Hi guys,
I'm trying to model an equalizer circuit in LTspice and ran across a schematic symbol that I'm kind of unsure of. Can someone advise what kind of pot would be used here for R121 and R122? It almost looks like the center tap is grounded? 😕
Thanks!
I'm trying to model an equalizer circuit in LTspice and ran across a schematic symbol that I'm kind of unsure of. Can someone advise what kind of pot would be used here for R121 and R122? It almost looks like the center tap is grounded? 😕
Thanks!
An externally hosted image should be here but it was not working when we last tested it.
That's exactly right, often used in graphic equalizers so as to effectively take the band out of circuit if it's centred
The tap (probably) ensures the action is zero when the knob is dead-center, not offset by pot track slop.
Since your SPICE pots are perfect, you can ignore this.
Since your SPICE pots are perfect, you can ignore this.
Thanks everyone - that makes more sense. And I found that the circuit does function a little differently if I leave them off, for example the low shelf occurs at -1.3 dB without the center grounded, but with it grounded the response is completely flat.
In the real world, what kind of pot would I use for this? It's called out as 100 KW, so does that W indicate a center detent? I dig around on Mouser quite a bit but couldn't come up with something that looked like it had the center gounding feature built in.
Just in case anyone is curious, this is the Rane bass/treble EQ from the 1991 patent.
Thanks!
In the real world, what kind of pot would I use for this? It's called out as 100 KW, so does that W indicate a center detent? I dig around on Mouser quite a bit but couldn't come up with something that looked like it had the center gounding feature built in.
Just in case anyone is curious, this is the Rane bass/treble EQ from the 1991 patent.
Thanks!
100k linear pots.
I think the grounded part is the pot body.
They do that in guitars to reduce hum.
I think the grounded part is the pot body.
They do that in guitars to reduce hum.
It is a pot with center tap. Unlikely you will find them on the shelf anywhere but Rane.
You could CALL Rane and ask if they still have any. That was a very long time ago, but you never know.
Shielding would have been represented by a dashed line around the part with a ground connection to the dashed line. Similar to how shielded cable is represented.
Most pots and sliders are made custom for OEMs. IF Rane wanted a tapped slider like that, they specified it, and Alps or whoever made them up. If you get an Alps catalog, you will find it describes how to make up a part number for them to make, it doesn't show stock numbers for already made stuff.
You could CALL Rane and ask if they still have any. That was a very long time ago, but you never know.
Shielding would have been represented by a dashed line around the part with a ground connection to the dashed line. Similar to how shielded cable is represented.
Most pots and sliders are made custom for OEMs. IF Rane wanted a tapped slider like that, they specified it, and Alps or whoever made them up. If you get an Alps catalog, you will find it describes how to make up a part number for them to make, it doesn't show stock numbers for already made stuff.
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