How to wire a phase switch - MMT12

In this Monday Maintenance Tip we cover adding a phase switch to your guitar using a DPDT switch.

[aprendedefinlandiaconunfin]

This is the simpliest explanation of out of phase wiring, thanks!

[chzzyg]

This cleared up my question. I had a brief confusion looking up two-conductor wiring for a phase switch. I guess all I'm doing is connecting the bare ground wire to the negative side, and the hot side to the positive side.

[olenfersoi]

In my experience, it is the physical middle 2 pins that are the "common" output pins...the ones that output hot & ground to the 3-way or 5-way switch & flipping this switch goes from connecting those middle pins to top pins rather than the bottom pins. So, yes, the input hot & ground can be connected in that "X" as you show...but the output should be connected to the middle pins.

More than one wiring arrangement will accomplish the switch, but having the output wires being the “common” wires of the DPDT switch is the usual arrangement. Having the switch swap output hot with ground rather than swapping the input wires, would be considered backwards by an electronics geek.

Ultimately, checking whether the switch will work as desired is easily verified with the continuity setting on a cheap multimeter...to determine which pin connection change when the switch is flipped. (You can also check which magnet pole is "up" on a pickup via another magnet whose poles are labeled...like poles repel, opposite poles attract)

Keep in mind that phase & polarity are two different thngs and reversing them is accomplished in two different ways: This switch is intended to interchange "start" w/ "finish" wires of a pickup...whereas reversing the polarity is accomplished by flipping the magnet(s), so that "north" up becomes "south" up, or vice versa. An electronics geek would say that you are swapping the "start" (inner) & the "finish" wires of a pickup. Note that reverser polarities may actually be "reverse wound"...but wwapping these two ends of the coil wire accomplishes the same thing as "reverse winding" the coil....except that the start wire would be outside, rather than (as is tradition) inside the coil, which makes no difference.

Also, one must consider that connecting two pickups (at least one of which is a single coil), so as to cancel hum...5-way Strat switch positions 2 or 4...requires that both the phase AND the polarity of the two pickups must be different. Hence, using this switch mod for one pickup...which changes phase but not polarity...& switching the 5 way Strat switch to join this pickup with the middle pickup, will only cancel hum in one position of the phase switch.

Last comment: Keep in mind that "flipping" a phase switch works by causing the output frequencies of one pickup to be deducted from, vs added to, those from another pickup. Hence, it is worthless if only a single pickup is used at any one time. The switch should not alter output tone of a single pickup The exception (...which is possible, I guess) is to use such a switch so as to be able to switch the phase of a single component coil of a true humbucker pickup whose individual coils are connected in a series.

But, consider that mixing the outputs of pickups, with different phases, works because the carry different sound. With humbucker coils, the outputs of the 2 coils are basically the same (but with opposite peaks if they have opposite phases), it is probably that deducting one output from the other would leave little or no actual sound.

Also, the phase switch would likely do nothing on the rare Les Paul humbuckers pickups whose individual coils are connected in parallel. On those pickups, the output of the two individual coils are always added together, regardless of their phases.

The question has been asked if a phase switch could be built into a pedal. The answer is: Not easily, & not possible with a normal pedal, because most pedals manipulate the final output of sound from the guitar...after the output of multiple selected pickups have been combined. The phase change, to have an effect, must be accomplished before the signals from two pickups are combined.

What you are suggesting is equivalent to asking if a pedal could be used to flip the 5 way switch...again, possible, but not easy or cheap.

To accomplish what you are asking would turn a passive switch into an active one, requiring a battery to power a relay that "flips" the switch, and a wireless receiver circuit to grab the "flip" signal from the pedal transmitter. In effect, your pedal would be replacing a simple toggle switch with an active wireless circuit like a TV remote.


I hope this info/correction is found to be helpful. If you work with mods, like this, enough, this stuff becomes intuitive. But, as with lots of things, it's all more complicated than you think at first!

[facefullofsteve]

Can this method be used for a 3pdt footswitch on a diy pedal to toggle reversing signal phase? If so, could you make a video showing that?

[anthonyoresteen]

1. You need to say the the poles first connected are the default CLOSED position of the switch. 2. This only works with TWO pickups that are ON in the guitar. If you have only one pickup in your guitar it will do nothing to the sound. 3. Only ONE pickup is connected to the phase switch.

[RandomoviesAreFun]

beauty
thanks for the help man!
love the right to the point vid

[danyvaldi]

Bro, is it posible make a pedal switch for phase only, no a phaser, a phase switch??

[astrotheages]

Could I just build this into a small box to put anywhere in line on a pedal board, or is there some info I'm missing particular to guitar pickups (I'm not a guitarist).

[NathanHassall]

Hello I could really use some help.. I followed this diagram and it works however, ...when the switch is engaged and my fingers touch the strings I get an un-grounded hum.. Do you know what could be causing this? When the switch is dis-engaged everything works normal and no hum.

[TheWordprophet]

Thank you for this video.
May I ask a question?
What would happen if I use an [on/on/on] or [on/off/on] DPDT switch?
I don't have an [on/off] switch like the one in the video...can this still work?

[c.lalremruata]

Does it work the same with brian may's red special ?

[joecinder]

How would I use a mini toggle On-On-On as a pickup selector?