Inverted output?

[chptunes]

I ordered an AMZ Multi-Purpose Opamp PCB.  I'm thinking of using it for a clean signal booster, with 2 independant outputs.  According to Mr. Orman's project notes, Output 1 is Non-Inverting and Output 2 can be set-up with selectable polarity (via a SPDT switch).

When would I need an Inverted Output?  Are there any ill affects (practical characteristics) of an Inverted Output?  Should I install this switch, just in case.. or should I just hardwire the output as Non-Inverting?

Thanks in advance,

-Corey

[Mike Burgundy]

Say you're running two parallel effects lines from the two outputs which later on get mixed again. Some pedals invert the signal input vs. output, some don't. Having one selectable polarity output lets you choose which combination sounds best (summing two anti-phase signals in real world applications removes bass, for one). Things can get quite complex with distortion and extensive filtering, so having a switch to just listen which one sounds best can be a nice thing.

[ashcat_lt]

To put a finer point on it:

The absolute polarity of the signal makes no practical difference unless you're trying to mix it with another similar signal.  There are folks who claim that they can tell the difference whether the speaker moves first toward them or away.  Maybe they can.  I can't, don't know anybody else who can, and I'd be willing to be that you can't (in blind test conditions) either.

There are some circuits which are asymmetrical for one reason or another.  I suppose it could be argued that these might react differently depending on whether the initial transient goes up or down, but that is really only accidental anyway.

So yeah, what Mike said.  Even splitting to two different amps can cause issues depending on how the signal is handled in each, and how the manufacturers were feeling on the day the speaker was wired.