7-pin triode questions

[tweedeluxe]

Anyone have any luck using 7-pin triodes in high-gain guitar amps?

I have a ton of NOS 6AV6 and 6AT6 tubes. They're just collecting dust so I'm thinking about using them for an upcoming build.

For those of you who've used them - what did you do with the 2 diodes - Ignore them, tie them to the cathode/ground?

I have also heard that these single triode tubes tend to be microphonic in guitar amps. Too much for a high-gain head, isolated from the speaker cab?

Thanks in advance for any advice. I'll let you all know how it turns out if I go ahead with the project.

[Phil_S]

These are roughly the equivalent of half a 12AX7 or half a 5751. Ignore the diodes, which are mostly useless. The thing is, these require 0.3A filament current and you need twice as many sockets to get the same number of sections. So, I suppose they are good to use if you've got enough extra filament current and enough extra real estate on the chassis.

I am contemplating using a 6C4 (half a 12AU7) because I only need one more section and the tube is cheap. This particular tube sips only 0.15A for the filaments.

I'd say, since you've got a pile lying around, for the price of a filament transformer, you might be able to manage some cost savings. Put pencil to paper and figure it out.

AFA the tubes, I don't know of a reason one way or the other to use them or not. It seems reasonable that they will function just fine.

You're looking at 7 pin tubes here. I just used a few octal 6AQ7's (like the 6AV6 but in a large bottle) in one of my amps and it worked out great. I was able to save he more expensive 6SL7's for other uses.

[Sonny ReVerb]

I wonder if you could use the diodes to bias the triodes like Andy did with his jam amp idea?

https://tubeamparchive.com/viewtopic.php?p=89112#89112

[flood]

i'm thinking of making a 6U8+6C4 based "propah tube saturation" overdrive pedal, with an output tranny, dummy load, etc.

[Phil_S]

I wonder if you could use the diodes to bias the triodes like Andy did with his jam amp idea?
https://tubeamparchive.com/viewtopic.php?p=89112#89112

I had the very same thought and suspect you can. Unfortunately, I don't have the knowledge to make a clear judgment on it. These are typically cheap tubes. If curious, try it and see. After all, you get two diodes!

[tweedeluxe]

Most of the 7-pin triode/duodiode datasheets mention that the diodes cannot be used to bias the triode. I'm not sure why. Maybe because the cathode is shared?

I've got a huge OT from an old Baldwin organ so I should be set for heater current.

Think I'll give it go, thanks!

[mojo2001]

Most of the 7-pin triode/duodiode datasheets mention that the diodes cannot be used to bias the triode.

How about using the diodes from different tubes to bias each other?


EDIT: Never mind...the cathode would have to be grounded. Duh.