6L6 Vs. EL84

[tot_Ou_tard]

Jim,

Whatdo you think the results would be if you took an AC30 but added negative feedback or removed the negative feedback from a blackface Fender?

My Gries 5 is a single ended class A blackface champ style with a 6V6 but no negative feedback. (You can also dial out the tonestack for a Tweedy vibe).

BigG's Swart is a Tweed-type circuit with no negative feedback, but it does have a switch allowing one to switch in some negative feedback.


As far as the original question, I thought that it was common knowledge that EL84s break up sooner than 6L6s regardless of transformer or of whether there was negative feedback. Is this not so?

[jim p]

I am not sure of the point at which the two types of tubes break up but I am sure there are differences. One big difference between the two types is the 6V6 and 6L6 are power beam tubes so they have no suppressor grid and are actually a tetrode not a pentode as the El tubes are.
With regard to feedback if you are after a clean sound and an increase in bass response it would be worth trying. In the mod #201 posted for the Crate V5 I explained how to add it to the V5 with a pot to control the level. In the posts at 300 Guitars they were taking the feedback out of the Champ 600 and making tone stack mods for a Vox sound so? To add feedback you need to know the over all gain of section of the amplifier you are going to add it to because your feedback gain needs to be less then this. Then need to use the proper phase so you don’t wind up with positive feedback and make an oscillator out of the amplifier.
Just wanted to bring up the point that the tonal differences may not just be due to the tubes.

[tot_Ou_tard]

One big difference between the two types is the 6V6 and 6L6 are power beam tubes so they have no suppressor grid and are actually a tetrode not a pentode as the El tubes are.

I've certainly heard these words before, but I don't have a clue as to what they might mean.