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6CA7 Tubes vs Svet 6L6?


 :
4/5/2000 8:54 PM
Graydon Stuckey
6CA7 Tubes vs Svet 6L6?
Guys,  
 
A tech is suggesting I try a quad of 6CA7 tubes instead of some Svet 6L6s which are on order but running very late. What will these sound like in my humble clone? I realise this is a tough question not knowing what my amp soudns like, however maybe someone can comment on their typical character.  
 
Thanks,  
Graydon  
http://elektro.cmhnet.org/~graydon
 
4/6/2000 12:12 PM
Stephen Conner

The 6CA7 is the US/Japanese equivalent of the EL34. They are practically the same tube. So, they will probably sound like EL34s, which play a part in the famous Marshall crunch sound.  
 
Obviously if you don't put them in a Marshall they won't sound like that, but they are likely to have a tighter and harder sound than 6L6s when played loud.  
 
Steve C.
 
4/6/2000 1:24 PM
Rebel420

quote:
"The 6CA7 is the US/Japanese equivalent of the EL34. They are practically the same tube. So, they will probably sound like EL34s, which play a part in the famous Marshall crunch sound. "
ACTUALLY, the 6ca7 wont sound like either... they acualy (in most cases) sound more like a 6550,but a bit softer... so essentially, they are a happy medium between the 6l6 sparkle and the el34 compression...
 
4/6/2000 3:46 PM
Ted Breaux

The problem is just the same as an EL34 or any other tube, the qualities of a 6CA7 will vary widely with the tube manufacturer. In general, as compared to a good EL34 (like a Mullard), a 6CA7 (Sylvania) will have a bigger, tighter sound, with better bottom and punch. Yes, the sound of a 6CA7 is softer than a 6550 (thank goodness), and the 6CA7 makes a great tube for Marshall amps. Unfortunately, the epitome of the 6CA7 (Sylvania) is well out of production, and is expensive when found for this very reason. I do not know of any modern tube which sounds quite like it. Just because a modern tube may be called a "6CA7" doesn't mean squat. I hear there is some Chinese EL34 (sold by Ruby) which comes fairly close to the old Sylvania 6CA7, but I don't know the details of this first hand.
 
4/6/2000 4:14 PM
Gil Ayan

Guys, I think there are two key issues here:  
 
1. What does it mean when a *current production* tube is labeled 6CA7? In my opinion, nothing... market hype? :) Same as GT and the 12AX7s, ECC83, 7025, etc...  
 
2. In the particular amp Graydon is talking about, the power section will run clean unless you play loud (remember, this is a 100W D-clone, with channel switching and master volume). So I think under those circumstances, the difference between any pair of power tubes (whether they be ELs, 6Ls, etc.) will not be the same. Very different from the Marshall sound, where the sound is caused in great part by the power section overdriving.  
 
Gil
 
4/11/2000 9:01 PM
Dave Charneski
Regarding power tube differences.
Gil,  
 
You stated, " 2. In the particular amp Graydon  
is talking about, the power section will run  
clean unless you play  
loud (remember, this is a 100W D-clone, with  
channel switching and master volume). So I  
think under those circumstances, the difference  
between any pair of power tubes (whether they be  
ELs, 6Ls, etc.) will not be the same. Very  
different from the Marshall sound, where the  
sound is caused in great part by the power  
section overdriving."  
 
I used to think the same thing myself and it may actually be true for many amps, but not for the Guytron I'm currently using. As you know, that amp runs a dual-channel preamp into a pair of EL84s which drive a transformer and dummy load and then a 100W EL34 output stage which hits the speakers. In my tonal tweaking escapades with the amp, I had always focused on everything *but* the EL34s 'cause I assumed that since they were running clean, they wouldn't affect the tone all that much. Boy, was I wrong. I blew a Tesla EL34 a couple months back and had a set of matched Svetlanas on hand. Threw 'em in and biased 'em up and...WOW, what a difference in tone(!), especially the overdrive tones where the EL84s and their transformer are distorting, but the EL34s are running clean as a whistle. The Svetlanas had much more high end, much tighter bass and a much more complex midrange, which really changed the whole character of the distortion tones. The clean tones were not affected much at all. Of course, the difference in this scenario is the fact that the harmonic content of the signal hitting those EL34s is much more complex than you'd normally get with 12AX7 preamp distortion. So, the only thing I can think of is that the EL34 differences are only highlighted when they're hit with a pretty complex signal (or, of course, they're clipping themselves). My old Tone-Master did the same thing with a change from 5881s to Svet 6L6s, but the Shiva sounded the same no matter what brand of EL34s (or 6L6s in the 6L6 version I owned) I threw at it. Have any other ideas why this might be so?  
 
Dave
 
4/11/2000 10:04 PM
Gil Ayan

quote:
"Gil,  
 
You stated, " 2. In the particular amp Graydon  
is talking about, the power section will run  
clean unless you play  
loud (remember, this is a 100W D-clone, with  
channel switching and master volume). So I  
think under those circumstances, the difference  
between any pair of power tubes (whether they be  
ELs, 6Ls, etc.) will not be the same. Very  
different from the Marshall sound, where the  
sound is caused in great part by the power  
section overdriving."
 
 
I used to think the same thing myself and it may actually be true for many amps, but not for the Guytron I'm currently using."
 
 
And you went on to describe the Guytron amp and its sensitivity to the different tubes. Dave, I know nothing about the Guytron amps, I played one a couple of times, and I think they sound OK. On the other hand, I built three variations of the same amp Graydon built, and I do know those amps pretty well by now... Little change in sound with different power tubes.  
 
Gil
 

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