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6SL7/6SN7 vs 12AX7

6/4/2003 4:52 PM
Alvin_Maiden 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?
6/4/2003 7:37 PM
Le Basseur

IMHO,if I could,I'd ALLWAYS replace the entire 12A*7 series with octals,even with some older locktals (6N7,7N7,etc).  
No matter how precious or "boutique" samples are,the 12A*7 series cannot compare with the most average octal.From the high-end point of view,this is maybe the decisive factor when someone is choosing the topology,(by comparison,12a*7's sound dull and lifeless),and,contrary to someone's belief,this is clearly heard in instrument amplification too.  
Be aware,though,that using directly a 6SL7 instead of a 12AX7 it's not the best move.The two tubes are different in every aspect,and the first thing is you'll have a mu of only 70 with the SL,instead of mu 100 with the 12AX7.You could substitute a 5751 with a 6SL7,though....  
Anyway,consulting a tube catalog and comparing the different spec tube datas will give you the (almost) complete picture!
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6/4/2003 9:16 PM
Chris ( CMW amps )

Didn't switch from 12AX7 to 6SL7 but I did use 6SL7s in a couple of amps and they're great ; very wide and dynamic sounding if you can get some nice sounding ones . Gain is less then a 12AX7 but the TONE .....  
6/4/2003 9:53 PM
Alvin_Maiden How about 6DJ8's?
Any comments on 6DJ8 compared to octals or 12AX7's? Seems lots of audio gurus like them for some reason.
6/4/2003 10:07 PM
Le Basseur

A big YES for the 6922/ECC88/6DJ8 family!  
Again,it's a medium-mu triode,so be wise.  
The "audio gurus" you mentioned like this tube because has a respectable transconductance,a low internal resistance,it's an "over 10 mA tube",and it's very transparent and detailed.And it's enough reilable,even in some weird application.  
If your hunger for gain (=mu) it's not so great,give them a try!  
.....and then try the REAL thing:5687!
6/5/2003 4:26 AM
Re: 6SL7/6SN7 vs 12AX7
I prefer the 6SL7s too. They have a nicer bass response, smoother sound, fatter overdrive. They are not for high gain as they can be microphonic if you drive them really hard.  
I actually sell adapters for using the 6SL7 in a 12AX7 slot.  
Here is a link to a pic:  
6/5/2003 2:51 PM

This is good! In a thread not too long ago someone posted info about an adapter to use 12A_7 tubes in place of the octals. LOL Now we get info about an adapter to go the other way!  
Anyway, I am putting together an amp now using a 6SL7 as the PI, so, I'll see how it works in that application. It was good to know about the 9 pin adapter, but it's just as good to know about your octal adapter. Thanks Josh.  
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