Where to place carbon comps

[james21789]

Forgive me for bringing up the well discussed topic of carbon comp lore, but I was merely wondering where carbon comps should be used in amp circuits. I understand the 'mojo' is most profound when they are pushed with a lot of voltage, so seems like the plates would be a likely candidate. Would it be a good idea to put CC's on ALL my plates, or just the preamp section, or even solely the plates on gain stages?

Just curious for any insight, not trying to start a debate between cc's and other resistors.

-j

[FYL]

Check http://www.geofex.com/article_folders/c ... oncomp.htm

[M Fowler]

I have some NOS CC resistors unsure what brand they are, where is best place to get AB or comparable quality brands of CC resistors?

[FYL]

There are no subjective differences between all quality vintage CC resistors - AB, IRC, Ohmite, Stackpole, TRW, you name it. I use what's available in my bins for restorations and don't care about the brand as long as it's the same type of R.

Modern versions from Xicon and others are better built and behave in a somewhat more linear fashion.

[M Fowler]

I was wondering if the new CC were good and you answered that question thanks.

I do use what I have but was considering some builds with CC.

Thanks

[David Root]

Would the same process happen in a carbon track pot? It seems pretty well established that most old pots sound better than new ones, although there are exceptions, eg PEC and Clarostat RV4 are very good modern pots.

This could be because an old Allen Bradley 2W pot is much better built than an Alpha or a modern CTS, in that the wiper is built properly and the track is heavy not flimsy.

For example, I have three CTS open style 1/2W pots. One, built in 2002, weighs 10 gm. Another, buit in 1977, weighs 17 gm. The third one, built in 1967, weighs 19 gm. The 2002 one has a plastic shaft, the others are metal.

From the outside, the '67 pot is clearly better made than the '77, and light years ahead of the '02. (I'm not about to take them apart because the '67 is NOS and worth about $20 on ebay).

[Structo]

Yeah, I have wondered about pots as well.
We spend so much time worrying about this resistor and that capacitor and this wire, we forget how much the signal is running through the control pots.
For example as brought up recently, the typical passive tone stack has the treble pot at the end where all the signal flows through to the volume pot or next stage.
So in reality the pots should in theory have a huge effect on tone.
I have been meaning to experiment with that a bit next time I pull the chassis out.

I have several different brands and ages of pots I want to try there to see what I hear.

If I had the time and money it would be interesting to use one brand of pot on an amp then change out them to another brand just to hear the difference.
I know tolerances and curve differences would account for some of the change but I can't help wondering if all the Alpha pots I have in my amp are hindering the tone.

[FYL]

Would the same process happen in a carbon track pot?

Most modern pots are built to a price point: cheap. Molded carbon, Cermet or plastic models are usually still really good but cost from 10x to 50x more than a basic Alpha Taiwan.

[james21789]

Thanks for the link!

-j

[rp]

For example, I have three CTS open style 1/2W pots. One, built in 2002, weighs 10 gm. Another, buit in 1977, weighs 17 gm. The third one, built in 1967, weighs 19 gm. The 2002 one has a plastic shaft, the others are metal. From the outside, the '67 pot is clearly better made than the '77, and light years ahead of the '02.

The history of American manufacturing in a nutshell

[PlinytheWelder]

I won't use CC resistors in new builds. I've pretty much settled on Dale RN metal films because I like how they sound and they don't have the wacky drawbacks of CC's

OTOH, I like PIO and BlackGate caps, so go figure...

Edit: and PEC pots, IMO they're worth it.

[David Root]

+1 on the PIO (but not in Dumbles) Blackgate caps and PEC pots.

PEC pots are I think good in everything, Blackgate high voltage PS electrolytic caps, work fine in brown Fender circuits, done that, probably BF too. Maybe not tweed. Blackgate cathode bypass, yes.

[C Moore]

Yeah, I'm embarrassed. For most resistors on the board, I use those carbon film components that cost 15 cents a piece. They do not seem to be noisy or problematic. But some of you guys have been doing this A LOT longer than I have.....

[flood]

Would the same process happen in a carbon track pot?

Most modern pots are built to a price point: cheap. Molded carbon, Cermet or plastic models are usually still really good but cost from 10x to 50x more than a basic Alpha Taiwan.

i just installed conductive plastic pots made by BI technologies in my 2061x. looked surprisingly good when it arrived. I purchased them through Farnell and was pretty impressed at the construction. the rear side of the pot is enclosed in a thin transparent plastic layer, effectively sealing the pot and isolating the insides from dust and moisture (both are biggies where i live).

sure, that means you can't solder to the back anymore, but if mr. aiken's star ground methods are to be followed, that's a no-no anyway.

here's the farnell link:

http://export.farnell.com/bi-technologi ... tt=1684832

and here's a link to the manufacturer's page:

http://www.bitechnologies.com/

mine was the P231 series from the "pro audio" segment. let's see how they hold up...

[james21789]

thanks a lot.

as far as the carbon comp resistors go, anyone got any opinions on brands?

mouser has ohmite brand...never heard of them before.