X100B Tube Swap

[Twitch]

So, I had some spare 6L6s lying around and decided to experiment with tone on my X100B. I swapped the EL34s out for the 6L6s, and my my, what a difference. However it wasnt the difference commonly claimed between the two types of tubes, at least not in this amp. The EL34s reproduce far more bass than the 6L6s and reproduce less mid-range. I like both sounds, while the EL34s are a bit more compressed, the 6L6s have a lot more grit and not quite as fluid sounding as the EL34s. Overall, I think I like the EL34s better but I do also like the feel of the 6L6s. Ill probly put EL34s back in it once Im able to find the cash for new ones though and keep the old 6L6s for back ups. Also this swap required no bias adjustment(other than flipping the switch to 6L6 on the back) as when I checked the bias it still in an acceptable range for the amp.


Furthermore, HEY CYGNUS, while I forgot to take pics of the inside of the amp per your earlier request(had my mind on the project at hand) I do have these pics of my tube tester.

[MetalMedal II]

Cool tube tester! What is that, circa 1935? Actually, I'm probably not that far off.

[Twitch]

1956

[Cygnus X1]

Oh, hi.
Now what were you saying?


Cool tester!
(I have to look it up...meantime Google Tone Lizard to see what he thinks).
Mine is a Hickock 6000, not on the top of the list, but good.
I think yours is similar, a mutual conductance tester.

Tonal differences:
Many different opinions there.
My experimentation has followed that Randal guy model...
(Mesa Guru Dude).
And Tone Lizard leans this way as well....

EL34, 6L6...hell, let's go 6550.
It is pretty rare to actually go much into power tube saturation in your common 50 to 100 watt amp unless you are really diming everything out.
Most of that natural distortion you hear is being created in the preamp and amplified through those power tubes.
So, yes you will hear a LARGE difference through changing power tubes, just don't wade into the dangerous hyperbole of thinking you are "pushing" the power tubes much one way or another.

Don't misread, sure there is power tube saturation...just not what you think it might be.

MMII ought to be able to tell what my theory is.
He owns what I designed.
Swap out the power tubes and the tone will change,
but the distortion itself doesn't change all that much.

I do throw in a very high powered 6550 for more headroom but it is really an illusion, it is just raising wattage potential.

So swapping out your X100B power tubes just changed the range that your preamp tubes are already delivering.
Changed the overall tone.
Kind of like a different power amp hooked up to the same old preamp.
You want more dirt?
Try some of those (underrated, but I think great) Chinese 12AX7's.

Another edit.
If you are really interested in learning some theory and whatnot this guy lives
just down the road from me.
His theory on grounding systems really helped me out and I think MMII can attest to
this as well....
Check his tech pages:

http://www.aikenamps.com/

[Twitch]

Oh, hi.
Now what were you saying?


Cool tester!
(I have to look it up...meantime Google Tone Lizard to see what he thinks).
Mine is a Hickock 6000, not on the top of the list, but good.
I think yours is similar, a mutual conductance tester.

Tonal differences:
Many different opinions there.
My experimentation has followed that Randal guy model...
(Mesa Guru Dude).
And Tone Lizard leans this way as well....

EL34, 6L6...hell, let's go 6550.
It is pretty rare to actually go much into power tube saturation in your common 50 to 100 watt amp unless you are really diming everything out.
Most of that natural distortion you hear is being created in the preamp and amplified through those power tubes.
So, yes you will hear a LARGE difference through changing power tubes, just don't wade into the dangerous hyperbole of thinking you are "pushing" the power tubes much one way or another.

Don't misread, sure there is power tube saturation...just not what you think it might be.

MMII ought to be able to tell what my theory is.
He owns what I designed.
Swap out the power tubes and the tone will change,
but the distortion itself doesn't change all that much.

I do throw in a very high powered 6550 for more headroom but it is really an illusion, it is just raising wattage potential.

So swapping out your X100B power tubes just changed the range that your preamp tubes are already delivering.
Changed the overall tone.
Kind of like a different power amp hooked up to the same old preamp.
You want more dirt?
Try some of those (underrated, but I think great) Chinese 12AX7's.

Im pretty sure my tester is something like just an ordinary continuity spec tester, simple but usable. Whenever I get new 12AX7s I spec them and the ones that score higher go in the V1 and phase inverter spot(I can also somewhat match tubes with it since spec scores are spec scores, they read the same than it can be inferred that theyre close enough in their specs to be considered matched, I understand this would be considered a crude way to do it though) As far as changing the tubes, like I said they pass different frequencies that are already present. If you recall from a previous post, this amp has had 12AX7C's from my old B52 AT100 installed. I do like them better than the GTs that were in it before. My point was the difference was different than most report. The EL34s at least in this amp are less mid-rangy and reproduce more bass. You hear others especially Marshall owners tell you EL34s are more "Marshall tone" than 6L6s, less bass with more mid-range. In this amp its the complete opposite.

[Cygnus X1]

Well that is one of the good things about the X100B in my opinion.
Voiced in a versatile way.

Just saying...(you know this as well as anyone), you will also
get a lot of bang for the buck by swapping out 12 dollar preamp tubes rather than over 100 dollars worth of power sets.

I was very well on my way to buying the X100B RI when I made a
left turn and decided to build some amps myself.

Might still get one.

[Twitch]

I wish I had the knowledge and resources to build an amp from the ground up. I dont so I modify ones that already exist.