Effects of an MTM arrangement on frq response?

Osafune · 13th October 2003, 10:26 PM

I was just wondering what the benefits or drawbacks are over a regular 2=way design.

How does the placement of the two midwoofers effect the frequency response and also dispersion characteristics?

Any knowledge you could share would be greatly appreciated.

Does this kind of arrangement limit the vertical dispersion?
What amount of sensitivity will be gained by using two drivers instead of just one? 3db?

Also if anyone can direct me to a site with good information on this or a related subject please do so.

Thanx!

GM · 14th October 2003, 12:25 AM

IIRC, this should give you a pretty good idea of what's going on:
http://www.birotechnology.com/articles/VSTWLA.html

GM

Osafune · 15th October 2003, 03:21 AM

Thank you I'm much obliged.

navin · 16th October 2003, 05:51 AM

i built a few MTM thinking that hte cylindrical wave front etc.. would be better but i still seem to prefer a standard 2 way dont know why. cant put my finger on it though.

MarcelvdG · 16th October 2003, 07:10 AM

I don't know if this helps, but as far as I recall, Joseph D'Appolito shows in his AES preprint that the main lobe of an MTM configuration for frequencies near the cross-over frequency is never tilted, regardless of what type of cross-over is used. (For a normal two-way system with one woofer and one tweeter, you need to use Linkwitz-Riley filters and to ensure that the drivers have roughly the same phase shift near the cross-over frequency to prevent a tilted main lobe.)

According to D'Appolito, the off-axis response in an MTM configuration is best when an odd-order Butterworth crossover is used and the vertical distances between the drivers are minimised. In order to get a flat on-axis response with a Butterworth cross-over, you again have to look out for driver phase shift differences.

13th October 2003, 10:26 PM	#1
Osafune diyAudio Member Join Date: Sep 2003 Location: Louisville Kentucky	Effects of an MTM arrangement on frq response? I was just wondering what the benefits or drawbacks are over a regular 2=way design. How does the placement of the two midwoofers effect the frequency response and also dispersion characteristics? Any knowledge you could share would be greatly appreciated. Does this kind of arrangement limit the vertical dispersion? What amount of sensitivity will be gained by using two drivers instead of just one? 3db? Also if anyone can direct me to a site with good information on this or a related subject please do so. Thanx!

14th October 2003, 12:25 AM	#2
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	IIRC, this should give you a pretty good idea of what's going on: http://www.birotechnology.com/articles/VSTWLA.html GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

16th October 2003, 05:51 AM	#4
navin diyAudio Member Join Date: Jan 2002 Location: Mumbai (Bombay), India	i built a few MTM thinking that hte cylindrical wave front etc.. would be better but i still seem to prefer a standard 2 way dont know why. cant put my finger on it though. __________________ ...still looking for the holy grail.

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15th October 2003, 03:21 AM	#3
Osafune diyAudio Member Join Date: Sep 2003 Location: Louisville Kentucky	Thank you I'm much obliged.

16th October 2003, 07:10 AM	#5
MarcelvdG diyAudio Member Join Date: Mar 2003 Location: Haarlem, the Netherlands	I don't know if this helps, but as far as I recall, Joseph D'Appolito shows in his AES preprint that the main lobe of an MTM configuration for frequencies near the cross-over frequency is never tilted, regardless of what type of cross-over is used. (For a normal two-way system with one woofer and one tweeter, you need to use Linkwitz-Riley filters and to ensure that the drivers have roughly the same phase shift near the cross-over frequency to prevent a tilted main lobe.) According to D'Appolito, the off-axis response in an MTM configuration is best when an odd-order Butterworth crossover is used and the vertical distances between the drivers are minimised. In order to get a flat on-axis response with a Butterworth cross-over, you again have to look out for driver phase shift differences.

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