Pot -> Elma Question

[MrG]

Hey All,

I’m converting a pultec from having pots to Elma switches, and I have some basic questions about converting the wiring.

The Elma is constructed for this exact purpose by a pro, and labeled with In, Out, and Ground.

Some of the pots use two of three tabs, others use all three.

Which tabs are equivalent to which labeled points on the Elma? Is the middle wiper tab Ground, or Output? And then do the outside tabs not matter - one is In and one is Ground/Output?

Sorry for the pedantic question, but I’m finding little direct explanation for this as I search.

Thanks,
MG

 

[andow]

If "the Elma is constructed for this exact purpose by a pro", then he should provide you with all the info you need to replace the potentiometers.

The labels In/Out/Ground don't really make sense, because the connections are dependent on what function the pot serves in the circuit.

But if I had to take a guess: with the shaft pointing at you and the pins facing down, Ground-Out-In from left to right.

 

[MrG]

Thanks, andow. And of course, you’re definitely right. I’m both waiting for them to clarify, and also hoping to understand more of the logic behind this in the meantime.

Understood that the design will determine what is what, so I’ll hang tight for that from the supplier.

Thanks!
M

 

[ruffrecords]

One thing you need to know about the pots in a Pultec is that some are a LIN law and other are LOG. In addition, the actual law required to get even steps is neither LOG nor LIN but can be calculated from the schematic (or more quickly via simulation). If you just want repeatability,. use LOG and LIN as required. If you want equal dB steps its a whole new ball game.

Cheers

Ian

 

[MrG]

Thanks for this, Ian! Definitely here you and will keep in mind.

Thanks!
Mark