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potentiometer in-accurate values
- Thread starter dudeonthebass
- Start date
- Aug 5, 2005
- 7,243
- 92
- Disclosures
- Endorsing Artist: J.C. Basses
Yep. That's the truth of it.
I believe there are a couple companies that can promise a 5% tolerance or so. If it matters that much to you, look there, or buy a bunch of pots and pick the ones that are closest to 250k, return the rest.
I believe there are a couple companies that can promise a 5% tolerance or so. If it matters that much to you, look there, or buy a bunch of pots and pick the ones that are closest to 250k, return the rest.
they're CTS pots, and its supposed to be +/- 20%
There is solder on there, so would that affect the reading on my multi meter ?
There is solder on there, so would that affect the reading on my multi meter ?
Hi.
As said before, perfectly normal.
If You disassemble a regular carbon track potentiometer and take a look at the track, you can easily see (/test) why the resistance varies so much. Scrape a bit of the resistive material off from one end or from the side of the track and You'll see an immediate result in an ohm-meter.
In certain circles fine tuning potentiometers was (is?) a fad.
Regards
Sam
As said before, perfectly normal.
If You disassemble a regular carbon track potentiometer and take a look at the track, you can easily see (/test) why the resistance varies so much. Scrape a bit of the resistive material off from one end or from the side of the track and You'll see an immediate result in an ohm-meter.
In certain circles fine tuning potentiometers was (is?) a fad.
Regards
Sam
- Aug 5, 2005
- 7,243
- 92
- Disclosures
- Endorsing Artist: J.C. Basses
I deal with hundreds of CTS pots and those values are certainly possible although I don't see too many as low as 218K. 225K to 270K seems to be the normal range. It is fairly easy to take the pot apart and adjust the value. It can be done as shown in the tutorial or I just do it using a little bit of steel wool and an ohmeter. I have done so many that I have it down where I can do it in about a minute!!
The value of the pot is essentially set by the total volume of the resistive material that is screened into the circular track around the edge of the PCB material. If you scrape or cut some away, this reduces the volume, and increases the resistance. On higher end pots with 5% tolerance, you can actually see a thin line where the material is trimmed with a laser.
The caveat with this is that you can only go UP in value, as you cannot add material.
All in all, it is doubtful anyone can hear the difference anyway between say, 220 and 270K.
The caveat with this is that you can only go UP in value, as you cannot add material.
All in all, it is doubtful anyone can hear the difference anyway between say, 220 and 270K.
It can be done either way, if the wiper is maxed and you read the wiper to the outer lug it will read within a few ohms of what you will read across the outer lugs.
On a bass I see where this might be true, on a guitar you can absolutely tell the difference on a 50K spread. Pot values can be a great fine tuning tool for your tone, but in all honesty you have to have a good handle on where your tone is currently at and where you want it to go or it is probably wasted effort.
Can't spare a couple of bucks?
I don't mean to be rude, but I've never heard anyone ask where was the cheapest place to buy potentiometers.
I can afford them, but then buying 30-50 pots it gets pricey I would like to try to cut my cost where ever I can.
