CTS pot specs

[Dwightlud]

I recently discovered four CTS 500k pots in the bottom of a box of parts in my basement. I recall that I bought them from a friend back in the late '70's. I ran the codes on them and discovered that they are from the mid 60's. I checked them with my multi-meter and found that they were all on the high side of 500k ( 577, 680, 670 and 715). My question is; do these specs negatively impact the way these pots perform and/or their value? I know just enough about electronics to be dangerous, so any insight will be appreciated.

[The Dude]

Welcome to the place!

Keep in mind this is just my opinion.

1) There is little or no "vintage" value for pots.
2) If I were looking to purchase pots, I wouldn't be interested in old parts, because it's likely there's corrosion and other potential problems. If I'm going to buy something, I'd buy it new.
3) Make sure your multimeter is zeroed and that you dig into the contacts with your probes. I haven't seen CTS pots that far off in value. That doesn't mean it's not possible.
4) Your readings may or may not negatively impact performance. It will depend on what they are to be used for and how critical tolerance is in that particular circuit. It will also depend on if the wiper still operates smoothly and without noise.

[Leo_Gnardo]

1) There is little or no "vintage" value for pots.

Local Craigslist has the same guy trying to sell his 4 'vintage' CTS pots for $25, been going on over 2 years, no sale. Proof enough!

Only if someone were looking for "proper year" marking to match a vintage amp or instrument - somehow we never run across that guy...

[Justin Thomas]

The 577k, I'd use in a customer's amp no problem, <IF> the taper was correct, it didn't make noise, turned freely, passes all the tests The Dude mentions, etc. The others I would use in a personal amp, where I can easily replace it or mark it's actual value, etc. I can think of times where I would have really liked some extra wiggle room on pots...

As far as value, I think the 577 is within spec for most pots/resistors (20%) of the time. If it were tested thoroughly, I'd pay maybe a dollar more than a modern equivalent, if I needed it to date-match a vintage amp and IF the customer wanted it.. The others are what I would call out of spec, though if they were tested for function as above, I'd pay half the market value of a new equivalent. Just be sure tobuse clip leads for testijg - no solder allowed. Otherwise it's "used."

Justin

[big_teee]

I always go through my guitar pots, and pick and choose which ones I use where.
If I need brighter or darker I sort them accordingly.
I just read them with a meter, outside to outside.
The 577k would be a great choice for a muddy neck bucker!

[Dwightlud]

Thanks everyone, for the response. It sound like my best option is to try these out. I have a couple of guitars I use to "experiment" on, so I will drop them in and see what happens.

[David King]

Keep in mind that sometime between then and now CTS moved all production to China. More important to me would be the smoothness or gradualness of the taper. I don't think the value matters much in most passive guitar situations.

[Mick Bailey]

Manufacturing tolerance on older parts could be quite wide +/- 20% maybe on pots. Even new manufacture can be off - I just measured some new Alpha 47k pots at between 50k and 52k (I guess the target on those is +/- 10%). There aren't many guitar/audio applications where a pot needs to be an exact value. Most of the time if a piece of equipment is working you wouldn't set about measuring the value of each component. If you did you may be surprised how far out everything is.

[Steve A.]

I question the accuracy of the meter. I usually measure pots before I install them or after I take them out and when they are off 5%+ more likely than not the measured value is lower than the rated value. Not that I have conducted extensive tests on them...

Steve

[J M Fahey]

Today's acceptable pot tolerances are +/- 20% , go figure; way back then even the 700k one might have been acceptable.
Remember cheap ceramic caps often used in tone controls might have had +50/-30% tolerance , so actual tone control frequencies easily were quite far from calculated.

This explains why you try , say, 5 Blacface Fenders, same model and vintage and all 5 sound different.

Now you know why

So if you only have those pots in your parts box and happen to need one, please do, no worries.

In most circuits (there are exceptions) , ratio matters much more than actual "full scale" value.