Found a TPA3255 4 channel module on AliExpress

[mcdn]

This looks quite handy, I just bought one for an active speaker project and will share pics when it arrives: https://www.aliexpress.com/item/100...der_detail.order_detail_item.3.5708f19cuzSL7O

The TPA3255 is one of the better performing chip amps, but most modules are two channel. In 4 channel configuration you still get 77W/ch @ 1% and 100dB S/N. Although this unit is specced as max 48V whereas the TI spec is at 53.5V (https://www.ti.com/lit/ds/symlink/tpa3255.pdf)

 

[ai1]

Great! I would be very interested to see what comes out of it. I have bought three TPA3251 4ch modules by 3e-audio

TPA3251-4CH-100W | 3e Audio

www.3e-audio.com

4 years ago. They work flawlessly ever since.
Unfortunately, 3e-audio stopped making those boards, so I was tempted to buy one like yours, which looks quite similar. However, these guys from other sellers have rather mediocre client ratings, people complain about their reliability.
But you probably already know about all that. Anyway, quite a bold move. Keep us posted.

 

[ai1]

PS: they put 50v capacitors on the board. Meaning that the max secure voltage will be ~40-42V. This still would be enough for ~160-200w/4ohms and 80-100w/8ohms per ch.

 

[mcdn]

PS: they put 50v capacitors on the board. Meaning that the max secure voltage will be ~40-42V. This still would be enough for ~160-200w/4ohms and 80-100w/8ohms per ch.

Exactly. To be fair they quote a recommended power supply of 36V, with a max of 48V. Your power estimates are a bit off though.

At 36V the 1% power would be 35W/ch at 4 ohms (77 * 36^2/53.5^2), or possibly bit more if the distortion curve is better at derated PVDD. I'll measure it when I get it, as I have a suitable 4ohm dummy load. 35W/ch is fine for my use, the drivers I'm using are only rated to 40W RMS. And it's only $12.50 per channel.

 

[ai1]

Do you mean that in 4ch configuration the output is not bridged? It is a completely different story then---this would be 60W/4ohms or 30w/8ohms.
I am quite a bit surprised though: I understand that the document

http://www.3e-audio.com/wp-content/uploads/2018/07/DS_EAUMT-0100-4-A_Rev1.0.pdf

mentions 100W/4ohms per channel (see the last plot), and this is just for TPA3251 with 30V supply. Well, these are not the same boards.

As for $/channel, there is still the guy on ebay

Boîtier de 45 @ ALC0100-2X00 carte amplificateur stéréo classe D 2x50 W / 115/230 vide | eBay

Les meilleures offres pour Boîtier de 45 @ ALC0100-2X00 carte amplificateur stéréo classe D 2x50 W / 115/230 vide sont sur eBay ✓ Comparez les prix et les spécificités des produits neufs et d'occasion ✓ Pleins d'articles en livraison gratuite!

www.ebay.fr

selling a case of 45 @ ALC0100-2300 Class D Stereo Amplifier Boards 2x50W for 108,00USD... And these come with the integrated power supply...

 

[voodooless]

I am quite a bit surprised though: I understand that the document

http://www.3e-audio.com/wp-content/uploads/2018/07/DS_EAUMT-0100-4-A_Rev1.0.pdf

mentions 100W/4ohms per channel (see the last plot), and this is just for TPA3251 with 30V supply. Well, these are not the same boards.

30V PP is about 21V RMS, into 4R, that is 110W. Sounds about right with some losses. 42V would probably get you around 200W into 4R.

 

[mcdn]

30V PP is about 21V RMS, into 4R, that is 110W. Sounds about right with some losses. 42V would probably get you around 200W into 4R.

Both the TPA3251 and TPA3255 are 4 channel single ended amps which can be run BTL for 2 channels or PBTL for 1 channel.

The TPA3251 is specced as 37w/ch into 4 ohms @ 1% THD when run single ended at full PVDD of 36V: https://www.ti.com/lit/ds/symlink/tpa3251.pdf

any higher numbers are for BTL or PBTL operation, and/or at 10% THD

 

[voodooless]

Both the TPA3251 and TPA3255 are 4 channel single ended amps which can be run BTL for 2 channels or PBTL for 1 channel.

