm wondering what the PL on the drivers I'm looking into stands for.

I believe the H in HPL states that it's a 8 ohm model(as it does with the 2226H model), but what does the PL mean?. Is it a lesser model in comparison to the 2226H or a better one, is it supposed to be a midbass driver or a subwoofer?.

Obviously these are all factors I need to be sure on. I found no reference to it on the JBL site, but I believe they may of come from a Bass Bin(which leads me to think they're probably a lesser model than the normal "H" variation or that they were designed specifically for sub bass usage).

Any information whatsoever would be most appreciated.

I finally got some decent plywood to build FHXL cabinets, and am halfway through reading the main build thread. I'm spite of being on page 100, this is my summary of all the posts so far:

Avoid MDF- Use plywood.
About 60g of stuffing in the V and about another 60 below the driver.
You can put a wire mesh at the bottom of the V and the front panel to hold stuffing
in place.
Measure your wood, as plywood is not always the same thickness.
Use titebond 2 glue
You can use Cat5 single wires for the interior driver wiring
Rebates for panels are not needed.
Some leave the top unglued until they have stuffing sorted out.

I have some questions:
What do people use for baffle fill, and where do you get it? (I am in Canada)
Where do you get 1/2 in thick felt?
Do there have to be rebates for the drivers, or can they be mounted flush with outside front panel (I have Alpair 10p)
Any tricks for cutting the circle for the driver in the front panel.

I will post pictures once I figure out how to insert them after I upload them!

Open to offers:



This URL is the offering with fully built boxes. https://web.archive.org/web/20150316033133/http://www.diysoundgroup.com/alpha-kits/minion/minion-duratex.html My purchase was earlier, when the boxes were not assembled, crossovers were unassembled, and no foam was included. Other necessaries purchased: glue, lining, binding posts, paint, boxes for (external) crossovers. Finish is black Duratex. Lining is ½” thick adhesive backed acoustical foam. Two sets of binding posts on back of cabinet, one set to each driver. Crossover is external. Crossover capacitors upgraded to SoniCap Gen 1, and Cornell Dubilier bypass capacitors added across each. Crossover schematic included. The speakers are packed in separate boxes, each 24" x 14" x 15" and 26 pounds each. Crossovers not yet packed, can go in one box, size TBD, weight should be 15 pounds. Not the best sanding or painting. Scratches on the front of the waveguides. No operational issues.

Price does not include stands or shipping.

Pickup in northeasten Pennsylvania, ZIP 18661 possible.

Thanks for looking.

This is the inside of a TKD potentiometer. the surface where the wipers sweep is very shiny and smooth as you can see in pictures, even though it has gold plated contacts (looks like gold), at the tip of wipers (contact) it is not the same material as the whole wipers, they look like silver or chrome (I am not an expert in metals).Compared to the inside of an Alps potentiometer(I took one apart a few months ago)....well it looks like the TKD will last way longer than the "carbon" path of the Alps. All this reminds me the Fluke 87 and the Fluke 87III that have "carbon" path for the inputs contacts and with time people had to open the meter and "clean" it, because with a lot of use the carbon particles from trace made false contacts with other ranges in the meter and started to show crazy readings. Now the new Fluke 87V has only gold plated contacts(best)and the wipers are very soft and gentle to the contact that for sure it will last for a long, long, long time.
ok, enough of Fluke lol. Now this TKD for around $40 USD it is a very good choice to replace an old broken potentiometer. This is the TKD potentiometer that I got from Partsconnexion long time ago:
TKD 10K LOG TAPER 6R25 (2CP-601)

Hi I just purchased a Crown XTi 800 amplifier to power my home subwoofers. This is a PA amp but is often used in home audio due to its quiet fan.

Can I use one of these smart plug below in link that uses the Australian (I am in Australia) 240V house supply wall socket. The smart plug allows wifi access with an on and off function included that can be can controlled via a phone.

Effectively I would be powering the amp on and off through the wall socket with my phone. Is this ok or perhaps harmful to the amp.
Tim

TP-Link KASA KP115 Smart Plug With Energy Monitoring - Bunnings Australia

There are lots of poly film caps for motor run use available out in the surplus world. These look like they'd be good for tube circuits, since they're available in fairly high capacitances and they have maximum AC voltage ratings of 220VAC, 440VAC, etc. My circuits usually call for DC working voltages of 400VDC or sometimes 450VDC.

Let's say I have a 10uF film cap that's rated at 220VAC max. There is no DC working voltage stated.

Can we infer the max DC working voltage from the max 220VAC voltage printed on the capacitor? Is there a formula that can be used, or is this a complex question that requires taking into account a number of considerations?

Thanks for any insight on this.
-

PS - I found this PDF from Panasonic entitled "Permissible AC voltage corresponding to DC rated voltage":
https://industrial.panasonic.com/cdbs/www-data/pdf/RDI0000/DMI0000COL75.pdf

It suggests that the maximum AC voltage will be somewhat lower than the rated DC working voltage of a capacitor. It looks like the rated DC working voltage will be somewhere between 1.5 and 2.5 times the permissible AC voltage.

Therefore, is it safe to assume that the working DC voltage of a poly film motor run cap rated at 220VAC will be somewhere around 350VDC?
-

Hi there,
I have several amps where I had to get a donor twin of to replace some parts so I also have quite a few duplicate transformers. I was wondering if it is possible and also if it makes sense to somehow squeeze a second transformer in for some amps or if it's a waste of time and copper.
Thanks for any thoughts.
Arne

I'm contemplating new bass solution for my system. The room is small, around 3x6 meters (10x20 feet), walls are rather thin and I would like not to bother neighbors but still get reasonably strong and deep bass at my listening position.

Design goals:

-Stereo (that is two cabs)
-Frequency response from 40(30 if possible)...300 Hz, where midrange takes over.
-Passive crossovers for the time being, bi-amping and active crossover later.
-More-or-less directional bass from ~30...100(preferably to ~200) Hz.
-SPL capabilities around 110 dB/m (of course, the more the merrier) for headroom. And for an occasional odd party now and then.
-Sensitivity over 90 dB/W/m.
-Size not much of an object.
-Cost is very much of an object.
-Good sounding, obviously.
-Simple construction since my tools and skills are limited.

So, after some research I've settled on U-frame and it's (pseudo)cardioid dispersion. But I have some questions:

1. Is directional bass in such small room viable? Has anyone got experience with any kind of directional bass solutions for home applications?

2. Any other simple solutions beside U-frame that do not use multiple speakers, amps and processing or sophisticated cabinets? What about regular dipoles (H-frames)?

3. Are there any guidelines (I couldn't find any) for the depth and stuffing amount for optimal performance or is it just trial-and error?

4. Drivers are the biggest problem - almost everything is just outrageously expensive here - Eminence Alpha 15 is over 114 € a piece! I'm limited to ~100€ for drivers. I could maybe afford two of these, it makes 135€ with shipping. But I found some interesting dirt cheap car subs here, 35€ for two. I'm inclining to buy two pairs of them and use push-pull to reduce distortion. Opinions?

Thanks in advance,
T🙂

Hi all, reading old post and still confused. The schematic and parts list are attached. When I re-capped this in 2011, I put NP orange dips in place of C71, C72, C73 & C74 which show as polarized. (Amp has not been running except a couple of times to test.) I am having difficulty locating anything close to 0.1 mF polarized, 400V . The search bars on most suppliers sites are pretty useless, but it looks like the only polarized caps are electrolytic and they just don't come that small. There are some Aerovox .1 uf @ 400 v capacitors on Ebay. They are 50s/60s parts. would they work? I' dubious about them.

