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Old 26th September 2009, 05:27 AM   #1
chipper is offline chipper  United States
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Default fosgate punch 400a4 get hot at low volumes

I just got this amp traded some xtra subs for it and connected it to some home stereo speakers that are 8 ohms and a kicker 10 SVC 8 ohm subwoofer bridged to rear channels. It gets hot with low volumes. Do you think it could bias? or is that normal? i was doing this just make sure it was working good. Thanks
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Old 26th September 2009, 10:23 AM   #2
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Power it up and let it idle (no audio). Does it get hot?

If so, the bias is likely set too high. Measure the DC voltage across each of the 0.1 ohm source resistors. If any have more than ~0.001v DC across them, the bias is likely set too high.
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Old 26th September 2009, 04:56 PM   #3
chipper is offline chipper  United States
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Quote:
Originally Posted by Perry Babin View Post
Power it up and let it idle (no audio). Does it get hot?

If so, the bias is likely set too high. Measure the DC voltage across each of the 0.1 ohm source resistors. If any have more than ~0.001v DC across them, the bias is likely set too high.
Do you know which resistors to check? Are they the one that are connected to the output transistors? And i see four Variable resistors inside are those the ones to set the bias? Thanks for helping.
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Old 26th September 2009, 05:05 PM   #4
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Yes. The large resistors connected to the output transistors.

Yes, the potentiometers near the outputs are for biasing but don't make any changes yet.
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