Good day, everyone.
I bought this class-D power amplifier module (pic attached). It came in the mail yesterday and I'm pretty excited to try it out. I was going to use it as a pedalboard amp due to its compact size. Before that happens, however, I'm going to test it to see how it performs.
The spec sheets I found online say it's capable of delivering 60W into 4 ohms at 10% THD. Personally, I take that with a pinch of salt, or even a handful perhaps, because, first of all, it doesn't employ a genuine TI TPA3118. The original chip has 32 pins, whereas this one has only 28, so some people online suggest it might be a relabeled (mislabeled?) TPA3110. No problem for me, though, as long as it behaves well.
I'm going to fan cool it because putting a heatsink on it looks tricky here. Correct me if I'm wrong, anyone.
I have questions, obviously.
I'm going to power it with a laptop charger / PSU capable of providing 20V, 3.25A. Good idea? Bad idea? Acceptable? I'm going to test it with an 8-ohm load.
Thanks for any help.
M.
Nice :dbtu:
What are the black "001" or "100" things
Quote from: saturated on October 23, 2024, 07:57:19 AMWhat are the black "001" or "100" things
They look like inductors to me.
They are inductors.
That amp will fit into a 125A stompbox with a small fan at the end, at least my one did and I used a 100 watt mono amp with a heatsink.
I got a small 5V fan from Tayda and a L7805 regulator to run the fan and that worked great.
I kept blowing up laptop power supplies on mine, but I used it to test stompboxes and I cranked the volume right up when I hooked up a bass guitar so I made it work hard until it did so no more.
One day I will get a better power supply and resurrect it again.
Good luck with it.
Thank you, sir :)
Quote from: Tassieviking on October 23, 2024, 12:20:13 PMThat amp will fit into a 125A stompbox
Do you mean a 1590A enclosure? (Search results for 125A spit out a tube amp output transformer)
In any case (pun intended :D ), the 1590A is awesomely small, which is exactly what I need on my pedalboard <3)
QuoteI cranked the volume right up when I hooked up a bass guitar so I made it work hard until it did so no more.
I understand that you pushed your power amp into clipping. How did that sound? Or did you use some sort of input signal clipping?
Quote from: Miyagi_83 on October 24, 2024, 02:23:34 AMQuoteI cranked the volume right up when I hooked up a bass guitar so I made it work hard until it did so no more.
I understand that you pushed your power amp into clipping. How did that sound? Or did you use some sort of input signal clipping?
I took that to mean he worked it hard until it died. :)
Quote from: g1 on October 24, 2024, 12:33:44 PMI took that to mean he worked it hard until it died. :)
I thought he meant that he'd abused the heck out of the power amp so the PSUs died and, consequently, the amp ???
It will work, with a 20V supply you´ll get some 20W into 8 ohms, not bad at all.
Remember output is balanced, so no output terminal is grounded, use a plastic jack.
It´s a common beginner´s mistake to use a metallic guitar speaker jack, screwed on chassis.
Quote from: J M Fahey on October 24, 2024, 11:58:33 PMRemember output is balanced, so no output terminal is grounded, use a plastic jack.
Thanks for the heads up, Mr. Fahey.
Fortunately, I don't have any of those metal ones on hand, so I wasn't going to use them anyway :D
Peace. I'll keep you people posted.
Quote from: Miyagi_83 on October 24, 2024, 02:23:34 AMThank you, sir :)
Quote from: Tassieviking on October 23, 2024, 12:20:13 PMThat amp will fit into a 125A stompbox
Do you mean a 1590A enclosure? (Search results for 125A spit out a tube amp output transformer)
In any case (pun intended :D ), the 1590A is awesomely small, which is exactly what I need on my pedalboard <3)
QuoteI cranked the volume right up when I hooked up a bass guitar so I made it work hard until it did so no more.
I understand that you pushed your power amp into clipping. How did that sound? Or did you use some sort of input signal clipping?
I meant to say 125B box, I have been looking at a lot of tube amp transformers lately so I can make a small tube amp in a pedal format so the 125A transformer must have been on my mind.
I think I overloaded the power supply with my pedal, I was using a HP laptop supply rated at 120 watts but I was playing loud testing a Bass speaker I had built.
I used a mono TPA3116D2 board with a heatsink on it and 2 top mounted insulated jacks for in and out sockets.
Power was a GX12 2 pin socket, I made leads with alligator clips so I could use it on a car battery if I wanted to.
A small 5V fan that ran of a L7805 regulator was sitting at the opposite end from the jacks.
https://www.taydaelectronics.com/hardware/enclosures/1590b-style-1.html
https://www.taydaelectronics.com/hardware/6-35mm-1-4-plugs-jacks/6-35mm-1-4-stereo-insulated-socket-jack-solder-lug.html
https://www.taydaelectronics.com/dc-brushless-fan-5vdc-1-2-inch.html
https://www.taydaelectronics.com/lm7805-l7805-7805-voltage-regulator-ic-5v-1-5a.html
https://www.taydaelectronics.com/connectors-sockets/2-pins-male-circular-connector-gx12.html
Ok, I launched this thing today. It works, so I guess I'm happy <3)
I didn't have the opportunity to play it super loud, though, because I live in an apartment, but next weekend I'm planning on visiting my good buddy in the countryside :dbtu: You can guess the rest :D
Hopefully, I'll manage to put it in an enclosure by that time because, obviously, it picks up noise from the air.