I search for an active replacement for the 2SJ115/2SK405 and only found that IRFP240/IRFP9240 could be a possible replacement? Mouser have them anyway. Is there any else that can replace them that are active an not discontinued?

Hey 🙂

I have a Sansui T-7 tuner that needs the wide string replaced.

Anyone in the GTA do repairs like this? I'm not feeling like I'll be successful since the service manual calls for a replacement assembly rather than replacing the string.

Thanks 🙂

Looking for a dsc2 dac, thanks.

Hello friends

We are on a quest to find the best solution for new hifi nightclub soundsystem. Chatting with off-the-shelf PA makers has been a bit disappointing, so figured I'd put out a call for help. I've read through many other threads, but none exactly matched our requirements.

A bit about the project:
New Brooklyn venue, focusing on Electronic Dance Music (nothing live).
The space is total about 15,000sf, with 5000sf of that being the dancefloor. We certainly need enough bass and subbass to move people's bodies, but we don't want to sacrifice warmth and intelligibility in the mids and highs. We also want to minimize signal processing, so ideally use only Drivers, HiFi Amps, and Crossovers. This is a nightclub, so extended listener comfort is more important than precision source reproduction.

Our best idea so far involves using about 20 Class AB amplifiers (1000-2000W each) to push 2-4 drivers each. Run the system around 50% load to keep ample headroom. We didnt select speakers yet, but imagining something like a Classic 4-point Dance Stacks (one in each corner of the room). Each point would have something like 2x 21", 2x 12", 4x 8" and some tweeters. These Dance Stacks could be a combination of smaller off-the-shelf speakers, or a completely custom selection of drivers and custom built cabinets.

Though we do not have extensive speaker-design knowledge, our team is sufficiently technical to fabricate high quality speaker boxes and assemble electronic components if that's what it takes.

We are open to any and all of the craziest ideas, so if you're itching to design a set of 50' exponential horns please do be in touch.

Thank you very much!

Hello, please, I need to have an idea (even if it is approximate) of the compliancy (Qts) of this speaker.

I've always wondered how a particular speaker can work efficiently in the boot or on the door of the car.

I have never seen published compliancy values (in car speakers of any brand), is it supposed to be low or high?

I have not found information on the web, can anyone here help me ?



https://www.vzdy.sk/buxus/docs/down...files/catalog_-_jbl_car_2006_(english_eu).pdf

Low-Q design – For improved bass
extension and better transient response
in infinite-baffle applications (doors and
rear package tray).

Hi guys. A friend gave me this JBL Charge 2+ that stopped taking a charge. When plugged in, the charging lights do not come on at all. The mini-usb charging port doesn't appear to be loose, corroded, or otherwise damaged from what I can tell. I've taken it apart and removed the battery. It's a 3.7v lithium poly pack. It has 2 black, 2 red, and 1 white wire going to the connector. I tried using my multi-meter to test across different wires, but got no results. However, since a new battery pack is around $25, so I was hoping to do some more testing before spending any money.

It occurs to me that even if the battery pack was toast, the charging lights would probably do something when the charger is attached. The fact that they don't leads me to think that perhaps it's the circuit board that has malfunctioned. Or perhaps it IS the battery pack, and the protection circuit in the battery is preventing power from reaching the unit?

I've built a number of custom bluetooth speakers, but am still lacking in a lot of knowledge. Do you guys have any suggestions of things I can test? I have a number of lithium ion 18650 batteries around, and probably still have some charging/protection circuits. I was thinking I could put together a temporary battery to test with, but am unsure about the 5 aforementioned wires on the original battery, and don't want to destroy it by cutting it apart for inspection. Any advice you can offer would be apricated.

Model: JBL Charge2+ (Looks like says M9, but the text is worn)
Battery:
Model P763098
22.2Wh Lithium Polymer
3.7v
6000mAh


Thank you for your time,
Jack

I'm playing DIY active crossover with a pair of PMC DB1+'s. (These are foot tall bookshelf sized speakers).

A quick estimate based on a few measurements of relative voice coil positions suggests that the in phase lobe at crossover points down at an angle of 8.5 degrees.

Since my listening position is slightly higher than the speakers, the solution is to turn the speakers upside down so that the tweeter is at the bottom and the in phase lobe then points up towards my head!

So, this has me wondering why speakers are almost universally made the wrong way up, with the tweeter at the top?

Discuss...

I'm trying to repair a nice Onkyo DX-6550 (sony chipset), it's built like a tank and isn't in a bad optical shape, also looks quite clean inside, so I'd really hope to repair it, but it's a tough one. The player turns on, all normal, drawer works, but CD doesn't spin. It moves the head (it's a magnetic pickup) if I manually put it away from centre, so radial movement/tracking seems ok, also focus coils move up and down (so, focus circuitry apparently working) and there IS a small red dot indicating that the laser is alive. Can't tell anything about it's health condition, though, as I can't get it to output eye pattern (disc doesn't spin). This seems to be because it can't get focus - the Focus OK signal never comes on.

I did all the obvious checks: laser lens cleaning, power supplies all measure perfect, no obviously damaged components in sight, CD appears to be correctly secured in place (although I have no way of confirming that distance is ok, but it's not adjustable, the platter motor is direct and fixed in height. CD also turns freely if done by hand.
The platter spindle motor is working, there's no voltage present (because of no focus) but when measuring around the microprocessor, I somehow got it to suddenly start spinning (wrong speed and didn't read anything) for a second, probably I induced some wrong signal to upc which decided to let it spin for a second.
Also, tray open and close switches work fine, i checked them, but I guess that would be obvious, otherwise I think it wouldn't try to focus after loading disk.

The "Laser ON signal" sent by microprocessor is also alright - 5V for a couple of seconds and then goes down again.

I hooked up my oscilloscope, obviously no relevant RF signal, as disc is not spinning.
But I could see amplitude changes of focus out testpoint (goes low and then high again, with amplitudes of about 0,5V, then stays again at 0,5V offset). Lens can be seen moving well up and down and all this seems about right (in a Philips CDM service manual this is described, I think it applies to most mechanisms).

I also had a look at the Laser out, before the driver transistor it has more amplitude, clearly goes on and off (don't remember if negative, but it doesn't matter for this), after transistor (PNP) it's inverted with less amplitude change (Still around 1,3V amplitude, looks normal to me) and when laser goes off, it returns slower to original amplitude (probably because of the cap at the base of the transistor). As I didn't know if this was normal, I exchanged that cap (100uF) with a new one. No change. Also took out the driver transistor (2SA950), to test it (wouldn't measure correct in circuit), it's fine. Put it back in. Also exchanged the filter cap at the abcdef diode array to GND, it's also 100uF. No change.

As this player has been tinkered with (the power chord is cut off, but inside someone got the leads out for testing, which made my life easier) and I don't know the history, I tried putting all adjustment trimmers to middle position (first I annotated down the values of resistance I measured, so I could get back later!), as normally this is starting point for adjustment procedure, but no luck, as it doesn't focus, all other settings are impossible.

Checked that clocks and oscillators are working - for what I could find with scope, yes. Can't figure out how to check the VCO, though. They refer to frequency counter, my DMM does have this function and I've used it in other players for similar purpose, but no display is shown here. Is it relevant for the laser unit working? Could this be the problem?

Had a look at the laser power trimmer on pickup, wasn't at any extreme position, measured it - 560 ohms. But there was a black mark and the thing wasn't adjusted to it, was slightly more to the left (more resistance), I tried putting to black mark - no difference. Put it back where it was.

Now a couple of things I find strange (but I'm still struggling with understanding the whole way of functioning of the APC circuit, photo diode array and everything, so maybe they are normal):

- measured 2,64V DC over the two parallel 33 ohm resistors at laser driver transistor (emitter), that would translate to 162mA being drawn from transistor (which only powers the laser diode, obviously), does that mean laser is being driven with that high of a current, adjusted by APC?!?! Is this an indication of a dying laser? Or malfunction of APC? Or am I doing the measurement/maths wrong?

