6SL7 alternatives?

[Cobra2]

I found this (chinese) 300B PP amp, using 6SL7 as first tube (and 6SN7 as driver).
But doing a drawing of the internals, I find the 6SL7 connected as one triode (both in paralell).
The 6SL7 has a touch much gain, so a 6SN7 does the job almost just as good...

Now, I was thinking, is there a single-triode (octal) 6SL7, or something between SL and SN, or would maybe a 6J5 be a simpler sollution?

Arne K

 

[Yvesm]

Take a look at 6EA7/6EM7.
OK, the large triode is a bit too beefy but it could easyly replace the half 6SN7 while the small section really loos like an half 6SL7.

Yves.

 

[jon_010101]

6SF5 and 7B4 are both pretty close to a single section of a 6SL7 or 12AX7.

 

[Cobra2]

thanks...

Loctal would fit (w/adapter)...octal preferred, so the existing socket could stay.

I do not think this first tube needs any "drive", but will disconnecting one half do any unexpected changes? (in front of the 6SN7, that is the splitter/driver).

Arne K

 

[jon_010101]

The 6SF5 is octal. You can also just use half of the 6SL7.

 

[jane]

6SQ7 (~1/2 6SL7 + 2 diodes).

jan.

 

[Cobra2]

The 6SF5 is octal. You can also just use half of the 6SL7.

This would be the simplest "upgrade", I think. But, since it has a tad too much gain, would a 6J5 (and maybe a reduction in feedback) do the job better?

Arne K

6SQ7 is interesting, but not in my collection (yet)...

 

[jon_010101]

If the 6SL7 is in parallel, using one section only won't change the gain. Both sections in parallel are likely important to allow sufficient drive for the 6SN7 stage. A 6SN7/6J5, however, would reduce gain significantly.

 

[aardvarkash10]

6j5 is your answer

octal smooth and cheap as chips

 

[Cobra2]

MingDa 300B PP

My napkin drawings..:

Arne K

Coments, please

 

[Bandersnatch]

I found this (chinese) 300B PP amp, using 6SL7 as first tube (and 6SN7 as driver).
But doing a drawing of the internals, I find the 6SL7 connected as one triode (both in paralell).
The 6SL7 has a touch much gain, so a 6SN7 does the job almost just as good...

Now, I was thinking, is there a single-triode (octal) 6SL7, or something between SL and SN, or would maybe a 6J5 be a simpler sollution?

Arne K

hey-Hey!!!,
I'd consider an octal-nine pin adapter and apply a single 6S3p Russian single for your 6SL7 stage. mu is ~40 so you'll loose jus' a bit of gain.
cheers,
Douglas

 

[Cobra2]

I found the pinout (6S3P), but no data?
(and I do not have any...- but I do have many of the more common small triodes, both Russian and Euro/US).

Arne K

 

[Wavebourn]

Do you have 6N2P?

 

[Cobra2]

Yes, lots...but 6N2P has lots of (too much) gain?

 

[Wavebourn]

It was developed as a miniature replacement to 6SL7, though due to different geometry parameters are a bit different.

 

[Cobra2]

MingDa MC300-AA

How clever, the front-end is 99% similar to their EL34 amp... ( MC34B )

Arne K

 

[Cobra2]

LTP-ccs

CCS... - source or sink?
I have some CCS-pcbs ready, what is their best use, source or sink?
The LTP (splitter) was my first choice...(?)

Arne K

 

[Bandersnatch]

CCS... - source or sink?
I have some CCS-pcbs ready, what is their best use, source or sink?
The LTP (splitter) was my first choice...(?)

Arne K

Both! For the plate load in the 6N2 and cathode 'tail' in the 6N1 section.
cheers,
Douglas

 

[vitalstates]

5670 ???

 

[Cobra2]

MingDa 300B WARNING...the 300B is running 5,8-6V on the filaments!!!
(and biased to 88mA)
No wonder they do not last...

Arne K