Hafler amp issue

kharp1

I have a pair of Hafler P230 amps and I'm having an issue with a loud pop through the speakers when they are powered on. It doesn't matter wherther they are powered up after the Pre or before. They run quiet after startup and would make a nice amp for soeone on a budget, but, I don't want to try and sell them with this issue. I did a little research online, but there wasn't much there. Anybody have any insight? What can cure this problem? I realize there could probably be a relay installed that would allow a "soft start" but was wondering if anyone had any info that may help me in tracking down this bug.

Any info is appreciated.

motorhead43026

Most likely the presence of DC voltage, commonly referred to as DC offset. Haflers are known for this especially as they age.

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kharp1

Yeah, I pulled the B&W 601's out to play around with it.

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motorhead43026

I have a Hafler XL600 beast. It has a pop when powered up on the right channel. The DC voltage on this channel is 50mv and the reason for the noise. The left channel is 10mv which is great. You can measure the voltage at the binding posts. Ideal voltage is under 20mv. Anything over 20 and under 100mv is not likely to cause damage, but sound quality (50mv+) issues are possible. Mine sounds fine, but I did take it out of service until it gets upgraded in 2017.

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