- Monitor photo diode (PD) of OPC circuit outputs -7,62V when laser is on (0V otherwise), I found that strange, if the whole circuit only works with +-5V power rails??? I'm measuring at anode of diode, where it is connected to laser power trimmer.

-At the outputs of the photo diode array abcdef (inputs of RF amp), I can only see very small amplitude signals, is that normal? If measured with DMM, they change in polarity when laser is ON, for example: -3mV goes to +3mV and then back, when laser is off and it stops trying to focus.

So, resuming: although the laser looks ok to me (I look at it through mobile phone, always, for safety), looks similar to what I've seen in other players, could it be weak? As I've measured that strange 162mA... but maybe wrong way of measuring.
Could the focus circuitry be bad, although it seems to work?
Could the RF amp (CXA1081S) be bad, so not amplifying photo diode array output well?
Could it be the VCO, not working?
Could the APC for laser not be working, although components measure ok? Maybe the photo diode? Those -7,6V...
Could there be some weird problem in the surrounding circuitry, not allowing focus circuit to have correct functioning? I'm referring to the circuit with all the adjustment trimmers.
Last idea I have: maybe the focus and tracking driver chip is defective, although it seems to work?
Maybe even some strange mechanical problem I haven't spotted which makes the lens not being at right distance of disc? I had this with a B&O player which came back to life after adjusting disc height. But this one has no adjustment.

Please, share your thoughts, I'm kind of lost here... thanks!

I remember the discussion on one of the threads but can not for the life of me remember the speaker brand. They were online only i think. Two-letter followed by acoustics. i.e AB Acoustics"

Hey guys, im trying to figure out why my ceiling speaker has no output from the woofer or tweeter. I cannot seem to get a resistance at the main input speaker terminals but i did measure resistance at the woofer and at the tweeter wires individually and everything seems to be OK. Ive done a little bit of troubleshooting on my own and when i was probing the negative terminal in combination with any component (PTC fuse, the capacitor, and any of the resistors) on the crossover i get no continuity what so ever. However, when i take the same model speaker but a fully working one and i probe the negative terminal in combination with any of the components listed above i get continuity. What section of the crossover would cause a no output condition? I've been toying with the fact that its the PTC resettable fuse but i am unsure if its used to only protect the tweeter or if its used to protect the entire design.

Hello Forum

I'm posting this thread because I would like to know if any of you are familiar with the "Rotel gateway player" (RDG1520).

If so - have you been able to receive dab+ stations on the player.

According to "Digicomparison.com" it should be compatible with dab+"
Unfortunately I have never been able to receive any dab+ - and have only seen the message "No service" in the units display. It has dab - band III - and I think that "Digicomparison" because of that have made the conclusion that it then should be able to receive dab+ /but right now I doubt that this is correct.

BR Benny

A sneak peek at the topology and preliminary simulation results for a new discrete opamp design called the LF03 - the 3rd in the Lake-Forest series of discrete opamps. The 1st was the single-opamp LF01 (whose Class-A output stage is also used by the LF03), and the 2nd design (LF02) was basically a dual LF01 which hasn't been prototyped yet. This is the 3rd, and the first fully-discrete unit. It borrows some concepts from the AD797 - I dropped the folded cascode of the AD797 in favour of a common-emitter PNP differential amp (similar to the Melcor 1731) for the VAS, which drives a Class-A driver biased at nearly constant current, followed by a Class-A push-pull output stage (borrowed from the LF01). The input LTP is generic, topologically similar to the Melcor 1731 and various other "classic" opamps. The compensation schema is a combination of that used in the Melcor 1731 and AD797B.

I've not included the component values, which are still evolving - though the topology is frozen and the layout has been completed and sent for panelization and PCB fabrication. The simulated LTSpice THD20 plot shows the output FFT of a non-inverting unity-gain buffer at 20 KHz, 4V amplitude into 600 ohms. As can be seen, H2 is down at about -100 dB and is the dominant distortion component, similar to OPA627 and AD797B (from where the floating current-mirror in the VAS has been borrowed from).

Typical uses are expected to be line-level stuff: I/V converters, gain stages, preamps, tone stages, active filters, headphone amps, etc. Basically, it can substitute most monolithic DIP8 dual opamps at almost any location where a Burson/OPA-Earth opamp can be used.

I am looking for a proven design 2 way diy active xover for use with my Nomex 164 and a sub which I will build using a Peerless 830668 and Lm3886 IC chipamp. I have googled and have found some schematics, but I do not want to waste time. As this will be my first active experience, I appeal to anyone that has actually built one from scratch. Tks in advance for the schematics.

Hello:

I just got my hands on a new (to me) scope. It is a fairly basic B&K model, analogue, 2 channel, 30 MHz. It seems to be in good shape. It was not expensive, so I don't have huge expectations.

It came without probes, so I purchased some cheapo units that looked decent... See the link below for reference:




I wonder if there is an issue with this scope. If I display a trace with a considerable vertical component, the trace seems skewed at the edges of the display but not at the center. I am wondering if this is a fault, an issue of cheap probes, and if there is an obvious fix...

To illustrate the issue, I am posting here two pictures of a 1 kHz sine wave (one with the probe at 1 Megaohm, and again with the probe at 10 Megaohm). The same is posted with a 10 kHz wave. The results are the same.

Any ideas? Suggestions, advice are hugely appreciated.

Thank you,

David

I have a pair of original, Australian made Sansui Silcron Monitor speakers.

Three way, 12" woofer, 5" mid, & 4" tweeter.
Rather than using a dedicated crossover, the tweeters have electrolytic caps in the wiring on the positive wire just before the tweeter + terminal.

They're not cutting edge, but for the right owner they're reasonably dynamic and listenable.

I'm finding they're a little hissy during vocals where "s" is involved

Is it worth experimenting with a resister to control the tweeter and where would I include it in the circuit?

Or, should I re[lace the cap with poly?

Don't want to over capitalise but would love to improve the sound.

Cheers

I'm trying to build a very basic 2-channel subwoofer amp from spare parts I have lying around.

I have a stereo TPA 3116D2 board TPA3116D2 Dual Channel Stereo Digital Audio Power Amplifier W6A6 Board C2T2 | eBayAnd a transformer from Bose Companion 5 Power Supplies, Block Diagram - Bose Companion 5 Service Manual [Page 36] | ManualsLib

Questions: (1) How many volts is the transformer? (2) What else do I need?


https://www.ebay.co.uk/itm/353599420814?hash=item52542af98e:g:mqUAAOSwZrhhA9Ph

Hi I'm trying to adapt a Lenovo IBM Thinkpad 20v 90w power brick to run a TPA 3116 Amp. To my knowledge the Lenovo has a round tip 7.9 x 5.5 mm jack. The amp power in is 5.5 x 2.1 mm. I've spent hours looking for a suitable adapter. Has anybody tried this on a Lenova? Can anybody help me out here please?

I need some information about the Dynaudio Sub500.
Inside connection cable broke, 6 wires from the front to the amplifier board.
The wires are soldered to the board, I think there have been a connector from the factory but now it's soldered. A few wires are loose from this board.
So I need to know which color wire goes where on the board.
It should be fit to the upper corner on the amplifier board.
Thanks in advance for your reply

I have a little experience building diy audio kits but this SSE build will be my first time building a tube amp. I populated the board over the last week or so in my free time but I realized yesterday that I made a mistake.

