Compact Ohm Omni Struts its Stuff

Tuesday, September 1, 2009 MicroWalsh Signature Edition Tall Speaker
Publisher: Stereo Times | Author: Frank Alles

Okay, I’ll admit it. I was delighted when the President of Ohm Acoustics Corporation, John Strohbeen, consented to send me his newly designed MicroWalsh Tall SE speakers for review. I have always held an interest in Ohm’s omni-directional speakers over the years, beginning in the mid 70’s, when I got to hear the original Ohm F’s at a friend’s apartment. As I recall, they were driven by one of the larger Marantz solid-state stereo amplifiers, as remember the classic gold face with the large blue level meters. Though they were far from being optimally set up, I could still hear that the Ohms had some special qualities.

The Ohm MicroWalsh Tall SE is the introductory model in Ohm’s new Thousand-Series speakers. There are five other models from the Ohm 1000 thru the Ohm 5000. The MicroWalsh SE is currently priced at $1400/pr., with the prices for the other siblings being spaced fairly evenly between $2000 for the Model 1000 and $6500 for the Model 5000.

As Ohm states on their website, the improvements to the new models are evolutionary rather than revolutionary. In other words they are enhancements and refinements to a solid original model. Cosmetic improvements include rounded edges, plinths, and grilles, veneer choices at no extra charge, and a hand-rubbed finish.

Performance enhancements begin with the main inverted driver having a new cast chassis, new voice coil, and a new cone. Additionally, butyl rubber surrounds instead of foam surrounds are now used in the MicroWalsh SE, Walsh 1000 and Walsh 2000 models to allow greater driver travel and longevity. The Walsh 4000 and 5000 models have switched to neodymium magnet structures and plastic coated cloth surrounds for increased efficiency and driver control.

Design

The Ohm-Walsh series of speakers use a nearly full-range driver. Ohm refers to their version of the Walsh-type driver as the “Coherent Line Source” (CLS) driver and describes it as “a vertical line source that combines inherently perfect time and phase alignment and uniform polar frequency response.” Ohm claims these characteristics are essential for achieving authentic 3-D sound reproduction.

The “face” of the speaker fires down into the cabinet, which is stuffed full of acoustical padding and is ported at the bottom to enhance the bass performance while not allowing higher frequencies to pass to the bottom. The voice coil is at the apex of the CLS driver and sound radiates down the cone and outward in a 360-degree dispersion pattern up to 8 kHz. Above 8 kHz, the signal crosses to a high performance cloth-dome tweeter via a very simple crossover network. The tweeter is rolled off more quickly than the CLS driver for power-handling concerns, and is isolated from the back wave of the CLS with an acoustically absorbent material.

The dome tweeter is mounted at the top of the Walsh driver and is angled in at 45 degrees toward the listening position. This provides for a very wide and stable stereo image and limits dispersion in the extreme high frequencies that could otherwise blur the sound by propagating too many room reflections. To further reduce unwanted reflections, a built-in acoustical attenuator reduces the rearward output of the CLS driver.

This arrangement has been used in previous Ohm/Walsh models and is an improvement over the original design, which used only the Walsh driver and radiated all frequencies a full 360 degrees. Since the crossover is so high, the CLS driver runs almost full-range and has the coherency of a single-driver design, but with much better dispersion, imaging, and perceived high-frequency response.
Setting Up
One day, a few months ago, I looked out on my patio after returning home from work and noticed two long slender boxes lying there. Those clever guys in the Brown outfits had left them there for me just to see how long it would take me to discover them. I brought them into the house and saw they were from Ohm and thought, “What a nice surprise!”

At any rate, there was no setup involved. The hardest part was getting them out of their boxes and packing, which was not too difficult at all.

The review speakers came in the rich-looking Rosewood finish. The fit and finish was acceptable but nothing special. The cloth caps did not interface between the drivers and the cabinets as flush and perfectly as I would prefer, and the speaker bases are small, with no provision for spikes. I used them directly on carpet, which seemed to work well enough.

I used the Ohms in two different systems, one in a fairly large room using a Pioneer DV-363 DVD player as a source and a vintage Onkyo TX-2500 solid-state receiver for amplification. I also incorporated a G&W TW-J1 headphone amp as a preamplifier (which seemed to sweeten the midrange) and provided an alternate reference using my Sennheiser HD595 headphones. The second system consisted of a Michell Orbe SE turntable, Whest Audio PS.30RDT phono stage, Parasound P/LD-2000 line stage and a VTL ST-85 tube amp with Svetlana “Winged C” EL34 tubes.

Preface
As a preface to my listening impressions I must confess that I received two different versions of the Ohm drivers, mainly because I complained to Ohm about the first version being a bit too bright. At that juncture, John Strohbeen came clean and confessed to me that he had sent me his new “European” version, which was voiced brighter, apparently to please the German distributor and his clientele. Part of the trouble with the brightness in the European version, was that the lower treble emphasis occurred in the area of female sibilance (with CD or LP as a source), and record surface noise when using a turntable as the source. This was not the best version for me, because in addition to making certain recordings sound too bright for my taste, I own a few turntables and favor lower surface noise. On the plus side, the European version did enhance the high-frequency detail on some of my CDs.

So, my listening tests, and this review will be based on my listening impressions of the second version of the Ohm MicroWalsh Tall SE, which Ohm intends for US and North American markets.

Curiously, John Strohbeen intimated that by changing the crossover values he could custom tailor the high-frequency profile of the speaker for an individual customer. To make the swap he only sends the top-mounted driver assemblies, not the entire speakers. It’s an easy installation, requiring only the removal and reinstallation of the four top-mounted screws, and plugging in a connector plug at the top of the speaker cabinet.

