Hello all, I have a alpine 3545 that I repaired some blown output transistors. Sound is good but there is a sizzle sound that's very noticeable coming from the transformer. I did the idle current adjust from manual and set it at 4 mv +- .5 both sides when warm and it makes the sound. If I go to like 6 or 7mv it gets quiet. Is it safe to run at that or do you think it's a capacitor or something else. Thanks
The noise is from the duty cycle changing quickly, and possibly going completely to zero duty cycle. Increasing the idle current increases the duty cycle. It shouldn't hurt anything.
If you have an adjustable 12v power supply, decreasing the voltage will help stabilize the amp supply if it's audible at low volume. It's not likely to be audible in the vehicle.
It's possible that an out of tolerance capacitor or one that's leaked onto the board (conducting between circuits) could cause this but it's normal for some amps.
The minimum bias that's high enough to quiet the amp may be OK as long as the amp doesn't heat up significantly at idle.
If you have an adjustable 12v power supply, decreasing the voltage will help stabilize the amp supply if it's audible at low volume. It's not likely to be audible in the vehicle.
It's possible that an out of tolerance capacitor or one that's leaked onto the board (conducting between circuits) could cause this but it's normal for some amps.
The minimum bias that's high enough to quiet the amp may be OK as long as the amp doesn't heat up significantly at idle.
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