18Watt.com

Heya..
New to this side of the forum. 36 watts that is..
I have a bunch of newbie questions as I haven't dealt with the 'quad' set of O/P tubes yet..
I'm thinking of running a 4 tube preamp section.. (including PI)
Modulus chassis's has a prototype that will do.
My OP TX is a 40 watt with an 4K2 input impedance
PX is a brute with 300-0-300 @ 300ma.
Heavy 5v and 6.3v heaters
4 6V6's (EL84's?)
7 hole face plate
2 inputs.. High and Low
channel switch in boost?

Just laying it out so you can play it out...
RJ

Start with one of the 36 watt schematics and go from there: viewtopic.php?f=25&t=24432

OT = Output Transformer
PT = Power Transformer

Thanks,
Josh

Ampman5150 wrote: ↑

Fri 02/14/20 1:33 am

I'm thinking of running a 4 tube preamp section.. (including PI)

Why?? Do you realize the insane level of gain that will give? I expect getting rid of squeals and other noises will be quite a challenge.

I'm guessing from your handle you want to build an 18W 5150? Cool idea, but likely to be a challenging build, all the same. EL84s have quite a high internal gain, which can make the overall distortion in a high - gain amp sound a bit out of control, so 6V6s may work better for you, or 6973s, which are actually 6V6s in a 9-pin bottle.

My initial thought was using a 100 watt 'marshall style' chassis but with a 4 6V6 power section (AC30 ish).
The preamp would be 'soldano style'.
Lower the gain a tad as to not have something cra-cra-crazy

For 6V6s,you will need to change the PI tail to 470R+20k, to give them the extra push they need compared to EL84s.