2. amps-preamps
  3. 123463-1475

6sn7 or 6sl7

I have an Almarro A318-B and would like to swap out one of the preamp tubes, but I cannot decide which one would have the greatest affect on the sound. The Almarro uses a 6sl7 as the input tube and the 6sn7 as an "anode follower" (I'm not sure what that is?). I can only afford to do one now, so hence my dilemma. I have three different 6sn7's at the moment with the following characteristics: RCA 6SN7-GTB that has a detailed but lush presentation; Electro-Harmonix that has a very detailed and airy sound, but is a little flat and edgy, and last is the stock Russian 6H8C that images very well but has limited frequency extension. I have only used the stock Russian 6sl7 (6H9C) with all of these because that is the only one I have. 

Any insight would be much appreciated. 

Thanks!! 
enobenetto

Showing 3 responses by atmasphere

atmasphere's avatar
atmasphere
12,116 posts
 
The two are not really all that interchangeable due to different characteristics. You can place a 6SN7 in a 6SL7 socket without damage, but it won't sound right because the bias points for a 6SL7 are so different.
atmasphere's avatar
atmasphere
12,116 posts
 
Hi,You can plug in any 6sn7 gt,gtb,gta wgt,w,& A / 5692/VT 231 or 6sL7 /  6SU7. without any problem with your amp or preamp,I been doing these any  time and I even have an adapter for 12AX7/12AU7/12AT7/12BZ7 to the 8BD BASE socket and they work fine if you are only looking for sound..
This statement is false. While it is true that you won't damage anything, the fact of the matter is that the two tube types have different characteristics and will not operate correctly at all if exchanged. For example, in many cases a 6SL7 can saturate if placed in a circuit designed for a 6SN7. The tube may well fail! If it does work, its guaranteed to have higher distortion- which is to say it will be a lot higher.

Miniature tubes can be made to work in some cases as suggested, but miniature tubes have a much lower cathode/filament arc-over spec and may instantly fail if placed in some circuits in which a 6SL7 or 6SN7 is perfectly comfortable. And again the miniature tubes have different operating points and so can't be swapped with the expectation that the circuit is going to sound as intended (read: more distortion).  
atmasphere's avatar
atmasphere
12,116 posts
 
FALSE?,Maybe you haven't tried but I've been doing this for almost 10 years and not a single tube fail,a living proof.BTW,my preamp has stock 12ax7.
I'm sure you've gotten away with it. I've done the same. But I can tell you for a fact that all those different tube types have different characteristics, each requiring a certain set of operating conditions for best results. I've already described what those results are about.
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