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Questions about tubes and gear that glows. FAQ

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Depends on your amp......

Posted by Chuck Y on August 8, 2012 at 11:43:15:
Some auto bias circuits are adjusted for optimum performance with certain groups of tubes, i.e. EL34's, 6L6's etc vs 6550's KT88's etc. While all of these tubes may sound OK, if the amp was optomized for EL34's is might not sound as good with KT88's or operate as well. I had this issue with a well known brand and got instructions from the distributor for changing the range to accomodate the tubes I preferred. Not your brand of amp BTW. Best check with the manufacturer. While I'm guessing consider that some tubes come 'hot', tubes that were not carfully screened by the manufacturer, distributor, or retail sales outfit, and they can blow out regardless of auto bias circuit you are using. That is why I prefer amps with provision for easily obtained manual bias, apart from the fact that you can also adjust bias with in the tubes range for the best possible tone.