8 channel power amp project

[geoffw]

Hi all...
Nice community you have here.
I'm installing 8 Klipsch speakers (8 Ohms nominal; 93 dB 2.83V at 1m) into the ceilings of a new house build. These will be used for 4 separate zones which may be playing different material at the same time. All speaker cables will be led to one place where there is room for signal sources and amplifiers. I'm thinking of putting together DIY amp(s) for this purpose.
Requirements are as follows:
- 8 channels.
- 50 W per channel into 8 ohms with < 0.1% THD+N).
- Must have low power consumption when idle.
- Inputs can be analog or digital (either Toslink or coax).
- Mains is 240V (Australia).
- Must not generate thump or spike on startup.
- Prefer to minimise the number of boards to avoid excessive clutter and cords.
- Budget around USD 400 (completed).
I haven't found many boards with 4 or more channels, but this one based on the TI TPA3251 is a possibility: https://www.3e-audio.com/amplifier-kits/tpa3251-4ch-100w/
However, power into 8 Ohms may not be sufficient.

I'd welcome any ideas for amplifier boards, power supplies and cases from you guys.

Thanks in advance,
Geoff.

 

[outlookrt]

Also interested in these 4ch 3251 boards to pair with my MiniDSP SHD powering 2 way speakers actively.

 

[somebodyelse]

3E are unusual in publishing AP plots for their boards, and they have a decent reputation. Pair with a decent SMPS (MeanWell or similar) and you should have a decent amp.

 

[howard416]

Budget sounds really low for 8 channels. Consider:

- minimum $50-200 for an enclosure, unless you can salvage
- minimum $80-110 for a 300W-400W SMPS (linear PS could cost more or less depending on transformer, caps, soft start, DC blocker, etc. etc.), unless again you can salvage. Connex makes audio SMPS units and has a decent reputation (Neurochrome uses their products for example)
- minimum $40-100 for input and speaker connectors (and that doesn't even get into the interconnects and speaker cables themselves)

What does that leave for the actual amp modules/boards/parts? Your only option is going to be Aliexpress. By the way, that TPA3251 amp you linked to says 4 channel operation, but you need to look up the performance specs in SE mode (4 channel); the TPA3251 in SE mode cannot give 50 W per channel into 8 ohms. Note that the specs listed by 3e are for BTL mode (2 channel operation).

https://www.ti.com/lit/ds/symlink/tpa3251.pdf (7.10)

 

[somebodyelse]

By the way, that TPA3251 amp you linked to says 4 channel operation, but you need to look up the performance specs in SE mode (4 channel); the TPA3251 in SE mode cannot give 50 W per channel into 8 ohms. Note that the specs listed by 3e are for BTL mode (2 channel operation).

The board has 2 x TPA2351, each configured in stereo BTL mode, so that part of your concern at least is misplaced.
http://www.3e-audio.com/wp-content/uploads/2018/07/DS_EAUMT-0100-4-A_Rev1.0.pdf

 

[howard416]

The board has 2 x TPA2351, each configured in stereo BTL mode, so that part of your concern at least is misplaced.
http://www.3e-audio.com/wp-content/uploads/2018/07/DS_EAUMT-0100-4-A_Rev1.0.pdf

Ah, didn't catch that but I do see that on the PCB layout now. If the measurements are correct, that is a hell of a deal.