Resistor

Manfred-Klose

Seeing that we dont have such a topic yet, i'll start it.
Reading the Capacitor thread, thought this might turn out interesting.

Found this link, going into detail with resistor noise:
http://www.aikenamps.com/ResistorNoise.htm

What type of resistors would you recommend for overdrive/distortion circuit pedals?

matta

Rule of thumb for me is 90% of the time to use 1% Metal Film, it is has lower noise (thermal) & better accuracy.... period.

As Aiken shared the best for accuracy and low noise are wire wounds, but their size and limited range of values makes them unusable in many applications. MOST commercial guitar pedals use 5% carbon film because they are half the price... but when building your own the difference is R0.05 for CF vs R0.11 for MF... it is worth spending the extra cash...

I'm a big fan of using carbon-film in amps, which I think is a good compromise and cost effective solution for using carbon composite, which are expensive and can be VERY noisy.... even boutique guys like Dr. Z are using carbon film over carbon comp for similar reasons.

I think there is a MOJO factor in using carbon in valve amps, yes it is noise as Aiken pointed out, but it still sounds musical to my ears, but I'd keep the power resistors as metal film, no need for them to be carbon.

Since you asked particularly about overdrive/distortion pedals, I'd STILL go with 1% Metal Film to lower noise, it is going to get noisy enough, you don't need the resistors adding MORE noise to the equation... a circuit is always the sum of it's parts.

I hope that helps ???

Matt

Manfred-Klose

Thanks.

Was just curious because i never used wirewound resistors before, but i'll stay with metal film for now.

How would the power rating of a resistor affect its performance?
Would it be better to get a higher power rating for less resistor noise?
(Not pedals in particular, just overall)

Gearhead

HOW it would affect its performance is thermally: more power rating = lower temperature increase = less resistance increase.

Remember: resistance is futile ?

matta

Exactlly, but using a 2 or 5 Watt resistor in a stomp box is... well silly ?

I suggest using 1/4 watts, you could use 1/8 Watt if you want and some do, but physically 1/4 is bigger, therefore less contact noise.

Matt

Manfred-Klose

thanks guys.

MikeM

Contact noise?

FenderBender

@Mike: http://www.aikenamps.com/ResistorNoise.htm

MikeM

Thanks G ?

Applauded.

FenderBender

LOL I often miss links ?

Trippp

Just read through that link ... love the catch22 in the "low noise design" tips:

(1) Keep resistance values low, because thermal noise is directly proportional to resistance value.
....
(2) Keep the DC and AC currents to a minimum because contact noise is proportional to current.

V= IR ... V is a fixed, so if you use low value resistors (as prescribed by 1), your current will increase, if you try to please 2, you need to use higher value resistors, thereby breaking rule number 1 ... hehehe

So you have to choose ... thermal noise or contact noise ... which will it be ?