Old Resistors - any good?

[Jamiroking]

I'm not trying to start the mojo war but I have a question about resistors.

I have access to a bunch of old Ohmite carbon comp resistors from at least the 60s called Little Devils. I've read a lot of carbon comp vs metal and the only difference I've been convinced of is a a possible reduction in noise in the metal films. I'm building a Sunking, Serendipity, Sabretooth, Egodriver, Quadrovibe, and Neutrino. Should these be ok or should I just buy new ones?  I don't mind buying new ones since resistors are cheap

[madbean]

Nothing wrong with using them. It's more of a personal stylistic choice than anything. I have a bunch of those myself, and I throw them in builds from time to time.

[CRBMoA]

I've read a lot of carbon comp vs metal and the only difference I've been convinced of is a a possible reduction in noise in the metal films.

IIRC, at the voltages we are running through our pedals, this is a non-issue. Possibly an issue with inductance or some other phenomena (it's past my bed time), but at amp voltages, not at 9V.

The greater issue might be the physical size of the comps.

[druz15]

yeah screw trying to fit those big carbon comp ones onto a little PCB, although I suppose you could just have them going vertically if you had enough room in the enclosure, but from memory the legs on them are real thick, at least the ones I used in my Plexi build were fat as, so you'd need to drill bigger holes

[bigmufffuzzwizz]

I really want some of those Ohmite Little Devil resistor draws. They look soo cool!! Keep those resistors for vero/perf/turret builds and make your vintage clones look "vintage".

[gtr2]

You could always sell em 

I'm game!

[Jamiroking]

We have one of these cases sitting around work. I'm sure no one would mind if I used a few for my builds but if I start selling them, I think that might be over the line 

Looking at them, they look like they should fit just fine. They're about the same size as the metal films I used last time. This time around I have a DMM though and checking them, they really seem to have earned their 10% tolerance marking. Last time I was a noob and just bought 1% and didn't bother measuring. Using these 10%, how close is close enough with the values. For example, the closest 1M I could find actually had a 1.04M reading. Am I splitting hairs here or is that too big of a difference?

[bigmufffuzzwizz]

Those are the ones I want. They are on ebay all the time for about $10 bucks a drawer and they usually come with NOS resistors, the Allen-Bradley ones. 1.04M would be about 4% tolerance so that's not too bad. 1.1M would be 10% tolerance.

[stecykmi]

10% is well within reason for most builds. For one, 10% anything in the audio realm is nearly impossible to pick out (ie 10% louder is almost indistinguishable), and if you use a few of them, the 10% averages out to about to listed spec (ie -10% with +10% averages to 0% difference).

I wouldn't bother checking them for precise values, only to check they're not dead.

[bigmufffuzzwizz]

10% is well within reason for most builds. For one, 10% anything in the audio realm is nearly impossible to pick out (ie 10% louder is almost indistinguishable), and if you use a few of them, the 10% averages out to about to listed spec (ie -10% with +10% averages to 0% difference).

I wouldn't bother checking them for precise values, only to check they're not dead.

Are you saying that old resistors can go bad or make sure they're not duds?

[stecykmi]

10% is well within reason for most builds. For one, 10% anything in the audio realm is nearly impossible to pick out (ie 10% louder is almost indistinguishable), and if you use a few of them, the 10% averages out to about to listed spec (ie -10% with +10% averages to 0% difference).

I wouldn't bother checking them for precise values, only to check they're not dead.

Are you saying that old resistors can go bad or make sure they're not duds?

no, resistors are fairly stable, i think. but if you were going to individually check every component, it would be a waste to throw out examples that were "out of spec". i would probably never do it myself cause i'm pretty lazy.

[bigmufffuzzwizz]

And if you think about it, out of spec means it could be used as another value..it make tracing a nightmare though 

[Jamiroking]

And if you think about it, out of spec means it could be used as another value..it make tracing a nightmare though  Smiley

I was thinking of doing this but was mostly wondering how off it needs to be for me to consider it "out of spec" for my boards

[bigmufffuzzwizz]

I was thinking of doing this but was mostly wondering how off it needs to be for me to consider it "out of spec" for my boards

Not sure completely what you mean, but I would consider past 10% out of spec. I'm not saying it's not useable but I feel like you almost have another value at that point. A 10K resistor 20% out of spec could replace a 8.2K resistor in theory. I wouldn't do this with modern day carbon film resistors that cost a penny, only something fun like the AB Carbon Comp resistors like what you have here.

[Jamiroking]

Thanks a lot, that makes sense. I just didn't know how much of a change to the circuit I was making with each percentage off.