First EL34 build question

[Hepcat]

I have built a number of American Style amps with 6V6s and 6L6s. I know that the tubes run plenty warm. I just finished a AC30-AC50-Marshall type with EL34s by JJ. (the 6L6s were too). I have the tubes running at about 450 volts plate voltage, 435 volts on the screens and using fixed bias at about 30 MA cathode current. It works great and sounds great but the EL 34s run pretty hot, so that I can smell them!
Is that common as I am new to British amps. I love them!
Ken

[Blackburn]

I think you're running that amp quite cool, actually. Dissipation is only at 13.5 watts and 450v on the plates is neither high nor low. Typically, I've noticed when tubes are just being burned in they can smell a little stronger, but to this day, amps that I built a long while back will still catch my nose if I've been playing for a bit. I don't have many in cabinets, so it isn't hard to smell em if you stand real close. If she's working fine now, she'll likely continue to do so. Maybe take a few more readings after putting some significant hours on and see how she's holding up.

David

[Hepcat]

Another thing I noticed is that it takes less drive to get full power out of EL34s compared to 6L6s. I had to go through each stage and reduce the gain so I could play through the amp without having the volume almost all the way down. The tone is noticably different from the Fenderlike sound of 6L6s. After this is in the cabinet, the next try will be 2 X EL84s.
Thanks for the advice!
Ken

[Hepcat]

The increased gain is due to no feedback! Duh! also it takes less drive for EL34s according to the spec sheets..

[Blackburn]

Pentodes are the shit! I'm not much of a beam power fan. Have you done any EL84s yet? I think you have quite a surprise waiting, if you like swirly, chimey cleans and a very distinctive jungle cat growl!

[Hepcat]

No I haven't built anything with EL84s yet. Just repaired Blues Juniors which I'm not impressed with. Biggest problem with them is the price point they aim for makes them use really flimsy parts. They also have insufficient bass for my taste. I have played through an AC-15 that one of my students has (i'm a music teacher and starting an amp business). The AC-15 sounds just like you describe, chimey sound with the growl. When I get the cabinet for this one covered, I'll post a picture. It sure sounds great!

[Blackburn]

Yeah, a Jr. shouldn't be any kind of platform for judging much of anything, really. Try building a little dual EL84 amp and enjoy beautiful cleans and a very interesting grind, especially with a pair of old British made.

[JoeCon]

Hepcat

I'm working on a 2 x EL84 Rocket right now. Check out the Rocket schematic and then this layout for the two tube version.
Thanks to Mark Fowler and KT66 for this work...

[M Fowler]

I had to put lower gain tubes in this amp NOS 12AU7 and 5751 so my son could play it at his home.

[Hepcat]

I've been thinking of trying a 12AT7 or a 12AU7 for the first tube. It's about 6 dB too hot.

[Hepcat]

The next one will certainly be a 2 x el84 and your Rocket derivation looks like what I want. Thanks for all of the hints, gents!

[Hepcat]

BTW, just finished the Vox-like build. 2XEL34, 3X12AX7, one Weber ceramic 12 inch Blue Dog, Everything made at home. It sounds fantastic! And I'm an American style amp fan (and maker)! I'll post some build pictures if anyone is interested. A video clip when I get my new phone(iPhone5) figured out.

[Hepcat]

The amp sounds great! it was also much fun to build. I didn't quite copy the design from the schematic but it is similar. messed with coupling cap values and power supply voltages. The thing really "jangles" I went with a 5Y3 rectifier to lower the plate voltage to about 307 to save the output tubes. Also went with cathode bias. Not as saggy as you might think. I'll post pictures soon if you want to see!

[JazzGuitarGimp]

Yes, we want to see! And hear!