Figuring Out a 1 Volume and 1 Blend Setup (instead of a 3 way switch).

[jasburbak]

I am trying to figure out a setup in which I wire 2 single coil pickups / 1 volume / 1 blend.

The blend pot acting as a 3 way switch at both extremes (100% Neck at one end, 100% Bridge at the other).
Both pickups on at center detente, and a blend of both pickups at various in between turns of the sweep. (25% Neck, 75% Bridge - etc.)
There will be no Tone or 3 way switch/blade.

What I have on hand are the alpha mini pots "Fender Alpha 250K solid shaft balance/blend/pan pot" with M/N taper.

What I don't have is a reliable diagram as to wire this setup. And a few questions to those with better understanding of such circuits:



1. As far as I understand, Source A and Source B are the hot wires from pickups 1 and 2. I am confused as to what I've indicated as the two red arrows. Where are these grounded to exactly?

2. Which connection made would enable series in the middle position? Which would enable parallel?

3. I've read on some threads regarding a reduction in output with such a setup, why would that be so, if true?

4. There is some idea regarding ungrounded and grounded blend pots, with regard to enabling a full isolated pickup output on both extremes, a bleedthrough of either pickup on both extremes, a drop in output in the center detente position, etc.. anyone with a better understanding perhaps simplify what grounding vs ungrounding achieves?

Appreciated.

[Justin Thomas]

I thought a Jazz Bass is 2 Singles, 1 Volume, 1 Tone, 1 Blend?

Justin

[jasburbak]

I thought a Jazz Bass is 2 Singles, 1 Volume, 1 Tone, 1 Blend?

Justin

Jazz Bass's are 2 Volumes and 1 Tone, if I recall correctly.

[Justin Thomas]

Ah. That sounds right. Sorry!

Justin

[bbsailor]

I am trying to figure out a setup in which I wire 2 single coil pickups / 1 volume / 1 blend.

The blend pot acting as a 3 way switch at both extremes (100% Neck at one end, 100% Bridge at the other).
Both pickups on at center detente, and a blend of both pickups at various in between turns of the sweep. (25% Neck, 75% Bridge - etc.)
There will be no Tone or 3 way switch/blade.

What I have on hand are the alpha mini pots "Fender Alpha 250K solid shaft balance/blend/pan pot" with M/N taper.

What I don't have is a reliable diagram as to wire this setup. And a few questions to those with better understanding of such circuits:



1. As far as I understand, Source A and Source B are the hot wires from pickups 1 and 2. I am confused as to what I've indicated as the two red arrows. Where are these grounded to exactly?

2. Which connection made would enable series in the middle position? Which would enable parallel?

3. I've read on some threads regarding a reduction in output with such a setup, why would that be so, if true?

4. There is some idea regarding ungrounded and grounded blend pots, with regard to enabling a full isolated pickup output on both extremes, a bleedthrough of either pickup on both extremes, a drop in output in the center detente position, etc.. anyone with a better understanding perhaps simplify what grounding vs ungrounding achieves?

Appreciated.

jasburbak,

Here is something I discovered by tinkering.

Traditional volume controls attach the pickup ground to the lower lug and the pickup hot lead to the pot upper lug. The pot output is taken from the center lug but this has one bad effect. When both pickups are wired this way, when using both pickups, adjusting either volume control adjusts the volume for both pickups. Here is a simple wiring variation to try that will allow you to have independent volume control. Wire the pickup ground to the lower lug (like before). Put the hot pickup lead to the center lug and now take the output from the top pot lug going to the pickup switch.

Here is the best thing from using this setup. Put a DPDT phase reversal switch on one pickup. Now when you use both pickups and put one pickup out of phase, you can adjust the volume control on either pickup about one tenth of a turn and have a variable out of phase effect with some interesting tonal effects totally passively, no other electronics needed. I have done this for a guitarist in the Atlantic City NJ area and he likes it. Other guitarists approach him and comment about his unique sound. If you try this and like it, try using pots with twice the resistance value for a little better effect.

Now I am sharing this simple wiring change that I discovered with MEF members.

Joseph J. Rogowski

[jasburbak]

Ah. That sounds right. Sorry!

Justin

Hey no problemo

jasburbak,

Here is something I discovered by tinkering.

Traditional volume controls attach the pickup ground to the lower lug and the pickup hot lead to the pot upper lug. The pot output is taken from the center lug but this has one bad effect. When both pickups are wired this way, when using both pickups, adjusting either volume control adjusts the volume for both pickups. Here is a simple wiring variation to try that will allow you to have independent volume control. Wire the pickup ground to the lower lug (like before). Put the hot pickup lead to the center lug and now take the output from the top pot lug going to the pickup switch.

