Explain Phase switch?

Goober1206 · #1 03-10-2010, 03:43 PM

Hey guys I'm thinking about adding a phase switch to my Jaguar bass but I'm not sure how it works/what it does and was hoping someone would be able to answer my questions. I'm able to put it together I'm sure I just can't rewire anything if I don't understand how it works. Thanks in advance everyone

i_got_a_mohawk · #2 03-10-2010, 04:07 PM

The bass signal is AC. Each pickup produces a similar (though slightly different signal), to do with the differences in pickup and the difference caused by differing string tensions as you move closer or further away from the bridge.

The identical parts of the wave will be constructive, adding to the amplitude of the wave. However, a phase switch will swap the ground and hot of one of the pickups. This means the parts which produced a +ve amplitude now produced a -ve amplitude. So now, instead of the identical parts of the wave, no longer add together, but they subtract. So if the signals were to be identical, they would cancel each other out.

What this means is that what you hear, when the pickups are out of phase, is the differences between the two pickups, as opposed to the sum of the signal.

Goober1206 · #3 03-10-2010, 04:12 PM

I think I understand that thank you very much. So now I have two questions more lol one is how would that work with a parralel series switch? And could someone explain how the diagram would work? And does someone have a diagram lol

**line6man** · #4 03-10-2010, 04:18 PM

As mohawk stated, a phase switch (also called a polarity switch) simply swaps the polarity of the two pickups so that they will be 180 degrees out of phase.

Look into destructive interference for more information on the matter.
FWIW, two pickups out of phase from each other will usually produce a very thin and nasally sound.
A lot of people would call it completely useless except for sound effects and such.

With a Series/Parallel switch, the principle is still the same, the pickups will still be able to be in or out of phase with each other, regardless of whether they are in series or parallel.

I'll draw you a diagram for Series/Parallel and Phase if you want it.

Goober1206 · #5 03-10-2010, 04:23 PM

I'd appreciate it if you did thanks a ton

**line6man** · #6 03-10-2010, 04:30 PM

Goober1206 · #7 03-10-2010, 04:46 PM

i dont really understand how that works :/

**line6man** · #8 03-10-2010, 04:55 PM

Quote:

Originally Posted by Goober1206

i dont really understand how that works :/

That's about as simple as it gets, other than I should mention the: http://upload.wikimedia.org/wikipedi...rth_Ground.svg
symbol means ground, and these are DPDT On/On switches.
The top switch is the phase, and the bottom switch is the series/parallel.

Goober1206 · #9 03-10-2010, 04:59 PM

I understand how I would do it, but it looks like they would get mixed up and not work..

lunarpollen · #10 03-10-2010, 05:01 PM

Phase switching on basses has very limited applications. Basically, if you want to be able to strangle your sound for the occasional baritone guitar role, then a phase switch on one of the pickups can be a way to achieve this (with two pickups you only need to switch phase on one of them to throw them out of phase with each other). Most of your low end will disappear, and the remaining overtones can sound "interesting." But an out-of-phase sound isn't useful for a bass role.

vin*tone · #11 03-10-2010, 05:26 PM

I just modded mine out of my '79 Sabre. It wasn't included in later Sabre versions for a reason: Totally. Friggen. Useless.

BassLife77 · #12 03-10-2010, 07:31 PM

I put the phase switch in the piccolo bass. interesting sound when playing chords through a phaser. it might sound good on a fretless for solos. I think Alphonso Johnson flipped a phase switch on his fretless Lobue bass during solos

Goober1206 · #13 03-10-2010, 11:25 PM

Success! Thanks for the help everyone I got it

i_got_a_mohawk · #14 03-11-2010, 04:29 AM

Quote:

Originally Posted by Goober1206

I understand how I would do it, but it looks like they would get mixed up and not work..

Bingo, that's pretty much what the phase switch does

FunkMetalBass · #15 03-11-2010, 07:05 AM

Quote:

Originally Posted by OP

...I'm thinking about adding a phase switch...

Quote:

Originally Posted by OP

...I'm not sure how it works/what it does...

**smacks forehead** Shouldn't you try to find out what something is before you do it? That's like taking cyanide capsules and asking what they do after you've already swallowed them.

What are you hoping to achieve with this mod? What tonal changes are you looking to get from the mod? A polarity switch may not really be what you are looking for.

PJSShearer · #16 03-11-2010, 07:12 AM

I have a phase switch on my PJ that has Jazz Bass wiring ie., two volume controls. When you the flick the phase reversal switch, if you back off one of the volume controls slightly you do get a useable sound - it is thinner, missing some mids, but it does have bottom!!.

Goober1206 · #17 03-11-2010, 12:05 PM

Quote:

Originally Posted by FunkMetalBass

**smacks forehead** Shouldn't you try to find out what something is before you do it? That's like taking cyanide capsules and asking what they do after you've already swallowed them.

What are you hoping to achieve with this mod? What tonal changes are you looking to get from the mod? A polarity switch may not really be what you are looking for.

Well obviously that's why I posted this thread

Goober1206 · #18 03-11-2010, 12:07 PM

My bass now has master volume, master tone, blend, series/parallel, pre amp on/off, bass, treble, phase switch, and kill switch.

JackANSI · #19 03-11-2010, 01:33 PM

Start here:

http://en.wikipedia.org/wiki/Phase_cancellation