As for the power supply, it didn't even get slightly warm, but I suppose that's due to my being rather lenient with the amplifier.
To be continued...
M.
Speaking of the enclosure for this thingy, of the fan, to be more specific, is it better when a fan moves the air from the inside out or the other way round?
When I mounted a fan in my pedal amp I had the fan blowing into the pedal, I did not make any other ventilation holes so I placed a spring-washer between the back lid and the box on the screws to make a small gap all the way around.
Since there is no heatsink on the module it might be a chip that dissipates the heat through the bottom of the chip, look at the back of the PCB and see what is under the 3118 IC.
Some PCB's have a lot of vias (small holes) in the PCB to transfer the heat to the bottom of the PCB to act like a heatsink, the back of the PCB becomes the heatsink in that case.
Make sure you mount the board with enough space under the board for airflow to get through since this might be the side that dissipates the heat from the amp.
Quote from: Tassieviking on October 27, 2024, 01:10:57 PMlook at the back of the PCB and see what is under the 3118 IC.
A warranty sticker :lmao:
I'll scrape it off tomorrow and see what's underneath.
From what I've read about this particular module, it uses the underside of the PCB as a heatsink.
QuoteI did not make any other ventilation holes so I placed a spring-washer between the back lid and the box on the screws to make a small gap all the way around.
This sounds like a splendid idea! I might give it a try.
What I'm also thinking about is getting a small fan, like super small, 25x25 mm, and make the air flow horizontally. I'll need to do some research on this.
It should make no difference whether the fan is set to suck or blow. Air flow should be equal either way.
If you are using a dust filter, the common way is with the fan sucking, and the dust filter at the fan. This collects the dust at the outside, where it is visible and easier to clean. Usually it's just a piece of loose weave foam material, maybe some velcro strips on the chassis to stick the foam to.
Quote from: g1 on October 27, 2024, 08:19:10 PMIt should make no difference whether the fan is set to suck or blow. Air flow should be equal either way.
Thanks, g1. Another question. Should I cool the chip or the heatsinking PCB plane on a class D amp?
Cooling is never a bad thing. Capacitor failure is a way higher percentage of faults in the modern era, and it is mostly caused by heat.
Quote from: g1 on October 28, 2024, 01:55:36 PMCooling is never a bad thing. Capacitor failure is a way higher percentage of faults in the modern era, and it is mostly caused by heat.
Ok, cool 8|
I'm asking because I read over at diyaudio that in a class AB amp it may be a bad idea to blow air at the transistors because the temperature sensing device might not operate correctly, so it was suggested to fan-cool the heatsink. I wasn't sure how it's done with class D.
Thanks.
Quote from: Miyagi_83 on October 28, 2024, 02:20:19 PMOk, cool 8|
I'm asking because I read over at diyaudio that in a class AB amp it may be a bad idea to blow air at the transistors because the temperature sensing device might not operate correctly, so it was suggested to fan-cool the heatsink. I wasn't sure how it's done with class D.
Thanks.
Biasing is not an issue in a class D power amp, the transistors are either on or off.
Quote from: Loudthud on October 28, 2024, 08:42:22 PMBiasing is not an issue in a class D power amp, the transistors are either on or off.
All right,thank you. There's still so much to learn :)
I cam across this today looking for something else so I took a picture.
I remember now that there were a trimpot on the input of the amp module so I removed it and put a pot on the front of the box
Quote from: Tassieviking on November 05, 2024, 04:13:41 AMI cam across this today looking for something else so I took a picture.
Thanks, Tassieviking :tu:
Looks really tight inside but, from what I understand, you had no issues with that, right?
Sadly, I didn't have a chance to do anything with mine last weekend :( but I'm not in a rush.
I have not had any problems with it, I just havent used it since I blew up the last laptop power supply, I think the amp is still fine.
If you want to see an even smaller one there is a company selling tiny 30 watt poweramps that are 25mm x 25mm x 100mm.
Even their 50 watt pedal is nice with a VU meter on it.
https://svisound.com/index.php/products/amps-cabs
Quote from: Tassieviking on November 05, 2024, 09:42:19 AMIf you want to see an even smaller one there is a company selling tiny 30 watt poweramps that are 25mm x 25mm x 100mm.
Even their 50 watt pedal is nice with a VU meter on it.
https://svisound.com/index.php/products/amps-cabs
Nice!
I wanted to test the amp today using an oscilloscope, so I connected a dummy load resistor and hooked up the probe and ground across it, but the waveform didn't even budge even when I applied a test signal to the input.
Later I remembered that the output on this module is bridged, hence such reading on the scope. I started wondering, what are the odds that I blew the amp? I shorted one of the outputs to ground, after all. When I connected a speaker and a guitar, it worked, but I don't know how to tell if it's working correctly.
