Help me understand early vs late breakup in power tubes

[AniML]

(I think) I understand the concept in that a later breakup tube provides more clean headroom.

I would think at low levels the early and late breakup tubes would sound very similar and then it's a just a matter of how steep they climb the curve as you increase the power

But when using an early breakup tube what kind of tonal qualities do you have when you are pushing them to the maximum? Or are they not really intended to be used in an amp that is going to be played near max volume, but rather to reach fuller saturation at lower levels?

Does anyone know of a Youtube video that A/Bs an early vs later breakup tube?

My interest in all of this is primarily in EL84s but I assume the concept is the same regardless of tube construction

 

[korovamilkdud]

Re: Help me understand early vs late breakup in power tubes

I think every tube is different. I unfortunately don't have a lot of experience with EL84. i can tell you that EL34 will break up much faster than the 6L6, and a pushed EL34 sounds smooth, with plenty of harmonics and a nice little "crunch". Not a bad sound at all.

I have also pushed 6L6 tubes and found them to be muddy. I wasn't impressed.

But there's an example of an early breakup tube and a late breakup tube, and the results of each under pressure.

Thing is, if 6L6 tubes sound muddy when pushed, does that mean ALL late breakup tubes sound muddy pushed? Well....I can't help you with that one. I know the two.

I do know however that EL84s are supposed to be similar to EL34, but with lower power. Not as "big" sounding.

 

[guitfiddle]

Re: Help me understand early vs late breakup in power tubes

It really boils down to how far off from the specs for that tube type each one is...the ones ranked 5 and 6 are in the spec zone...the others are more or less, dependeing on the rating, defective in that regard.

A tube with a rating of 1, 2 or 3 would have been thrown in the trash back in the day of good tubes being made in tons of factories, as would the ones with a 8 or higher rating.

Then, Groove Tubes started rating and matching the out of spec tubes so they could sell sets.

 

[jeremy]

Re: Help me understand early vs late breakup in power tubes

different tubes do different things in different amps and biasing makes a difference too. the 6L6 in my tweed bassman got mushy (so did the p10r speakers) with the volume really high unless i rolled the bass control all the way down and even then it could be mushy. in a bf super reverb that doesnt seem to be as much of an issue. you still need to roll the bass down but if you do the bottom stays pretty tight.

when i had a marshall running 6l6 tubes the bottom end was tight as hell.

 

[FuseG4]

Re: Help me understand early vs late breakup in power tubes

If the tube has a ceiling where if the wave goes beyond it gets compressed or clipped to where it's within the tube's limits, well if you keep feeding more signal (more volume) to it while it's already hit that ceiling than it's gonna clip more of the signal.

Early vs. late breakup seems to be a measure of how high the ceiling is.

an early breakup tube should have more power tube distortion at it's max than other kinds. wether this really is good or not, I'm not sure.

 

[AniML]

Re: Help me understand early vs late breakup in power tubes

If the tube has a ceiling where if the wave goes beyond it gets compressed or clipped to where it's within the tube's limits, well if you keep feeding more signal (more volume) to it while it's already hit that ceiling than it's gonna clip more of the signal.

Early vs. late breakup seems to be a measure of how high the ceiling is.

That's a description I can understand. Nice job

an early breakup tube should have more power tube distortion at it's max than other kinds. wether this really is good or not, I'm not sure.

This is what I am still trying to get a handle on where "good" (as you say) = desirable quality

 

[jeremy]

Re: Help me understand early vs late breakup in power tubes

its very subjective. what i might think is great you might find horrible.

is there a specific amp you are looking at?

 

[AniML]

Re: Help me understand early vs late breakup in power tubes

its very subjective. what i might think is great you might find horrible.

is there a specific amp you are looking at?

Fuse and I both recently got Vox Night Trains and have been exchanging ideas with tube swaps.

I am trying to understand what it would mean to put in an early breakup EL84 pair and crank it. I already get that I will lose headroom, but what does it mean to oversaturate an early breakup tube at max volume - fizzy garbage or sweetness?

 

[guitfiddle]

Re: Help me understand early vs late breakup in power tubes

Fuse and I both recently got Vox Night Trains and have been exchanging ideas with tube swaps.

I am trying to understand what it would mean to put in an early breakup EL84 pair and crank it. I already get that I will lose headroom, but what does it mean to oversaturate an early breakup tube at max volume - fizzy garbage or sweetness?

That would depend on your circuit, and what you think of as sweet.

Early breakup isn't really about the maxed tone...it's about getting into the sweet spot for your style at a lower volume. I would think that completely maxing one would make it get closer to square wave, hard clipping than a later breakup tube would.

 

[baritone]

Re: Help me understand early vs late breakup in power tubes

I usually aim for early breakup power tubes, but it never really gets fizzy. But maybe my amp is too loud for me to push it to that level.

 

[FuseG4]

Re: Help me understand early vs late breakup in power tubes

I have no idea what my el84's are as far as early middle or late breakup. All I know is that they don't start adding their own dirt until around 2/3 on the master. Their breakup is very subtle, but there's this smooth, buttery grind that starts happening after that.

But since I have no idea what the bias is on the tubes I dunno if that's middle or late breakup or what. I'm tending to think that's a little late, but I have an attenuator so i don't really care if i have to turn up the master a notch or two more.

unfortunately the real magic is when the greenback starts working hard too, and the attenuator takes that out a bit. 15W dimed is a bit much unless I know the neighbors are on vacation

 

[AniML]

Re: Help me understand early vs late breakup in power tubes

I have no idea what my el84's are as far as early middle or late breakup. All I know is that they don't start adding their own dirt until around 2/3 on the master. Their breakup is very subtle, but there's this smooth, buttery grind that starts happening after that.

But since I have no idea what the bias is on the tubes I dunno if that's middle or late breakup or what. I'm tending to think that's a little late, but I have an attenuator so i don't really care if i have to turn up the master a notch or two more.

unfortunately the real magic is when the greenback starts working hard too, and the attenuator takes that out a bit. 15W dimed is a bit much unless I know the neighbors are on vacation

I think if they break up at 2/3 they are certainly not early. Probably average breakup is what are used in stock tubes.

I have some JJs that are supposed to be "average". They definitely breakup a little earlier than the stock Sovteks in the NT. Even with the Mullard 12ax7s I got today :friday: I like the Sovteks better

 

[eggman]

Re: Help me understand early vs late breakup in power tubes

Howdy,

I believe that some tubes leave the factory with slightly higher plate voltages than others, even within the same tube designation i.e., 6V6, 12ax7. And these admittedly slight variations can lead to uneven results with respect to power..and ultimately tone.
Perhaps I'm wrong? Any real amp gurus wanna chime in?

Eggman