Low volume issue with Power Amp

sergedc · 3rd July 2012, 03:12 PM

Hi,

I have a 5.1 channel power amplifier (only power, not integrated). It is a Audio Image AP-5400 (impossible to find anything on the internet, I suspect it was from a very small production, but high end). It is old, like 20years old possibly.

I connect my UBS dac straight to it and control the volume from my computer.

When I turn it on and play low volume, the right or left channel (depending on the day, sometimes but rarely both) would play, then stop then play (feels like crackling) and ultimately stop playing completely.

If volume is loud, I have no problem. Also, If I turn the volume up, and let it play loud for 5 minutes, I can then reduce the volume and listen quietly for hours. It feels like the amp needs a warm up at high volume.

I tried putting a preamp between the Dac and the power amp: it did not solve the problem.

Any idea what it could be?

Thanks,
Serge

jaycee · 3rd July 2012, 03:20 PM

Coupling capacitors need replacing most likely, along with any other electrolytic capacitor in there.

discrete · 3rd July 2012, 04:00 PM

Quote:

Originally Posted by sergedc

Any idea what it could be?

If the amp has relays on the outputs you may want to check their contacts and clean them, or totally replace the relays.

gmphadte · 4th July 2012, 04:31 AM

Resoldering the boards will mostly solve this type of problem.

Gajanan Phadte

jaycee · 4th July 2012, 09:02 AM

Actually yes I'd agree with discrete - if there is a speaker relay then it probably needs to have its contacts cleaned. I would consider capacitor renewal as well though.

kimberlator · 28th July 2012, 05:48 AM

Quote:

Originally Posted by discrete

If the amp has relays on the outputs you may want to check their contacts and clean them, or totally replace the relays.

Totally agree, most of the time this kind of malfunction is due to a poor connection at relay contacts, there's a very real good chance that if you perform this simple fix you will get rid of that issue.

tiefbassuebertr · 28th July 2012, 12:47 PM

Quote:

Originally Posted by sergedc

Hi,

I have a 5.1 channel power amplifier (only power, not integrated). It is a Audio Image AP-5400 (impossible to find anything on the internet, I suspect it was from a very small production, but high end). It is old, like 20years old possibly.
Thanks,
Serge

Perhaps you mean the brand "Nelson Audio Image" ??
Audio Image AP-5400 - Google-Suche

3rd July 2012, 03:12 PM	#1
sergedc diyAudio Member Join Date: Apr 2011	Low volume issue with Power Amp Hi, I have a 5.1 channel power amplifier (only power, not integrated). It is a Audio Image AP-5400 (impossible to find anything on the internet, I suspect it was from a very small production, but high end). It is old, like 20years old possibly. I connect my UBS dac straight to it and control the volume from my computer. When I turn it on and play low volume, the right or left channel (depending on the day, sometimes but rarely both) would play, then stop then play (feels like crackling) and ultimately stop playing completely. If volume is loud, I have no problem. Also, If I turn the volume up, and let it play loud for 5 minutes, I can then reduce the volume and listen quietly for hours. It feels like the amp needs a warm up at high volume. I tried putting a preamp between the Dac and the power amp: it did not solve the problem. Any idea what it could be? Thanks, Serge

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3rd July 2012, 03:20 PM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Coupling capacitors need replacing most likely, along with any other electrolytic capacitor in there.

4th July 2012, 04:31 AM	#4
gmphadte diyAudio Member Join Date: Jul 2003 Location: Dona paula, Goa	Resoldering the boards will mostly solve this type of problem. Gajanan Phadte

4th July 2012, 09:02 AM	#5
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Actually yes I'd agree with discrete - if there is a speaker relay then it probably needs to have its contacts cleaned. I would consider capacitor renewal as well though.