18Watt.com

what's the procedure for the outer foil test? bear in mind some of us are neanderthal with analogue scopes!

Bieworm wrote: ↑

Sun 01/17/21 5:11 am

Did the testing. Great feature!!! It's really obvious.. and you were right about those striped vishays.. some are correct, while others are not.

Yeah, that stripe is basically just a label design now, and has nothing to do with the foils. But at least it's fun to test. Did you try doing it with some measurements on the screen?

geoff 1965 wrote: ↑

Sun 01/17/21 7:43 am

what's the procedure for the outer foil test? bear in mind some of us are neanderthal with analogue scopes!

Aiken's post about it: https://www.aikenamps.com/index.php/whe ... capacitors

If you're using a digital scope, having measurements on screen can help when the difference isn't obvious.

JMPGuitars wrote: ↑

Sun 01/17/21 8:44 am

Bieworm wrote: ↑

Sun 01/17/21 5:11 am

Did the testing. Great feature!!! It's really obvious.. and you were right about those striped vishays.. some are correct, while others are not.

Yeah, that stripe is basically just a label design now, and has nothing to do with the foils. But at least it's fun to test. Did you try doing it with some measurements on the screen?

Ofcourse. I should have made screen shots.. but it was really obvious which side was the outside foil. So I marked all caps in my stash. The bigger caps were somewhat difficult, but the small ones were really obvious

Here I am again with some questions...sorry but I'd like the opinions of the good ones

After converting the (no longer) imperial to the kinda british preamp ...or how should I call this?.. I found out the OD was not enough. So I replaced the voltage divider 470k-250k pot-47k to ground with a 1M pot to 47k to ground.. in order to release more signal to the grid of the 2nd gain stage. While that works just great I noticed that the clean channel looses clarity when the gain knob on the OD channel is set too low. I figure that part of the signal escapes to ground via the 1M pot for it probably chooses the least resistent path? I schematically added a 220k resistor between the plate and the coupling cap between stage 1 and 2 of thr OD channel. Is that something I shoild try? Or are there better options? What say yee?
Schematic attached...

Ok I took a shot at it.. but started with 180k. Took too much signal from the OD channel, but at least the clean channel maintained its clarity. Sot I tried some more values and settled for 100k. Now it's a rockin'bird!!!
I might call it that way.. because there is not much left of the imperial at this stage of tweaking and altering. Thanks to y'all there is now a seriously good amp added to my collection!!!

Listen.. clean and moderate drive demo:

https://www.dropbox.com/s/6sz9lv2vi1ylu ... b.m4a?dl=0

Playing the amp makes it grow on me more and more. The OD is really nice since the last tweaks. Really raunchy and fattt. A cross-breed of a 5E3 and an 18W. Less tight but a real blooming buzzy mush in a very nice way. A nice addition to my collection..

Excellent, love the sound! Congrats!

TriodeLuvr wrote: ↑

Wed 02/03/21 2:14 am

Excellent, love the sound! Congrats!

I'll make a recording with more OD. This was only half of it..
It only gets fatter and more saturated