mojo parts: carbon comps

[Haberdasher]

I know there's really not much use in using carbon comp resistors, (and that often times they do more harm than good by introducing hiss) but I've never used them before and would like to try them out.

Let's say I want to build one of the awesome 5 knob Zygotes with nice germaniums, and I want to trick it out a little with some of these resistors.  There are only 7 resistors in the circuit, so my question is- where would I use carbon comps to do the most good, and where would I want to stick to film in order to keep from introducing too much noise?  Would I use film for the 2 1M values since they are of higher ohmage, and use cc's for the rest?

Thanks

[jkokura]

Just use all CC's. I have, and it's negligible noise. It's a fuzz circuit, and noise is the least of your worries there.

If you were building a hifi delay or tremolo, where you clean signal needs to be pristine, then I would make a better choice on the resistors. But with Fuzzes, it's all moot.

Jacob

[stevewire]

Interesting subject.  I am sure some will dismiss it immediately for the fact that it's most likely not making a positive difference at such low voltages.  Whether or not, they are still kind of cool.

I am not an expert by far.  My first thought is to use them in the signal path.  All resistors going to ground are probably best served as metal film.  Some might say that it is also best to use them after a gain increase.  So probably after an IC, diode or transistor.  I've read that some people prefer not to use them before the gain increase to limit noise; although this makes me question as the effects of a boost from a previous pedal.  Most likely a fuzz should be at the begining of the signal chain.

Like I said, I really have no idea.  I have used CC in some builds.  They haven't particularly turned out noisey.  They look pretty cool.  I can't really tell you if it improved the tone.  I'd probably have the build the same circuit quite a few times to have any idea.

If I were building the Zygote, I'd give R3, R4, R5 and R6 a try.  Or maybe most specificly R6.  I'd also buy a bunch/few of each value, measure them all and use the most correct values.

R.G. Keen doesn't think much of them in 9v circuits - http://www.geofex.com/article_folders/carbon_comp/carboncomp.htm.  Analog Mike sites Keen as the expert on RangeMasters, but then you see that Analog Mike uses CC in multiple different circuits.  

[madbean]

I use CC's for fun, not because they really change the tone very much. It's more of a style thing. Anyone who claims that CC in a 9v pedal makes magic is probably blowing smoke. In an amp, probably yes!

In a FF, I will use them for everything unless I have a pulldown in which case I use carbon film. But, I also almost never use a pulldown in a FF anyway. I have stacks of 1k CC's that I bought a couple of years ago that I will throw in a random build just for the hell of it.

You can still order CCs off Mouser, BTW. They are pricey.

[Haberdasher]

thanks guys.

I think I screwed up using the fuzz face as an example here.  for the sake of discussion, let's assume my question was more of a hypothetical/theoretical one that possibly concerned other pedals where noise may be more of an issue.  And I know they don't necessarily add anything to a 9v circuit, so let's assume someone is using them for eye candy.

In general what is the best practice then?  is there some sort of "rule of thumb" where to use them? where not to?

I know stevewire already  addressed this a bit (thanks steve).  Anyone else?

[mjcyates]

I built an overdrive, I believe it was a TS808 of some sort using all carbon comps. I did not notice any noise issues nor did I notice any particular mojo in the sound. They looked cool and were expensive, that was about the extent of the difference.

[Haberdasher]

Cool.  I'm really not under any illusions that using these resistors will give me overnight Jimi tone.  It's just more of a thing where I can "pop the hood" one day and make my buddies a little jealous.  Good to know that I shouldn't expect tons of noise, though.

[jtn191]

some guys over on the D*A*M forum use NOS stuff like that all the time. I suppose it's mostly for people who crack the things open and see--more or less--what pedals used to look like in the time of our heroes/legends