18watt tmb plate and screens filtering ?

[mark enger]

I'm working on a 18watt tmb plexi with ss recto, being its ss recto a how much filtering should i go with for the plate and screens? I have a 80uf sprague atom id like to use for the plates,or is this too much? and does it help screen any to use more than a 32uf, mark

[Bob S]

A wise man told me less is more with Marshall builds.
He was right IMHO.
Thanks Miles.

[Colossal]

Hi Mark and Bob,

I concur, go lighter on the filtering. An amp with too much can feel dead under the fingers with a hard, uninspiring, and clanky sound. Those 18W amps have it just right and you should feel as if holding your fretting hand very lightly, you can strike a chord with ease and you get the shimmering grind that wants to take off into harmonic feedback. Too much filtering and it's flat and stiff and you find yourself mashing the fretboard trying to make something happen that ain't gonna. My experience anyway.

Are you planning to add a sag resistor in series with your SS rectifier? What are your PT voltages?

[mark enger]

I should have 332v one powertube plates, I'll go with a 32-32 for plates and screens filtering, you are right the amp likes a ruff and raw feel You guys ever done a variable sag? thats something i'd like to try, other wise i think about 100 ohms would be fine, here's a couple pix, The pt i pulled from a old stereo, the ot is a 25watt 8k with 16 0hm only tap not a true 18watt ot but i've used them before and they sound pretty good, heres some pix mark

[LeftyStrat]

Just to be contrarian, the filtering to me is a big part of the difference between "nice" and "omfg."

I agree that less is best, but personally the JTM45 has too little. I prefer 32uf with the tube rectifier.

But the cathode bypass caps also play a role. Lower them and then the lowered PS filtering isn't so bad.

It's the difference between big beautiful ass, and a fat ass.