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Active loudspeakers...how to check if all drivers are in phase?

Discussion in 'd.i.y.' started by vintageaxeman, Sep 4, 2019.

  1. vintageaxeman

    vintageaxeman Member

    I've been checking out a pair of active speakers where the 3 drive units (in each) are almost bonded in position, they are that tightly installed. A such it would be difficult to get inside to check the wiring and speaker / amp connections.
    My problem is this...I used a non-specific system setup CD the other day to test the system out, and while I was doing so, I reached a possible problem on regarding phase. The speakers in question have built-in active crossovers and power amps. When I tried the 'phase check' track of the CD, the sound 'image' was NOT as centralised as I expected it to be.
    I have not been able to find out whether there is any way to check each individual drive unit to see whether each pair are in phase, other than by dismantling it.
    Any ideas please, folks?
  2. Julf

    Julf Facts are our friends

    No way, as the active crossover might do tricks to the phase. The phase relationship between the drivers will be whatever the manufacturer deemed best. Only thing you can affect is the relative phase between the left and right speaker. You can check that by placing the speakers against each other, facing each other. If the sound cancels out, they are in antiphase.
    mondie likes this.
  3. vintageaxeman

    vintageaxeman Member

    Of course, I'd forgotten that. However, even though I've never tried that before, I guess there will be some residual air movement resulting in some sound escape? I really need to check each pair of drive units in turn, as pairs, with the other units silenced.
    Whatever I do, I'm not looking forward to moving these 100kg beasts!
  4. Julf

    Julf Facts are our friends

    Yes, some, but the difference compared to reversing the connectors to one of them is pretty clear :)
  5. cooky1257

    cooky1257 pfm Member

    To check the individual L/R sets of drivers run pink noise through each cab and using at RTA app on your phone look for suck outs at the designated crossover frequencies-there shouldn't be any but if a driver has been incorrectly wired up it'll show up-it'll also sound phasey when the pair is running..
  6. Fatmarley

    Fatmarley pfm Member

    Yep, this should work if the crossovers are even order. Just make sure that the microphone is on the tweeter axis when measuring (assuming the tweeters are supposed to be at ear height) and about 1.5mtr from the baffle to allow enough distance for the drivers to integrate.
  7. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    My guess is speaker positioning and/or location of other objects/surfaces relative to the speakers was spoiling the centralisation and definition of the central image in the OP's tests...
  8. vintageaxeman

    vintageaxeman Member

    Thank you guys.....ANy recommendations for an RTA app?
  9. cooky1257

    cooky1257 pfm Member

    Octave RTA and RTA audio Pro, iphone/ipad, cheap as chips.

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