Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Doc58 on January 31, 2013, 10:54:37 am
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:help:
Hey all you Builders & Geetarrr Slinger's Out there.....
Has anyone had any experience with the Ceramic Disc Caps Doug H. sells on his site marked {251k}?
***(I believe these to be 251pf>500v Ceramic Disc Caps) Am I correct on the Value?***
One thing I noticed is the Ceramic disc is no larger than a "BB" whereas the Factory Ceramic 250 pf Cap that came in my
67' Super Reverb is about 10x the SIZE of that Tiny little Hoffman Cap! (THIS MAKES ME WONDER) :w2:
My Question;
I'd like to know if;
1. Has anyone used these Hoffman Ceramic Disc Caps in their Fender Tone stacks for Treble and if so, how did they perform?
How did they Sound? :m9
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Am I correct on the Value?
No, but you got lucky with that one.
Here's how it works for those...
250 = 25pF
251 = 250pF
252 = 2500pF
See the pattern? The third digit is the multiplier, or the number of zeros to tack on to the first two digits.
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I have used many of them. I have not noticed much difference over silver mica. The only thing I noticed is they are brighter, but not any more harsh. Being curious as to why some people use ceramic and others use dipped caps I A/B them. It is sort of a coin toss so I use whichever I have on hand. Not really enough difference to concern me.
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So that's how it works...251k = 25 +1 Zero = 250pf OK....That helps me, thanks a million.
I tried a 250pf Silver Mica in the Normal Channel...they're smoother, I noticed that right off...
Thankyou guys for the Info...I found it all very helpful.
I got freaked out by the Size of that Ceramic Disc Cap of Doug's...it's so small...Modern Technology I guess...
I DON'T REALLY UNDERSTAND WHY, BUT WHEN I REMOVED THE MULLARD 5AR4 NOS RECTIFIER TUBE MY TREBLE IMPROVED FROM BEING VERY BRIGHT TO NICE AND CHIMEY AND VIOLIN'ISH...
So now I have a Silver Mica in the Normal Channel and the Original Ceramic in the Vibrato Channel...a bit of a different flavor...
I never use the Normal Channel Anyway.
I'll pass this on...I found the new 803S JJ Long Plate High OutPut 12ax7's to work great in the Phase Inverter...
Doc :l2:
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Mica is a rock. It has good electrical properties, but it is what it is.
Ceramic is a mix of stuff, like a cake. You can put in more sugar or less oil, get different kinds of cake, whole books of recipes. Ceramic-cap recipes have been developed and refined for VERY small size. And, up to 1,000pFd, really good electrical properties. Good as mica, but smaller. (And these days, cheaper: don't have to pay dudes in India to dig and split rock.)
Caps can be even smaller. These mica are large partly because it costs more to split mica very thin, and partly because they have heavy epoxy coating. These ceramics are probably limited by the need to have well-attached leads.