Are Ohm Walsh Speakers the Poor Man's MBLs?

Marty,

You may be right about the front to back imaging in that the mbl demo was as good as I have heard in that regard, particularly with a state of the art reel to reel orchestral recording as the source, but I would have to hear both, probably larger 300s or 5s on the OHM side, in the same larger, acoustically conditioned room that I heard the mbls in to be sure.

I'd attribute the mbls exceptional performance in this regard somewhat to use of omni drivers for the high end whereas OHM Walsh speakers are not omni in the uppermost frequency range that most people can hear. Original Ohm As and Fs were.

OHM speakers also use a single Walsh driver for most of the frequency range (all of the frequency range covered in the case of original As and Fs) which gives them an edge in overall coherence I believe.

OHM and German Physics use similar technology based on the Walsh driver concept but their Walsh driver technology and speaker designs are quite different, I believe.

GErman Physiks uses the Walsh driver for the top end and supplements that with conventional woofers on the low end in most models (except the horn loaded Unicorn, I believe), as does mbl with the exception of the 101s.

OHM does the opposite. The omni Walsh driver covers the low end, mids and some highs but supplements that with more conventional cloth dome tweeters for the high end in the newer series 3 models.

Interestingly, we were informed here on another A'gon thread recently by John Strohbeen, the man behind OHM, that they now have a distributor in GErmany, mbl and German Physiks home turf.

I wonder how well they will do there?

It seems that a lot of Omnis do no limit the tweeter (Deuvel and Morrison come to mind) . Does limiting the tweeter from being full omni help the coherence but hurt the imaging? Does it also make it easier to place by letting it be closer to the rear wall?

Very good questions!

"(I)t seems that a lot of Omnis do no(t) limit the tweeter (Deuvel and Morrison come to mind) . "

"Does limiting the tweeter from being full omni help the coherence but hurt the imaging? "

No. I think coherence is mostly due to sonic waveforms being in phase at all frequencies top to bottom. Crossovers and multiple drivers present an extra challenge in accomplishing this I believe. A single Walsh driver that covers a wide frequency range has an advantage here I think.

"Does it also make it easier to place by letting it be closer to the rear wall? "

In general, yes. However there are other ways to accomplish this otherwise with any omni driver.

OHm Walsh speakers accomplish it by design with acoustic dampening material inside the cage and around the drivers that attenuate SPL of sound from the omni Walsh driver in the wall facing directions.

I believe it is possible to special order CLS Walsh drivers from OHM that do not use the acoustic dampening material to attenuate sound in wall facing directions if desired. This would be more mbl and German Physiks like in radation pattern and resulting effect on optimal location of speaks relative to walls. I think OHM may use this approach for some of their Walsh A/V surround sound speakers, but I am not certain.

So the tweeter being limited has only the benefit of increasing placement options. Does it in any way degrade the sound? Is there a price to be paid in sound quality for the ease of placement?

"So the tweeter being limited has only the benefit of increasing placement options. "

I believe increasing placement options for most users is the intent of OHMs design decision to attenuate the omni sound levels in wall facing directions. The tweeter being omni or not would not matter because I would assume they would/could be damped easily as well if desired.

There are several benefits of the more conventional tweeter used in the OHM Walshes compared to the original OHM Fs and As, which, other than the GP Unicorn, are the only designs I know of using only a single wide range Walsh driver:

1) lower cost
2) greater durability
3) higher SPLS possible without damaging the driver

The disadvantage is that the conventional tweeter does reduce sound stage size somewhat. I can hear this when I adjust the tweeter levels on my F-5s. The soundstage expands slightly and becomes more transparent at lower tweeter levels and appears to shrink somewhat and become less transparent at higher tweeter levels. At any level, soundstage and transparency is extremely good however.

Another disadvantage which does not really matter much in my opinion is that you will hear a slight but noticeable roll-off of the very top end if you stand behind the speakers. Coherency is not affected however which means you can listen from almost anywhere with mostly just a change in perspective in relation to the instruments and recording tracks within the soundstage.



" Is there a price to be paid in sound quality for the ease of placement? "

I think the price to pay might be the depth of soundstage at least compared to mbl, as Marty suggested.

Never heard Morrison or Dueval so I cannot speak to those, though I've heard good things about both. Both use more conventional drivers compared to OHM, mbl, or GP, but in a unique configuration for their omni sound, I believe.