5e3 with more power?

[AEA]

Hi guys

I am looking at building an amp soon. I will most probably do a 5e3 circuit as I really like the simplicity of the circuit.

Now my problem comes when I need more power than 2 6v6 tubes are going to give me. I know many people have used 6l6 tubes with some modding but these aren't really the sound I am after. I would rather use kt66s or possibly el34s.

Would this be similar to the designs for 6l6s? What further mods would I need to make to the circuit?

This would get in the realm of about 20w yea?
I am looking to between 20 - 30w. Would I be better off taking the poweramp section of a higher powered amp and the front end of the 5e3 to build something more to my suiting or will there be problems here as well?

On the other hand if there are other designs that are simple (just volume and tone) I would love to hear about them. I know Dr Z has a few designed this way so I am hoping there is others out there that share this philosophy and there is some info on simple designs.

Thanks for any help you can give me. Sorry for the long windedness of my post but I hope it all makes sense.

Cheers

Adam

[pdf64]

Although output tube type / brand does have an effect on tone etc, my feeling is it's the circuit that they're used in that makes a greater difference. If you've never heard 6L6 with a low B+ and cathode bias, then now is the time. Pretty similar to 6V6 and all the other octals in that configuration. If you buy suitable transformers and wire it appropriately, use a 10 watt bias resistor, then your amp could used a variety of output tubes. See the 5Dx series of amps.

[AEA]

I have heard some 6l6 5e3s and was kind of underwhelmed. they didn't really have that 5e3 tone.

I have read that kt66s or el34s should be closer in tone than the 6l6s.

would it be more likely the other changes to the circuit changing the tone more than the tubes?

thanks for the reply.

[MWJB]

I don't think that traditional KT66 are going to be closer in tone to 6V6 that 6L6, usually the opposite is true.

35W with 6L6/5881/EL34/KT66 is possible, either install a fixed/cathode bias switch, or dump cathode bias altogether. You will need to increase B+ voltage to more like 450v+. With a BF Deluxe PT (& B+ somewhere above 400vdc, possibly try a SS rectifier) 30W-ish should be feasible in fixed bias with 6L6/EL34. With enough sweep on your bias pot, you can run JJ/EH 6V6 as well as the bigger tubes.

EL34 & KT66 draw more heater current than 6L6, but as you are only running 2 preamp tubes, a 2x6L6 BF/SF power transformer will suffice.
If you build the amp to run typical 6V6 voltage & bias conditions, then simply fit 6L6, without increasing the B+/rebiasing as necessary...you amp won't make any more power, in fact it may even sound quieter.

Use discrete 1K 5W screen grid resistors on each power tube socket, reduce the value of the B+ to screen power supply dropping resistor to 2.7K 3-5W. Wire the main filter cap as 2x series caps of 100uf 450v each, each bypassed with a 220K 2W resistor.

[Casey4s]

Why not 4 x 6V6GT? I have a DIY Bassman 5F6A with 4 x 6v6's and it has great tone and plenty of power. (39.2W @ 70%)

[pdf64]

'plenty of power. (39.2W @ 70%)'
What do you mean by that?

[Casey4s]

'plenty of power. (39.2W @ 70%)'
What do you mean by that?

Mayge I could have been more specific. I meant that 4 6V6GT's at 14 max watts each would be a total of 56 watts maximum dissipation, but biased at seventy percent would yeild approxmently 39 watts. Of course that's with a fixed biased amp. Since we were talking about a more powerful version of a 5E3 circuit it seems a 4 x 6V6 version would yeild similar results in a cahode biased amp.

[MWJB]

Casey, you are confusing W dc plate dissipation with W AC output, the 2 rarely match.

[Casey4s]

Casey, you are confusing W dc plate dissipation with W AC output, the 2 rarely match.

In my best Edith Bunker voice..OOOOOOOOOOHHHHHHH Thanks for the correction/distinction. I did a little reading since your post and now I am curious to get a real measurement. I am looking at an attenuator at anoter fourm to load the amp with.

[Dave H]

I use this one. It's in the 25-30W range. EL34 30W.pdf

Dave H.

[Bruce / Mission Amps]

A 4x6V6 5E3, each pair cathode biased with 270 ohms using a 180ma power tranny, 5U4GB rectifier, 360vdc on the plates, and a well made, solid 40 watt, 4Kohm output transformer will make an honest 22-24 watts output all day long. Got the Tee shirt....