Any drawbacks to using resistors with higher power ratings?

AfterDarkMusic · Post by **AfterDarkMusic** » 30 Nov 2007, 22:56

Hey guys. I've been looking at sourcing some carbon comp resistors, specifically off eBay. I was wondering if there are any sonic drawbacks using resistors with higher power ratings than your circuit calls for (other than size, obviously)?

Thanks very much

R.G. · Post by **R.G.** » 01 Dec 2007, 03:04

AfterDarkMusic wrote:Hey guys. I've been looking at sourcing some carbon comp resistors, specifically off eBay. I was wondering if there are any sonic drawbacks using resistors with higher power ratings than your circuit calls for (other than size, obviously)?

Well, there's price too.

By the way, carbon comp resistors do NOT have any magical properties in low voltage pedals other than excess hiss. There is a very limited set of circumstances where CC can and does have an effect on sound, sweetening it a bit, but that circumstance can't happen in a low voltage powered pedal.

It's a reliable indicator that someone doesn't really know about CCs if they put them in pedals, unless they are there purely to pull in the gullible with advertising mojo.

AfterDarkMusic · Post by **AfterDarkMusic** » 01 Dec 2007, 03:11

Ok. I was planning to build a gainster using the schem thats been posted here. It calls for all 1/2W CC 10% resistors. So there will be no difference between these and metal film resistors?

R.G. · Post by **R.G.** » 01 Dec 2007, 03:31

AfterDarkMusic wrote:Ok. I was planning to build a gainster using the schem thats been posted here. It calls for all 1/2W CC 10% resistors. So there will be no difference between these and metal film resistors?

Yes, there will be a difference.

The CCs will contribute excess noise. How much depends on where they are in the circuit and how much gain comes after them.

They will not have any magic sweetening effect at low voltages. Metal film is the second quietest resistor technology, the quietest being wirewound.

Redhouse · Post by **Redhouse** » 02 Dec 2007, 05:27

R.G. wrote:
AfterDarkMusic wrote:Ok. I was planning to build a gainster using the schem thats been posted here. It calls for all 1/2W CC 10% resistors. So there will be no difference between these and metal film resistors?
Yes, there will be a difference.

The CCs will contribute excess noise. How much depends on where they are in the circuit and how much gain comes after them.

They will not have any magic sweetening effect at low voltages. Metal film is the second quietest resistor technology, the quietest being wirewound.

Most definately agree with that RG, and I would like to add a small tidbit I got from a National Semiconductor white paper some years ago (early 80's) which I think was titled "The truth About Noise" (don't recall the Appnote #, I'll look for it later) but it indicated that to a certain degree a higher power resistor of the same resistance value can be measurably quiter that the same lesser power resitor in low level applications such as audio.

IIRC it spoke of a 1/2w resistor of the same value being measurably (by them anyway) quiter that the same value resistor in 1/4 or 1/8th watt type, something about the resistive material being more dense per given resistance in a physically smaller area equated to more noise voltage. It was a long time ago I read it so I may have it a bit wrong, but it was something like that anyway.

Definately agree with the wirewound's, in fact I have used quality non-inductive wirewounds as the plate resistor's in amps for some years, they seem to be noticably quieter (even by a novice) ok maybe not night-n-day but noticable at least.

Some tend to dismiss the value of using wirewound's because they are both expensive ($1 -vs- .07¢) and because in an amp we're talking about much higher voltages (>400 volts as opposed to <20 volts) which seems to emphasise noise voltage issues.

AfterDarkMusic · Post by **AfterDarkMusic** » 02 Dec 2007, 08:11

So, what that suggests is that 1/2 watt CC resistors would be about as quiet as 1/4 watt or even 1/8 watt carbon film resistors? Interesting, I wondered if it might have been something like that.

What it boils down to is that there's no reason to spend the dough for the mojo parts.

analogguru · Post by **analogguru** » 02 Dec 2007, 10:11

So, what that suggests is that 1/2 watt CC resistors would be about as quiet as 1/4 watt or even 1/8 watt carbon film resistors?

That you should forget about the use of any carbon comp resistors in stompboxes....

analogguru

AfterDarkMusic · Post by **AfterDarkMusic** » 02 Dec 2007, 20:30

I'd gathered that much, I was simply putting Redhouse's post into my own words.

Redhouse · Post by **Redhouse** » 02 Dec 2007, 22:39

AfterDarkMusic wrote:So, what that suggests is that 1/2 watt CC resistors would be about as quiet as 1/4 watt or even 1/8 watt carbon film resistors? Interesting, I wondered if it might have been something like that.

What it boils down to is that there's no reason to spend the dough for the mojo parts.

Sorry, I thought I was speaking of resistors of a similar type, with larger/smaller ratings (1/2w -vs- 1/4w -vs- 1/8th watt) not so much regarding your 2nd question/post.

I was trying to chime-in with RG's point while bringing in another thought relative to the 1st question you posted.

(ie; "I was wondering if there are any sonic drawbacks using resistors with higher power ratings than your circuit calls for ")

There is an order (which RG already made clear) regarding comparing by type, the CC/CF/MF/WW types are not equal, and I would highly agree with what has already been posted. I just meant that when you do decide which type, then there is that one little tidbit more to consider regarding rating.

R.G. · Post by **R.G.** » 02 Dec 2007, 23:55

Redhouse wrote: Sorry, I thought I was speaking of resistors of a similar type, with larger/smaller ratings (1/2w -vs- 1/4w -vs- 1/8th watt) not so much regarding your 2nd question/post.
...
I just meant that when you do decide which type, then there is that one little tidbit more to consider regarding rating.

Well said. There is really no substitute for actually knowing the characteristics of the things you're using.

In fact, now that I think about it a bit, this may well be one of the underlying foundations of mojo-speak. People kind of know in the back of their heads that techno-things come in two varieties - the merely obscure and the truly, really deeply complex. The promise of mojo-speak and the reason that people buy into it is that they hope that some wizard is going to give them the simple key (i.e. just obscure, not complex) that lets them achieve almost magical results.

Because some techie things are just obscure (like reading schematics) they hope that with one guideline or one wizard's advice, they can just grab the techno-goodies without all that pesky studying, testing, trial and error, time and money, and so on that goes with really learning. Sometimes, for a limited set of things, it works. CC resistors really do sound better in tube amps... in certain very specific places. If you ignore the "specific places" and shotgun replace them all, you get the better sound, but pay for it with higher noise.

To AfterDarkMusic:
Find a library. Go check out "The Art of Electronics" and read it. You'll be better than 90% of your peers just for having done that one thing. After that, there are a few other places to really learn more.

AfterDarkMusic · Post by **AfterDarkMusic** » 03 Dec 2007, 01:06

I'll check it out tomorrow. I have some books to return anyways

Thanks for the suggestion. I'm entirely new to this but even with limited knowledge and not having actually built anything yet, its extremely interesting to me.