Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: mikek200 on April 09, 2013, 10:57:16 AM
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Have the Crack with speedball.
Can the above 2 tubes ,be used on it
Thanks
M.
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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.
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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.
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OK,
Thanks guys