From 6CA7 to 6L6 ?

[hebaton]

Can a power section built for 6CA7 be easllisy modded to use 6L6 ? ...
,,, And then 6V6 ?

[Stevem]

Yes, if you can get a 10 additional volts of negative bias to play with.
As a sub note the 6CA7 / EL34 type tubes really want a different impeadance OT to work their best.

[hebaton]

Yes, if you can get a 10 additional volts of negative bias to play with.
As a sub note the 6CA7 / EL34 type tubes really want a different impeadance OT to work there best.

THanks, I read somewhere that 6CA7 are somewhat similar tyo 6L6 being a beam forming tetrode. Would that not warrant a different OT than for EL34s

[martin manning]

Can a power section built for 6CA7 be easllisy modded to use 6L6 ? ...
,,, And then 6V6 ?

EL34/6CA7 and 6L6GC will be fine with just the tube swap and rebiasing, and 4k primary impedance will be fine for both. You will need a bit more negative voltage for 6L6, about 4-5V if both types are on-spec, and depending upon your B+ voltage. For 6V6 you will need to miss match the speaker to double the primary impedance (4 ohm setting with 8 ohm cab, e.g.).

[R.G.]

THanks, I read somewhere that 6CA7 are somewhat similar tyo 6L6 being a beam forming tetrode. Would that not warrant a different OT than for EL34s

Almost certainly not. Beam forming tetrodes and pentodes have very similar plate characteristics. What differences exist are part of that "need a slightly different plate load impedance" thing.

[johnnyreece]

Guys a lot smarter than me have chimed in so far, but I thought I'd mention: You said something about 6V6 in your first post. Unless you're using JJ, you're going to want to keep an eye on your plate voltages. Traditional 6V6 can't handle what 6L6, EL34, etc. can.

[Stevem]

For sure any amps power supply that had enough V+ to make over 35 watts out of a two 6L6 or 6Ca7/ EL34 would need to run JJ brand 6V6’s.

[pdf64]

... I read somewhere that 6CA7 are somewhat similar tyo 6L6 being a beam forming tetrode. Would that not warrant a different OT than for EL34s

My old pair of GE 6CA7 do seem to be a beam pentode. But I think they have been engineered to perform the same as, and seem entirely functionally equivilant to, EL34.
Even to the point that their g2 current draw is closely similar, about twice that drawn by 6L6 in the same circuit, biased to the same idle current.

[pdf64]

For sure any amps power supply that had enough V+ to make over 35 watts out of a two 6L6 or 6Ca7/ EL34 would need to run JJ brand 6V6’s.

Dunno about that, as per the Mullard info, EL34 can put out 50W with the loaded HT at 400V https://frank.pocnet.net/sheets/129/e/EL34_Mullard.pdf
My Sound City can idle at 400V, at full unclipped output of about 44W the HT drops to 370V.
Wouldn't any Delux Reverb would put more stress on its 6V6 than that?

[mhuss]

Here in the States, the "120v" nominal might be 127v coming out of the wall, which makes the B+ 6% higher as well, e.g., 400v -> 423v or 450v -> 476v. This is particularly a problem with older amps using a 115v primary.

Certainly the old original RCA 6V6s Fender used were robust, but I don't know if I would trust most modern 6V6s to be as forgiving, with the JJ being an exception.

The 6CA7 was designed to be equivalent (i.e., direct replacement) for EL34s, and in fact I have some old European "6CA7s" that clearly have EL34 construction (3 grids vs 2 + beam-forming plates). They have basically similar specs, output impedance and bias requirements.

The 6L6GC and 6C6GT have different bias requirements than the EL34/6CA7 and using those in a '6CA7' amp may require modification to the bias supply.

[Stevem]

A coworker a few weeks ago asked me what the heck could be happening with the bulb in his son’s pet snake tank burning out every 4 days, so I lent him my spare voltmeter to take home and check things out .

It turns out he had 137 volts at his wall outlets!!
I had him that very minute call his power company and let them know.
Later in the day when he got home his wife said the power company was there within 2 hours replacing a transformer out on his pole that took a lighting hit last summer.

Luck he had no tube amps in his house!