The TPA3251 is specced as 37w/ch into 4 ohms @ 1% THD when run single ended at full PVDD of 36V: https://www.ti.com/lit/ds/symlink/tpa3251.pdf

any higher numbers are for BTL or PBTL operation, and/or at 10% THD

For SE operation, that makes sense. It’s about 12VRMS into 4R, gives you ~36W. My figures are for BTL operation, which is the most common for these chips. The 3e board uses two of them to get to 4 channels.

 

[mcdn]

For SE operation, that makes sense. It’s about 12VRMS into 4R, gives you ~36W. My figures are for BTL operation, which is the most common for these chips. The 3e board uses two of them to get to 4 channels.

Your 110W estimate for BTL on the TPA3251 @ 1% into 4 ohms is a tiny bit high I think, 97W is what I get by multiplying the 140W spec by 30^2/36^2. But yeah close enough! And again, there may be some benefit from running at lower than max PVDD, so it could be a bit more. I'll run that test on the TPA3255 module when I get it

 

[voodooless]

Your 110W estimate for BTL on the TPA3251 @ 1% into 4 ohms is a tiny bit high I think, 97W is what I get by multiplying the 140W spec by 30^2/36^2. But yeah close enough!

Close enough indeed. The e3 amps specs 100W. With some heat losses it will draw 110W from the supply.

 

[mcdn]

I am genuinely curious as to whether derating PVDD improves the distortion performance. If the distortion performance is limited by current somewhere, then it could be possible.

 

[voodooless]

Current limit will only influence THD at the actual limit. Below the limit it will note or less just follow the spec sheet.

 

[mcdn]

Current limit will only influence THD at the actual limit. Below the limit it will note or less just follow the spec sheet.

Right, but if current _is_ the limiting factor for 1% THD, then dropping PVDD might not reduce 1% power as much as we think, because the maximum current will be lower, so 1% could be achievable at output levels closer to Vout == PVDD. Do you see what I mean?

Ignore that I'm being an idiot.

 

[voodooless]

This illustrates pretty well what happens with various voltage and current values. I’m not exactly sure why the high voltage PSU has more noise though. But clearly in both cases, the amp is limited by PSU current.

 

[AddamR]

This looks quite handy, I just bought one for an active speaker project and will share pics when it arrives: https://www.aliexpress.com/item/100...der_detail.order_detail_item.3.5708f19cuzSL7O

The TPA3255 is one of the better performing chip amps, but most modules are two channel. In 4 channel configuration you still get 77W/ch @ 1% and 100dB S/N. Although this unit is specced as max 48V whereas the TI spec is at 53.5V (https://www.ti.com/lit/ds/symlink/tpa3255.pdf)

I'm in possession of 2 of these for an 8 channel stereo project with active xovers into 2 x 3 ways with 2 x subs, just waiting on the ADAU1701s and other associated hardware to arrive (PCM1808 for analog to I2S, 4 x DRV134 SE to balanced outputs), I'm also yet to design the speaker boxes, using some Vifa P17WJ 6.5" woofers and Vifa D25 tweeters, mids I'm yet to decide on. Also in this project is the steep learning curve of Sigmastudio, I'm a complete noob when it comes to digital audio programming, but have experience with speaker builds and passive crossovers in the past. Should be a challenge.

 

[ldarieut]

I have one of these and they make a loud hiss (on a 108dB sensibility compression driver...), so loud as they are not useful for a hifi setup. My hypex doesnt exhibit any noise in the same configuration: you get what you pay for.

 

[mcdn]

The unit arrived today but I am going on holiday so it will be a while before I can measure it. I bought one $40 power supply and one $7 power supply, so that should make for some interesting results

I’ll make sure to test for residual noise. What specific hypex module are you using?

 

[ai1]

FWIW, I use 3e-audio 4ch board with 2 Peerless OX20SC02-08 (86dB sensitivity), no hiss even when I put my ears to the driver. Well, maybe a very tiny bit...

 

[ldarieut]

The unit arrived today but I am going on holiday so it will be a while before I can measure it. I bought one $40 power supply and one $7 power supply, so that should make for some interesting results

I’ll make sure to test for residual noise. What specific hypex module are you using?

nc400

 

[ldarieut]

FWIW, I use 3e-audio 4ch board with 2 Peerless OX20SC02-08 (86dB sensitivity), no hiss even when I put my ears to the driver. Well, maybe a very tiny bit...

yes, my 96dB woofer hisses a lot less, so I would guess at 86dB you hear almost nothing.