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Phase alignment

soundextremetoddsoundextremetodd Posts: 10
edited April 2006 in PA General Discussion
Ok here we go...

Just bought a brand spanking new system consisting of (all Yamaha) 2-CW218V, 2-C215V, QSC4050HD(onsubs), and QSC1850HD(on mains). Wow!!! I think this is one of the best sounding systems I have heard in a while, but I am never satisfied, and just want to see if I am on the right track? All of my speaker cables are speakon at the amp end, so I am unable to reverse polarity to make the necessary adjustments in delay. Would I be better off to?

A) Carry a Banana to 1/4 cable to make my adjustments and then switch over to the speakons, or...

B) Make a short Speakon jumper that reverses the polarity and remove it after making all adjustments?

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    Once you set the delay for the tops over the subs the first time, what are you wanting to check every time you set up?

    In answer to you either/or question:
    None of the above :shock:

    Buy or make up a polarity reversing male xlr to female xlr cable/adapter. Simpler to make and readily available for purchase. Invert the polarity on the FRONT end of the amp. This adapter can come in handy if you don't have polarity switches on each mixer input, like for bottom snare micing or dual opposite kick drum head micing.

    If you decide to make your own, get enough parts for a couple AND for a few, male to male, female to female, and lifted ground adapter cables. They all come in handy 8)

    Mike McNany
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    GadgetGadget Posts: 4,915
    I recommend a test connector........ bare leads to an NL4 female connector. Then, plug the cable (plugged into the speaker) into the test setup... take polarity into consideration and touch a 9V battery + to + and minus... if the cone moves OUT, the polarity is normal... If not, the output needs to be reversed.

    This is before 'Xover', Eq's, Delay's... :shock:

    understanding hf polarity requires a bit more, sice you can't see the diaphram move. You need a tool, or at least the MFG spec.

    Gadget
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    Gadget,

    I think you misunderstood the OP's polarity reversal's reasoning. AFAICT, he's looking at using the reversed polarity to find the optimum delay. I.e., adjusting delay for maximum signal loss around the crossover point with polarity reversed between tops & subs to find the optimum delay.
    NOT for testing speaker polarity.
    Mike McNany
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    GadgetGadget Posts: 4,915
    Mike,
    No, I have this as a test setup for multiple purposes... Thats what I was saying, it makes it easier to do the battery check.. and for the delay purpose it would work also...

    Thanks
    G
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    Ok I am back... Yes All I was wondering was what is the proper way to reverse polarity to set my delay. Am I correct in assuming that the answer is still to do it on the front end of the amp insted of on the speaker leads themselves?
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    GadgetGadget Posts: 4,915
    I guess, if you have to make an adaptor, it really doesn't make much difference... I tend to go with the one that offers the most flexibility. We could make an XLR phase swap, (and this comes in handy if you put the Kick mic inside the kick, and the monitor, behind the drummer. The mic is moving the oposite dirrection of the speaker. This cancellation has been treated by flipping the phase of the mic. :arrow:

    With the DR260, you can do so, with the push of a button. That also has the benefit of being, PRE - amps, but wasn't put there for that specific purpose, has more to do with the speaker tuning aspect...which spills over into usefullness where aligning the speakers components is concerned. The important thing is to reverse the polarity and listen for a null...there may be several. It doesn't matter how you do it as long as it gets done... there are easier ways to do it, but usually require lots of knowledge in acoustics, and measurement technologies (Hi Mikey) :wink:

    Oh well...you get the the idea...

    Wow, its my birthday :roll:

    G
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    Thank you all for your input. My board (A&H GL3300-40) does have the phase reverse switches per channel for the double mic'ing like you mention. So looks like i should be able to get it from here...


    Thanks All
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    GadgetGadget Posts: 4,915
    Remember if you reverse the input @ the mixer it will reverse all those outputs. If you were running aux fed subs that would be the only way it would work..
    G
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