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12AU7 Gain Question

I recently purchased (3) 12AU7LG tubes. Two for my PS Audio BHK pre amp, and one as the input for my tube amp. The tubes were selected by the seller based on my equipment, and have different gain.

2 pre amp tubes are Mu A=16 and B=16

1 power amp tube is MU A=2016 and B=16

Ok, so I'm a dummy, and although the boxes were marked as such, I mixed the 3 tubes up, and they all look exactly the same.

Question is, can I use a multi meter on the tube pins to test the gain difference? How can I identify the odd power tube?

Do I need a tube tester?

Can I just keep rotating the tubes to try to find a gain in DBs in the room, or channel?

Thanks Mark O

 

 

128x128marktheshark

Showing 1 response by tomcy6

tomcy6's avatar
tomcy6
2,544 posts
 

The right tube tester will give you the gain for each triode, but I don’t think that a 12AU7 can have a gain of 2016, that number may just be to mark the box of the tube intended for your power amp. I think you have 3 tubes with a gain of 16 for each triode.

The seller may have selected one of the tubes for the amp for another reason, though. I don’t see any harm in swapping the tubes around to see if one combination sounds better than another. Call the tube seller and ask him how the tube for the power amp is supposed to be different. There may be no difference between the tubes.  If you need to get them tested for some reason, I can do that.

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