Silver Mica Caps

[Robert8192]

Well , thanks to Steve, JHow, tubeswell, and Robert.
A huge help.
I have had all my questions answered as to my issues on the preamp.

Glad to see so many responces. There appears to be some oppinion-oriented

reasons to like SM and some prefer CD. I think since SM lasts longer, I would go
with SM on my treble caps, IE in my tone-ckt it is the 470pF (#13, 16, 18)

As to the question about Alessandro coupling caps?? Since the 1940,s many
different kinds of amps were built. Many purists took to their favorite
kind of parts and believe they are best. Remember, that parts and
manufacturing processes sometimes get better, and better parts can arrise.
I've even seen on the internet a beeswax-film caps that sell for 55$ for a .4uF and a 6uF was like 155.00$ FOF-LOL- OMG - WTF.
To nwguy, anything from .1 to .05 Ceramic. and the smaller stuff , make it
poly.. It just has a better ring to it. But I am knew to this myself..

Maybe someone having the schematic for the Bassman can list the caps
compliment by number and give some pointers there...

So when the smoke and flux fly for nwguy, he's putting in the most
perfect caps for that old amp. and remember , give Electrolitics about
5-10 yrs before they die and ceramic about 10-15 yrs before they die.
(depending on use)
Again, a huge thanks.

[Robert M. Martinelli]

Most class 1 ceramics (NP0, C0G, SL) are good in this sense, and you may be hardpressed to tell the difference tone wise from a SM

Joey,
If you re-read my post, you will find I actually dealt with NP0s by stating "with the obvious exception of NP0s" - obvious because NP0 means "no temperature drift, neither positive nor negative". Ceramics with other temperature coefficients (e.g. N750 - standing for Negative Temperature Coefficient, drift 750 ppm/°C) are usually found in RF circuits (e.g. oscillators) to compensate for other components' thermal drifts which may affect the RF circuit's frequency stability.

Tone-wise, maybe I'm a cork-sniffer, maybe not, but I find ceramics "gravelly", furthermore, they have a known tendency to change their capacitance depending on the voltage applied, so I think I'll stick with the more stable poly (-propylene, -styrene, -whatever) and SM caps when possible, relegating ceramics to the "RF realm" only.

Cheers

Bob

[Joey Voltage]

Joey,
If you re-read my post, you will find I actually dealt with NP0s by stating "with the obvious exception of NP0s" - obvious because NP0 means "no temperature drift, neither positive nor negative". Ceramics with other temperature coefficients (e.g. N750 - standing for Negative Temperature Coefficient, drift 750 ppm/°C) are usually found in RF circuits (e.g. oscillators) to compensate for other components' thermal drifts which may affect the RF circuit's frequency stability.

Tone-wise, maybe I'm a cork-sniffer, maybe not, but I find ceramics "gravelly", furthermore, they have a known tendency to change their capacitance depending on the voltage applied, so I think I'll stick with the more stable poly (-propylene, -styrene, -whatever) and SM caps when possible, relegating ceramics to the "RF realm" only.

Cheers

Bob

Bob,

I was mostly just clarifying what I meant by "class 1" ceramic, that part may not be too obvious to some

It is true that ceramics may impose some non-linearities, but yes most noticeable when being run very close to their maximum working voltage, this actually may not be a bad thing though. although I tend to use poly's whenever I can find them.