WR125 combing with MTM or TMM

[davidallancole]

Hi guys,

I have seen a few speakers using the WR125ST from CSS as an MTM or TMM kind of setup like these,
http://us.alegriaaudio.com/RosaLCR.htm
http://www.timn8er.com/alegria_audio_rosa_tl.htm

The first one in the list is crossed over to the tweeter at 3kHz with a 4th order crossover and the second one is left wide open on the WRs and has the tweeter cut in around ~14kHz with a 1st order crossover.

I was thinking of building a box with two of these in it around 1 cft sealed. The -3db point on the system would be 80 Hz making it easy to crossover to a sub. What I was wondering is about the top end. I have looked all over for the formulas and theory on combing with two speakers producing the same frequencies but I can not find it. Is it all right to leave the WRs run fullrange with the tweeter cut in high or is there a level where it should be rolled off on the WRs to avoid combing? I would orientate the WRs like that of the second link so that the frames are right against each other.

This is the tweeter I would probably use snuggled up right close to the frames where the speakers comes together right before it flattens out.
http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=275-025
The guys using the Pioneer B20 seem to love this tweeter.

 

[bjorno]

FYI, Use ArrayShow to model the vertical combing for the suggested TMM: s where only the T driver is using a low filter.

Look at the submitted 3 simulations and note that the filter phase at the chosen frequency is expressed in time delay instead, or as the T phase at 4 kHz is chosen to be = 180 degrees, with the polarity switch instead in use.

Where you place your crossover point is a matter of preferences, in the first polar plot you can see the vertical dispersion of the TMM: s suffering from combing, even as low as at 4 kHz if the T driver too is in phase with the MM: s

b

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