Forum Index > Music Electronics > Guitar Amps

--- Design & Construction +
--- Mods & Tweeks
--- Repair & Maintenance
--- Vintage Amps

flat || threaded

good use for 6sn7
stan ( )
Thu Jan 29 03:07:08 2004
I have become a bit bored with 12ax7s, so I picked up a handful of NOS 6sn7's (they were cheap). And of course now I am wonding if I can put these to use in a new project.  Can someone point me to a fat/clean preamp design using this tube?  
thanks.
---
danf ( )
Fri Jan 30 04:04:59 2004
Hi Stan  
 
 
 
Gibson used 6SN7's in some early amps (the BR-9 ? - not sure, I'll have to check the schematics). Also, I think some early Ampeg amps. I'm using 6SN7's as the preamp tube in two old mono audio amps. When I was wiring them up I looked into some guitar and audio amps that used them.  
 
 
 
Dan
---
stan ( )
Fri Jan 30 07:48:23 2004
Thanks for the reply Dan.  I have looked at a bunch of old schematics, and I have seen the ampeg schematic using the 6sn7 (and a few other schematics), but it seems that this tube was used for phase-inverters or to drive a reverb tank, rather than as a straight ahead gain stage.  I'll go hunting through Gibson schematics now...thanks for the tip.
------
Andy ( )
Fri Jan 30 15:18:25 2004
the 6SL7 is far more useful as a gain stage, since it has a voltage gain of about 70, while the 6SN7 is only about 20
------
bruce ( )
Fri Jan 30 15:56:35 2004
Stan,  
The Gibson BR-9 I once owned had a 6SN7 as the pre-amp with a xfmr PI driving PP 6V6's.  
Very clean sounding amp. As previously noted, I tried a 6SL7 and the amp had a lot more grind.  
bruce
---------
Bruce /Mission Amps ( )
Fri Jan 30 16:41:09 2004
I've used a couple 6SN7s as power tubes in small low power SE and push pull amp...they sounded great!  
 
Bruce
------------
Jim C. ( )
Fri Jan 30 18:38:21 2004
I've got an old Gibson GA50T that I got in highschool back in the 60's. It has a 6SN7 for the phase inverter driving a pair of 6l6's for the final stage. The preamps are 6SJ7's. That sure is a sweet old amp! To my ears, the 6SJ7's and 6SN7's sound smoother and less "gainy" (if that's even a word) than the 12ax7's do in my Deluxe Reverb. But there are a lot of ckt. differances between those two amps too. The old amps with the 6s::'s made great jazz amps!
---
Mike Conner ( )
Fri Jan 30 19:24:29 2004
the komet constellation uses a 6SN7 for the clean channel.  
 
You could wire a preamp up like a Fender (stage-tonestack-stage), or maybe like a tweed deluxe (two seperate triode / channels into a shared second triode).  
 
Just look up some plate load and cathode resistor values etc. under "resistance coupled amplifier" http://tdsl.duncanamps.com/dcigna/tubes/sheets/ge/6sn7-3h.gif. For a ~200vdc B+ node try perhaps a 220-250K plate R and a 4.7K cathode R, bypass it with a 5 uF or 20 uF or whatever uF cap, use .047 or .022uf dc coupling caps, etc.  
 
Bruce had an interesting idea regarding 6SN7s as power tubes - their relatively low plate resistance makes it easy to do that. If you could figure out a PI you could do an entirely 6SN7 amp!
------
Bruce /Mission Amps ( )
Fri Jan 30 22:13:58 2004

Bruce had an interesting idea regarding 6SN7s as power tubes - their relatively low plate resistance makes it easy to do that. If you could figure out a PI you could do an entirely 6SN7 amp!

Been there and done that too!! ha ha....  
How about this:  
1.5 to 2.5 watts output using three 6SN7s with tremolo.  
Two triodes for preamp and simple tone stack recovery, one triode as the cathodyne push pull driver, two triodes in the same TUBE envelope in push pull class A and the final triode as an oscillator, AC coupled back to the cathode of the tone recovery preamp tube for cathode bias altering tremolo!!  
 
Bruce
---------
Ben N ( )
Tue Feb 3 04:00:07 2004
Bruce:  
That sounds wicked cool.  Care to draw up a schematic? :)
---------
Mikko Kankaanpää
Tue Feb 3 06:30:51 2004
Wouldn´t it be hard to desing oscillator with 6SN7 since it has so low gain.  
 
Mikko
------------
Bruce /Mission Amps ( )
Tue Feb 3 17:07:32 2004
Yes... have to work on that.  
I'd do it so the slow, albeit weak, pulsing AC was connected right to the unbypassed cathode of a preampstage biased at only 1 or 2 volts...  
I guess in a pinch you could sub in a 6SL7 if you wanted more drive and a triode with enough gain for an oscillator... sort of off the path of the basic idea of 6SN7s! ha ha.  
Seems like it should be doable though... if not use it as an extra gainstage for preamp overdrive.  
 
Bruce

Forum Index > Music Electronics > Guitar Amps