Half power switch in a fender 40w or AC30

[TonyM]

Ive put in pentode/triode switch in my 50w marshall clone.
Thinking about building  a fender 40w style or perhaps an AC 30 style. Can a half power switch be added to one of these styled amps so as give an option in volume?

[EL34]

Posted in wrong board... moving

[sluckey]

Ive put in pentode/triode switch in my 50w marshall clone.
Thinking about building  a fender 40w style or perhaps an AC 30 style. Can a half power switch be added to one of these styled amps so as give an option in volume?

You can put a pentode/triode switch in either of those amps. Some people call this a half power switch. This will not be the same as half volume. To cut volume in half you need to reduce power to one tenth.

[stratomaster]

You're better off with a good post phase inverter master volume if your goal is to tame the volume of the amp.

In the AC30 you can change the cathode circuitry to have two pairs of tubes sharing cathode networks instead of all 4.  This way you can shut off 2 of them.  You'll have to play with the resistor values to get it to behave in both half and full power modes. 

Again, master volume will get you there with less headache.

[sluckey]

I just remembered the Ceriatone 36 Watt amp. It uses a half power switch to switch two of the output tubes off by disconnecting the cathodes. It also switches the cathode resistors to compensate the bias. This same scheme would work on any 4xEL84 amps, including Vox AC-30.

[passaloutre]

I used a similar switching scheme in a 70s Twin reverb that had 4 cathode biased 6V6s (JJs for the higher voltage rating, as well as some heavy sag resistors). A DPDT switch disconnected two of the cathodes and one of the speakers with the other pole. It was better than pentode/triode switch in my opinion.

It eventually occurred to me I was carrying around an 80 lb, 20 watt amp, so I returned it to stock and sold it.

[Jennings]

I’ve got a Ceriatone Rock-it that I’ve sort of AC30-ised a bit. It’s got a switch for shutting off two of the four output valves and adjusting the cathode resistor accordingly. See schematic. Also attached original Ceriatone layout.

[Latole]

I used a similar switching scheme in a 70s Twin reverb that had 4 cathode biased 6V6s (JJs for the higher voltage rating, as well as some heavy sag resistors). A DPDT switch disconnected two of the cathodes and one of the speakers with the other pole. It was better than pentode/triode switch in my opinion.

It eventually occurred to me I was carrying around an 80 lb, 20 watt amp, so I returned it to stock and sold it.

Typo error  ? Twin Reverb use 6L6 not 6V6

[Esquirefreak]

That's probably why he used JJs. They often work with voltages more often associated with 6L6GCs

/Max

[Latole]

That's probably why he used JJs. They often work with voltages more often associated with 6L6GCs

/Max

Both JJ's work at same voltages

https://www.jj-electronic.com/en/6v6s

[Esquirefreak]

The JJs have a higher plate voltage rating than most other 6v6 tubes. So they tend to work okay in 6L6 amps.

[Latole]

The JJs have a higher plate voltage rating than most other 6v6 tubes. So they tend to work okay in 6L6 amps.

I just ask , is it a typo error ?