Re: Hoffman Plexi50 Turret Board

[Hellawatt]

Hi, I noticed the Plexi 6v6 and the Plexi 50 schematics are almost identical, but the 6v6 board is much smaller. Wouldn't it be possible to use the 6v6 board for a plexi 50 build, with a few small changes?

How small of a chassis do you think it would be possible to build a 50 watt amp in? Could you cram a plexi 50 into a stout size chassis, using the 6v6 board?

I would like to make something very simple and very loud, that could sit on top of a 1x12 cab, or a vertical 2x12. So like 18" wide or less, including head cabinet.

[Paul1453]

I just built a 6V6 Plexi, and am now working on a modified Quad 6V6 Plexi.

I think the original Quad 6V6 chassis I have modified to use is around or under 18" in both length and width.

The turret board is another matter.  I removed the PS and bias components from the board.

Mainly did Point to Point wiring for that.

It significantly shrunk the size of board needed.

I didn't use the Hoffman board, and actually chopped my redesigned board layouts into 3 pieces on the Quad build.

You can check my Quad thread for ideas, if you want.

http://el34world.com/Forum/index.php?topic=20220.0

I think that if you can make your own layouts and board designs, your goal may be possible. 

[Paul1453]

I just checked my Quad chassis' dimensions.

L = 15"  W = 10"  including the flanges on the ends.

Your 50W amp would probably have bigger PT/OT/choke dimensions.

Depending on the size of those, and your ability to lay them out properly to not interact with the preamp.

Your goal seems achievable to me. 

I would try to have all that heavy metal and output tubes in the back.
Preamp tubes in the front near the pots, to keep all the wiring as short as possible.

No one will really be able to tell you if it will work or not.
I think that if you plan the layouts well, you have a reasonable chance of success.

[Hellawatt]

I tried mapping the dimensions of the plexi 50 transformers onto a stout chassis. It looks like it would all fit, I don't know if there would be interference or noise though. I guess if it didn't work out I could just move everything to a larger enclosure.

[EL34]

The only difference between different powered marshalls is the engine under the hood
What's the difference between any one of the many Fender AB763 amps?

Transformer sets and power tubes = the engine

I designed the Plexi 6V6 board to fit into the Stout chassis
Looks at the Stout Chassis info
That's about as small as I would ever try and cram in a Plexi type circuit

http://hoffmanamps.com/MyStore/catalog/Chassis.htm

[Paul1453]

Well there you go, Hellawatt.

Straight from the big boss man himself.   

His board and chassis would be the way to go, for sure.

Especially, if you had any doubts at all about your being able to customize your own design.   

[HotBluePlates]

I tried mapping the dimensions of the plexi 50 transformers onto a stout chassis. It looks like it would all fit ...

It could probably work, but my preference would be a bigger chassis and wider spacing given the EL34 tubes will run hotter than 6V6's at both idle & full power.

Caps also suffer from being heated by the output tubes.

You might be able to mitigate some of that with a fan blowing across the tubes to cool them.

[drew]

I would like to make something very simple and very loud,

and Marshall?  Or just simple and loud?  There is a Dumble amp called a Small Special; there are a few threads on the ampgarage forum about guys building them in small chassis.  It's pretty simple - two preamp tubes, two power tubes (in 50w form), 4 knobs. 

[Hellawatt]

Thanks for the replies. I still have a lot of research to do...