6SL7 preamp

andrew · Post by **andrew** » Wed Nov 26, 2008 4:01 am

Does anyone have a favorite 6SL7 preamp design? Thanks.

funkmeblue · Post by **funkmeblue** » Wed Nov 26, 2008 11:29 am

I used 6sl7's in my "express" build and a modified houndog redbone pre in single ended amp. These don't have as much gain, but I really like them alot. Something about the overall bandwith of these things, the highs are syruppy and the lows are huge.

Andy Le Blanc · Post by **Andy Le Blanc** » Wed Nov 26, 2008 4:21 pm

they are a great tube...... I like them best with a simple tone and volume
plate resistance is about 20k lower than a 12ax7.... try to keep the resistance
following the output as high as possible.....

Alexo · Post by **Alexo** » Wed Nov 26, 2008 7:19 pm

Anybody else find them to be a little noisy in high gain situations, or is this just my bad luck on the few amps I've built with them? I know they don't have the heater humbucking effects that 12AX7's can.

Great sounding tubes though, one of my favorite amps is a 6SL7 into a single-ended 6V6.

Andy Le Blanc · Post by **Andy Le Blanc** » Wed Nov 26, 2008 7:26 pm

They can be noisey,the metal parts are large and have a life of their own,
you really do need to let them warm up.

jjman · Post by **jjman** » Wed Nov 26, 2008 8:11 pm

I overhauled a friend’s Ampeg Mercury which has 3 of these. He had newer Sovtek 6SL7s in there and they all hummed. I picked up some NOS ones which are quiet. I suspect they may have actually been used but they are much better than the newer Sovteks he had.

Only one preamp stage then the PI so I can’t comment on how they might sound clipping.

http://www.schematicheaven.com/ampegamps/m12_6v6.pdf

FUCHSAUDIO · Post by **FUCHSAUDIO** » Wed Nov 26, 2008 8:43 pm

Were these the new Tungsol 6SL7's ? I hear those are good. I know the older Sovtek's were pretty grim....

Andy Le Blanc · Post by **Andy Le Blanc** » Wed Nov 26, 2008 9:53 pm

some of those sovtek didn't even have the envelopes in the base straight.
havent heard anything about the new tungsol.

Chappy · Post by **Chappy** » Thu Nov 27, 2008 1:44 am

I built a homebrew amp with 6SL7's and a 6V6PP output stage. I'm using used mil spec tubes and the amp is dead quiet. These old tubes are pretty plentiful, and you can probably snag some quality used ones for cheaper than current production tubes.

Steve

funkmeblue · Post by **funkmeblue** » Thu Nov 27, 2008 6:10 am

the tung sol's didn't last long, liked the sound. the chinese 6n9p sounded more like an nos 6sl7, and outlasted the russian tubes

jjman · Post by **jjman** » Fri Nov 28, 2008 2:38 am

FUCHSAUDIO wrote:Were these the new Tungsol 6SL7's ? I hear those are good. I know the older Sovtek's were pretty grim....

No they were old. Got them from Radio Daze.

davent · Post by **davent** » Fri Nov 28, 2008 4:05 am

Hello,
I've got a little two tube SE with parallel preamp sockets so I can run 6s?7's, 6eu7's or 12a?7's (singly or paralleled). The 6sl7's are slightly noisier then the other two options if you're sitting there doing critical comparison with no guitar plugged in but it's really not anything to worry about. I also have a 6v6 PP hifi power amp amp that uses 6sl7's for the PI and it's dead quiet, even when using Sovtek's. The hifi amp uses DC heaters the SE, AC heaters, i seem to recall seeing others mention that it is advantageous to run the 6sl7's with DC heaters but haven't done a proper comparison.

dave

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