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Re: underbiasing / overbiasing of tubes. Will it damage tubes, circuits?

24.205.10.224

Posted by steven oda on January 9, 2004 at 18:32:22

In Reply to: underbiasing / overbiasing of tubes. Will it damage tubes, circuits? posted by audioman on January 9, 2004 at 16:35:52:

AM,

Warning, un-professional response:

1.) Under-biasing the power tubes can make them run hot and shorten their life. Usually, you can tell by the tone of the amp, especially when cranked. Amps tend to distort and even clip too early in the volume range, when under-biased.

2.) Over-biasing power tubes tends to make them run too cold. The resultant tone is lifeless, sterile, with poor midrange response. If you really over-bias a power tube, you get this God awful crossover distortion---which you will never forget once you've heard it.

Since, over-biasing tends to run the power tubes too cold there is less danger of shortening their lives (all else being equal, in the amp), than if you under-bias them.

I know, biasing for dummies... But, it's a basic starting point.

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