EL84/6l6 Tube Selector Switch.........Feasible?

caglej · Post by **caglej** » Thu 01/05/06 4:29 pm

I was just curious as to whether building a "36 watt" with 2 El84's and 2 6l6's would be feasible. The idea would be to be able to select each pair individually as well as blend them using a 3-way selector or even a variable one. Could this possibly be done easily?

Post by **rjgtr** » Thu 01/05/06 4:56 pm

It could be done, but would be easier using EL84s and 6V6s. Each pair would need its own set of cathode bias resistors and you'd need different grid resistors to drive the tubes differently. You'd also need a good way to silence the pair not in use.

I believe there have been a couple of amps built that switch output tubes. I know Mesa had one. The schematic may be available somewhere online.

BBQLS1 · Post by **BBQLS1** » Thu 01/05/06 5:07 pm

rjgtr wrote:It could be done, but would be easier using EL84s and 6V6s. Each pair would need its own set of cathode bias resistors and you'd need different grid resistors to drive the tubes differently. You'd also need a good way to silence the pair not in use.

I believe there have been a couple of amps built that switch output tubes. I know Mesa had one. The schematic may be available somewhere online.

The MarkIV and Dual and Triple Rectifiers let you do all kind of stuff. Download the MarkIV manual from thier site for some ideas.

keith · Post by **keith** » Thu 01/05/06 5:24 pm

The link is to the Mesa Boogie schematics, scroll down to the Blue Angel power amp.
They are cathode switching el84 and 6v6 tubes.

http://www.tubefreak.com/mesa.htm#angel

Keith

novemberrain · Post by **novemberrain** » Thu 01/05/06 6:04 pm

The most likely mix of EL84s and 6L6s would be four EL84s and two 6L6s.

caglej · Post by **caglej** » Thu 01/05/06 10:10 pm

Thanks guys.........that was exactly what I needed to know!

csbradley · Post by **csbradley** » Wed 02/08/06 10:15 pm

I'm working on one with a pair of 6V6's and a pair of EL84s. I have the chassis all done, and have been wiring up the power supply tonight. Still have a few parts coming. I started with a Weber 6M36 kit, and then just started modifying things.

I built up an eyelet board the other day. One channel will be an EF86, the other will be either the Stout preamp, a Deluxe preamp, or my own combination of whatever I like. So it will be only one tone control per channel.

Each set of tubes will have their own master volume so I can blend channels. I would like to make them footswitchable, so I could switch between the two or use both at once, but I decided to get the amp up and working first before I start adding "extras".

Hopefully I will get it up and running in a few weeks.

CSB

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EL84/6l6 Tube Selector Switch.........Feasible?

EL84/6l6 Tube Selector Switch.........Feasible?