A working amp went silent

[ipetruk]

Hi,

I enjoyed Sublime amp with my subettes for a few months. It worked very well, super happy with it.

Now it went silent. No hum, no sound. All LEDs are on. What I have tried so far:

1) Re-do checks according to the manual. The readings seem to all be in order. This should imply that at least the power supply is ok
2) Eyeballed all solder joints and checked the wires
3) Replaced Sublime with a different sub amp, keeping the same input and output wiring. It worked, so it means the problem is not in the rest of my setup.

Is there a way to further test it? Or is there a way to narrow it down to preamp block or the power amp part?

Thanks,
Igor.

[ipetruk]

I think the issue is the power amp. Plugging in high impedance headphones directly into the preamp output and gradually increasing volume produces a mumbling sound, consistent with what is expected of a subwoofer filtering.

[ipetruk]

There seems to be plenty of the XH-M311 power amps on Amazon, cheap.

I'll get one, for example this one: https://www.amazon.com/dp/B0822RDW6J?

Are they all the same provided they are XH-M311? Or are there kinds of it?

[Doc B.]

Looks identical. Probably fine to use. Not sure what the  failure might be due to. I have two that have been running fine for many months so I don’t have any ideas. The boards are inexpensive and simply replacing one is probably the most reliable way to resolve the issue. Do adjust the power supply voltage again after you replace the amp board. Over voltage will definitely shorten the lifespan.

[ipetruk]

Thanks, ordered.

About voltage, I've noticed the spec on the power amp mentions 10-24V. The manual suggests aiming for 24V, which is the exact upper range. I don't really need max volume for my room. Should I just drop it to 20V?

My main suspicion for the failure is my speaker amp causing a voltage spike when turned off inappropriately. I am not sure if mitigation by reducing the voltage on the Sublime power supply can help against that. Not sure if one mitigates another - power supply voltage and input spike voltage

[Doc B.]

I think the chip itself is rated a wee bit above 24V. Turning the voltage down a bit will just give a bit less peak power and is not a problem at all.