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Issues with kenwood KAC-511 1000w amp

Codok2201

Jun 22, 2022
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Hello my amp recently has out of nowhere been intermittently working but mostly just dead. I have it hooked up to some 12 in subs in the back. All connections are good no blown fuses, no pinched wires everything is how it should be and yet it randomly turns on but will stop working just as fast. Something I did notice before the fist time it stopped working was my speakers had a static here and there in the middle of songs but it was random and not too noticeable unless you were listening for it witch it’s never done that before. Not sure if anyone else has had the same problem, my guess is just replace the amp but before I spend the 250 I wanted to know for sure
 

Bluejets

Oct 5, 2014
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5,884
Probably electrolytic capacitors in the power supply.
Look for bulging or leaking large electrolytics.
Plenty of info about what to look for on the internet, possibly even a video or two.
 

Audioguru

Sep 24, 2016
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The amplifier produces 300W into 4 ohms or 500W into 2 ohms. You are overloading it with 12 subs.
 

Codok2201

Jun 22, 2022
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The amplifier produces 300W into 4 ohms or 500W into 2 ohms. You are overloading it with 12 subs.
Even if it is a 1000 w amp ? There are 2 subs and I have an adjustment knob it came with to increase or decrease the output to the subs
 

kellys_eye

Jun 25, 2010
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The subs will have a label (or at least should have) that states their impedance (ac resistance). Common vales are 16 ohms, 8 ohms and 4 ohms etc.

Your amplifier will have a power output rating of x-watts into x-ohms. You can connect as many subs as you want provided you keep the total impedance within the specc'd range of the amplifier. This is done by wiring the subs in a series/parallel arrangement (i.e. 2 off 8-ohm subs in parallel will result in 4 ohms, two 4 ohm subs in series will result in 8 ohms etc - check out Ohms' Law).

If you have too LOW an impedance (say drive a 4 ohm speaker when the amplifier is rated at 8 ohms) then you're over-loading the amp and may cause damage. Too HIGH an impedance is much less of a problem for the amplifier but results in lost volume.

Your amp states 500W into 2 ohms. You would need to wire two 4 ohm speakers in parallel (observe polarity please) to get 2 ohms (or 4-off 8 ohm speakers). It is unusual to find a single speaker rated at 2 ohms.

The better amps have protection circuitry that cuts in if you over-load or over-drive the output - this MAY be the reason for the intermittent output.
 

kellys_eye

Jun 25, 2010
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Probably electrolytic capacitors in the power supply.
Look for bulging or leaking large electrolytics.
Seconded.

Being a Class-D amp you will have an SMPS in there (especially since we're talking 100's watts and the case is 'small').
 

Codok2201

Jun 22, 2022
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Jun 22, 2022
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The subs will have a label (or at least should have) that states their impedance (ac resistance). Common vales are 16 ohms, 8 ohms and 4 ohms etc.

Your amplifier will have a power output rating of x-watts into x-ohms. You can connect as many subs as you want provided you keep the total impedance within the specc'd range of the amplifier. This is done by wiring the subs in a series/parallel arrangement (i.e. 2 off 8-ohm subs in parallel will result in 4 ohms, two 4 ohm subs in series will result in 8 ohms etc - check out Ohms' Law).

If you have too LOW an impedance (say drive a 4 ohm speaker when the amplifier is rated at 8 ohms) then you're over-loading the amp and may cause damage. Too HIGH an impedance is much less of a problem for the amplifier but results in lost volume.

Your amp states 500W into 2 ohms. You would need to wire two 4 ohm speakers in parallel (observe polarity please) to get 2 ohms (or 4-off 8 ohm speakers). It is unusual to find a single speaker rated at 2 ohms.

The better amps have protection circuitry that cuts in if you over-load or over-drive the output - this MAY be the reason for the intermittent output.
I just checked my subs and they say 8 ohms 250w rms and 500w peak. I’ve had these subs hooked up for 2 years now without issue so it’s strange that out of nowhere they are bugging out. This is all very helpful info though thank you
 

Audioguru

Sep 24, 2016
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I see that he said 12 in subs which is probably 12 inch subwoofers.
The amplifier specs say "continuous power into 4 ohms is 300W" but without saying how much clipping distortion.
Two 8 ohm subs in parallel make a 4 ohms load on the amplifier. Then each sub gets 150W.
 
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