Anyone tried EL34's in a 5E3 circuit?

[MKB]

Apparently it is easy to replace the EL34's in a Marshall with 6V6's, as the bias requirements are similar. Has anyone tried to make a higher power 5E3 with EL34's? I'm wondering if you would get a similar gain structure at higher power (obviously you'd need to use a higher power PT and OT). Anyone?

[elpops]

You can't do it without replacing the power transformer. EL34s have a different filament heater and the voltage draw is higher, so you'd burn out your PT. Too bad though, I'd love to hear a 5E3 on EL34s.

[Bruce / Mission Amps]

Yes, I've done it!
You can do it too with the MA20 PT or new MA20/18 PT in the Mission Kits because both have filament windings with a +4a 6v3 secondary and a 3a 5v secondary.
Use a GZ30/5V4 rectifier or a Weber WR4 copper cap rectifier, a 10-15 watt 300 ohm cathode biasing resistor, a 5 watt, 2K2 first B+ node screen dropping resistor, install a min of a 1K-2W screen resistor on each power tube (like a black face Fender 6L6 amp or 50 watt Marshall) and if possible, use 4 ohm speaker load on the 8 ohm tap.

[MKB]

Thanks for the replies! I wasn;t thinking as much about replacing the 6V6's in a standard 5E3, but rather building a louder 5E3 by using the proper OT and PT that could handle the current for EL34's. The EL34's look promising as their biasing and gain are similar to a 6V6, so the preamp wouldn't have to work harder to get the same gain as 6V6's, which building a 5E3 with 6L6's would require.

Bruce, could you please describe the sound as compared to a standard 5E3 (other than being louder)?

[Bruce / Mission Amps]

Well the last time I tried this is was in one of mine that uses the Paul C modded phase inverter, split cathode 12AY7 and my dual gang tone volume mod thingy.
I did not use a different PT (stock MA20PT) but I did use a Russian GZ30 (super stiff 5Y3GT) and the same Heyboer OT I use in the 6L6 tweed amp kits.
Yes it was louder and a bit more muscular and made about 17 watts dead clean... but what it really did when driven hard was sound more and more like a baby cranked to the hilt Marshall 50 watter.

That experiment is what prompted me to have all those octal to 9pin adapters made for us so builders that wanted to use a pair of El84s in their 5E3 could buyild them that way from the start, or if already built, yank the two octal sockets off and use the adapeter plate with the 9 pin socket installed later.

[elpops]

So, with my Mission 5E3 kit with the Super OT (the one with two taps, one for 6V6 and one for 6L6) and I have changed the resistors to handle 6L6s, I should be able to pop EL34s in with no modifications, and it will be stable?

[elpops]

I did not use a different PT (stock MA20PT) but I did use a Russian GZ30 (super stiff 5Y3GT) and the same Heyboer OT I use in the 6L6 tweed amp kits.


If I used a 5U4-style copper cap with EL34s (it might be WU4GB), would it be safe? (Looks like I already have 1K5 across pins 5 and 6 on the power tubes, based on the Mission kit schematic.)

[Amp Kat]

I am currently using them in my 5E3 but it is a higher wattage than the normal. I would also recommend the big bottle type instead of the slim type. I spent lots of time with this amp and can get this chimey tone that is quite pleasing. Toatally different sound than the EL-34 svet or Sovtek. You may also have to change some cathode values and coupling cap values to get what you want. I also like 2x12's at 4 ohms and I promise I've blown away some 50 and 100 watt amps as far as volume goes. Everyone tells me "damn that's a loud amp"

[elpops]

I have some Chinese EL-34s that I want to try out, but I just want to be sure I am safe with the power transformer I have, the WU4GB model copper cap, the wiring changes I made to accomodate the 6L6 tubes, and the OT I have. The OT is the Super OT that Bruce sells/sold that I bought maybe 2 years a go. The PT is from a kit I bought four years ago. I made the Paul C mod and the mods to the resistors in the power section to accomodate 6L6 tubes. I have a tap from the OT that is supposed to be used with my 8 ohm speakers, but I think it's a 4 ohm tap--using 8 ohm speakers just brings the Z up to where it sounds best, I think is the deal.

Thanks for your help--if you can answer my question about safety and stability, I appreciate it.

[Amp Kat]

Elpops I made a new thread above on safety and stability as this is MKB's thread and don't want to step on it so let's keep the EL-34 topic for the 5E3 in tact as I would like to hear somemore opinions on the issue.

