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Forums :: Ask Amp Tech Expert Skip Simmons

12DW7

1 reply [Last post]
Mon, 06/25/2012 - 11:11
marcos
marcos's picture
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Teacher 9Level 10
Joined: 01/11/2010

Hey, Skip.

What do you think about using a 12DW7 in the V3 position of, say, a Bassman RI?

I have read that this is a "hybrid" tube, like a 12ax7 on one side and a 12au7 on the other, that causes the power tubes to be driven "out of synch" and gives more/different distortion in the power amp stage. Sounds magical to me.

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Tue, 07/03/2012 - 19:27
#1
Expert Skip Simmons
Expert Skip Simmons's picture
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Joined: 01/18/2010
12DW7 tubes for harp

Hello Marcos- All 12AX7-type tubes are dual triodes- they are really two tubes in one. Almost all of them have identical halves, but the 12DW7 has a high-gain half and a lower-gain half. If you like the sound of it that's great, but when used in the phase-inverter position (V3 in a Bassman circuit) you will certainly create an unbalanced signal to the power tubes. I would say that distortion created by this tweak would be fairly unpleasant rather than "magic", but give it a try and see what you think. If you have one, (good quality 12DW7s are hard to find!) why not try it in the V1 and V2 as well? Report back.......BH.com readers are awaiting you thoughts!

Skip Simmons

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