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In Reply to: Biasing AE-25 Superamp monoblocks posted by sgbmpt on June 5, 2007 at 22:31:28:
Greetings- I don't own this particular amp, but the biasing procedure should be similar to my Cary 300b monos. You will need a DMM (multimeter) or standalone milliampmeter to measure and then adjust the bias. To be safe, I would call Cary and find out what the setting is supposed to be before attempting this. I'm just guessing, but they probably bias each pair of KT88 together, not individually. This would probably give you a reading of between 100-110 ma. per pair of output tubes (just guessing). There is probably a toggle switch to go back and forth between the two pair of tubes. It is then just a matter of inserting the 1/4 inch plug into the amp, hooking the two wires (coming out of the plug) to the two leads of your meter, making sure the meter is properly set to read current (milliamperes). Most multi-meters that I have used will require that you also plug the positive lead into the 400 ma or 10A jack on the meter as well. Until you get the hang of it (it's easy), it's recommended that you set the bias with no signal applied (volume off) but with the amp hooked up to a pair of 8 ohm load resistors or cheap pair of speakers. Hopefully this will give you an idea of what is involved, perhaps somone else that actually own the amp can fill in the details for you. If I remember correctly, the only versions of that amp that had fixed (adjustable) bias were the premium models, so you've got yourself a nice amp. However, you will need to address your "cold tube" problem first as this is probably unrelated to the bias adjustment. First try swapping tubes to see if it is the tube or the socket that is causing the problem. If a known "good" tube wont light in that socket, then you know that there is an open connection somewhere.Fixing it may be as simple as retensioning the tube socket contacts. Just be very careful of the high voltages that may be present even after the amp is unplugged. Let the caps discharge for a while before attempting any trouble shooting.Post your results and we can try to help you diagnose the problem. Good luck and be safe, Regards, wpod
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- RE: Biasing AE-25 Superamp monoblocks - wpod 06/6/0708:59:40 06/6/07 (0)
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