WR125 combing with MTM or TMM

Hi guys,

I have seen a few speakers using the WR125ST from CSS as an MTM or TMM kind of setup like these,

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.
The guys using the Pioneer B20 seem to love this tweeter.
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




  • tmm_wr125st_dayton nd16fa-6.gif
    tmm_wr125st_dayton nd16fa-6.gif
    59.7 KB · Views: 114