1634 dual triode

[Original Burnedfingers]

I recently purchased a large number of the 1634 tube for a relatively cheap price. I would like to try to use them in place of a 6SL7. If I'm not mistaken they are the same as a 6SL7 except the cathode is common to both triodes and the pin out is different. So would one use it with both sections paralled together or could you just use one section and let the other alone?

[DigitalJunkie]

Paralleling the sections is one option. Another is to use them in a circuit where the cathodes are tied together,Perhaps an LTP phase splitter,or something.

I don't think leaving one section 'hanging' is a good option.

[Original Burnedfingers]

Ok, I have a driver board on my dynaco that has a 6sl7 input and a long tail
6sl7. If I understand correctly I could replace the long tail with the 1634.

Could I also parallel the two sections of the 1634 and replace the input 6sl7 tube? Do I cut the cathode resistor value in half if I parallel the two sections?
Haven't done any figuring with paralleled sections before therefore the stupid question.

[Bandersnatch]

hey-Hey!!!,
The 1634 is lower gm than the 6SL7. So with equivalent gain, plate resistance is higher. Available swing from its plates will be lower than a 6SL7, and with a 6SL7 as input a 6SN7 would make a better LTP stage; more voltage at lower output Z are available.
cheers,
Douglas

[Original Burnedfingers]

But I have 50 or so of them and would like to try them to see what I can come up with. Can I parallel up a 1634 for input and then make a long tail out of another?

[Tony]

you can use them if you have them......circuits for 12SC7 should work, are those metal enveloped like the 12SC7's....the rca manual have a resistance coupled chart that you can look up for values of resistors based on B+....

[Bandersnatch]

Originally Posted by Original Burnedfingers

But I have 50 or so of them and would like to try them to see what I can come up with. Can I parallel up a 1634 for input and then make a long tail out of another?

Of course you can do that. How well it works is quite enother thing. Do try it, you'll find out the best way.
cheers,
Douglas

[Original Burnedfingers]

Douglas,

As one that has followed your marvelous designs I will not doubt that your 100% correct. The 6SL7 is a better tube but I just have to play with the 1634 just to see how it will sound and behave.

Quote:

you can use them if you have them......circuits for 12SC7 should work, are those metal enveloped like the 12SC7's....the rca manual have a resistance coupled chart that you can look up for values of resistors based on B+....

Yes, metal enveloped like the 12SC7's or VT-268. I think they are supposed to be a premium low noise version.

[Bandersnatch]

Originally Posted by Original Burnedfingers

Douglas,

As one that has followed your marvelous designs I will not doubt that your 100% correct. The 6SL7 is a better tube but I just have to play with the 1634 just to see how it will sound and behave.

Quote:

you can use them if you have them......circuits for 12SC7 should work, are those metal enveloped like the 12SC7's....the rca manual have a resistance coupled chart that you can look up for values of resistors based on B+....

Yes, metal enveloped like the 12SC7's or VT-268. I think they are supposed to be a premium low noise version.

The first thing I did for a pair of M.iii I was given was to put in a new front end. 6SL7 LTP driving a 6SN7 LTP and it had more than enough gain. Two high gain stages will probably get you a very sensitive amp. Drive on though; I do like the single cathode connection. Leave yourself room to play with the second stage, perhaps with another single cathode tube like RK34... Dual plate caps and an ST bottle with a septar socket. Cheap too.
cheers,
Douglas

[Original Burnedfingers]

Douglas can you post something or possibly email me something?

Thanks,
Joe