I wanted to have the board underneath the chassis with the tubes on the opposite side facing up. Unfortunately I put all the components on the top side except for the tube sockets on the other side. Is there a reason why the tube sockets and resistors should be on the same side if doing a reverse layout. Also is it still possible to mount the board the way I have it with just the tube sockets on the opposite side facing up?

Here are some photos.

With the help of many contributors to the http://www.diyaudio.com/forums/digi...dac-pcm1794-waveio-usb-input.html#post3252373 thread I implemented a series of upgrades to Doede’s DDDAC which resulted in my single board DDDAC-Buffer-Cinemags sounding far better than I thought ever possible by any DAC. Doede’s brilliant NOS PCM1794 design and the optimized operating parameters are the foundation on which these upgrades are applied.

I reported my upgrades on the main forum thread but they are so scattered that I decided to put them all together here with even more explanation and pictures. Everything except the buffer applies to multiple DDDAC stacks as well.

The following is a summary list of the upgrades in order of sq improvement/cost:

1. Digital Sources. I have a WaveIO with a Belleson Vreg and simple reclocker which I am very happy with. I plan to try a BBB with an Acko reclocker because of the many posts that the rpi and BBB sound even better. Clean digital source stream is a must.
2. ½ clock delay circuit. If you have a blue Main Board then you already have this. If you have a red Main Board then you MUST add a 2 chip circuit which provides this I2S Data delay. Four out of 4 persons who have done this report a major improvement in sq. Music and voices sound more coherent and real. See group buy for 2 chip PCB at end of thread.
3. Analog 8VDC power supply. I use a Salas Shunt power supply. Others have had great results from Tent Shunt supplies. A Belleson series Vreg can also be used. This increases the musical energy and dynamics as well as more detail. This power supply may partially offset the need for a buffer.
4. CCS. The standard circuit for pin 20 is a 6K resistor to ground. Changing the resistor to a premium type provides very little improvement in sq. Single JFET CCS circuits using the 2SK246Y or the 2SK208 “O” or “R” sound more “musically exciting” and increase detail. When changing back from a CCS to the 6K resistor on pin 20 the sound became a bit compressed with less detail by comparison. Why does the CCS circuit sound so much better than a resistor? I've concluded that it actually makes the PCM1794 DAC chips sound better. Both JFETS also have a low temperature coefficient. Toshiba officially lists the 2SK208 as the replacement for the discontinued 2SK246. They sound the same to me. See Assembly instructions for CCS circuit board. http://www.diyaudio.com/forums/digi...e-board-pcm1794-nos-dddac-37.html#post4229210
5. Buffer. A single board DDDAC is inadequate to drive the DAC output through a transformer without sounding a bit thin and weak in the bass. The music sounded pleasant and polite but I was left wanting a more real musical experience. Four or more DAC boards can properly drive the signal through a transformer. The forum consensus suggests that a partially upgraded single board DAC sounds better in some ways than a standard 4 DAC stack. A fully modded 4+ DAC stack sounds incredible but is expensive and tall and requires a huge power supply. A fully modded single board DAC with an output buffer is the alternative. The buffer increases the musical authority, bass and detail through the Cinemags. The Cinemags no longer sound weak or thin. The downside of the buffer is that it requires +12V and -12V power supplies, 4 matched pairs of BF862 SMD JFETS, and a PCB. This post has more explanation of the Buffer: http://www.diyaudio.com/forums/digi...e-board-pcm1794-nos-dddac-11.html#post4163372 Direct feed NOT recommended as discussed in this post: http://www.diyaudio.com/forums/digi...e-board-pcm1794-nos-dddac-18.html#post4173717 See GB for CCS circuit board.
6. Digital Vreg. I use Belleson SPM 3.3V regulators on the PCM1794 digital circuits. Others report using the Tent shunt regulator with success. Even if the standard LF33 Vregs are not replaced, the digital caps should still be OSCONs. I also use Belleson SPM 5V regulators with additional caps on the main board. The sound improvement from the Belleson’s and OSCONs was modest, but the music sounded more “settled down” and the details seemed to have much fewer unnatural artifacts.
7. Rload Resistors. A premium resistor like the tantalums, Rhopoints, TX2575, or Susumu SMD sounds clearer than the standard Dale or the PRP. I use tantalums and Susumu’s on my two DDDACs. I also tried 120 ohm tantalum resistors which didn’t sound quite as good as the 135 (2x270) ohm Tantalums. Doede tested many different resistor values and 133/number of DAC boards is the sweet spot for sq. I tried 135 (2X270) ohm Susumu RG's with success. See http://www.diyaudio.com/forums/digi...e-board-pcm1794-nos-dddac-32.html#post4202948
8. Cinemag Load. Having a load of 8K-15K on the outputs of the Cinemags, including the preamp input resistor, sounds best. Having a 220k ohm preamp load sounded unstable in the higher frequencies to me. Adding extra resistance in the output requires high quality resistors. I use two LDRs in series set at 11Kohms. Dwjames and I tested Wima FKP 3 film caps on the Cinemag outputs and found that 150pf brings the musical detail into proper focus. Higher capacitor values start to collapse the sound stage.

I will add posts to this thread which provide more details on each of the above items. In order to keep this thread from getting “scattered” please confine comments to the buffer only. All other topics should be posted on the http://www.diyaudio.com/forums/digi...dac-pcm1794-waveio-usb-input.html#post3252373 thread because they are of more general interest. You can also send me a PM if you wish.

Hello everyone- I am new here and would like to get some advice about my tube amp where one of the capacitors for the power tube has starting blowing smoke and I plan to have replaced. I would also like to upgrade the caps to the driver tube as well but would like to do this one at a time. I've included a photo of the driver socket (it's the one on the right side of the close up photo) and its associated caps. I was hoping someone could tell me which cap out of this trio would make the most difference in terms of potential sonic improvement. I've decided on using Miflex caps and would welcome any suggestions on which values for the caps I should be aiming for to try to avoid another blowout. While I've been an hi-fi enthusiast for over 15 years- I've actually never worked on any of my equipment before and am having a friend who works with electronics help me with this project though he is not into audio himself. If I am posting in the wrong place or if more information is needed please do let me know where I should be or what more information is needed. Any help is greatly appreciated.

Over the last few months I have been using and tweaking this for a 5v 1A shunt regulated supply for a Raspberry Pi based music server, http://http://www.analogmetric.com/goods.php?id=2211 and though I would share my findings with the forum members.

First of all I need to make clear that a lot of my findings have been based on simulated Spice CAD results (NI Multisim) and my test equipment is very basic, oscilloscope, frequency counter, dvm. Now this may ruffle a few feathers, but all measurements are comparative and the reason in sharing my findings is to offer them up to my peers for review and criticism even! Hopefully, someone with better equipment might try a few ideas and make some real world measurements? Glad to get that out of the way!

Now this kit gives excellent value for money and is of good quality, but it will not provided 1A @ 5v and it will only provide around 89dB of PSRR in its original form. However, a couple of simple mods will give the required current and significantly improve the PSRR. If you follow the link below it will give the schematic for reference.

Mod 1 - to get 1A at 5v simply replace Q2 with a Darlington type, I used a TIP137, which is a pin for pin replacement for the MJ15031. The Darlington increases the vbe of Q2 to allow Q1 to turn on enough to enable the current source at this level. This mod also improves PSRR due probably to the higher hfe of the Darlington. R1 needs to be around 0.5Ohm to give 1A out.

Mod 2 - to improve PSRR even further, disconnect R4 (10k) from the junction of R3, D1 and Q3 and connect it directly to the +ve regulator output, i.e. collector of Q2. This is in line with the typical applications part of the TL431 datasheet. The pot will have to be adjusted to get the right Vout of 5v, but it is within its adjustment range. This mod increases PSRR to almost 140dB up to around 20KHz and from there it deteriorates back to around 88dB at 600KHz

There are further mods that can be carried out to improve PSRR even further over a wider bandwidth, but they require more "surgery". If this thread generates any interest then I will be happy to share those too.

