EL34 in a 124 build.

[Guy77]

When I first finished my #124 I used 820 ohm screen resistors on the power tubes so I could switch between 6L6 (5881) and jj EL34. When i ran the el34's it sounded harsh and not as smooth as the 6L6 tubes. Now that I have my dumbleator up and running I decided to switch in the el34's and rebias the amp at 40ma. Wow, the dumbleator made the el34 sound just as smooth as the 6L6 on the cleans and they have a nice midrange umph (is that a word ?) on the overdrive channel that the 6L6 does not have.


Cheers

Guy77

[Structo]

Hey as long as the power transformer and the output transformer are up to the task, why not?

[Guy77]

Hey as long as the power transformer and the output transformer are up to the task, why not?

Yes good point. I am running the 290DX power transformer right about at its 4A limit. I will keep an eye on it too see how hot it gets. I heard that their specs are under rated.

The output transformer I use is for a 50 watt Marshall.

Cheers

Guy77

[Structo]

So this is a two power tube amp?

[Guy77]

Yes its a 2 power tube amp. Here is a rear shot of my #124 amp. It has the 2 tube reverb fender used on all their blackface amps. It is only engaged on the clean channel. There is a 5th power tube that is hidden. Footswitch automatically cuts off the reverb when you go into overdrive so the most I have going at the same time is 3.5 preamp tubes and the 2 power tubes.

This photo shows her with 6L6 tubes.

Cheers

Guy77

[Structo]

OK, why don't you start your first post with details about the actual amp you built.
At best your are compromising the ultimate tone of the amp by changing things in the power amp that may not result in the best tone possible.

What schematic did you use to build this amp?

The #124 ODS amp was a 4x 6L6GT amp that used Fender Twin iron.

There is a 5th power tube that is hidden.

What does that mean?

[Structo]

Another point I would like to make is that while a 2x power amp or 50w amp is generally not the same 'Tone Wise' as the 100w version.
You can get close but it will lack certain things.

Even though you might not think you need the power, the 4 power tube power amp is pretty much the preferred power amp for the Dumble ODS amps.

I fought that for a couple years after I bought a Brown Note D'Lite 44, which was a 40w 2x 6L6 amp.
It just didn't have the ooomph or that Dumble sound. (close but no cigar)

I came here after I had researched Dumble amps for awhile.

Once here I read 100's of threads learning about these amps and trying to make my amps sound the same.
After making adjustments (tweaks) recommended by the pros here, I came to the conclusion that I needed a 4x 6L6 amp.

I built that and the (Stand alone) Dumbleator for what I consider the ultimate guitar tube amp/ loop for my application and style of play.
There is just more of everything good with a 4x 6L6 ODS, more girth, more punch, etc.
And coupled with the Dumbleator, you can get the amp in the sweet zone at just about any volume.

I didn't even know what a Dumble amp was until I started listening to Larry Carlton and Robben Ford in the early 90's.

Then I got the connection and researched the amp, which led me here.

These guys know their stuff and I was lucky enough to benefit from it all.

So I guess what I am saying is, the forum knows Dumble amps, follow their advice.

[Guy77]

I meant to say there is a 5th pre-amp (not power tube) tube that is hidden under the far right of the back panel. The schematic I used was from a Brown Note D'Lite 44. I just added fender 2 tube reverb to the circuit that I can bypass completely with a switch on the back.

Thanks Tom, I will take your advice on the 4x 6L6 power section. I have read a lot of good things about that here and will most likely make that my next project.

I recently started using G1265 speakers from the advice on this forum and that has also been a great leap in better tone over the Jensen speakers I had!

Cheers

Guy77