Use the scope to see if there is signal on each side to ground.
Quote from: Loudthud on November 07, 2024, 02:03:50 PMUse the scope to see if there is signal on each side to ground.
Thank you for the suggestion. I'll do that tomorrow (it's 11 pm in this part of the world) and report back.
M.
Quote from: Loudthud on November 07, 2024, 02:03:50 PMUse the scope to see if there is signal on each side to ground.
Perhaps it's important to mention first, my oscilloscope is nothing fancy. It's a 1 MHz, single-channel digital unit by FNIRSI (DSO-153) with a built in signal generator. I wanted something cheap for starters in case I were to mess it up.
I tried the following just now. I used the built-in signal generator, plugged it into a Tube Screamer clone to be able to change the signal amplitude more easily. I tested this setup with my scope and it worked ok.
Next, I plugged it into the amp module, turned it on and tried testing it following your suggestion. A sine wave appeared on the screen when the volume knob was at minimum, but nothing happened to its shape when I turned the volume knob up. It just started floating up and down. The same was true for both outputs.
EDIT: Attached is the sine wave with the Screamer's volume knob at 0.
Quote from: Miyagi_83 on November 08, 2024, 05:41:49 AMNext, I plugged it into the amp module, turned it on and tried testing it following your suggestion. A sine wave appeared on the screen when the volume knob was at minimum, but nothing happened to its shape when I turned the volume knob up. It just started floating up and down. The same was true for both outputs.
See on the screen where it says the frequency is 284.09 kHz ? That is the class D modulation being filtered by the output filters on the class D amp. The floating up and down, that is the signal from the generator. Set the frequency of the generator to 500 Hz and set the scope to 10mS (Ten millisecond) per division. Set the Volts per division to 5 to 10 Volts per division, whatever it takes so the trace doesn't go off the screen vertically. The scope trace will look really thick or out of focus because the 284 kHz will still be there.
Thanks, Loudthud. I'll do that as soon as I get some time on my hands.
It happened sooner than I expected, but that's good.
I tested it like you said, Loudthud, and it appears to be behaving correctly on both sides. Is it safe to assume that the amp isn't blown, in that case?
I think it's safe to assume the amp is working correctly. The vast majority of the Class D chips will protect themselves against shorts on one or both outputs.
Quote from: Loudthud on November 08, 2024, 10:41:21 AMThe vast majority of the Class D chips will protect themselves against shorts on one or both outputs.
This is good to know indeed. Thanks for the help.
Next stop - machining the enclosure and building an input stage. Stay tuned.
Good day, everyone.
I'm slowly getting round to putting this whole thing together. As I have mentioned, I want to add an input stage of sorts to be able to use this power amp with low-level signals, but because I also intend to use a cooling fan, I'm not sure how to arrange the power supply, noise from the fan being a consideration.
Should I run the voltage regulators in series or is it a better idea to make a parallel connection? Or maybe it makes no difference at all?
The voltage regulator for the input stage is arbitrary. I'm also considering having it before the fan supply and using an 18V regulator.
Any input will be appreciated.
M.
Quote from: Tassieviking on November 05, 2024, 09:42:19 AMI have not had any problems with it, I just havent used it since I blew up the last laptop power supply, I think the amp is still fine.
If you want to see an even smaller one there is a company selling tiny 30 watt poweramps that are 25mm x 25mm x 100mm.
Even their 50 watt pedal is nice with a VU meter on it.
https://svisound.com/index.php/products/amps-cabs
I found a picture of this tiny amp, it is just a basic 30watt amplifier module glued inside the metal box.
It would be really easy to make one the same.
As far as the series or parallel regulators, I think parallel would be better.
It will reduce the current through the 12V reg., and possibly also reduce noise due to the fan current (which would appear at input of 9V reg.).
Quote from: g1 on December 02, 2024, 02:31:44 PMAs far as the series or parallel regulators, I think parallel would be better.
It will reduce the current through the 12V reg., and possibly also reduce noise due to the fan current (which would appear at input of 9V reg.).
I'll go parallel then. Thanks for the suggestion, g1.
Quote from: Tassieviking on December 02, 2024, 12:08:44 PMI found a picture of this tiny amp, it is just a basic 30watt amplifier module glued inside the metal box.
It would be really easy to make one the same.
Oh, man, it's so beautifully compact! I wonder what kind of glue that is.
I imagine it's some sort of 2 part epoxy glue like Araldite.
I would have used a couple of screws myself.
Maybe they glued it down so it got some thermal contact to use the case as a heatsink, but I would think a small 30 watt class D amp would not generate much heat anyway.
The module is only 22mm x 26mm and under $10, 20 watts at 12V @ 4 ohm and 10 watts at 12V @ 8 ohm.
That is plenty for a practice amp, 10 watts into 8 ohm most likely means you run it easily on a wall wart if not a pedal supply.
Want an amp when you go camping ?, you could run it on a small solar panel with some rechargeable batteries.