ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

previous: Scott IMO, they sound pretty similar to a... -- 10/26/1999 4:00 PM

Re: 6SF5 preamp tubes?!?

10/26/1999 5:35 PM
Doc	Re: 6SF5 preamp tubes?!? You'll find that most of the older, octal based audio tubes sound fuller and have richer bass than their miniature successors. The 6SF5 is a single high mu triode, and is exactly a 6SQ7 without the two little detector diodes. These tubes have a mu and Rp equal to one section of a 12AX7, so they are equivalent to a 12AX7 from a biasing and voltage gain standpoint. Any circuit designed for a 12AX7 can use a 6SF5 as a direct electrical replacement, although 6SF5s are a little hard to come by. When I need one for an antique piece that requires one, I have a tough time finding a good, non-microphonic one. Keith, if you decide to pull the 6SF5s and use something else for your circuit, please keep me in mind. Thanks, Doc

10/26/1999 5:35 PM

Doc

Re: 6SF5 preamp tubes?!?

You'll find that most of the older, octal based audio tubes sound fuller and have richer bass than their miniature successors.

The 6SF5 is a single high mu triode, and is exactly a 6SQ7 without the two little detector diodes. These tubes have a mu and Rp equal to one section of a 12AX7, so they are equivalent to a 12AX7 from a biasing and voltage gain standpoint. Any circuit designed for a 12AX7 can use a 6SF5 as a direct electrical replacement, although 6SF5s are a little hard to come by. When I need one for an antique piece that requires one, I have a tough time finding a good, non-microphonic one.

Keith, if you decide to pull the 6SF5s and use something else for your circuit, please keep me in mind.

Thanks,
Doc

Replies:

keith Doc, I'm still not sure what I'll e... -- 10/26/1999 7:31 PM