carbon comp or carbon film or metal film opinions wanted.

[Blue Jinn]

OK,

I've googled this and come up with basically metal film is quieter but in certain quarters carbon is preferred that they sound better, this primarily in guitar amps. However, there doesn't seem to be a consensus regarding carbon comp vs carbon film. Looking for opinions here.

There does appear to be a consensus that metal film are more stable. The difference in cost for carbon film vs. metal film seems to be pennies.

 

[timtimtim]

No resistors sound better than any other resistors, resistors are just resistors, they have no sound. The worst thing they can do is add a little hiss, but only if the input circuit is badly designed.

 

[Blue Jinn]

Thanks. I did come across an article about thermal noise, but again it would seem to be something measurable vs. noticeable....

 

[pcnj50a]

Besides excess noise (that is, noise above and beyond the Johnson noise), carbon comps have more nonlinearity (voltage coefficient of resistance) than metal film or wirewound. Enough to hear? I'm skeptical. But excess noise can definitely be an issue if used in the wrong circuit position.

 

[ranjam]

Resistors don't have a sound per se, but self taught tube 'experts' concluded the resistor type had to make a difference since everything else was identical in a reissue amp, but the tone wasn't identical.
Remember when it was the cloth covered wire? You could even buy 'reissue' cloth wire.
If you like the sound of bacon frying on top of your guitar playing, get carbon comp resistors. Mmmmm, bacon! One way around that is to use maybe 2-watt Plate load resistors, as Matchless did.
Every expert concludes it is a certain part; the capacitor type, the resistor type, point-to-point vs. a PC board, whatever. When you're busy focusing on each leaf of the tree, never mind the tree itself, you miss the forest. But think about Allen-Bradley or any resistor maker. Did they advertise their resistors made redder reds on your TV? Did they say they used only the finest carbon? Buy what you want, but don't expect any difference that you can hear.

 

[drumslinger]

I just use what i have in stock when building tube amps. I have amps that use all CF, CC, MF or a mix of all 3. I measure each component before solder hits it and haven't had a problem with noise issues. Noise issues is due to the resistors drifting too far and sometimes age which makes the circuit unstable.

 

[ranjam]

Noise is the result of thermal agitation and the instability of the resistor. Sometimes for fun (I am a very lonely man) I'll meter a CC resistor, and then take my soldering iron to the body. Not enough to scorch the poor resistor, but just enough to get the body toasty warm, like it was in a tube amplifier absorbing a lot of heat from the tubes. A lot of times the value changes all over the map. So I don't use that resistor as a Plate load. If it seems stable, I'm good to go. But 1/2-watt CC resistors are the worst for drift, and 1-watt or 2-watt are a lot better. I believe I read somewhere in an interview with Mark Sampson (Matchless) that this is why they used 2-watt Plate load resistors.