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TheFox84 29th July 2012 03:34 PM

Kenwood KAC-X811D, Low power output
Hi Guys,

I'm new here and I would like to fix this my self, so I'm really hoping someone can help me.

I have a Kenwood KAC-X811D it WORKS! but it has very low power output. I think some FETs are gone.

I have it all set up right, gain, volume, speaker, power wire.
I have opened it up and I don't see any physical damage.

I think it might be the power FETs Q57,58,60,61,64,65,67-70
or the amp FETs Q48-51

Do I have to remove them to check them?

Perry Babin 30th July 2012 12:01 AM

How do you define low power output? Low volume but clean, low volume and distorted...

TheFox84 30th July 2012 01:10 AM

Low volume clean, the display is reading around 3 amps and has a measured voltage of 35. So it sounds and is about 100watts.

Perry Babin 30th July 2012 01:39 AM

Are you sure that the woofer isn't defective?

35v is over 300 watts into 4 ohms and over 1200 watts into 1 ohm.

TheFox84 30th July 2012 11:49 AM

But at 3 amps its only 100watts. I have no reason to believe the woofer is defective. It seams to me its an amperage problem.

TheFox84 30th July 2012 12:49 PM

So the VAS seams to be OK, but the output stage is defective?

TheFox84 30th July 2012 09:44 PM

The amp is hooked up 2ohm to a 300watt RMS woofer. If this was working correctly it should be destroying the woofer, but it hardly moves, sounds like ~100watts.

I never thought if I asked for help I would get help from Perry Babin... I have been reading your entire webpage religiously over the passed few months. Thanks!

Perry Babin 30th July 2012 11:42 PM

Disconnect the woofer from the amp and measure the resistance across the speaker wires. Post the resistance.

TheFox84 30th July 2012 11:49 PM

I measured it before. I don't have the exact number but it was very close to 2ohms.

The speaker was at 8ohms (Dual 4ohm VC) and it was not very loud, so I changed to 2ohm and no noticeable change in volume.

TheFox84 31st July 2012 12:12 AM


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