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A phase cancellation question


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My next bass build will have a 4-coil humbucker pickup, as outlined below. Assume that the coils are designated 1,2,3,4 in clockwise rotation starting at top left.

There will be a switching option allowing the following:

Full humbucking - all coils

"Single coil" - coils 1 and 2 active

"Humbucking single coil" - coils 1 and 3 active

 

 

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I am also considering a second pickup, as designed below.

What should the magnet orientation and winding direction for these coils be in order to avoid phase cancellation/reversal issues?

Thanks in advance.

 

fetch?id=31488631

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My next bass build will have a 4-coil humbucker pickup, as outlined below. Assume that the coils are designated 1,2,3,4 in clockwise rotation starting at top left.

There will be a switching option allowing the following:

Full humbucking - all coils

"Single coil" - coils 1 and 2 active

"Humbucking single coil" - coils 1 and 3 active

 

 

fetch?id=31488630

 

 

I am also considering a second pickup, as designed below.

What should the magnet orientation and winding direction for these coils be in order to avoid phase cancellation/reversal issues?

Thanks in advance.

 

fetch?id=31488631

 

Are they using the same magnet or separate magnets?

 

If its the same magnet, wind both in the same direction and use the same start/inside wind as positive and outer wind/end as negative.

This minimizes hum. You really don't get phase problems in side by side configs. You only get phase cancellation from two coils on the same strings and one has reverse polarity "and" has the same magnetic pole.

 

Hum cancellation occurs when you have a pickup that has both a reverse polarity and a reverse magnetic pole from another.

 

Since you're using essentially one Humbucker and one single you may have the single out of phase or non hum cancelling with one of the Humbucking coils no matter what you do. Luckily there should be enough space between the HB and singles to avoid too much phase problems.

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There are eight magnets in the top pickup and four in the bottom. The coils of the bottom pickup will be RWRP with respect to each other, so that one will be a humbucker. And yes, I'm primarily concerned about a phase issue between the two pickups. They will be separated by a fair distance, so it sounds like I shouldn't worry too much?

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You will only have phase issues if you wind the bottom pups reverse compared to one of the top ones.

 

For example, your north poles on the top are wound CCW (counter clockwise). If the bottom pickups are North poles, make sure they are wound CCW as well and you wont have any phase problems. (or you could reverse the electrical polarity of a CW wind)

 

If the bottom pickups are South poles, just wind them CW. (or reverse the electrical polarity of a CCW wind)

 

If you ignore the fact that you have two pickups side by side, this is no different then a Stratocaster setup that uses hum canceling. Strats can be North South North, or South, North, South and only the center pickup has the reverse wind and reverse polarity.

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In order for the bottom pickup to work the way I want it to, the two coils will have to be RWRP with respect to each other, so I can't orient the magnets the same way or wind them the same direction. This new diagram shows what I mean. This is what concerns me about the phase issue between the two pickups.

 

 

fetch?id=31489226

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In order for the bottom pickup to work the way I want it to, the two coils will have to be RWRP with respect to each other, so I can't orient the magnets the same way or wind them the same direction. This new diagram shows what I mean. This is what concerns me about the phase issue between the two pickups.

 

 

fetch?id=31489226

 

Since both the magnets and winds are reversed they are in phase. They will also be in phase with the upper pickup "BUT" they are in phase in a leap frog manor with the top pickup. I'm not sure how much tonal difference you will have because of that but I suspect it may be negligible.

 

Question. Are you connecting the two pickups together on the top vertically with a North and South? Or are you going to connect two norths and two souths together?

 

If you want Humbucking on the top left to right then swap one north and south around so you have N>S on the top row, Then S>N on thr bottom row. This should prevent any weird issues with two pickups on the same string. Otherwise wire them vertically with the north above, south below and wire them in series.

 

Again, You can swap the N & S around on the right so your other set is will have a uniform polarity.

 

 

N - S

S- N

 

N- S "Or" S - N

 

If you have N > N in series in your top example you wont have Humbucking but you shouldn't have phase issues between those two because they are on separate strings.

 

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The top pickup, as stated in the initial post, will have a switch to allow three combinations: all four coils; coil 1 and 2 (non-humbucking but technically "single coil"), and coil 1 and 3 (humbucking "single coil"). It is the addition of the second pickup that concerns me about phase cancellation.

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Your switching on the first has pickup issues. Running two north poles together provides no hum bucking so there will only be increased hum with no tonal benefits. Running 1&3 will have hum bucking but little tonal differences over 1&2 because the pickups are so close together on the strings.

 

I suggest you rethink your switching and go with a series parallel switching for the pickups. Series parallel has some major differences in tone and gain which is very useful. I have a series parallel switch in my precision bass for its two pickups and its a nice tone/gain option with side by side pickups. (or any humbucker for that matter)

 

Again, Running N&S for the top side by side, and S&N in the bottom row is the best option. Then you can switch the two rows from series to parallel for some nice tone options. Series or parallel with both north or south poles has no tonal benefits over a hum bucking config other then a first hand educational experience you'll get learning what does or doesn't work.

 

If you have to have them both north in one row and both south in the other then wire both sets in and X or vertical config.

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