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TPA3255 4-channel module review - $12.50 per channel but is it any good?

mcdn

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We see a lot of 2-channel TPA3255 based modules, but 4 channel ones are rarer. I bought this one off AliExpress for $50 including shipping - that's $12.50 per channel!

Build quality is OK but not great. The power and speaker I/O is all screw terminals, where better modules use spades. The capacitors are rated at 50V which is a bit tight - but then again the vendor does suggest a 36V supply. We'll see later that this is sensible as raising the power supply voltage to 42V doesn't do much to help performance. The heatsink is fine. There are no pins to expose the TPA3255 control and status signals, which is a bit annoying if trying to build a more sophisticated amp with soft-start, or clipping detection.

Does it do what a TPA3255 should do in terms of power and distortion? Yes it does :). It's wonderful to be able to get this level of performance so cheaply. Full details below...

The test rig is a Topping D10 Balanced, a 150W/4.7ohm dummy load, a DIY AES17-25 filter (https://github.com/mattclarkdotnet/aes17_filter_25), and a Cosmos ADC. Power was from my bench DC supply - I have some cheap AliExpress supplies to test later.
IMG_0935.jpeg

The TPA3255 Single Ended THD+N should be this (from the TI data sheet), so about 0.01% THD+N at 1W, and 60-70W available before distortion takes off:
TPA3255 spec.png

Starting with frequency response it's as expected, just 1dB down at 20KHz
Frequency response 1W.png


At 36V power performance is as expected, topping out at around 70W, with 0.01% THD+N at 1W
EDIT: my bench supply was the limiting factor, it actually does more like 85W at 0.1% THD:
Sample 1 R1 SS.png


Increasing the power supply to 42V gives pretty much the same result: EDIT - this is a limitation of my bench supply
Stepped THD 42V power.png

The 1KHz FFT is very clean:
1KHz 5W THD+N.png

The 1/3 octave multitone less so, though I think I need to adjust my REW settings a bit:
3rd octave multitone.png

And finally the 19/20KHz multitone is also good for the price:
19,20 Multitone.png
 

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Thank you for this.
I was looking at these some time ago, but didn't buy because of lack of measurements and discussion. Happy to see they measure decently.
I just wonder what kind of current will be needed when you have all 4 channels driven at the rated power. Did the vendor suggest any particular PSU in terms of current?
 
Thank you for this.
I was looking at these some time ago, but didn't buy because of lack of measurements and discussion. Happy to see they measure decently.
I just wonder what kind of current will be needed when you have all 4 channels driven at the rated power. Did the vendor suggest any particular PSU in terms of current?
Depends on what you want to use it for really. I will be using this in a stereo active system, where 50Wx2 for the bass and 25Wx2 for the mid/tweeters is more than enough for peaks. That's 150W/36V=4A, so very doable.
 
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Great? No. But amazing for $12.50.
 
Great? No. But amazing for $12.50.
88dB SINAD puts it well up into the top half of the green section of @amirm ’s amp list, which is definitely amazing for the money! I have a $10 PSU to test with it too. Should be fine if it meets its PSRR spec.
 
88dB SINAD puts it well up into the top half of the green section of @amirm ’s amp list, which is definitely amazing for the money! I have a $10 PSU to test with it too. Should be fine if it meets its PSRR spec.
I doubt you'll hear any distortion. Good start for an active speaker.
 
Very nice to see one of these cheap boards measured! I’ve been wondering about these for a while. This is actually one of the better looking ones. I would need 3 for an active project I’m planning, but 36V would be too tight for me. 42V may work though. Do you have the exact measurements of the board and height of the heatsink?

The idea is to stick them in a broken vintage amp enclosure complete with a software DSP solution. Some may find this sacrilege, but I just don’t care :p
 
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Very nice to see one of these cheap boards measured! I’ve been wondering about these for a while. This is actually one of the better looking ones. I would need 3 or 4 for an active project I’m planning, but 36V would be too tight for me. 42V may work though. Do you have the exact measurements of the board and height of the heatsink?

The idea is to stick them in a broken vintage amp enclosure complete with a software DSP solution. Some may find this sacrilege, but I just don’t care :p
100x93x35mm. In my main system I use the 3e-audio BTL modules which are a totally different level of quality, but this one seems fine for a second system or experimental setup.
 
100x93x35mm. In my main system I use the 3e-audio BTL modules which are a totally different level of quality, but this one seems fine for a second system or experimental setup.
Thanks! I’m after super value, so these will do just fine for that. though I wouldn’t dare a super SMPS…
 
I really like the balanced inputs - possible to avoid ground loops easily while feeding with 8ch onboard PC line-outs - e.g. 2ch active setup with CamillaDSP
 
Isn't this the same board:

 
Really interesting post, thank you. I've just got the Nelson Pass' active crossover kit for my LXminis and was thinking of putting it in a case with something like this. At the mo the miniDSP units (two because I use them with the Peerless subwoofers designed by Dave R) and the associated power supplies, cables etc. are a bit of a mess.
 
... I see that you have LX Studios, so more background, before you ask... :)
I made the LXminis about 9 years ago when the only crossover option was the miniDSP 2x4 (not HD). A year or two later I added the Peerless subs so I needed another 2x4. Initially I powered the speakers through an AV receiver that had direct inputs with no processing but now I use a Wiim mini to SMSL SU-1 to DCB1 to a huge Nakamichi 8 channel amp.
The project that I had in mind was a one box Pass active crossover/amp for just the LXminis (no subs) although I might play with integrating the subs with REW and a miniDSP, treating each LXmini as a single unit for the purposes of equalisation.
 
@AIYIMA, is this indeed your product? Are the AliExpress sellers selling copies of your product?
 
My Connex SMPS300RS 36V supply arrived, here's the stepped sine using that instead of the awful cheap power supplies I was testing before. Single channel power at 0.01% distortion is up to ~120W. This is way beyond the spec! Obviously with all channels driven power would drop, but in my intended use for an active speaker that's not a big issue. -90dB at 40W is really nice.

Stepped THD powered by Connex.png
 
Damn you @mcdn, now you made me order a couple :facepalm:

I’ll try a cheap 350W 48V SMPS first, can always upgrade.
 
Would it be possible to bridge 2 of the channels to get a 2.1 setup for an active 3 way with extra power for the woofer? Or would it make more sense to use all 4 channels by wiring 1 channel to each of the voice coils on the woofer (woofer has 2 voice coils)?
 
Would it be possible to bridge 2 of the channels to get a 2.1 setup for an active 3 way with extra power for the woofer? Or would it make more sense to use all 4 channels by wiring 1 channel to each of the voice coils on the woofer (woofer has 2 voice coils)?
Yes, or wire the voice coils in series if they are 2ohms. See section 10.1 of the tpa3255 datasheet: https://www.ti.com/lit/ds/symlink/t...=https%3A%2F%2Fwww.ti.com%2Fproduct%2FTPA3255

The reference design has different output inductor values for each choice, but this won’t affect a subwoofer application I don’t think.
.
 
Yes, or wire the voice coils in series if they are 2ohms. See section 10.1 of the tpa3255 datasheet: https://www.ti.com/lit/ds/symlink/tpa3255.pdf?ts=1703225496349&ref_url=https%3A%2F%2Fwww.ti.com%2Fproduct%2FTPA3255

The reference design has different output inductor values for each choice, but this won’t affect a subwoofer application I don’t think.
.

For the diver I'm thinking of, the voice coils are 4 ohms each: https://www.daytonaudio.com/images/resources/295-104--epique-e180he-44-spec-sheet.pdf
 
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