Power Tubes Questions

5:25 and 5:50's

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Len Rabinowitz
Mark II
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Joined: Fri Apr 04, 2014 4:38 pm

Power Tubes Questions

Post by Len Rabinowitz » Sun Jul 20, 2014 9:52 am

All:

1. I have an Express Plus 5:25 head. I also have some EL84's that came out of an Egnater Rebel 30 combo. Can they be used in the 5:25? All they say on them is "China." Would they be at least good enough to finish a night if the stock tubes blew?

2. I also have a non-plus Express 5:50 Combo. I know that takes 6L6's. Would 6V6's work in there? They are Electro-Harmonix that I got from the Tube Store. They are 6V6GT and have the number 33 written on them.

Both sets of power tubes are matched pairs.

Thanks!
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Newysurfer
Mark IV
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Re: Power Tubes Questions

Post by Newysurfer » Sun Jul 20, 2014 5:00 pm

Len Rabinowitz wrote:All:

1. I have an Express Plus 5:25 head. I also have some EL84's that came out of an Egnater Rebel 30 combo. Can they be used in the 5:25? All they say on them is "China." Would they be at least good enough to finish a night if the stock tubes blew?

2. I also have a non-plus Express 5:50 Combo. I know that takes 6L6's. Would 6V6's work in there? They are Electro-Harmonix that I got from the Tube Store. They are 6V6GT and have the number 33 written on them.

Both sets of power tubes are matched pairs.

Thanks!
Len - I think I recall the 6V6s won't physically fit - mine were bigger tubes than the 6L6s.
Check this plus I'd call Mesa also to check on any potential damage to the amp.
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MrMarkIII
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Re: Power Tubes Questions

Post by MrMarkIII » Sun Jul 20, 2014 5:42 pm

The EL-84's should not be a problem.
The 6V6's may not be a good idea.

They will fit the sockets, but the voltages for 6L6's is higher.
I'd steer clear, unless you want to try the JJ 6V6, which is supposed to be very rugged, and even an "almost" 6L6.

And plug the 8 ohm speaker into the 4 ohm jack if you do swap the 6L6's out for the 6V6's.

On the Mark IV, you could easily do this 6L6/6V6 swap, as that amp has a voltage reducing switch ("Tweed Power").

But, as I recall, the change is not dramatic, mostly just a rounding off of the glassy 6L6 top end. You still are not going to be able to crank the amp to 10 in your bedroom.

There's a gizmo called "Yellow Jackets" which permit the use of EL-84's in 6L6 amps. Something else to try.
Also, try plugging the 8 ohm Express speaker into the 4 ohm jack, see what that does for you.

Len Rabinowitz
Mark II
Posts: 74
Joined: Fri Apr 04, 2014 4:38 pm

Re: Power Tubes Questions

Post by Len Rabinowitz » Sun Jul 20, 2014 6:32 pm

That's kind of what I thought. The El's I just wanted as back up and was wondering if I needed to buy some, but I kind thought these would get me through the night so to speak.

With the 6V6s, I used them in an Egnater Renegade. I checked with Bruce Egnater and he said they would work if they could handle 450 plate volts. These can. With these I was just curious. They are a lower power quieter tube and thought it might be interesting.
2003 Ash Tele
2005 Sunburst Les Paul
2007 Natural ES 335
2007 Custom Classic Strat
Martin Custom D35
Taylor 314ce
Fender Mexican Jazz Bass
Mesa Mark V:35 Head
Dr. Z 2x12
Eventide H9
Pigtronix Mothership
Boss Slicer
Boss RC 30 Looper

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