12BH7 and 7247 in my 5E3

[ValveBytes]

Hey,

Wasn't too convinced by the sound of my 5E3 with the stock valve line-up, didn't chime and seems too clean my PT/rectifier setup is a bit odd so I put it down to that, started trying different triodes, tried out 2x 12ax7's better overdrive but the harmonics seem predictable and like other amps I already have, got hold of a 7247 unbalanced triode one triode has the gain of a 12AX7 and the other has the gain of 12AT7 or something, gives you one pretty good drive channel and one clean channel with a manageable volume.. Then I found a 12BH7 in my collection stuck that in the first stage and the result was amazing! very chimey with the kind of drive I was after not too over the top like a 12AX7 and has very nice harmonics too.

Anybody else tried a 12BH7? maybe it wouldn't sound so good in a 5E3 with specified voltage, but it sure brought a lot of life to mine!

I have a 4.7uf cap on the first stage and a .022uf cap coupling the bright channel, the PT is running a 6AX5GT so I only get about 315v.

[Bruce / Mission Amps]

A 12BH7 is like a heavy duty 12AU7... your 7247/12DW7 has one 12AX7 and one 12AU7 triode...
And, the 12AU7 section on the 12DW7 is on the dull normal channel side.
That would be lugs 1,2,3 if you built it the stock way.
If used in the second socket, the low gain 12AU7 side would be connected to the volume controls and
you'd have 1/5 the gain of the 12AX7.
The high gain 12AX7 side would be on the phase inverter/cathodyne driver triode side and that works very well since that is the way a stock one is anyhow.
So all you are doing is using the 12AU7 in both configurations
Measure your actual plate voltages with the 12BH7.. I'm curious where it runs now because, to my ears, the sweet spot for preamp voltages in a 5E3 using a 12AY7 (twice the gain of your 12BH7) is right around 110vdc to 120vdc.

[ValveBytes]

the voltages are:

B+ 318.5

12BH7
Pin1 48.8
Pin3 2.22
Pin6 54.5

Quite different compared to a 12AX7.

I haven't had a chance to turn this thing up loud with the 12BH7 yet, so I'll have to check out what it is like Vol above 3. I have installed EH 6V6GT, a NOS US 12AX7 and the 12BH7 as the first gain stage.

[Bruce / Mission Amps]

the voltages are:

B+ 318.5

12BH7
Pin1 48.8
Pin3 2.22
Pin6 54.5

Quite different compared to a 12AX7.

I haven't had a chance to turn this thing up loud with the 12BH7 yet, so I'll have to check out what it is like Vol above 3. I have installed EH 6V6GT, a NOS US 12AX7 and the 12BH7 as the first gain stage.

Because the impedance is so low in a 12AU7/12BH7... pull your 100K plate load resistors off and use 27K to 39K instead and watch what happens.