Blend Pots, what are they and how many kinds are there?

[trickster1234]

Hi......new here~ I was wondering what are blend pots and what do they do?

[Jazz P Bass]

The context that you want to apply a 'blendpot' was not specified.
Usually the term is applied to two pickups.
The potentiometer is a 'dual ganged' type.
There are two pots on one shaft.
Turning the shaft turns both controls.
The pickups can be wired up so the blendpot acts like a balance control.
Link: STEWMAC.COM : Blend Pot Wiring Free information

[eschertron]

+1 to what JazzP said regarding the application. There are other pots out there, but they do essentially the same thing. The blend pots offered by stewmac look like the right choice for someone modding their guitar (something I am thinking about doing.. which is why I dropped in on this thread.. so great link!). If the idea is to use it in an audio mixing application, be advised that the pots from stewmac - if fed two identical signals - will give the summed output a +3dB boost at the mid position. Probably not an issue for the majority of applications.

[big_teee]

These look like a good deal.
They are small, and would fit lots of places.
http://www.tubesandmore.com/products/R-VBM2
T

[eschertron]

and the maker has an app note for guitars HERE

[Mark Hammer]

Blending can be achieved in reciprocal and non-reciprocal fashion. "Reciprocal" would imply that the more you add of A, the more you take away of B, and vice versa. It does not provide any mean of having mostly A, and almost as much B. "Non-reciprocal" would permit a mostly-A/B-with-some-of-the-other-thrown-in.

The textbook case is channel-to-channel balance on a stereo. Usually, in those instances the "Balance" control has its wiper going to ground. With identical resistance on each side of the wiper, the balance pot provides the same amount of attenuation (bleed to ground) on one side as the other, when centered. Moving it in either direction introduces more attenuation for one channel, and less for the other.

As others have noted, such reciprocal blend pots can occur in different ways. One form is the bleed-type I just described. Another is the opposite-functioning volume pot, that jazz p bass described. Given that log pots (the preferred type for volume controls) are not always matched for taper, such dual-ganged volume pots are rarely all that precise. They're not way off, mind you, but they may be difficult to nail a desired blend with, when the tapers of the two sections are not perfectly complementary. In some respects, the bleed-type linear pot can be easier to work with and more precise, since there is only one pot involved.

The textbook non-reciprocal balance is the traditional dual volume tone controls on a 2-pickup guitar. Within limits, turning down one pickup, when both are on, does not impact on the other pickup. It is possible to have 100% neck and 70% bridge, for example. Both pickups are combined at the output, in the "blend" that one has opted for.

The plus side to this is that ANY blend can be achieved, and pot taper matching is a non-issue. The down-side is that it takes two pots/knobs, and requires more actions by users to set things just right.

[eschertron]

@Mark,
I'd like to learn more. Can you provide links or drawings for these applications? Thanks.

[big_teee]

Blending can be achieved in reciprocal and non-reciprocal fashion. "Reciprocal" would imply that the more you add of A, the more you take away of B, and vice versa. It does not provide any mean of having mostly A, and almost as much B. "Non-reciprocal" would permit a mostly-A/B-with-some-of-the-other-thrown-in.

The textbook case is channel-to-channel balance on a stereo. Usually, in those instances the "Balance" control has its wiper going to ground. With identical resistance on each side of the wiper, the balance pot provides the same amount of attenuation (bleed to ground) on one side as the other, when centered. Moving it in either direction introduces more attenuation for one channel, and less for the other.

As others have noted, such reciprocal blend pots can occur in different ways. One form is the bleed-type I just described. Another is the opposite-functioning volume pot, that jazz p bass described. Given that log pots (the preferred type for volume controls) are not always matched for taper, such dual-ganged volume pots are rarely all that precise. They're not way off, mind you, but they may be difficult to nail a desired blend with, when the tapers of the two sections are not perfectly complementary. In some respects, the bleed-type linear pot can be easier to work with and more precise, since there is only one pot involved.

The textbook non-reciprocal balance is the traditional dual volume tone controls on a 2-pickup guitar. Within limits, turning down one pickup, when both are on, does not impact on the other pickup. It is possible to have 100% neck and 70% bridge, for example. Both pickups are combined at the output, in the "blend" that one has opted for.

The plus side to this is that ANY blend can be achieved, and pot taper matching is a non-issue. The down-side is that it takes two pots/knobs, and requires more actions by users to set things just right.

I thought most of the above was accomplished by 2 vol. controls, like in the J-Bass.
You take out one of the volumes, and put in the blend.
It should be full on both at the middle detent position.
Am I missing something?
T