12AU7A swapped for 12BH7A
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12AU7A swapped for 12BH7A
by mesherm » Wed Oct 06, 2004 3:58 pm
I had some NOS 12BH7As I found laying around at work in the back and in checking them in the RCA manual found they could replace a 12AU7. I tried this with my ST-35, swapped out the 12AU7, and noticed no difference. Makes me happy because I have way more 12BH7As than 12AU7As.
Mike's N-1 Rule: When looking for N number of components to finish a job, you have a 95% chance of only finding N-1 of them.
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mesherm - KT88
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Re: 12AU7A swapped for 12BH7A
by Shannon Parks » Wed Oct 06, 2004 6:16 pm
mesherm wrote:I had some NOS 12BH7As I found laying around at work in the back and in checking them in the RCA manual found they could replace a 12AU7. I tried this with my ST-35, swapped out the 12AU7, and noticed no difference. Makes me happy because I have way more 12BH7As than 12AU7As.
When testing my prototype linestage, I tried some 12BH7s vs the stock 12AU7s. They tested very well. But, they use twice as much filament current - .6A vs .3A for a 12AU7. If you have an original PA774, take note.
Shannon
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by mesherm » Wed Oct 06, 2004 6:31 pm
The assembly inside seems about twice as long so it makes sense that the filament would draw twice the current. I left out the extra 3 tubes I was going to use for a line preamp so with Uncle Ned's clone PT there was plenty of extra electrons though.
Mike's N-1 Rule: When looking for N number of components to finish a job, you have a 95% chance of only finding N-1 of them.
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mesherm - KT88
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by EWBrown » Mon Oct 25, 2004 11:19 am
The PA774 should have enough reserve, as it also can drive the two extra 12AX7s in the SCA-35, THough I don't immediately recall the current consumption of 2 7199s they use in place of 12DW7/7247s.
Same caveat applies is one uses 6N1Ps and 6N2Ps (with 6.3VAC applied to pins 4&5, these also consume 0.6 to 0.66 amps each.
/ed B in NH back from NC
Same caveat applies is one uses 6N1Ps and 6N2Ps (with 6.3VAC applied to pins 4&5, these also consume 0.6 to 0.66 amps each.
/ed B in NH back from NC
Real Radios Glow in the Dark
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