Inverting phase

[Gumby212]

Can someone help rnlighten me on what it means to invert the phase, or more correctly the polarity, or an effects pedal? Would i be correct in saying that if signal enters the neg side of an op amp, its inverting, and if it enters the pos side its non inverting? Ive also read that any single transistor pedal, or ones with odd numbers of gain stages, will invert the phase. I ask this bc i built a two in one pedal for a friend who plays a stereo rig. He wanted to activate 2 overdrives at once (one circuit going to one amp, the other circuit going to the other). I made it with red fuzz and a king if tone. I was told that the king of tone, being a phased reverse pedal, was causing phasing issues in the guitar rig. He wants a "transparent" OD, but now im having a hard time finding one that diesnt reverse the phase. Is recersing the phase in OD circuits super common? Why? Whats its benefit? Any idea hos to solve the ussue im having with two circuits in one, and one causing phasing issues through a stereo rig bc it inverts the phase? I was hoping to put a lovepedal amp11 or an eqd speaker crsnkef in it to replace the KaoT, but it looks like those may reverse the phase as well. Im lost and need help. Any tips would be greatly appreciated. Thanks!

[thermionix]

Would i be correct in saying that if signal enters the neg side of an op amp, its inverting, and if it enters the pos side its non inverting?

They call them the inverting and non-inverting inputs, so yeah.

Ive also read that any single transistor pedal, or ones with odd numbers of gain stages, will invert the phase.

It depends if the output is taken from the collector or emitter.  But I guess emitter follower isn't technically a gain stage, so you're right again.

Is recersing the phase in OD circuits super common?

I would assume it's about 50/50.  Because usually it doesn't matter, so the number and type of stages are whatever's needed to get the circuit to work properly.

[PRR]

If it is two separate (or different) amplifiers, phase cancellation is much less of a problem than when mixing in- and out-phase signals to a single speaker.

In Hi-Fi stereo, two identical channels but with the possibility of connecting the speakers differently, out-of-phase is not noticed by everybody (but bugs the heck out of some, like me). And strictly it is never really IN-phase unless you sit exactly equal distances from both speakers.

In stereo headphones: in-phase puts the sound "inside your head", out-phase puts it "out there somewhere".

[antonis]

In case of signal phase reversal causes any issue (real or imaginary) you simply re-reverse it..   

To be more serious, there is no case in which reactive items are involved without some phase shift..
(when "some" reaches 180^o we are talking about phase inversion..)

[ElectricDruid]

The simplest way to fix it is to build a little unity-gain inverting op-amp and stick it after the pedal that's inverting the signal. There's an example (the very last buffer) on this page:

http://www.muzique.com/lab/buffers.htm

[Fender3D]

If you get 2 different signals (you got 2 different fuzzes plus 2 different amps) I doubt you'll get any major phase-cancelling...

the chance where one frequency is exactly 180° reversed just because 1 circut "inverts" is the same as having the same freq reversed by an RC filter in a non-inverting stage...

[anotherjim]

The simple fact is that not many designers care to keep true polarity because it usually doesn't matter. It could be that a super high gain design suffered uncontrollable squealing if true polarity, due to positive feedback stray coupling between input and output. Also, how many equipment reviewers bother to find out or comment?

When it does matter, and you have series chains of pedals, one or more of them being inverting makes it a bit of nightmare since it depends which combination is in use or bypassed, since bypassing an inverting circuit results in a non-inverting situation. Adding a utility pedal just to correct it isn't an ideal solution, but if it's a simpler rig it's probably the way to go as not everyone wants to mod commercial pedals.

[Gumby212]

The buddy i built the pedal for says that the amp that has the out of phase circuit going to it is significantly quiter and has no low end unless he inverts the phase in his tonebone ABY pedal that is splitting his signal (before the stereo dirt pedal i built with the out of phase circuit in it). All his stereo modulation pedals after this pedal also dont work properly because of this. Of course this only solves the problem when the stereo dirt pedal is enguaged. Once he turns the pedal off, his clean signal is now out of phase. I guess i was curious how to make sure a circuit does this or not by looking at its schematic or layout. But i am curious about possibly installing a phase reversal circuit inside the pedal to maybe fix the issue. Thanks for all the feedback