12BH7 optimization instead of 12au7

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12BH7 optimization instead of 12au7

Postby battradio » Wed Oct 17, 2012 7:23 pm

Hi to optimize a ST 70 driver board For 12BH7 would R18 need to be changed .

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Postby Geek » Wed Oct 17, 2012 9:38 pm

Depends.... whose ST-70 board? (???)
-= Gregg =-
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Postby battradio » Thu Oct 18, 2012 12:49 am

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Postby Shannon Parks » Wed Oct 31, 2012 6:03 am

Just ran the sims via John Broskie's TubeCAD. No change is necessary for subbing a 12BH7 as the long tail phase splitter. The bias voltages remain unchanged in this arrangement.

But using a 6DJ8/6922 doesn't get the right voltages as the LTP, and it's lower max voltage rating is a problem. The bias is more suited for small signals as a voltage amplifier. Unfortunately, it doesn't have suitable gain for a simple sub in the diytube ST70 driver.

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