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New synth potentiometers: unintended consequences?
Old 8th August 2020
  #1
Gear Maniac
 

Question New synth potentiometers: unintended consequences?

I'd like to replace all of the pots in my Pro-One for higher quality ones, but it's got me thinking. Since this synth has pots that are in the middle of the actual synth circuitry (no patch memory), would changing all of them out throw off other things in the system?

The factory installed Centralab pots are supposed to be 100k but I don't think they are close to 100k in real life, so replacing all of them would likely result in significantly different resistance everywhere there is a pot.

Technical reference: http://www.musictechnologiesgroup.co...cal_Manual.pdf
Old 9th August 2020
  #2
Here for the gear
 

Raid,
I don't know the tolerance on the pots used in the P1, they are typically +/- 10-20%.
Changing out all the pots may alter a sound that you had previously set-up (pots may need to be slightly +/_ from the previous position for that sound).
The overall range of individual pots may also be slightly different, but this would be the case with all P1s as they are each a collection of pots with variations as to each pots actual spec. Maybe someone with more knowledge can shed more light on this.
Old 9th August 2020
  #3
Gear Maniac
 

Quote:
Originally Posted by yesman View Post
Changing out all the pots may alter a sound that you had previously set-up (pots may need to be slightly +/_ from the previous position for that sound).
This makes good sense, but I'm not worried about this as much as I am about any circuitry "downstream" from the pots getting wrong voltages or something. I know very little about electronics but I imagine the whole thing is like a big system where if you change a little something in one place it could end up making other things in the system start working differently, especially since I'd be making many changes to this synth and not just one (there are something like 28 or 32 pots).

But the thing you pointed out about tolerances also makes me think that the engineer who designed this would have expected these to not be exactly 100k every time.
Old 10th August 2020
  #4
It would be wise to make sure the replacement pots have the same taper as the originals. The common tapers are linear and log (AKA audio taper). They do not interchange well.
Old 10th August 2020
  #5
Gear Maniac
 

Pro-One pots are linear, are there any other relevant specs to observe with regard to pots?
Old 12th August 2020
  #6
rez
Lives for gear
 
rez's Avatar
Hello!

One thing to look out for is the turning resistance or "feel" of the pot - some of them turn real easy with virtually no resistance and others have that "buttery" turning resistance that makes them feel "expensive".
The second thing that can differ is the turning angle - while most of the pots come in 270° there are other angles out there, so beware.

The other thing as was mentioned above is the tolerances - some pots have 20% tolerance and that can be a lot depending on the circuit in kontext and what values are resulting in moving the pot to different positions.

In some of the circuits it might do not much harm if the tolerance is big and the absolute pot resistance values differ over the way of the pots travel, but in other circumstances it might be noticeable.

For instance if you have a pot and lettering with values on your device it might happen that the new pot is diverting from those letterings and is now showing a wrong position on the legend for a particular value.

If there is no lettering with absolute values this could be no problem at all, because then only relative values are shifted a bit. In this case you might have to set our pots slightly off to get the same settings as before.

To minimize that problem you first should measure all of your old pots for two values: overall resistance and the resistance in the middle position.

Now you could select new pots based on that measurements and come close to the original values. Handpicking of components is often the best way to get to a certain goal with tight tolerances, because as mentioned above those tolerances add up and then the whole circuit can be out of whack.

peace, rez
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