Guess the power tube! (Single Ended Class A test)

[Wolfeman]

Hey guys, was messing around with my 10 watter today, had the opportunity to try several different tubes in it to see what kind of a difference it made. It's much more drastic of a difference in a SE class A amp than it would be in a push pull class AB amp.

Unfortunately I wasn't able to record clips of all tubes, but I was able to get 4 clips.

So, guess which one is which, and which one you like the best! I know the Mic position isn't great, and the amp setting weren't either, but you should still be able to hear the difference, it's night and day. Excuse the shitty wanking on the guitar as well.

Mic position and amp settings remained the same, the only that that changed was the tubes and bias (each tube was biased to 90% max dissipation, class A, so the 6L6's were at 77mA and the EL-34's were at 64mA)

Tubes tested here-

Ruby EL-34BSRT
SED EL-34
SED 6L6GC
Sovtek 6L6WXT

You're going to have to turn up the volume, I didn't want to add any post processing.

 

[JeffTD]

A is noticably louder than the others. I'd say that C is definitely a 6L6, but the rest I'm not too sure on. Inclined to say that A is an EL34. I'll just venture a guess and say that the order is:

A. Ruby EL-34BSRT
B. SED 6L6GC
C. Sovtek 6L6WXT
D. SED EL-34

I like the fatness of C but it's a bit mucky - the others have a more annoying top end, in comparison.

 

[Wolfeman]

I should also add that the grindy sound on palm mutes is power tube overdrive, the clips were recorded at 'cops getting called' volume. When I measure the output of this amp I'm getting around 14 watts with the 6L6s and around 16 watts with the EL-34's. But it's hard to measure properly since the power tubes are being over-driven(square waves don't give accurate RMS calculations)

 

[jangoux]

B and C are 6l6s, B being the Sovtek

 

[Wolfeman]

You guys are gonna be surprised.

 

[jangoux]

You guys are gonna be surprised.

B and C are El34 then lol

 

[jangoux]

It'd be interesting to see a 6550 or something...those mofos can get to 20˜22w, dont they eric?

 

[Wolfeman]

It'd be interesting to see a 6550 or something...those mofos can get to 20˜22w, dont they eric?

Yeah you could easily get 20w with a 6550 or KT-88 with the proper plate voltage. I did have a KT-88 here today, which was my 3rd favorite of the group I tested. Sounded like an EL-34 with a ton more 'clean' bass.

I measured 19 watts from it, probably could have gotten more with a little higher plate voltage. (My amp is running at 350)

 

[Wolfeman]

Eeek I know the clips were recorded shitty, but I figured I'd have a few more guesses.

Oh well, here they are-

A- Ruby EL-34BSRT
B- SED 6L6
C- SED EL-34
D- Sovtek 6L6