Here is the best thing from using this setup. Put a DPDT phase reversal switch on one pickup. Now when you use both pickups and put one pickup out of phase, you can adjust the volume control on either pickup about one tenth of a turn and have a variable out of phase effect with some interesting tonal effects totally passively, no other electronics needed. I have done this for a guitarist in the Atlantic City NJ area and he likes it. Other guitarists approach him and comment about his unique sound. If you try this and like it, try using pots with twice the resistance value for a little better effect.

Now I am sharing this simple wiring change that I discovered with MEF members.

Joseph J. Rogowski

Joseph,

Thanks for this novel approach, the only problem is; I'm quite confused

Is this for a 1 Volume / 1 Blend setup? or for a 2 Volume setup, as you said:

when using both pickups, adjusting either volume control adjusts the volume for both pickups

When describing as the upper lug and lower lug, are we talking about the top and bottom lugs as per the dual gang nature of blend pots? or as in the lugs that are to the left and right of the center wiper lug? My apologies, the follow through went a bit over my head

[bbsailor]

jasburbak,

I was offering an alternative to your illustrated pickup wiring using two independent volume controls wired differently and a selector switch, as I described.

The pots I am talking about are the traditional 3 lug pots with the center being the wiper used as individual volume pots. This approach is designed for a 2 volume pot setup but when two pickups are on you can independently set the volume of each pickup. When you change the phase of one pickup, when both pickups are on, you get another effect of having a variable notch-like effect but with only a small turn of either pot. I hope this helps you experience the unique setup. Let us know if you try it?

Joseph J. Rogowski

[Fluoroscope 5000]

Good plan. I'd stick with 250k pots for more subtle control. Higher value pots will require smaller adjustments for the same effect. Wire the pots so the pickups are on full when the knobs are at 0 for the best control.

[Fluoroscope 5000]

I am trying to figure out a setup in which I wire 2 single coil pickups / 1 volume / 1 blend.

The blend pot acting as a 3 way switch at both extremes (100% Neck at one end, 100% Bridge at the other).
Both pickups on at center detente, and a blend of both pickups at various in between turns of the sweep. (25% Neck, 75% Bridge - etc.)
There will be no Tone or 3 way switch/blade.

What I have on hand are the alpha mini pots "Fender Alpha 250K solid shaft balance/blend/pan pot" with M/N taper.

What I don't have is a reliable diagram as to wire this setup. And a few questions to those with better understanding of such circuits:



1. As far as I understand, Source A and Source B are the hot wires from pickups 1 and 2. I am confused as to what I've indicated as the two red arrows. Where are these grounded to exactly?

2. Which connection made would enable series in the middle position? Which would enable parallel?

3. I've read on some threads regarding a reduction in output with such a setup, why would that be so, if true?

4. There is some idea regarding ungrounded and grounded blend pots, with regard to enabling a full isolated pickup output on both extremes, a bleedthrough of either pickup on both extremes, a drop in output in the center detente position, etc.. anyone with a better understanding perhaps simplify what grounding vs ungrounding achieves?

Appreciated.

I'll answer what I can here.

1. The red arrows you added point to the tip and sleeve of the output jack. The sleeve is grounded to the back of the master volume pot. The tip is not grounded because it is the hot signal from the pickups.

2. The diagram is pickups in parallel. I don't know how to blend pickups in series. I guess you could send one pickup though one pot (via the hot input lead on one outside lug, the hot pickup lead on the other and the center lug going to one of the inputs on the other pot) into the other pickup on the other pot. You could then bring the output up of the first pickup into the second or something? I dunno.

3. I think the volume loss at center is because the blend pot is just two stacked linear pots. That means they are at half their total R at center. That means there is 125k resistance on either pickup at center for 250kpots. There will also be substantial high end loss unless you use a "Treble Bleed" on both pots. A parallel wired 80k R & 330pF C is good for an even response throughout the sweep with typical 2~4H inductance SC's, but your cable Capacitance will affect the result. A mid to low C cable is best.

4. I imagine that not grounding the two diagonally opposed pot lugs increases output at center because none of the signal is sent to ground, but there will still be half the pot R in front of the pickups. You may then want to wire resistors over the hot pickup lugs or the master hot lug to achieve the total desired R load. Neither pickup will ever be fully off in that case, but the signal will be be so low from the pickup with the max resistance in front as to be fairly insignificant. Remember to ground the blend pot casing, regardless.

That's the best I can do. Understanding the signal flow and how all the parts work is the key to figuring out any wiring scheme.