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cdeveza 21st May 2003 04:30 PM

Single section equivalent of 6SL7
Anybody knows if there is a tube with single section, that is electrically equivalent to 6SL7? Also a single section equivalent
of 6BL7?

Alex Deveza

EC8010 21st May 2003 05:15 PM

6AH4 is half of a 6BX7 (fairly similar to 6BL7), and I'm sure there must be a single triode that is half of a 6SL7, but I can't think of it. How equivalent do you need? Is it the mu, the maximum Va, or must it be truly and fully equivalent?

Colt45 21st May 2003 08:10 PM

6SQ7 is pretty similar, but it has 2 diodes in it as well (you could always just ground them though)

Sch3mat1c 21st May 2003 08:12 PM

6AV6 is a half a 12AX7. Closest I can think of, it has higher mu and Rp I think.


fdegrove 21st May 2003 08:22 PM



6AV6 is a half a 12AX7. Closest I can think of, it has higher mu and Rp I think.
Yes, plus it contains a pair of diodes and requires a different socket (B7G), the 6AV6 I mean.

I remember looking for 1/2 6SL7 years ago and could find any, which doesn't mean there aren't any.

The SL7 has an Ra of 44K whereas the 12AX7 has 62K.


SHiFTY 21st May 2003 10:37 PM

Maybe a 6K5? Most of them are old metal tubes, however.

Also a 6Q7 is like half a 6SL7 plus a couple of diodes.

These are old old old tubes :)

bournville 21st May 2003 11:00 PM

...The loctal 7C5 is the equivalent of a 6Q7 and it would avoid the use of a top tap - the grid on the 6Q7 (and a potential hum source).

Tom Bavis 21st May 2003 11:33 PM

6SF5, 6SQ7 are octal hi mu triodes, 6F5, 6K5, 6Q7 with top cap. I think all have higher mu and higher Rp than 6SL7. 6SC7 is 6SL7 with common cathode - they're cheap enough to use as a single triode.

In miniature, 6AT6, 6AV6, 6AQ4, 6BK6, probably others.

AKSA 22nd May 2003 12:02 AM


I don't think such a beast exists. However, I often use the 6SL7 - it's one of the best high mu tubes around, with a lovely sound and huge soundstage. I T-bar the two sections - with no loss of quality I can detect - that is, connect the two plates, the two cathodes, and connect two 1K grid stoppers, with each to a grid.

In this role the tube delivers an rp of 22K, mu of 70, and I use a 50K combined plate load. With 175V on the plate it runs 3.36mA, and has quite good drive. If your application can tolerate using the one tube for a single voltage amplifier amplification, this is the way I'd do it.



fdegrove 22nd May 2003 12:27 AM

High Hugh,

For that to work without penalty both halves need to be perfectly matched...

I use that kind of configuration with a 6DJ8 type of headamp (MC Hammer) CCS loaded, and matching all section of two twin triodes per channel is a bit of a headache.

Pros are halve Ra, doubled Gm, halved req but...current hogging may occur...

It's a bit like putting caps in //, they're notoriously tough to perfectly share current creating a see saw effect on the whole circuit...
Well, not just know what I mean.


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