I have used this modified regulator for a few months and can report that it has been rock solid and quiet and the sound quality improved with every mod that I tried.

Your feedback would be appreciated ladies and gents!

230V 2x24V 1000VA for 50.93 EUR.
230V 2x24V 3000VA for 104.43 EUR.

6.90 EUR shipping to Germany.

I ordered two of the 1000VA transformers for my Sony VFET amp and I can say they look great. Haven't hooked them up yet though.

Ringkerntransformator 230 V | 2 x 24 V | 1000 VA | -A2- Trafo Transformator | eBay

Ringkerntransformator 230 V | 2 x 24 V | 3000 VA | -A1- Trafo Transformator | eBay

--Manfred

Hi I own the Akai for some 40 years but now the synchronous motor driving the switch on/off mechanism failed. I don’t think I’ll be able to find a replacement with the same specs and shaft (D-shape). I can scrap it and start using the Technics or modify the Akai, make it fully manual. Please advise, would this modification be worth it or is the SL-5 in the same range or maybe even better? I guess you’re going to say it depends on the cartridge/stylus but suppose I’ll make sure those are in the same league; what would you say?
The rubber ‘feet’ of the Akai are fairly worn btw.

Hi all.
I'm about to put together an SPP. I'm going to use el86, just because NOS el84 have become ridiculously high priced. This draws a lot of B+ current. I'm thinking of using a couple of TV damper diodes for the rectification. Has anyone done this or do you have any thoughts about an appropriate candidate?
Thanks!

I've built up all 3 of George's boards, and finished the SSE. And an remarkable little amp she is, I listen to her daily.
I was planning on doing the 45 amp next, but lack of money for the transformers has put that on hold. So because I have a pair of old Sansui 1000 tube receiver output transformers, I figured I'd build the SPP next. It seems a no brainer to use these outputs with the EL86 tube, but my question is this. Does an EL86 amp sound as good as an EL84 amp? Any thoughts?

Sold

Unit: MFA Luminescence preamp. Separate power supply, tube regulation, octal tubes, decoupling electrolytic on each tube. Just replaced large coupling caps with Dynamicaps 4 mf

Problem: Not motorboating in the classic sense, but a steady thump, not heavy, short, like a soft rim shot in a snare drum. If I were playing LPs, I'd say it's a steady once-per-second or so sound of a stuck record. But I'm playing CDs. The CD plays, the music is there, but so is the thump. It's much louder on one side than on the other. I'm assuming the cause is on the loud side and is being picked up on the other.

I'm thinking maybe it's a defective Dynamicap (or solder joint, but I'm not there to check it) or a decoupling cap. I'm assuming it's not the power supply because of the disparity between the two channels. Thoughts?

Is anyone familiar or is using this class D amplifier?

https://www.aliexpress.com/item/1005001708649867.html?ug_edm_item_id=1005001708649867&creative_img_ind=3&creative_img_tpl=153709&edm_click_module=alg_product&tracelog=rowan&rowan_id1=spaml_product_2_picture_square_2_1_pt_BR_2021-07-24&rowan_msg_id=carlCOWS_220_$f08acb0364e94e4faa4e602f62e09931&ck=in_edm_other

Hi friends

I inherited (a gift from my father who luckily is still doing very well 🙂 ) a quite big collection of vinyl classical records (close to 4 m of records), all sort of—from baroque to modern, chamber, solo, orchestral, symphonies, operas, and a few exotic things...

Classic records are quite complicated, as many are just a "work" (like a piano-concert etc.) while many are compilations of something (great sonatas, Schubert's piano-sonatas 1,3,8 etc.), and the interprets are "never" the same—the conductor, soloists, orchestra are very often interchanging.

We (my wife and I) haven't found a common ground as to how to organize it, and settled on the simplest and least clear structure: alphabetical by composer, which causes "problems" with records where a certain interpret is playing various pieces...

What are your recommendations for a clever structure?

Thank you!

Anyone use these and or know anything about them, where they fit among current new production 2A3's and if they're worth buying?

1pc for brand new ceramic dog bone version 2A3K 2A3 tube | eBay

Hi guys lately ive been obsessed with squeezing the most out of my lm317 supply. My question now is how the layout should be around the adjust pin, involving the variable resistor and the bypass cap. The layout for my board is such that the two components cant be equal distance from the adjust pin. So my question is should the resistor be closer or the cap closer to the adust pin, and why?

Can you relieve my little head ....
Consider an order 4 Linkwitz Riley filter.
From the manufacturer's measurements, I have the data allowing me to plot the SPL curves of my speakers on the "CALC" spreadsheet and visualize the SPL dispersion margin.
In the cross zone (point at -6 dB with LR4), I want to draw the sum line of the filter (0 dB link of the SPL).
How to do this? What mathematics?
All I can do now is add sound levels => L = 10 x log ((10 ^ L1 / 10) + (10 ^ L2 / 10)) ... and that doesn't work not at all here !!!
Moreover, if I reason at the crossing point (-6 dB), the two speakers each give the same level, so (for me ...), acoustic sum = 3 dB ...
THANK YOU for relieving my little head ...😀

hello

I received a shanling SCD-T200C cd player (in fact it is a SACD player) for free.

the board at the laser mechanism is destroyed, as somebody tried to fix it.

I am aware that there are no spare parts from shanling due a patent problem with the SACD technology.

I would like to convert this unit to a plain vanilla cd player, maybe installing a normal mechanism as KSM whatever number. it fits...

I just would need a controller for the laser, maybe I will need to remove the display electronics and put something else. I am handy with pic controllers.

is this a mad idea ? somebody has done such a modification (downgrade, I know) ?

but the case is so awesome that I don't want to scrap it

any ideas ?

thanx

Alexander

Hi all again!


I'm replacing a few resistors in my Sugden monoblocks but I am not sure what to replace the coloured resistors with. What do all the different shades of blue resistors mean? Is there anyway to tell? Are they all simply 'blue' from different manufacturers? I have attached a couple photos. Particularly that big resistor inbetween the relay and cap. Does it mean they're metal film?



Also when ordering online and unsure what the resistors power rating is, is it safe to assume that if the dimensions of the resistor are the same it'll be the same power rating? I assume it's okay to replace with slightly higher power rated resistor?


Thanks,
Byron

Boogie on brother.

Hi folks,

So I have this turntable & speaker system, it's very old and seems to be very un-documented online. Thankfully the internal circuit is extremely simple with a mains transformer, a metal 2 prong rectifier, an EL84 tube, a 2x32uf smoothing cap and an audio transformer. Additionally a couple resistors and small caps.

I've fully serviced the turntable, stripping down all the mechanics and cleaning them - it runs like a dream. I've replaced the metal rectifier with a 1n4007 diode + a 100ohm resistor. The smoothing cap is in-spec so I left it, as are the 2 resistors and small caps found elsewhere. The EL84 seems fine, but I've got another on hand too - have tested it with both with the same results.

Voltages are good, turntable is good, sound is good - what's the problem?
Well, the mains transformer makes a REALLY loud buzzing noise. I've never heard a transformer make this kind of noise before, it sounds like a ratchet constantly spinning. It's loud enough to make the deck basically unusable for listening to music. Having physically detached the transformer and moved it away from the rest of the deck while keeping it connected by wires, i can confirm that the noise is 100% definitely coming from it and not the rest of the circuit or the speaker.

