Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: mikek200 on April 09, 2013, 10:57:16 AM

Title: 12ax7,12at7,on Crack?
Post by: mikek200 on April 09, 2013, 10:57:16 AM
Have the Crack with speedball.
Can the above 2 tubes ,be used on it

Thanks
M.
Title: Re: 12ax7,12at7,on Crack?
Post by: Paul Joppa on April 09, 2013, 01:25:07 PM
No. In order to get the plate voltage low enough, they would have to be run in the grid current region, where distortion is increased.
Title: Re: 12ax7,12at7,on Crack?
Post by: Paul Birkeland on April 09, 2013, 05:08:27 PM
In actuality, the first Crack that Doc B. and I built ran the 12AT7, but it had way, way too much gain for any headphones that we tried.  The 12AX7 will be much worse.

A 5687, 12BH7, 6CG7, or 12AU7 are the families of tubes that run well in this arrangement, with the 6CG7 having a different heater arrangement and the 5687 having an unusual and very different pinout.
Title: Re: 12ax7,12at7,on Crack?
Post by: mikek200 on April 10, 2013, 05:13:11 AM
OK,
Thanks guys