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Is bias setting necessary on matched tubes?

Hi Guys,

Just bought my first tube amp and it was delivered with broken/defective tubes. I just bought a matched quad of Genalex KT88's to replace them and was wondering if biasing is a must, or can I just "plug and play" them as they say.

I'm pretty much a newbie with tubes so any advice is really helpful.

Thanks!

Geoff
geoffcin
brf
1,699 posts
 
Yes, the bias will need to be reset. Make sure the bias pot is turned all the way down before turning on the amp. Let the tubes warm up for 10 minutes and then bring the bias up slowly to the recommended settings. With new tubes, check the bias again after a couple of hours playing time and again in a weeks time. Enjoy.
hanaleimike
125 posts
 
yes, and they will sound different at different bias settings.
dusty
60 posts
 
Unless your amp is of the "audobias" type (primaluna is one brand) then you will have to readjust the bias. Matched tubes just means that they are very similair in terms of operating characteristics. Important! If your amp has only one bias adjustment for each channel then it's recommended that you ONLY buy matched tube sets and replace them all when one goes bad. RAM tubes website has a good primer on matched tubes.
Cheers!
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