weigh in on acoustic lobing (center channel design) ?

[Tom1315]

Anyone want to weigh in on the issue/problem (or non-issue/non-problem) of acoustic lobing that supposedly results from the traditional M-T-M design for center channel speakers?
I've read articles and threads which suggest that horizontally aligned drivers and their soundwave patterns interfere with each other to a certain extent when they emit the same frequencies (most notably at or near the cross-over point).

My local ML salesman feels this is a non-issue that, if it was ever a problem at all, has been adressed and compensated for with the latest design techniques and technologies.

Any and all opinions on this topic will be greatly appreciated ... thanks

 

[jmschnur]

I am told that the new X series centers do a better job on this on the high end. Not sure about the lower end. There cetainly are beaming issues in the earlier models. Cinema i for example.

I should have a Stage X in my home in a few weeks . After break in I should be able to give you my reactions to it. It will be replacing a Stage that has a power supply issue.

The Stage is perfectly fine for movies and dialogue. I feel it falls short in 5 channel piano SACDs and classical Blu Rays.

 

[MrBT]

......The Stage is perfectly fine for movies and dialogue. I feel it falls short in 5 channel piano SACDs and classical Blu Rays.....

I totally agree. Stage is the weakest link in full electrostats multichannel system.
However you dont have to have Stage as center channel. It was my sane choice to buy stage as a compact and flexible alternative to full range electrostatic like Vista for example. But with this option I would have to redesign my room completely and buy acoustically transparent projector screen.

 

[Peter Soderberg]

on the Motion 30, C2, we use 2 1/2 way xover designs where one of two woofers roll off so lobing is not an issue. When drivers are smaller such as in the Motion 8, there isn't much lobing but it is a simplerer design. I have one, don't notice much off axis and we are aware of it in the bigger designs. with the stats, we have a controlled dispersion pattern so do not have the typical interaction with cone and domes. Hope that helped.

 

[Tom1315]

Thanks Peter That gives me the green light to buy the Motion 30 I've been wondering about ... I'll move my LX16 from the center, bring the other 16 back on line as the surrounds to go with my Motion 40s and Dyno 700 ... just thinking - two months ago it was Bose 701s, 161s, JBL sub and a Polk center

One more question though ...the 2 1/2 way xover design for the Motion 30- is that why there are xover points at both 800 & 2,600 Hz?
Is one mid-range for frequencies between 800 & 2,600 and the other for frequencies below 800Hz?

Thanks again Peter

 

[Tom1315]

well one more question if you will ... how do we know which one is designed to roll off, or does it not matter? Thank you ... I'm new to this, quite interested, and have always had a passion for music ... i love the sound of my new MartinLogans

 

[Peter Soderberg]

the two woofers run in parallel with one rolling off at the first frequency, the other continuing on. try both ways, but we do not define a top or bottom. Watch the Home Theater review coming up with 40s, 30, 15s(16s are the same) that is a rave up on both the 30, 15s.

 

[Tom1315]

Yes, that's a wonderful review of the Motion speaker system !

The reviewer finds that the Motion 40s, 30, and 15s have "that special essence of completeness that is extremely difficult to find at any price" and along with a Dynamo sub is "one of the most phenomenally cohesive, startlingly emersive HT systems you can buy".

Additionally, he says that it is "amazing at how close the Motion speakers get to the light and airy sonic character of an ESL".

I feel very fortunate, that while researching a set of bookshelf speakers for my son last December, that I found out that my old Bose 701s weren't really all that good ... James and I were zeroing in on a pair of Def Tech 55s for him, and I wanted to give a listen to some Monitor Audio bronze series towers ...

Thankfully, the local high end audio store sells MartinLogans as well ... James now has a nice pair of Motion 15s and Dad has the beginnings of a "phenomenally cohesive, startingly emersive" HT set up ... Looking forward to adding the Motion 30 someday soon ... For now the 40s, along with the Dyno 700 and the LX16 in the center sound great : )