Carbon Film vs. Metal Resistors

[Hailstorm350]

I have read up on the differences between Carbon Film and Metal film type resistors, but how do they REALLY affect sound?  as I understand, Metal film caps are more precision compared to carbon films.  In, say for an example, the BSIABII, where would Metal Film resistors sound best, and where would Carbons sound best?  I'm pretty sure that there's a reason for using them in different spots because in professionally made pedals like DynaComp they use different types all over the place.  Not just all Metal Film or Carbon Film.
I am just wondering because I am learning about the way components affect sound differently.
Thanks,
ken

[Alpha579]

theres not alot of difference in sound (tone snobs will tell me otherwise :wink: ) , but 1% metal films will be slightly quieter than 5%carbon comps...

[MartyMart]

Hmmm, are we talking about "Carbon film"  or "Carbon comp"  here ?

There is a HUGE difference, carbon film are just regular resistors, not particularly bad/good, but "carbon comp" are those "brown" vintage jobs from Fuzz Faces  etc... very different "tone" but can be noisey as hell !!
I use a mixture of "Metal film" and normal "Carbon film" all the time with no noticable difference.

Marty.

[Peter Snowberg]

Carbon comps are great to bias Zener noise sources.

Metal film is necessary if you're wanting to get rid of any possible noise source you can, but for stompboxes carbon film works just fine.

[bioroids]

Hi!

For my line of pedals I'm starting to use (just ordered) metal film resistors for the high values (greater than 470k).

As you know the higher the resistance the higher the noise, so the difference (if any) would be greater in these values than in, say, 1k resistors. Besides they tend to apear at the opamp's inputs, or biasing the base of a BJT, critical places I think.

Maybe is just a waste of money, but is not that much money anyway

Wich other places could be critical regarding noise? Everything on the signal path I assume, but perhaps other places?

Luck!

Miguel

[Paul Marossy]

I think that I remember reading in RG's write up on carbon comp resistors that they just added more hiss in 9V stombox circuits...

[mojotron]

The power rating has a lot to do with the noise level you get out of carbon comp resisters - the noise is really noticable on 1/8W carbon comp parts. I just use metal film for everything in the signal path, and carbon film once in a while for biasing - the pots already add enough noise to the circuit. Normally I reduce noise everywhere I can, but I actually like the sound of 1/4W carbon comp parts in a Ge fuzz face.

[NaBo]

i use metal film if the store has the value in stock... if they're out or don't have it, i go to the 1/4 watt carbon films before i resort to the 1/2 watt metal films (which i only had to do once).  and i don't give it another thought.  everything i've built has been totally silent, even without an enclosure...  and practically no rf interference cuz i ground to my metal desk... i find an alligator clip fits quite nicely into the keyhole...  im getting off-topic.

anyways, in most cases you probably wont hear or notice the difference

[Alpha579]

Hmmm, are we talking about "Carbon film"  or "Carbon comp"  here ?

There is a HUGE difference, carbon film are just regular resistors, not particularly bad/good, but "carbon comp" are those "brown" vintage jobs from Fuzz Faces  etc... very different "tone" but can be noisey as hell !!
I use a mixture of "Metal film" and normal "Carbon film" all the time with no noticable difference.

Marty.

have you actually heard the difference in tone between metal film and carbon comp? Im sure there will be more of a difference in high voltage tube amps, but at 9v the difference in tone will probably be value drift due to bad tolerance...

[RedHouse]

Easy;

Carbon Composition = HISSSSSS
Carbon Film = HISSSSSS
Metal Film = HISSSSSS

Look elsewhere for Mojo.

[Hailstorm350]

thanks guys, that help a lot
Ken

[jimbob]

For the 9v circuits we mess with around here, I bet youll never hear any difference. I say go with either= .02 cent price difference at mouser so u cant lose. I use both.

[Peter Snowberg]

Easy;

Carbon Composition = HISSSSSS
Carbon Film = HISSSSSS
Metal Film = HISSSSSS

Look elsewhere for Mojo.

Beautifully stated!!!

[Paul Marossy]

Beautifully stated!!!

Agreed.  

[bigjonny]

I have no strong opinions, but for what its worth: I built the BSIAB II with all metal film resistors.  Quiet as mouse.

I guess my perspective is: when you're talking a couple bucks price difference for bulk purchase, why not go with the best?  Plus, ¼W metal film resistors are physically much smaller, and thus easier to fit into perfboard/stripboard designs.

That said, i still use carbon film when its more convenient for me.

[NaBo]

they're also a pretty blue colour!    ...  :oops:

[vdm]

ive always used a mixture of carbon film and metal film, and i was wondering what the difference between the watts rating is. is higher wattage more or less noisy? my local shop only sells 1/2W metal films, but they're the same size as 1/4W carbon films.

im getting having carbon comp resistors put in my vibrochamp 'kit' from ceriatone... it's a pretty clean amp, so hopefully the hiss wont be too much of a worry, and the tone will be great :wink:

then again isnt that what we all wish for ....

trent