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[John Schalk]

So I believe what Merlijn van Veen‘s method is doing is basically putting both speakers in approximately the same equidistant plane from the mic (at least as far as a laser measure would regard it), then using the full-range speaker to measure that impulse (timing) and applying it to both the full-range speaker and the sub.

No.  Merlijn's method places the main and sub speakers next to one another to remove any physical separation from the phase alignment calculations for the initial alignment.  I believe that Open Sound Meter's method of delay finding uses the impulse response peak, just like Smaart.  This works well for fullrange speakers but is generally not useful with subwoofers.  Once you have the two speakers placed next to each other and have captured an impulse response to set the delay time to the main speaker, the remainder of the process is a bit more art than science.  You have to adjust the delay of one of the two speakers until their phase traces are in alignment in the crossover region.  I'm not going to attempt to explain the process any further because I am still learning how to recognize what I see in Smaart and to take the correct actions myself.

There are quite a few YouTube videos on this topic, some better than others.  I recommend that you search for videos from Nathan Lively and Michael Curtis.  Both of them have videos that run through the basics of using OSM, but both of them have also switched to using Smaart for their in depth analysis.  I took a look at OSM, but decided to buy a license for Smaart primarily because I knew that I would need help learning how to use the software and posting questions to a FB group was not good enough (for me).  I paid $450 for a license of Smaart LE during Rational's December sale.  I looked at it as just another "equipment" purchase.  My biggest challenge with measuring systems is doing it often enough to learn and retain what I've learned.  I can't blast pink noise in my neighborhood too often!

[George Reiswig]

No.  Merlijn's method places the main and sub speakers next to one another to remove any physical separation from the phase alignment calculations for the initial alignment.  (Snip)

Thanks again, John! Lots of patient explanation on this forum, which I appreciate. I have looked at Michael Curtis’ videos, and between that and reading (and watching) Merlijn’s stuff on his process, I probably have just about enough knowledge to be at the peak of the Dunning-Kruger curve.

With respect to your quote above, it feels like we were saying the same thing, but perhaps not since you said “No…”. Are you saying the speakers have to be co-located for this to work? I was thinking that as long as your mic is omni, and both speakers are on the ground and equidistant from the mic, it should work. Practically, putting them together makes sense, but I’m trying to understand theory here, so…

[John Schalk]

With respect to your quote above, it feels like we were saying the same thing, but perhaps not since you said “No…”. Are you saying the speakers have to be co-located for this to work? I was thinking that as long as your mic is omni, and both speakers are on the ground and equidistant from the mic, it should work. Practically, putting them together makes sense, but I’m trying to understand theory here, so…

Yes, I think that the speakers have to be co-located if you are going to try following Merlijn's process.  Think about is this way; your sub and main speakers are both self-powered and have built in DSP features.  Therefore, there will be some amount of latency in each signal path, main & sub, which is difficult to measure electronically.  By that I mean, we can easily measure the latency in our digital consoles or in an external DSP unit like a Driverack, but unless your powered speakers include a processed output, it's hard to measure it.  This is why you can't use a simple physical alignment of the drivers in your speakers to time align them.

Going back to the start, the purpose of co-location is to provide a known distance from which you can make adjustments later on when the system is deployed out in the field.  I suppose you could locate your main and sub 6' apart, and exactly the same distance from your PZM mic, but then you'd have to remember that you aligned your system with 6' of separation as the default.  Why would you do that?

Well, that is what I think I know about this process.  But bear in mind that Michael Lawrence has written that main to sub alignment is probably the most over discussed topic in sound system optimization and not so important as many folks tend to believe.  I can recommend his book, "Between The Lines." 

[Art Welter]

Yess! That sure made me go “hmmmm!”

I just put the mistake in to see if you were paying attention

[ProSoundWeb Community]