On 01/28/16 06:36, Peter Wieck so wittily quipped:
On Saturday, January 23, 2016 at 6:23:51 PM UTC-5, Patrick Turner wrote:
On Tuesday, 19 January 2016 05:52:28 UTC+11, wrote:
Hello!
Which tube is equivalent to 1/2 12BH7?
Mr Wieck typed....
"The standard equivalent in use today is the 12AU7, with perhaps a little bit less gain on the latter.
There are those who find that they are indistinguishable as drivers in low-power amps, favoring the 12BH7 over the 12AU in higher-power amps."
Just who says the 12AU7 "the standard equivalent" to 12BH7? The 12BH7 has a much lower Ra and higher Gm, and although both BH7 and AU7 are able to be used in the same audio circuit along with 6CG7, the BH7 has a significantly higher Ea swing because the Ra curve for EG1=0 is a more vertical line than in the AU7 or CG7.
Snippage:
Patrick Turner.
Two people on our little block are instrument amp types.
Explains much.
probably - it's something I'd want to do [again].
looking for output transformers, ran across THIS one.
https://www.amplifiedparts.com/products/P-T125A
it's a 3W somewhat-universal output transformer [push pull] with a
complicated secondary winding that lets you configure the primary Z,
apparently.
My guess is that it would make an interesting TRIODE OUTPUT STAGE using
the 12BH7 and this transformer.
bass response isn't ideal, perhaps, but it might work well as a small
P.A. or "distortion" guitar amp where you want to create a really nice
overdrive sound, but at a relatively low output power...