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previous: Alvin_Maiden Are there any real tone differences... -- 6/4/2003 4:52 PM View Thread

Re: 6SL7/6SN7 vs 12AX7

7/7/2003 5:49 PM
Trace - Voodoo Amps
Re: 6SL7/6SN7 vs 12AX7
"Are there any real tone differences bewteen using 6sl7/6sn7 vs 12ax7's? I've heard that the sn/sl's give a warmer tone. Is that true? Anybody do some comparisons directly to a 12ax7?"
I have not read the entire thread so forgive me if this was already covered! (ha, ha)  
In my experience; I've built numerous amps using the octal preamp tubes and my favorite octal tube is the black base RCA 6SL7. RCA also made a 6SL7 that is all glass (no plastic black base) and it sounds very different from the black-based version (less bass, lower mids).  
The 6SL7 is not going to put out the same amount of gain as a 12AX7. I really enjoy the tone of the 6SL7's but the two drawbacks are;  
1.) They can easily go microphonic and it's getting harder to find NOS 6SL7's that are not already microphonic. As I understand it this is why the industry moved away from the octal tubes and went with the 12AX7 (more rugged and reliable).  
2.) They do not like to be hit with a lot of signal (IE: they do not work well in amps with a fair amount of gain). I once built a JCM800 style preamp using 6SL7's and I had to weed through several to find some tubes that would not squeal in that circuit.  
If you are looking for a tube that has a great tone then these certainly have a good tone! (You just have to sort through some). They have a unique tone that I really enjoy!  
Hope it helps