Hafler amp issue

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kharp1
kharp1 Posts: 3,453
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.

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  • motorhead43026
    motorhead43026 Posts: 3,892
    edited December 2016
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    Most likely the presence of DC voltage, commonly referred to as DC offset. Haflers are known for this especially as they age.
    Post edited by motorhead43026 on
    2 channel: Anthem 225 Integrated amp; Parasound Ztuner; TechnicsTT SL1350; Vincent PHO-8 phono pre; Marantz CD6005 spinner; Polk SDA2BTL's; LAT International speaker cables, ZU Mission IC's and power cables all into a PS Audio Dectet Power center.

    Other; M10 series II, M7C's, Hafler XL600 amp, RB-980BX, Parasound HCA-1500 amp , P5 preamp, all in storage. All vintage Polk have had crossover rebuilds and tweeter upgrades.

    The best way to predict the future is to invent it.

    It is imperative that we recognize that an opinion is not a fact.

    Imagine making politics your entire personality.
  • kharp1
    kharp1 Posts: 3,453
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    Yeah, I pulled the B&W 601's out to play around with it.
  • motorhead43026
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    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.
    2 channel: Anthem 225 Integrated amp; Parasound Ztuner; TechnicsTT SL1350; Vincent PHO-8 phono pre; Marantz CD6005 spinner; Polk SDA2BTL's; LAT International speaker cables, ZU Mission IC's and power cables all into a PS Audio Dectet Power center.

    Other; M10 series II, M7C's, Hafler XL600 amp, RB-980BX, Parasound HCA-1500 amp , P5 preamp, all in storage. All vintage Polk have had crossover rebuilds and tweeter upgrades.

    The best way to predict the future is to invent it.

    It is imperative that we recognize that an opinion is not a fact.

    Imagine making politics your entire personality.