why phase reversal?

[bassguitarded]

i know what it does.... but why do it? can anyone give me an example of its use in a song?

[Zooberwerx]

No I can't give an example. Phase reversal cancels out certain freq's which, to my ears, provides an interesting and useful mid- scooped tone. Interestingly enough, my SWR IOD preamp had the same capability. You could kick the SS and tube channels into a 180 deg. out-of-phase setting which provided a super-clean, mellow tone. Never had the option on a bass but the phase switch was all the rage back in the 80's.

Riis

[lug]

Who does it? My old Peavey T-40's are the only basses I have with a phase switch, and I only had use for it on one song in 30 years. It cuts all the bottom out leaving a very tinny sound.

[bassguitarded]

i just fixed up a t-40 which made me start thinking about the whys of it all... also my 1980's Japanese made aria pro II cs-350 does the same thing... but i'm about to turn the switch into a coil tap instead...

[WalterBush]

Guitar players liked it for a different lead tone, special effects, whatever. I don't think it's much of a standard option on basses anymore--too much "push" leaves the tone.

[lug]

Originally Posted by WalterBush

Guitar players liked it for a different lead tone, special effects, whatever. I don't think it's much of a standard option on basses anymore--too much "push" leaves the tone.

That would explain the T40. It's electronics are the same as the T60 guitar.

[Jo6Pak]

Originally Posted by lug

Who does it?

My circa 1986 Carvin LB60 has one (bottom right switch). The two switches to the left of that one are dual/single coil:

[doctec]

Phase reversal is usually used when there are two sources that are related to each other, like two pickups on a guitar/bass or the SS/Tube signals on the SWR IOD mentioned by a previous poster.

Normally, sources are combined 'in phase' which produces the 'sum' of the two signals. But if you reverse the polarity of one source, the resulting signal is the 'difference' of the two signals.

In the case of a bridge and neck pickup, combining the two sources with a phase reversal will cause the sounds that are common to both sources to cancel out. You'll get sort of a scooped mid sound, although it doesn't sound exactly like an EQ. Same with the SWR IOD.

I can't think of any examples with a bass, but IIRC the rhythm guitar parts at the beginning of "Listen to the Music" and "China Grove" by the Doobie Brothers were done with a Gibson SG with the pickups out of phase.

[i_got_a_mohawk]

I added one to a bass when I did up the wiring (also added a pile of series/parallel switches too).

It's a different tone, that's for sure. Probably not terribly useful in most band situations tho.