Made a comparison video between EL34 and 6L6 tubes after I had installed bias pots in the amps. The amps are 90´s carvin x amps. The eq is flat, and setting is set to 5 ( or 12 o´clock)the gain is set on 3/4
YouTube - carvin x100b el 34 vs x50b with 6l6 power tubes

excellent post


thank you!

these little details IMO are more important and more significant than the difference of two preamps

Keep in mind there are a few other factors that determine which tube is best for the amp, not just how they're biased. That said, you can still safely run either tube type as long as the bias is set correctly.

Cool comparison, but youtube video isn't exactly the best quality to listen on.

In my experience:
6L6 - wide frequency response, tight/hard sounding
EL34 - more midrange focused, softer/more pleasant

Both have their place of course, neither is better. Right now I'm rockin' all 6L6s in my amps but I'm considering a quad of EL34s for a more British voicing.

Gona agree with you on that danbronson. Neither is better, but my favourite for the time beeing is the 6l6 amp. I use dimarzio paf pro in two of my guitars, and in my ears the 6l6 tubes " open" the sound with those pups, but with the el 34 the sound is more is "muddy".

I had an x100b and it never sounded anywhere close to that good. I didn't know that amp was capable of such sounds. If I still had it, I'd be picking your brain to figure out how to make it come alive. Maybe the bias pots were a big factor, or maybe my amp was way out of spec, but it sounded like shit when I had it.

My 2 cents worth:

6L6s typically have a soft top end and are FAT, and EL34s are thinner and meaner. There are exceptions like the Peavy Rockmaster, 4 6L6s and huge tone, immense.

IMO 6L6s are more versitile and EL34s are a one trick pony, AKA Marshall.

Running the tubes either in Class A or Class AB drastically changes the sound.

I'm grateful to Mesa Boogie for making interchangeable output tubes; my Mk III is going on 21 years old!

New tubes from eurotubes and trim pot installed finally made my amps sound the way I wanted, so yes. The possibility to adjust the bias on these amps seems like the way too go to make them alive.

I have a really hard time picking which one I prefer, simply because of the range of tones you can get depending on what kind of amp is using either tubes.

I was absolutely in love with 6L6s for a while, preferred the tone of my '68 Twin much more than a Marshall with 34's. That said, I eventually bought a Matchless Chieftain that runs the EL34's class A. Phil Jamison definitely builds his amps in the British tradition, but the Chieftain kinda brings the tubes' tone much closer to that of a 6L6, American-ish tone. A little more bottom end and overall air. I still have these two amps, and couldn't part with either.

Now if you get into small bottle tube comparisons like EL84's to 6V6's, I think the latter wins without questions. EL84's sound like piercing, dry glass to me. The irony is that I've heard so many great records recorded with AC-30s, but I've never had a really great personal experience with one.

agree with everyone so far.

what I hear in my class AB amps. the 6L6 are a little more bold, and tight on the top. the EL34, more aggressive on top and loose on the bottom, yet with a soft compression and smoother breakup, for an overall effect that's pretty unique and not completely versatile. I guess I like em both

I like 6V6 champs and EL84 amps, too. so many great designs out there

for a real trip, try some JJ KT77 (halfway between 6l6 and 34s) and see what you think!

the groove tubes "Substitubes" are also really cool for getting class A EL84s into your class AB 6l6 or el34 amp...plug and play!

I've been doing some tests lately, comparing 6l6 to el34 in my dual rectifier, I'm using a 1960BV cab.

When I got the amp (used) it came with JJ E34L installed in it and 2 electro harmonix rectifier tubes and 2 JJ 12AX7.
It also came with the original tubes so I can try them too.

I played with the E34L installed for a while then after recording the amp a little I decided to try the 6l6 and see if I'd get better results.

I didn't change the rectifier and 12ax7 tubes yet (still has the non original ones installed) but so far I think I prefer the sound of the 6l6 for recording.

The E34L doesn't have enough hig and low and the mid peak is cool but it has some frequency to it that make it sound harsh more easily.

With the 6L6 I can boost the mid on the amp eq and it seems to sound more even without the nasty peak...

So far so good, I'm curious to try a better set of 6L6, apparantly the mesa ones aren't the best, but they're still better for recording than the E34L IMO.
The E34L have a cool in your face tone to it which is nice for live though.

I'd be curious to try out different preamp tubes as well, any idea of what I should try for my mesa?