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vman's picture
Last seen: 2 years 9 months ago
Joined: Oct 29 2007 - 12:33pm
Biasing with different tubes

I have a Cayin a-50T amp and I am replacing the stock output tubes with a set of Gold Lions.

I checked the bias of each Cayin tube before pulling them out - they were all at 32, which is within spec per the manual.

The Gold Lions were marked on the box at 31.7, but when I plugged them in and tested them they read 11. They sound fine, but I'm wondering if I need to now adjust the bias back up to 31.7 - assuming I do.

Is this normal behavior? Is this because one set are EL-34 and the other are 6CA7?


JoeE SP9
JoeE SP9's picture
Last seen: 5 days 8 hours ago
Joined: Oct 31 2005 - 6:02pm
I don't know about the bias

I don't know about the bias but the RCA tube manual uses the designation 6CA7 for EL34. Some research I've been doing has informed me that EL34's, 6550's and KT88's are all variations on the 6CA7 type tube.

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