Q about managing polarity in the rig

[mentoneman]

John S. has mentioned a few times that certain pedals can flip polarity, and even changing channels on amps can alter polarity. Most of us have experienced speaker polarity error, and touching a 9V battery to the speaker wires to check things, but how can you identify, and manage correct signal path polarity?

When I asked Bob Bradshaw point blank about how to keep his megarig's polarity in check he just lifted an eyebrow and pointed to his ears.

Is there a more accurate method or economical testing instrument that can be recommended?

I really appreciate John's experience and attention to detail, and imagine he would be the best resource to explain the ins and outs of such an elusive topic. I loved the thread a while back where he discussed how to properly dress insulation when building an instrument cable.

 

[mentoneman]

here's a start-but beware it comes in the truest audiophile style of rhetoric and is fairly long, but to me very interesting because i tend to be a technonerd:

http://www.positive-feedback.com/Issue1/cjwoodeffect.htm

(i am now curious as to how much effect a CD player's resolving performance can increase on a vibration stabilizing device!)

overall i totally sympathize with this author's frustration regarding the cryptic and misinformed aura that surrounds this topic, and commenting on how for the most part people are left to use their ears to weed out the problems instead of using scientific methodology and test equipment.

couple that with the potential for how many times this polarity error can infiltrate a given signal path and the task of correction can seem overwhelming.


of particular interest to me is the idea that each guitar pedal in the chain can potentially reverse polarity when engaged,

guitar amps can potentially reverse polarity on different channels,

the effects loop can potentially reverse polarity,

speaker cabs can be improperly wired,

power amps can reverse intended polarity,

wet/dry/wet rigs can be out of phase (i've experienced that one and boy does it sound BAD)


my personal idea to check my rig involves downloading this app for my iphone:

http://www.studiosixdigital.com/speaker_pop.html

and sending the signal through my rig, first just my eggie amp into a 1x12 cab, and switching between all 4 channels.

then testing my second 2x12 cab on it's own,

then adding the thd hotplate,

then plugging in each of my pedals one at a time,

then placing my tc gforce in the loop of the eggie,

then applying the full stereo rig with the inclusion of the stereo power amp i'm using



does that sound like reasonable methodology?

eric johnson touched on how important he found polarity management to be in the making of his venus isle CD, from microphone to studio wiring to his rig to mixing and mastering, and said he could write a book on it from all he learned.


i can only speculate that gauging by his live and recorded tone, Mike Landau has polarity/phase NAILED!

 

[Ed Yoon]

I'll have to get John to answer this one. This is way over my head!

 

[Suhr]

I test it on a scope
You have 1 main issue, if you are running stereo rig or multiple amps with the same signal you need to make sure your phase is correct or you loose your bass.
So if you step on a pedal in one part of your Y chain it could flip your phase.

Being able to hear flipped phase with one amp might be a stretch and it might be difficult to check your phase all the way from the pickups to the speakers. Also consider Fender single coils swing negative when metal approaches the pickup, Duncans and my pickups swing positive. Most channel switching amps flip phase, even a Fender reverb channel compared to standard flips phase. If you are shooting for same phase from the guitar to the speakers it might not be easy.

 

[mentoneman]

ah yes the pickup factor; i didn't add that to my list!
interesting about the fender reverb.

i am currently running a stereo rig
with the stereo split occurs within my tc gforce

it does seem like on certain patches when i change amp channels and add a pedal my bass end feels sucked in/phasey instead of punchy and bold. a'testing i will go

great info---i knew you'd be the ideal one to ask as an authority on pickup/pedal/amp/rack design!

thank you maestro (and tone brother Ed for flagging down the guru!)

 

[guitarslinger]

doesn't matter if you're on the equator