dsavitsk said:
They're quite popular as driver tubes for both audio and guitar amps, you see them used a lot, are you sure you need to ask?
I bought some to make a driver stage for a 6L6 amp, and Blackie's amp looks quite cool:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=59687
6SL7 is a high mu (70), high impedance (45k nominal) double triode, used similarly to 12AX7/ECC83, i.e. as a low current voltage amplification stage that is not required to drive a difficult load. It is more linear than a 12AX7 but suffers similarly from rather high Miller capacitance, which means it should be fed from a low impedance source, preferably 100k or less.
6SL7 is typically run at 2mA plate current or less. It makes a great voltage amplification stage but is generally not suitable as a driver, particularly if the output stage is a beam tetrode or triode, because such output stages have a relatively low input impedance which makes them difficult to drive. Even driving a pentode with fixed bias might be too demanding for a 6SL7.
A popular combination in a power amp is 6SL7 for the first stage, 6SN7 for the second (driver) stage and whatever tube you want to use as the output stage. (The 6SN7 is also very linear but has a much lower plate resistance (7.7k) and can drive most OP tubes easily.)
6SL7 is typically run at 2mA plate current or less. It makes a great voltage amplification stage but is generally not suitable as a driver, particularly if the output stage is a beam tetrode or triode, because such output stages have a relatively low input impedance which makes them difficult to drive. Even driving a pentode with fixed bias might be too demanding for a 6SL7.
A popular combination in a power amp is 6SL7 for the first stage, 6SN7 for the second (driver) stage and whatever tube you want to use as the output stage. (The 6SN7 is also very linear but has a much lower plate resistance (7.7k) and can drive most OP tubes easily.)
I wouldn't use a 6SL7 as a driver either, for the reasons mentioned above. However if you dig through the old Fender schematics you will find the 6SL7 used as an input stage and as a driver/phase splitter. In their later designs they switched to a 6SC7. They are also found as the input tube in a lot of HiFi amplifiers, usually followed by a 6SN7.
The 5B2 amp used the 6SL7 for the input stage.
The 5A3 and 5B6 used it for the driver/phase splitter.
The schematics are here:
http://www.schematicheaven.com/fender.htm
I have a bunch of these tubes also. They can often work in a 12AX7 type circuit with slightly less gain. Some are seriously microphonic while others are dead quiet.
The 5B2 amp used the 6SL7 for the input stage.
The 5A3 and 5B6 used it for the driver/phase splitter.
The schematics are here:
http://www.schematicheaven.com/fender.htm
I have a bunch of these tubes also. They can often work in a 12AX7 type circuit with slightly less gain. Some are seriously microphonic while others are dead quiet.
SY said:
True - but since the 6SL7 is essentially a 12AX7 (or more accurately, a 5751) in an octal bottle, it can be used under certain circumstances. Heck, look at all the Fisher amps that use 12AX7s to drive the output section.
Me? I'm with Sy, I think it's not well suited to be a driver, but that's not to say it can't be done - because it has been done.
Funny I've used them for years to drive 45s and 2A3's in SRPP configuration and no complaints so far. I run them off of approximately 320V @ 2mA.
Bandwidth last time I checked was at least 80kHz into the miller capacitance of a typical 45 dht..
I doubt that they would have much trouble driving a triode connected EL34 either.
Perhaps they aren't the most logical choice, but in SRPP they do the job very well and sound as good as any competing topology/tube type I've yet to try.
Look at my site for an example amplifier that uses this driver stage (45 dht amp) - it was good enough to convert me from high powered pushpull amplifiers to SE.
edit
Bandwidth last time I checked was at least 80kHz into the miller capacitance of a typical 45 dht..
I doubt that they would have much trouble driving a triode connected EL34 either.
Perhaps they aren't the most logical choice, but in SRPP they do the job very well and sound as good as any competing topology/tube type I've yet to try.
Look at my site for an example amplifier that uses this driver stage (45 dht amp) - it was good enough to convert me from high powered pushpull amplifiers to SE.
edit
6SL7
Hi dsavitsk !
I´m sure that a lot of guys think that you are lucky!
However, I don´t know if my suggestion will be a little too easy for you, but look at the link below - it is John Broskies Aikido construction. It is possible to use a lot of different tubes (8-pin + 9-pin tubes) and you can choose from mono boards or a stereo board.
If you do not want to biuld an Aikido amplifier the link will hopefully supply some general (and valuable?) information.
In the link an example is given with the 6SL7 as an input tube and a 6SN7 as output tube. Together with the tubes all necessary values for resistors, capacitors etc. are suggested.
http://www.tubecad.com/Octal_Aikido_PCB.pdf
Kind regards
Karsten
Hi dsavitsk !
I´m sure that a lot of guys think that you are lucky!
However, I don´t know if my suggestion will be a little too easy for you, but look at the link below - it is John Broskies Aikido construction. It is possible to use a lot of different tubes (8-pin + 9-pin tubes) and you can choose from mono boards or a stereo board.
If you do not want to biuld an Aikido amplifier the link will hopefully supply some general (and valuable?) information.
In the link an example is given with the 6SL7 as an input tube and a 6SN7 as output tube. Together with the tubes all necessary values for resistors, capacitors etc. are suggested.
http://www.tubecad.com/Octal_Aikido_PCB.pdf
Kind regards
Karsten
6SL7 is a great sounding tube! It can also be used as driver for EL34, EL84, etc.
A very nice design with truly exceptional sound is the following, by Steve Bench.
http://members.aol.com/sbench102/PowerAmps/e34lamp.gif
I wish I had some NOS pairs, but unfortunately these are becoming more and more scarce...lucky you!
A very nice design with truly exceptional sound is the following, by Steve Bench.
http://members.aol.com/sbench102/PowerAmps/e34lamp.gif
I wish I had some NOS pairs, but unfortunately these are becoming more and more scarce...lucky you!
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