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Blender Pot From Stewmac Etc : What Taper


lvs
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Hi everybody, I wonder if you can help me with the following.

A few days ago I adressed a question to several guitar electronics suppliers about the exact taper of the so-called blender pot, which consists of two stacked pots each to be connected to a pickup, so it's possible to have a panning control instead of a traditional 3-way selector. Only from Stewmac I got an answer but it didn't help me much further... I already knew that the pots are mirrored and they have zero resistance over 50% rotation.

Here's an example.

What I would like to know is which of the following diagrams depicts this pot's taper. The guy at Stewmac said it's Log but that still leaves a choice between diagram b and c. If you're not sure yourself, please don't post a guessing answer... thanks.

blender.gif

If anyone has such a pot and a multimeter lying around, you're invited to do the following measurement and post it here :

- Set multimeter to resistance measurement.

- Connect one probe to a middle lug, other probe to a corresponding outer lug, doesn't matter if it's the CW or CCW.

- Measure resistance at 0 - 1/4 - 1/2 - 3/4 - full rotation.

Those data are sufficient for me to determine what taper these pots have.

lvs

Edited by lvs
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The answer would be D: None of the above.

First, the audio would never taper off or end at the mid point; then you wouldn't have any sound/signal when you panned to the center position.

Instead, the Stew-Mac blend pots provide a flat 100% from one end of the sweep to the middle of the sweep, so that when you pan to the center position, you have 100% of each.

The closest diagram would be "C"... but you need to fill in the right side of the top bar and the left side of the bottom bar, to represent 100% signal out to the center position, with an audio log-curve decaying to the end from there.

D~s

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Wether the white zones should be black or not is actually not important, as long as it's understood they depict a zero resistance track portion over 50% rotation, while the black zones depict a logaritmically (or linear for diagram a) increasing resistance track over the other 50%.

Based upon experiences with single Log tapered pots, I don't agree that b is impossible. Just hooking the resistive lugs of b to ground and the non-resistive lugs to hot, would actually give a much smoother pan transition around the center detent than c, and disconnecting the resistive lugs from ground so that it becomes hooked up ala Fralin would even be better. But I read at various places that all the action of this pot concentrates around the center detent - in a completely passive circuit, well understood.

Edited by lvs
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...If you're not sure yourself, please don't post a guessing answer... thanks.

Well, that's nice - and then when somebody gives you the answer, instead of saying "Thank you", you're busy defending your diagrams. For the record, regardless of what anything in your little pictures represents, Dug gave you the answer - unless you didn't understand what he said, any further comment was unnecessary. Why are so many people so eager to bite the hand that feeds them?

Dug, much respect for your reply - I wish I had your restraint!

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