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[compasspnt]

Hello,

Anyone have ideas concerning possibility of substituting from 6550 to 7027A valves?  Our book shows that KT88 would replace either, so looks to me like it would work.

This is to go in a Hammond Leslie amp.

Thanks!

[rwj1313]

compasspnt wrote on Wed, 04 January 2006 11:27

Hello, Anyone have ideas concerning possibility of substituting from 6550 to 7027A valves?  Our book shows that KT88 would replace either, so looks to me like it would work. This is to go in a Hammond Leslie amp. Thanks!

Hi Terry,

I don't have my Groove Tubes book handy but it might be possible with some kind of bias modification. I'll look tonight when I get home. My guess is that it can be done. I'll see what the difference in bias voltage is and let you know. On a 100W Marshall it is a simple resistor change to switch from 6550's to EL-34's. You might want to e-mail Myles Rose at GT's Special Applications Group. He has been a big help to me in the past.

Rick

[rwj1313]

Hey Terry,

I need to know which amp you have. Year and model. It should be in my Groove Tubes Tube Amp Book. Hey if you don't have the GT book you should pick one up. In fact all studio owners that are tech savvy should probably get one. This book has saved my butt more times than I can count over the past 25 years. The newest issue is sold $25.00 paperback and I think $50.00 for the hard cover version. I have an original first edition paperback and the newest one also in paperback. It also has some really good history of the various tube amp manufacturors and some pics of rare tube amps and rare guitars.

Rick

[Larrchild]

http://www.triodeel.com/7027.htm