Does anyone have any suggestions here? I cannot find any information about this transformer online, or schematics for the deck, but the transformer seems to be stepping mains voltage up to about 330v for the EL84. I presume I have no choice but to replace it, but I have no idea how to gather the information I'd need to do this correctly. It has 4 wires on its secondary, two going to the EL84, one going to the rectifier diode (which then goes to the smoothing cap) and one going to the metal chassis. If there's any other solution available please let me know.

I can say one thing - the noise isn't present when you first turn it on. It comes on as soon as the valve starts warmly glowing, after about 10-15 seconds.

I'm testing the device through a dim-bulb tester with a 70w bulb, which barely lights up at all. The buzz happens when plugged directly into the wall too.

R

Hello forum,


I'm thinking about building a symasym amp but I think I missed the right time by 10 or 15 years or so. It still has a good reputation for sound and it doesn't look so hard to build. I'm not an expert but I'm OK with the soldering and the enclosure building. For the AC part, first powering up and trouble shooting I have some help from a friend so I should be covered at this end.


Just wondering if there are other, similar diy "open source" amps out there. To fit the shoe it should have an active community, parts should be easy to come by and of course it must sound nice. Power is not too important, symasym classic has plenty of power for what I need.

So please let me know if there are alternatives worth researching or if you have built a symasym recently (withing the last 5 years or so) and you would do it again I'd be happy to hear about that, too.




Thanks for your time

Hi All,

I am looking to improve my living room setup (detailed below), and have a proposition I’d like to pass by you all to check I’m barking up the right tree!


Current setup

I currently own a pair of Void Mycro 6s (http://voidacoustics.com/uploads/Mycro-6-manual_1.pdf). They just about satisfy my SPL requirements, but are far from Hifi. I have modded them by filling ports and extra wadding - but still fall a little short.

Bass is handled by my dual 8” PPSL (http://www.diyaudio.com/forums/subwoofers/303976-sorely-tempted-ppsl-3.html), filling in below 120Hz. Power is a Lab Gruppen FP2400Q, providing 380w per Mycro 6 and 1280w to the 8” PPSL. DSP is handled via a DCX2496, with a Focusrite Saffire DAC.


Proposal

I would like to build pair of replacement speakers for the Mycro 6s that will, in approximately the same package, exceed their SQ - while maintaining SPL output. Budget approx £450.

I aim to do this by a new cabinet, that improves on several areas of the Mycros:

⁃ BMS 4524 compression driver, crossed at 2kHz.
⁃ Elliptical (?) horn, W90, H40 dispersion (?). 3D printed in ceramic.

⁃ B&C 6NDL38, crossed to sub at 120Hz
⁃ Sealed cabinet (4.5L), Q=0.707

⁃ Stiff cabinet (18mm MR MDF)
⁃ Zero parallel cabinet walls (heavily trapezoid, slanted top)
⁃ Flat front with tapered edges, minimising baffle step / effects

⁃ Active crossover. I have a spare TAS5630 I can use for tweeter (100w @ 0.1% THD @ 8R)
⁃ EQ through REW


Crossovers

BMS4524 was chosen due to its ideal 2kHz crossover, and extended response (20kHz+). Also heard great things about it on the interwebs.

HF response of the B&C is fantastic, but LF is a little on the edge. I propose to cross it at 120Hz to the sub, but by letting its natural roll-off do the work, with a 70Hz 2nd order to protect excursion @ 200w. This sims the same as a ported version of the same with a 120Hz 2nd order crossover. (The sub will have a 120Hz LP)


Summary / questions

⁃ My original plan was for a sealed 8” driver, but struggled to find a nice 1” that would cover the extended range to prevent beaming (1.3kHz+). Is there anyway around this or is there any need? 6.5” + 1” seems to be a nice sweet spot.
⁃ I have chosen Elliptical horn due to its constant directivity. My listening position shifts alot in the horizontal plane, hence the 90x40 dispersion. Is this still the best choice? I was toying with Tractrix, but is a little to directional maybe.
⁃ Would MTM make sense / be worth the extra space?
⁃ Is the natural roll-off a suitable method for crossing the LF of the 6.5”? Or will I run into phase weirdness?
⁃ Any other driver suggestions? I have looked primarily at BMS, B&C and Beyma offerings.
⁃ Will this sound a marked improvement better!? (Or do I need to go further…)


Thanks everyone who made it this far. I am looking forwards to your responses 😀

Jacob Desvarieu,
Composer and member of carraibean's band KASSAV' passed away at 65 ( covid).

The guy was a GREAT musician and had an incredible voice ( most women i know just melt when they hear his deep 'rocky' voice).

KASSAV' - LIVE MWEN DIW AWA - PARIS ARENA LA DEFENSE - YouTube

He was very friendly and human guy too as other members of the band ( was lucky to work in a room next to them for some weeks 20 years ago).

We lost some great artists this last week... 🙁

First, AV400v2 is much improved amplifier compared to the old AV400 amp. So, AV400v2 is a personal version of the amplifier AV400 or, in other words, how should it look old AV400. If I've sparked your curiosity even a little, then I invite you in this topic to buy even a piece of PCB AV400v2 which includes documentation of the amplifier assembly (including circuit diagram). Documentation amplifier is printed on paper (black and white).

AV400v2 is a (400W - 4 Ohm) compact audio amplifier, Hi-Fi, with good performance, which we subjected to various tests, as you'll see in the videos below. In the two videos below (excuse me, I haven't made ​​a subtitle, but the images are quite suggestive), I tried to highlight what this amp is capable. Unfortunately, Xvid video quality is not the best, maybe even the sound (which is compressed to 192kb/s), but important things you can see see and hear.

AV400v2 is presented in two versions: AV400v2.1 and AV400v2.2 (using the same PCB). AV400v2.1 is MOSFET output transistor and AV400v2.2 is BJT output transistors.

1. TEST AV400v2 - BJT version:
https://www.youtube.com/watch?v=AzytSB64M6M

2. TEST AV400v2 - MOSFET version:
https://www.youtube.com/watch?v=hCpAUlpthC0

In recent years, I have performed various tests, especially with MOS-FET pair IRFP240 and IRFP9240 and, one thing revealed in many technical audio books, indeed, an audio amplifier with MOS-FETs sounds best if he sandwiched one driver pair transistors between VAS amp stage and output stage.
I even made ​​a comparison in this respect. In fact, both AV400v2 amplifier, and GX400 have passed in recent years by some tests - including tests of various topologies (example: Output Triple amplifier...) - and after this I got the version presented.

AV400v2 PROJECT or AV400v2 Documentation contains 10 pages with these "chapters":

1. AV400v2 - Cover
2. AV400v2 - Electrical diagram v2.1 and 2.2
3. AV400v2 - List of electronic components
4. AV400v2 - Indications for operation amplifier
5. AV400v2 - All Layers PCB
6. AV400 v2 - PCB Copper Top
7. AV400 v2 - PCB Copper Bottom
8. AV400 v2 - Drill Info

DOCUMENTATION (printed black and white) is valid in English.

PCBs prices are as follows (PCB size = 216 x 79 mm) :

1 pcs. PCB AV400v2 = 19 USD (includes printed above project to help in assembling the amplifier).

2 pcs. PCB AV400v2 = 36 USD (two pieces include with printed project mentioned above, to assemble the amplifier)

Who buys more than two pieces, the price is 17 USD/pcs. PCB.

I have available built units in two forms (without the heatsink):

a) fully assembled at the price of 85 USD / piece (see pictures below - in this moment only one piece available with MOS-FET).

b) semi-assembly built units - price of 82 USD / piece (I currently only available 4 pieces but depending on demand, I can assemble some extra).
WARNING! semi-assembly built units isn't soldered output transistors, drivers and bias transistor. So, these components will come separately along PCB. After that, depending on how the PCB clamping the heat sink, you have glue them.

