Need Help... 6L6 amp but it has EL34s?

[Andrew Lamprecht]

Hey guys, thought I would come to you with this question.

I got this used amp... it is supposed to have a pair of 6L6s in it according to the manual... but it is used and there are EL34s in it. I don't know anything about the history of this specific unit so I don't know if any mods were done, I just know it sounds GREAT. but will this damage the amp or should I look out for anything?

The amp is a mid 90s Ampeg Super Jet.

[vinta9e]

Re: Need Help... 6L6 amp but it has EL34s?

As far as I know, EL34s have a higher plate voltage limit but also draw more heater current compared to 6L6s. Now if the power transformer does its job without overload, and the amp sounds great without power tubes redplating you should probably be safe. But take that with a grain of salt because I don't really know what I'm talking about here.

[guitfiddle]

Re: Need Help... 6L6 amp but it has EL34s?

Those amps shipped with a pair of 6L6 in them, but yours may have been modified to take the EL34s. I'd take it to a tech and verify that they have been biased properly.

Good on ya for getting an Ampeg. Those mid '90s models are really cool, even though they sound nothing at all like a '60s Peg. If you ever sell, I'd like first dibs...

[the guy who invented fire]

Re: Need Help... 6L6 amp but it has EL34s?

The amp came stock with 6L6's...in 90+% of situations a 6L6 amp will need to be modded to run EL34's but it's very easy and common.

The thing to keep in mind is heater current...6L6's draw a little less than an amp, EL34's draw just at 1.5 amps....if the power transformer can handle that it's all good, if they can not it will run for a little while then will die and you will then need a new power tranny...

Best bet is to email the folks at Ampeg and see if the stock trannys can handle the extra draw...

[Chickenwings]

Re: Need Help... 6L6 amp but it has EL34s?

the seller didn't tell you that it had been modded? Or maybe they just stuck any old toobs in and didn't know what they were doing. Either way its dicy. Send it back before you are stuck with it.

[dr. ad]

Re: Need Help... 6L6 amp but it has EL34s?

were they 6L6s or 5881s, originally?
seems trivial, but may suggest whether it's had components changed or if someone's just decided that "if it catches fire, i'll put it out"

[ItsaBass]

Re: Need Help... 6L6 amp but it has EL34s?

It'd be uncommon, but not unheard of, for that amp to have come with EL-34's. They had EL-34's when the Diamond Blue Series first came out, but Ampeg phased over to 6L6's, and at times would use EL-34's later...with no changes to the transformer specs from the beginning to the end of the model. (My '98 Reverberocket head originally had EL-34's, and I have kept it that way.) The date sticker on the board is a slight clue as to whether or not the amp had EL-34's originally – the earlier the date, the more likely it is. Not that it matters in this case, though. The two tube types are interchangeable – not in general, but in that particular amp.