So why is it that my turbosound TMS-3 rig calls to invert the polarity of the mid and high drivers? I thought it was because of the phase problems of analog crossovers but when i spoke with them they said that I could achive the same results by wiring my system in phase at all points and placing a 1ms delay on the mids and highs. So now that we all have digital crossovers should everything be wired in phase and not delayed to preserve the phase coherent design of the box or should we use the delays availible in modern crossovers to more acurately time-allign the box OR should it be left alone and wired out of phase and not delayed? I suppose my question is why were they designed to run mid/high out of phase and would that change when switching to a 4 way system.

Your initial assumption is, so far as I know, correct.

The inverting of polarity is intended to reduce destructive interference at the crossover frequencies, while ignoring the compartively minor issues of polarity in the driver's passband.

I wouldn't be so casual about simply applying a 1 ms. delay. However, if you are triamping and have DSP/xovers prior to the amps you can certainly do a nicer job of cleaning up the driver interactions than can be done with passive crossovers. To get it relly good, you are going to need some pretty good measurement instrumentation.

As for the last part of your question, I don't know why they were designed as they were, or what assumptions they are making. Unfortunately, it sounds like they aren't being entirely clear with you.

I hope this helps.

Dave

Hello! I've found in some articles that phase shifting in EQ'ing can really affect the attack of the sound... Having known this, I've got to ask whether it could be a problem when you are setting up your amplifiers at a concert hall or a rehearsal room. I'm a guitarist and I started to wonder the thing I've mentioned before.
There are tips and tricks to avoid that phase shifting effect (using broad Q's for boosting, using only a small amount, and cutting with narrow Q's) in mixing, that I know, but is this useful for a rock band, setting up their amplifiers? (2 guitars, 1 bass)

For anyone's interest, a similar article on this topic can be seen over at Whalco Development:

http://www.whalco.ca

In your tutorial explained polarity change of one of srereo signal and given that to chnge the pola rity if one channel for the solution for this If same frequency components in both channels this is ok But if same frequency component not totally in both channel this solution some time give wrong solutions. But phase correlation meter indicate phase out please give explaination about this also from your tutorial

I'm not sure I completely understand your comment/question. Any "difference" components in a stereo signal will NOT be cancelled when polarity is inverted for one channel and the signals are summed to mono, while all the identical components will be cancelled. See my pieces on A+B/A-B listening and analysis techniques.

The phase correlation meter simply indicates the relative amplitude of the "sum" and "difference" components (the in-polarity vs. out-of-polarity parts) of a stereo signal. It's a simplified view of what is going on in a stereo signal that has some limited usefulness.

I hope this helps.

Best,

Dave