Payment can be made via pay-pal at:

tehnium[dot]azi@gmail[dot]com

For more details please contact me via private messaging diyaudio.com or via email: donpetru@gmail[dot]com

AV400v2 amplifier needs 1.2Vrms on the input in order to deliver nominal power. Supply voltages are +/-(40 ... 80)Vdc.

This is another design stemming from my forays into low power, reasonably high performance amps with jellybean transistors (BC547, 2N3904/3906, BD179/180).

My "power amp" designs from this are in the single-digit PPM distortion range, so I wanted something to preserve that and give me an accurate volume control.

The first section is a three-stage amp with a diamond follower after the VAS, this then drives a six-bit relay based attenuator, then the output of that goes into a driver stage (another three-stage amp), with a cascaded diamond driver on the output.

On simulation for the composite amp I'm getting around 3nV/sqrtHz input referred noise, gain adjustable from -31dB to +32dB (in 63 1dB steps), and 1 PPM 10KHz THD pushing 10V into 50 ohms.

It's designed to be reasonably friendly, with DC servo to keep offset down, plus clipping management in the output stage. It'll drive loads down to ~8Ω with no problems, including headphones and little full-range speakers.

I've added a few parts to the input to allow flexibility in source - it can be set up so that either (or both) sides are inverting or non, so can be used as either a stereo single-ended preamp or a mono differential preamp.

I've added a regulator for the front end stage and DC servo, as the DC servo compromises PSRR a little (reducing it from ~90dB to ~60dB). The reg adds ~60dB PSRR.

The whole lot is on a simple 127mm x 100mm PCB. MELF resistors and diodes, 1206 caps, and a mere 157 through-hole transistors. With no exotic parts it should be fairly straightforward and reasonably inexpensive to build.

Attached LTspice sim of the amplifier chain, plus a couple of screen grabs of schematic and PCB, plus zip file containing all the design files in KiCAD format, including Gerbers for manufacture.

Sorry newbie question. I am looking at purchasing amp innards.

In the link below, the power supply and channel modules are clearly evident.
https://sc04.alicdn.com/kf/H0e65a56...026994/H0e65a56cbe0e49cb893374ad487ff089y.jpg

This is a two channel class D amp, but I'm looking at putting together a one channel sub amp based on the innards of this one.

Am I able to simply use one channel module or is the power supply designed to only run with two channel boards connected?

Cheers

Searching a TransportPI in good conditions

Thanks + regards

Josoeff

This is a power amplifier i bild 5 years a go.
it measers as follows :
Uout 14V 20hz 0,30% 25W bij 8ohm
Uout 14V 1kc 0,90% 25W bij 8ohm
Uout 14V 10kc 1% 25W bij 8ohm
Uout 2,8V 20hz 0,08% 1W bij 8ohm
Uout 2,8V 1kc 0,02% 1W bij 8ohm
Uout 2,8V 10kc 0,03% 1W bij 8ohm

R.out 20Hz tot 20kc 0,45ohm df =18 bij 8ohm
10V 8ohm 10hz -0,4db tot 200kc -3db

28db (0,6V =14volt out)

it is stil in use by a freind of mine in combination with Ariel (lynn olson)

I'm interested in trying a Neurochrome amp to pair with 101db horns (Wayne Parham's 7pi) Can anyone help me with sonic differences between 186, 286 and 686 amps? I'm looking smooth, transparent, effortless sound and I want to get the most out of the build in terms of sound quality without overspending on unused power. Thanks so much for the help!

How to store the inductor after purchase? Here have three methods help you management the extra inductor .

1. The storage conditions of the product in the package: temperature 5～40℃, relative humidity less than or equal to 70%, if taken out and used, please seal the remaining product with a plastic bag and store it in accordance with the above conditions to avoid oxidation of the terminal (electrode) and affect the welding state .

2. The storage period of Kedajia electronic products is not recommended to exceed 12 months. Under other influences, the terminals may be degraded, resulting in poor solderability. Therefore, all products should be used within 12 months based on the shipping date.

3. Please do not store CODACA product in an unsuitable environment with high temperature, high humidity, dust and corrosive gas. .

Amp came in with blown power supply fets .

I replaced the fets and 2 driver ic’s didn’t replace the smd transistors yet .

When trying to power the amp up it shows no signs of life .

Any ideas ?

May I draw attention of the respected diyers to a new amp by Mr. Renardson
http://www.angelfire.com/ab3/mjramp/newamp2.html
The PCB will be available soon, if you need it, drop a note to Mr. Renardson

Hi

I've found this site whilst trying to research a problem I have with my technics SL1210 Mk2. I've searched the forum but can't find anyone describing the subtle speed changes I am experiencing.

I have two of these decks, for DJ'ing, but recently one of the decks has developed a fault where the speed constantly oscillates around what I presume is the speed it should be turning at.

This isn't audibly noticable, but it causes huge problems when trying to beat match records as one record drifts all over the place and continual correction of this 'drift' means the mix will never actually sound cohesive.

The fluctuation is in the order of tenths of a percent, and occurs at all positions of the pitch fader, including at the zero position. I have come to this conclusion by playing two copies of the same record and hearing it drift from being in time, to too fast, to back in time, to too slow, etc., etc., so I'm pretty certain this is what is happening.

I've put a new pitch fader in the deck anyway as it is 15 years old and never needed servicing, but I guess something else is wrong and causing this problem... I am very willing and able with a soldering iron, but I don't have anything other than basic test equipment, i.e. a multimeter. I'm up for replacing as much stuff as it takes to fix this problem and have a bit of a stock of capacitors, etc.

If anyone can offer any advice it would be seriously appreciated as I don't have the time to send the deck off for repair anywhere.

Thanks.

Hi, I just bought a few Texas Instruments TPA3118 boards to test out for a mono boom box. I bought the very plain type with only the chip and in/mute/power/out solder points.

The other components in my test bench are a Dayton Audio PS65LP-4 (4 Ohm, 99 dB sensitivity), a multi-purpose laptop charger set at 19V output, and a 100K log pot on the signal. The input jack has the two channel positives shorted to mono. All components are brand new.

After putting everything together I noticed a few obvious issues with the sound that I had not heard about in any of the forums dealing with this chip:

1. The sound is extremely low, with no bass. With the pot at max level I get a sound that's similar to a budget laptop speaker, even worse in terms of bass (I am regulating the volume from my cell phone). With a 99dB speaker and a 60W amp, I should have blown up my neighbor's ears by now...

2. The pot seems to do very little difference. Even at minimum I have a signal, and it's clearly lower than at max, but not what I expected from a 100K pot. I even soldered an additional 100K resistor in series, which made little difference.

3. Even changing the input voltage from 19 to 15V and back makes very little difference.

OK, the speaker has no enclosure and the system has not been broken in, but this is way worse than any other brand new system I have put together before.

See attached photo of the assembled system. I double checked input and speaker polarity, and input signals. Can anybody think of any obvious flaw (except for a defective board)?

Thanks.
gm

Hallo all.
I need some advise plse. I have a pair of Spendor S100. I have read about rubber surrounds getting hard and stiff. I have checked and saw that the surrounds on the midrange and 12inch woofer are indeed extremely stiff. So you will need an extreme amount of watts to move the speakers. I suppose there is no way to soften the rubber surrounds. I have read about brake fluid but are to scared to try it. Do you guy's have any advice plse. If I can get replacement surrounds, do anybody perhaps now where. The bass woofer has weird surrounds, not like normal ones.
Help appreciated !
Regards

Hello All,

What can you build with 2n5457 and 2N5460 JFET's?

Years ago I back ordered 2500 each of 2N5457 and 2N5460 JFETS. Mouser shipped these just a couple of days ago , they will arrive soon.

