Omnitop JArray x8 and T48 x4

[Boyd]

Acoustic absorption http://lenardaudio.com/education/04_acoustics_3.html

[lancemhorsley]

he slight 'increase in smoothness' you said about the sound, it wouldn't be to do with the lack of parallel surfaces in the J Array design would it?

I have no Idea but hope someone that does will chime in. And I wonder if its SPL Chart will be any different. Thanks for the links and info hopefully tomorrow I can do some more reading on those sites. http://www.tectum.com/fabri_tough.htm This is what i can get an unlimited supply of do you think it would work as good as a curtain?

[lancemhorsley]

Here are a few pictures of the brackets made to adjust the tilt of the arrays.

[maxo]

Are those mounts the right ones ?

[lancemhorsley]

They are not in the plans, they were made by a local guy.

[gzc_stageTech]

i'm curious, what's the stack "hanging" weight?

It sure looks good. Great job. I bet it's loud when fired up too. the array should give you good coverage in that sanctuary too.

Chris

[lancemhorsley]

The hanging weight with hardware was 168lbs. In the center of the room from the front to the back there is something strange happening, it sounds like a hole it gets quiet and sounds terrible but if you step once left or right its gone any help or suggestions for a solution would be much appreciated. The sound from the system is pretty darn good but still needs some tweaking. Is it necessary to delay the tops to match the subs at the crossover point? Here are a few pics.

[Bill Fitzmaurice]

In the center of the room from the front to the back there is something strange happening, it sounds like a hole it gets quiet and sounds terrible but if you step once left or right its gone any help or suggestions for a solution would be much appreciated.

I'd first try reversing polarity on one of the arrays, keep it whichever way sounds better. The try some additional toe in, if required.

Is it necessary to delay the tops to match the subs at the crossover point?

Try it if you have the ability to, but the path length of the T48s should reduce or even eliminate the need.

[lancemhorsley]

Thanks for the quick reply. Do you mean To the left or right side reverse ones polarity?

[Bill Fitzmaurice]

Thanks for the quick reply. Do you mean To the left or right side reverse ones polarity?

One or the other, it doesn't matter which. Do it with a 200Hz test tone first, then confirm the result with pink noise. When the polarity of the two arrays is right then run a test tone at the crossover frequency and bring the subs up, try the polarity on them both ways, go with whichever is louder.

[lancemhorsley]

Im planning on getting up early so I can go make some adjustments tomorrow. In this setup I have the left and right bottom boxes on the same amp channel, the next 2 boxes on the same amp channel and so on and so on.. Since changing polarity at the crossover will change both sides I was wondering whats the best/easiest way to reverse one sides polarity would be? Sorry for all the questions I just wont have much time for trial and error in the AM.

[Bill Fitzmaurice]

Start with just the two bottom boxes. Play pink noise though them alone, switch the speaker cable polarity on one, at the amp, see which way is best; that's best done with someone else listening in the middle where you're having the problem, but you can do it alone. Then disconnect the speakers at the amps for the other speakers. At a low level play a 200Hz test tone, with all the amps on. One one side connect the other speakers going up the array, one at a time. As each as added the level will go either up or down; level up is the correct connection. Mark each wire so you know which is which. After doing one side repeat on the other side. Then use a 100Hz tone to check the mains/subs polarity, with one sub. Add each additional sub in turn, making sure the level goes up each time.

[lancemhorsley]

Thank you. I will do this in the morning and post my results.

[lancemhorsley]

So I Did everything suggested except adding additional towing, I ran out of time. It helped but only the back portion of the room. The Left top speaker needed its polarity switched but everything else was correct. Is it possible its being caused by the room? I Have the arrays towed in at 14 degrees now and will add some more the next free chance I get.

[Bill Fitzmaurice]

Is it possible its being caused by the room?

It's possible, but a cancellation mode down the center of the room at shorter wavelengths isn't likely. You also can try aiming them straight out with no toe. You never know til you try what will work best.