Does it Exist? A Dual Pot with Log & Rev. Log Tapers?

[Alexo]

Hi Everyone, hope you're well.

I'm working on a design that really wants a "blend" control - basically a stereo pot that turns "up" on one set of lugs while turning "down" the other, and vice versa. The catch is that it needs to be an audio taper pot, which means half of the pot has to have a reverse audio taper, while the other half should just be a normal audio taper, around 500K on each side.

Anyone ever run across one of these? If not, can anyone recommend a good custom pot-maker?

Thanks very much for your time!

-A

[M Fowler]

Guitar player magazine ran a built for the Fender Bassman using a blend control but it had two pots I believe. It was called the bluesmaker by John McIntyre. I have the article and schematic but need to get better copies made.

Mark

[paulster]

You could check out what taper they use for 'balance' pots in hifi units.

I believe these are log taper to the centre detent and then a staight track, and mirrored on the other pot, so that you get 0dB in the centre.

It does mean that neither of the two pots will keep increasing level past the centre point, but could probably work well as a blend.

[benoit]

If you find a body for it that can be taken apart you could sub in the correct resistance/taper wafers.

[Alexo]

Thanks for the advice, guys. I have looked into the balance controls, and while they aren't completely ideal, that sort of thing could work pretty well. However, a commercially available balance pot seems just as hard to find as a stereo log/rev log pot. I'll hopefully find some time to pry some dual pots apart tonight and see how that goes.

[Aurora]

You can "synthesize" a dual log/reverse log to some extent by using a dual gang lin pot of higher than spec'ed value, and tying fixed resistors from the wiper to the resp. end point. A resistor from the bottom end to the wiper gives an appx log taper, and tying the resistor from the wiper to the top end gives an appx reverse log. Some experiments might be necesseary, though. The parallelled value of the pot section and the fixed resistor should together be set for the original pot value you want. Combined log/reverse log is a strange animal by all accounts, and was never easily available.
Hifi balance pots should be fairly easily available. Have you checked Digikey, Mouser etc?

[DonMoose]

One of these?

[M Fowler]

Check these guys out they offer custom pots to your order in metal or plastic.

Mark

http://www.potentiometer.com/series70.c ... 0709173251

[Sonny ReVerb]

Check out RG Keen's 'Secret Life of Pots':

http://www.geofex.com/Article_Folders/p ... tscret.htm

He covers converting linear taper to log or reverse log pretty well.

[drz400]

Hi Everyone, hope you're well.

I'm working on a design that really wants a "blend" control - basically a stereo pot that turns "up" on one set of lugs while turning "down" the other, and vice versa. The catch is that it needs to be an audio taper pot, which means half of the pot has to have a reverse audio taper, while the other half should just be a normal audio taper, around 500K on each side.

Anyone ever run across one of these? If not, can anyone recommend a good custom pot-maker?

Thanks very much for your time!

-A

You can use linear
You can also feed it with buffered signals and just use a single pot
You could also play with Pan pots made for Bass guitars, in the center they have 100% signal from both inputs
You can also build one using CTS parts
Not knowing your exact application makes it difficult

[Alexo]

Thanks again, guys. I may try out the single linear pot with either channel hitting the outer lugs...