Thanks DT

I'm helping my brother repurpose some speakers for a new place that he's putting together. Amongst them are two old W-Bins containing B&C 18TBX1000 drivers. I took the opportunity to do some measurements of one of them (see attached). They are vented, and I used the transfer function method to measure the contribution of the vent to the output.

Apart from a narrow dip around 119 Hz, these W-Bins seem to have a pretty decent and smooth output. -3dB point is at 45 Hz, and the vents tune the chamber to around 33 Hz, which is pretty low, but it seems to do the job, with the vents adding around 2dB of additional output between Fb and 60 Hz. The vents are two 3.5" cylindrical tubs though, which might be on the small side for a 18" driver.

I told my brother that I might design a different box for him based around the same drivers, but I think it might be a bit difficult to get something noticeably better than these W-Bins, considering the type of music that they usually play.

10-JUL-2021: Added corrected response curve, as previous measurement included the impact of my car stereo's "ASL". See post #20

I need to separate a burst of three triggers into only one pulse so I can only use the first one to trigger another circuit, as I don't want it to re-trigger with every pulse, is there a simple circuit that can do this? It's coming from a sequencer cpu so I can't really reprogram anything.

First post here! Have been lurking around here for over three years, but never registered. Last weekend I bought a really nice early Quad 303 along with an early Quad 33 unit. Both have serial numbers #11xx. I have been recapping both during the last couple of days. I tuned the rail voltage as well as quiescent current last night and fired the 303 up. Left channel is working flawlessly but the right one is noisy with volume set to zero. I thought the first order of business was to order replacement resistors for the larger carbon composite ones, which usually go bad. I thought of 0.5w metal film resistors. Would that be appropriate? As I've understood it this version has the first boards, and it's hard to find any info on these on the web. Thankfully it included schematic for the 303, which seems impossible to find online. I'm gonna make a scan of it later on if somebody might need it as well. My second question is, C104 is a bipolar electrolytic (I assume?) capacitor on this version on the driver boards. Is it okay to change it with a polarized capacitor instead as in the later versions of the boards? See pictures. Thankful for any input!

I have just started soldering parts on a TSE-II board.

Can I do inverted assembly, i.e. just the sockets on the top side of the board (the one where TUBELAB TSE-II is printed), and place all the rest of the parts on the other side?

How about Mosfet and other semiconductors? Will I run into issues with polarity and heath-sink position?

Thanks

First a little bit of context, I've already built the SSE and since doing that my main speakers I liked listening to on tube power were sold (la scalas) and were replaced with jubescalas, since they require active crossover I now need four channels of amplification.

Few questions:

-Would the Edcor XPWR222 be up to the task of running a pair of SSE boards? For reference it's rated at 350mA 375-0-375, 6A 6.3V and 6A 5V. I feel like the 6.3V filament winding won't be able to handle two boards but I want to be told that instinct is correct.

-Assuming the Edcor I have won't be up to the challenge, is there anything out there that would be? The One Electron BFT-1B looks promising but will the secondary at 385-0-385 be too high? (For reference my mains voltage runs a pretty consistent 119V)

-Will there be any fundamental issues introduced by running a pair of SSE boards from one PT? Should I be considering dual PTs?

-If I'm running these purely as power amplifiers with no need for volume control do I just omit that and run the inputs directly into the board?

-My outputs are balanced, has anyone done a balanced input mod on the SSE? Is there any value to that besides the "Shlick-snap" satisfaction of XLR connections at both ends?

-I currently have 15W GXSE edcor OPTs I will be re-using for the high frequency portion of this 4 channel thing. They'll be powering a pair of B&C de75p compression drivers that are 8 ohm nominal and 108db sensitivity. For the low frequency pair of channels should I go with the larger Edcors? The frequency response isn't that important as the horn bins can barely touch 50Hz but they are around 3dB less sensitive so will be getting more power day to day.

A few notes, I'll be tube rectifying and my output tubes right now are a pair of Shuguang Black Treasure KT88's so I'll probably grab another pair of those.

Thanks for any tips or guidance, and yes most of the desire to make this in one unit is the visual spectacle of 8 warm tubes and a small city of transformers, chokes and caps.

Hi all,

New here, though I've learned a lot from lurking threads for a while. I'm basically a noob when it comes to this stuff despite being a reasonably experienced sound engineer.

I've rigged a hifimediy T1 tk2050 amp up to an old passive PA cabinet (an EV SH1512ER, rated to 200W at 8ohms) to run off 24v battery power. I have a small powered Rolls powered mixer as a preamp adding about 26db of gain running into a small passive crossover and mono sum i built (off of this design MonoXover 2-way Pre-amp Audio Crossover : 4 Steps - Instructables), which runs directly into the the amp's inputs (so its bi-amped as one channel to the tweet one channel to the 15" woofer).

It all works and i'm stoked on it, it sounds quite amazing in fact. However, I'm quite sure that I'm not getting what I think should be max output of the system and am trying to figure out where my weak point is. I have a few clues and wonder if anyone here has thoughts or suggestions:

1) First, obviously the amp is underpowered for the speakers. I might consider replacing the T1 (2x100W) with a T4 (2x180W) which i know might give me close to double the clean volume I currently have. Still i think i can get more with the T1.

2) The T1's input voltage is rated up to 39v. If i add another 12v battery in series to what i have to bring it up to 36v, I'm sure i'll get more power - would this increase my output significantly or only marginally? Anyone with experience here?

3) I'm running the Rolls preamp at 12v instead of 15. I'm probably losing some headroom here. Unfortunately they seem to have changed the input voltage of the MX51s to 15v without updating the specs online, i thought it was 12v max when i got it. Still dont imagine this is the main problem (although I do hear it cracking up at the very top 10% of its range).

4) Lastly I wonder about input impedance on the amp itself. I've seen people reference changing 2 resistor values on the PCB of the amp itself to decrease impedance on the input section of the amp and get more volume flowing. Any experience with this?

Thanks in advance for any thoughts or ideas. Best wishes to all

Hello.
Has anyone tried Jeff's Kairos with a pp tube amp? Is this a good combination? Or does the Kairos need a transistor amplifier?

Sorry for my poor english.

Hello everyone. I want to build an amp to drive a 20" 4ohm 150w max subwoofer in a car. I'm planing to use boostor project to boost supply voltage from 12v to +-22v. I'm looking for an ic amp to deliver 70w-100w from said supply.



I've found the schematic below using TDA2050's in a bridge configuration claiming to output over 70w which is enough for me but TDA2050 is obsolete and i'm concerned fakes won't be able to handle +-22v supply voltage. Even if its a TDA2040 rebranded as 2050 it should fry according to datasheets.


What experience do you have on fake 2050 chips? Is it worth the shot? I'm open to new ic suggestions. Or maybe should i go with transistor amps? Any idea or recommendation is welcome. Thanks for reading.

I have the v1 of this board and fancy trying out the plus version. Just wondering if any diyers in the UK have any surplus boards before I order a new one.

Behringer UltraCurve Pro 2496

D[book=]%[/book]oes anyone have the hex and bin file for the Behringer Ultra Curve 2496
version 1.4 or 1.7 so that i can write to the chip using the TL866II programmer, i have version two point five bin and hex which is not compatible with my older ultra curve
I am willing to share my version two point five rom
thanks please help

Its monday and I feel like asking a dumb question.
I read somewhere that out of phase stages in a preamp can cause some loss of listening pleasure.
So the dumb question is I have 2 stages in my preamp for phono (Ixys current reg on each anode with output of 1st stage off anode into grid on stage 2 (which also has an Ixys reg on it) feeding into an srpp line stage?
So what is the rule of thumb here?
Thanks
Nick