I just ran across the Immortal Amplifier articles...

[Bob Simpson]

by R.G.Keen at Premier Guitar.
In this article:
https://www.premierguitar.com/Magazine/ ... _Pt_4.aspx

he's talking about replacing filter/bias caps with plastic film caps.

I didn't know that could be done...

If it's truly better, why not? Any audio issues?

Bob Simpson

[John_P_WI]

Yes it can be done.

Kevin O' Connor talked about this in his first TUT series back in the 90's, if you are interested.

I built a Plexi with it them in the 90's too. It does change the tone dramatically as the plastic caps don't suffer from ESR issues that the cans do. You can make "plastic" caps sound similar if needed.

Solens caps are generally used and they are huge. I mean ginormous compared to the new E lytics.

John

[briane]

Mostly size and cost issues. Take a look at solen fast.

I have a few solens lieing around. The 22uf/450v (I think) was about 2 inches in diameter and 3 inches long. I seem to recall the price was about 3x for the same uf.

[Structo]

Yeah, I remember reading that article and I believe I posted something about it here.

The problem is as mentioned, in order to get the rated voltage the caps are necessarily huge.

[Tubetwang]

I think Carr amps use the fast caps.

They will last.

[Plexibreath]

It looks like a great idea, film caps last so much longer than electrolytics. I really wanted to go that direction with my amps and was willing to go the extra mile to make the much larger film caps (in this case Solen metalized) fit in my design. But you never know if it will have a negative or positive impact on the tone until you do a shootout, so that's what I did. I anticipated that the most likely scenario would be that I would not hear a difference, that, or the difference would be minor but that the film caps would sound a little bit better than the electrolytics. Unfortunately when I did the shootout the electrolytics sounded slightly better than the films. It's a tone difference that's slight and hard to describe, but the electrolytics had and edgier tone that works out better for my needs, the film caps were a little subdued sounding. But like anythings else in guitar amps, sometimes what doesn't sound as good in one amp, may sound killer in another, so I wouldn't give up on the idea, do a shootout to see how they perform for your application.

Kelley

[John_P_WI]

My experience was that it was much brighter, nearly trasnparent with the plastics. E lytics seem to impart more "grain" to the tone, ie distortion.

Remember, the tone that we all know is from amps with e lytic cans. A good comprimise is to parallel a small poly cap with the first can(s) to remove the diode noise and make up for the lower performance of the e lytic cans. This works well.

John

[briane]

My experience was that it was much brighter, nearly trasnparent with the plastics

I recall someone saying similar (was it huss?)

[heisthl]

Carr Slant 6 amps use them everywhere and it's hard to find any fault with the clean tone those amps have.