Fender Champ with one 6L6 Tube

[opacheco]

Hi,

I would like to know where I can do in order to install a 6L6 power tube (instance to 6V6) in order to get a more output power???

Any comment will be appreciated!!

Thanks
Opacheco

[txstrat]

You're probably looking for noticable output power.
By only changing the power tube to a 6L6 you might get some more power (maybe 1-3 watts) but you wouldn't notice it's more.
Changing to a push pull design would give you noticable more power, but there's more to it than just using two tubes. You'll need a different OT and PT at least. And an appropriate speaker.

[trevorus]

Output power would be barely noticeably increased, and you might have some more clean headroom, but if you are looking for more output, use more speakers (with a proper ohm load), or a bigger amp.

[opacheco]

I would like to keep on the CLASS A sound, that is very important for me. Would I need to change the output transformer to bigger one??..Which one(for class A)??....How about the bias?

How about the 6550 tube(just one!!)?..Could the 6550 work into this amp??.

What I will to do????????????

Thanks
Opacheco.

You're probably looking for noticable output power.
By only changing the power tube to a 6L6 you might get some more power (maybe 1-3 watts) but you wouldn't notice it's more.
Changing to a push pull design would give you noticable more power, but there's more to it than just using two tubes. You'll need a different OT and PT at least. And an appropriate speaker.

[txstrat]

The 6550 might be a way to go BUT only with a bigger (single ended) OT .....AND a bigger PT because the 6550 needs 1.6 amperes of heater current, while the 6V6 you have now, needs 450mA only.
The PT you have now can't supply the current for the 6550 (assumed it's the original PT).
But even then the sound you'll hear is not that much of a different loudness. More cleaner headroom, though.
I dig the idea trevorus proposed. More speakers...
Don't get stuck on the class A thing. Many amps sound great even though they are not class A. And most people can't tell the difference anyway.

[R.G.]

Changing tubes will make only small changes in output power. Given that the human ear has an approximately logarithmic response to changes in loudness, the change in loudness for a doubling of power is heard as a just perceptible change in loudness. You need about 10X the power to get the perception of twice the loudness.

Beyond that, a power amp is best looked at as a wart on the power supply. The power supply is what really sets the limit on how much power you can get out. The power amp circuit can make better or worse use of the available power, but cannot exceed what the power supply can make. So changing the tubes, even if you had a magical "perfect" tube, will not make really big changes in output power, especially if you must remain in the same operating class. To get double, triple, or 10X the power, you're probably going to have to rebuild the power supply to make that much more DC for the amp to work with. The power transformer and output transformer are the #1 and #2 most expensive things in the electronics, so this will get expensive fast.

This is all in the Guitar Effects FAQ at GEO, from over a decade ago.

[dai h.]

compare the sizes of the PT and OT:

this is my Guyatone GA-100, which is basically a silverface Champ clone with a 6L6 output and a solid state reverb section (look at the middle pic with the back off where you can see the transformers) :

http://music-electronics-forum.com/t19234/

this is supposed to be a '79 silverface Champ

http://www.tdpri.com/telephoto/data/...Champ_back.JPG

'68 Vibro Champ with back off:

Photo 4 of 4, Fender Vibro Champ Silverface 1968

so just plugging in a 6550 is not going to work and can be dangerous to the amp