[Bruce / Mission Amps]

NO!! Not yet, becasue I am not totally sure which version you have.

It should be OK if it wired as a stock 6V6s amp but with the larger +25W OT.

But if it was a 6L6 version of the 5E3, it should be fine with EL34s as long as you wired the power tube sockets so the amp would run EL34s from the start!!! You didn't say you were going to do that so I don't think you have a diagram from me to do it.
The 6L6 wiring uses #1 pin/lug to hold the 1500 ohm grid stopper resistor and that very same lug/pin on an EL34 is a grid of sorts in the tube and needs to be at ground in the cathode biased 5E3. SO that means a complete rewiring of the power tube sockets.

After those mods, a WeberVST WV4 copper cap is also good choice with this application and it takes a little load off the primary side of the power transformer.

[Bruce / Mission Amps]

But I thought Kerry's amp is my 5E3X2, which , when sold by WeberVST, used a 150ma-200ma Weber power tranny and a smaller 35w OT unless he swapped them out for something better.
Amp Kat can tell us better....
My 5E3X2 amps at +30w, would use a 200ma Heyboer and 45w TMI output tranny.

[Amp Kat]

All I remeber is you telling me it was your Blue Stone tranny's and later I talked to you and you said it was a Habour. The OT is also a larger than normal 5E3 Weber

[Bruce / Mission Amps]

OK I'm confused.... for some reason I thought yours was the 5E3 with four 6V6s.
Probably due to that fiasco over my stock 5E3X2 (2x12) cabinet but this one with a standard 5E3 chassis cutout, .... and the difficulty I had with getting the WeberVST 5E3X2 chassis.
However, if you used one of my tweed 6L6 OTs in a standard 5E3, it would be a custom wound, Heybour MA25w OT, which is good for well over 35watts with 10% distortion.

The Bluestone OTs were custom wound for me by Hammond years ago and were used in my 15-18w Soulkicker amps.
The newest Soulkicker chassis is still very much like a 5E3 in topology, but the chassis is more like the size of a tweed Super, has reverb, reverb tone and uses a pair of 6L6s with the proper power and output trannys,... just like a Mission 5F4, 5E5A or 5E7.
That really makes it more like a reverb version of a 5E5 cathode biased Pro.

[Amp Kat]

Yeah it was a 2X6L6 OT and it is much beefier than the stock 5E3 tranny. Love it though as it rocks like a big dog with the Big Bottle 34's.
Hey BTW check your email !

[teletroy]

Apparently it is easy to replace the EL34's in a Marshall with 6V6's, as the bias requirements are similar. Has anyone tried to make a higher power 5E3 with EL34's? I'm wondering if you would get a similar gain structure at higher power (obviously you'd need to use a higher power PT and OT). Anyone?

YES AND IT KICKS BUTT! I did it in conjunction with Bruce's tonemod, and it's real pretty

[elpops]

It should be OK if it wired as a stock 6V6s amp but with the larger +25W OT.

The 6L6 wiring uses #1 pin/lug to hold the 1500 ohm grid stopper resistor and that very same lug/pin on an EL34 is a grid of sorts in the tube and needs to be at ground in the cathode biased 5E3. SO that means a complete rewiring of the power tube sockets.


So if I DON'T have the 1500 ohm grid stopper resistor going to pin 1 on the power tube socket, I am OK?

The first time I built it, it was just for 6V6. Then I did the 6L6 mod, but I don't remember changing the power tube wiring when I changed the resistors for 6L6s. I'll have to check over the weekend.

[Bruce / Mission Amps]

Well, when running 6L6s in the 5E3 it is not really necessary to change anything other then the cathode bias resistor (on the power tube sockets) to a 10 to 15 watt one.
I like to add ther 470 ohm resistor to the screens for a little safety's sake.

When you rewire for cathode biased EL34s, you need to ground lug/pin 1 and feed the signal to lug/pin 5.
What most builders do is run a 1K5W resistor from lug/pin 3 to lug/pin 6 and then feed the screen voltage to lug/pin 6.
After this mod the amp can use 6L6s or EL34s with no changes, just pop them in and out.

[elpops]

Nope, I'm pretty sure I have the 1K5 across pins 5 and 6, and 1 is unused. I'll double check, but if this is the case I should take the EL34s out and go back to 6V6s then. That's too bad, though. I hope I didn't damage my amp when I used EL34s in it.

[Bruce / Mission Amps]

It's OK to have 6 to 5 but you should ground lug 1, or at the least connect it to lug 8.

Bruce