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Old 19th November 2007, 02:54 PM   #21
anatech is offline anatech  Canada
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Hi Tom,
Sometimes fan noise can be reduced with a good cleaning. Behind the fan blades too. You really have to remove it for this. Failing that, a new fan is required. These should not be very noisy in normal use as they are not turning at full speed, that's why I think there may be an issue there.

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Yes, it's too bad that there's at least 45 min driving from Ajax to Georgetown.
I used to drive that often enough. I'd call it 1 1/2 hours if traffic is really good. The moon if your running around after 4:30 PM on a weekday.

-Chris
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Old 22nd November 2007, 01:09 AM   #22
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Hi Chris,

Thank you so much for the information. I will try to clean the fan again in X'mas time.

Tom
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Old 28th December 2007, 02:50 AM   #23
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Question to those with the P-500 - Which potentiometer do you adjust the bias at and which fuse do you use to measure?

On my P-500 I see 4 potentiometers and 2 pairs of fuses. A picture would be great.


Thanks
Mike
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Old 28th December 2007, 06:04 AM   #24
djk is offline djk
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http://www.hafler.com/techsupport/pd...00_amp_man.pdf

Bias pot P2 is right in the middle of the board. Adjust to 350mA.

There is one dual fuseholder per channel. Pull one fuse (either one) and measure the current (to avoid killing yourself turn amp off and wait a minute before sticking your fingers in it). Repeat for other channel.
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Old 28th December 2007, 12:11 PM   #25
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Thanks djk. I do have the DH-500 manual but the layout of the P-500 is different, so I wasn't sure how similar it was.

Will give it a try and report back. Also, I'll try cleaning the heat sink as I am still trying to eliminate the high-speed fan mode after only a few minutes of listening.

Mike
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Old 29th December 2007, 07:17 AM   #26
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"Also, I'll try cleaning the heat sink as I am still trying to eliminate the high-speed fan mode after only a few minutes of listening."

They get hot when you run them hard, or at 4R.

I replaced the quiet 35CFM stock fan with a 110CFM howler to keep the amp running at 4R (with the stock fan it will shut down).

No matter how quiet of a fan you use, you will still be able to hear it at low volume levels.

This is one of the quieter fans on the market:

http://www.comairrotron.com/cgi-bin/...ameter_unit=in

You might want to try something like this and re-wire the fan switches for medium and high speed only with a single resistor for an appropriate speed. I find it less annoying if it isn't switching speeds all the time.
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