All that said, following are my impressions of the standard US-version of the Ohm MicroWalsh Tall SE speakers.

Groove is in the heart
And the heart of this speaker is certainly the nearly full-range CLS driver. The question I had in my head going into this review was, “can this speaker sound precise and immediate?” I am happy to report that my answer is “Absolutely, yes!”

I listened to a group of female vocalists: Ingrid Michaelson, Regina Spektor, Ella Fitzgerald, and Joni Mitchell. All of them sounded tonally natural and correct. Reproduction of lyrics and consonant sounds is first rate and the proportion of sibilance is on the money to my ears. Male vocalists such as Jack Johnson, Vinx, and Johnny Cash were likewise well-rendered by the MicroWalsh Talls, with no undue chestiness or nasality.

All this adds up to a speaker that is very coherent and harmonically accurate through the critical midrange. And this was backed up by the fact that midrange instruments such as brasses (especially brasses!) and piano sounded uncannily convincing when experienced through the Ohms.

I’ve heard a lot of expensive speakers sound strident on Joni Mitchell’s voice or spitty and sharp on Regina Spektor’s, but the MicroWalsh SE’s maintained their composure and delivered natural facsimiles of these difficult voices, making the feat appear and sound easy.

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Playing through Vinx’s I Love My Job (Pangaea 2-13152) showed me that the Ohms are extremely crisp and detailed in the high frequencies without sounding the least bit hard or irritating. All manner of bells, whistles, shakers and cymbals came across with nuance of detail, shimmer, and a great sense of focus. Fast high-frequency transients like those in the beginning of Jack Johnson’s “times like these,” from on and on (Universal 440 075 012 2) emitted a sharp crack and were suitably incisive without overdoing it. The sound started and stopped on a dime.

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Meanwhile, the bass area seemed to be cut from the same cloth as the midrange and highs in that it was musical, articulate, and not overdone. I was impressed with the tonality of drums on CDs like Vinx’s I Love My Job, and further impressed by the extension of the small 5-inch driver on Alicia Keys’ Songs in A-minor CD (J-records JB 20002). For such small drivers, the MicroWalsh Tall SE’s did a credible job. Obviously they won’t move as much air or extend as low as speakers with larger, more powerful drivers. But I’d say they were solid down to about 50Hz. I believe the specs state -3.5dB at 47Hz, and that seems commensurate with my experience. The fact that they are linear and articulate is what impresses me the most.

As far as the reproduction of dynamic contrasts is concerned, I would judge the MicroWalsh Tall SE’s to be very good in this regard… at least as good as most other speakers I have heard near this price range. I believe my former reference speakers, the Silverline Preludes, are a touch more dynamic, but overall, the Preludes are not quite as natural and transparent sounding as the Ohms. That said, the MicroWalsh SE’s sounded fairly dynamic in my smaller 11’ x 14’ room, and even filled my 14’ x 30’ room at moderate levels. Ohm recommends this model for small to mid-size rooms and I can find no fault with that. Of course Ohm’s larger models are capable of playing at considerably higher levels in large and extra-large rooms.

The Impossible Made Possible?
I cannot conclude this review in good conscience without mentioning some areas where the Ohm Walsh-design speakers, including the MicroWalsh Tall SE’s, are head and shoulders above the competition.

Pure and simple, the speaker’s sonic imagery is fantastic. Not only does this speaker sound extremely good in the sweet spot… it sounds very nearly that good in just about any position in the room. With most conventional speakers, and especially with speakers like my Magnepan MG 1.6QR’s, the sound can be wonderful when you’re lounging on that center-cushion sweet spot. But move slightly to the left and the sound field collapses toward the left speaker; move slightly right and the sound collapses to the right side. In other words, if I have more than one listener present in my room, there’s no way that they can both hear how great my Maggies can sound, and if neither one is in the sweet spot then nobody is going to hear the speakers at their best.

With the Ohm speakers, when you shift your seat to the left, it seems like the right speaker gets louder—effectively maintaining a centered, well-balanced stereo image. Moving to the right, the left speaker gets louder, again maintaining the integrity of the soundstage. It’s almost like magic. Even if you walk beyond the respective left or right speaker boundaries you still get the effect of keeping a stable stereo image. Could anything be better? Yes, it could!

Although Ohm rates the efficiency of the MicroWalsh Tall SE at about 87dB/watt, I played it at very respectable levels with only 30 watts/channel. My Maggie 1.6’s, on the other hand, needed an 85Wpc tube amp in the small room before it seemed like they weren’t sucking the amp dry (though in fairness I believe they were playing at a louder level).

Also, the Ohms seem to be more amenable to a broader range of placement within a given room. Plunk them down a couple of feet from the walls just about anywhere, aim them straight ahead, and they will sound decent. I’ll take that deal any day! If you’ve ever played with Magnepans, or just about any big-panel speakers for that matter, you’ll know that even just shifting the toe-in a hair’s breadth can make noticeable changes in the quality of the sound. Please, please, nobody breathe on my Maggies!

Caveats
The only caveats I have about the Ohm MicroWalsh Tall SE’s aside from not being finished as nicely as a Sonus Faber, are mostly related to their output constraints. They miss that last octave of bass and will not play as loudly or dynamically as some speakers in their price range. But after all, this is one of Ohm’s smallest Walsh-type models and it is intended for use in smaller rooms.

Kudos and Salutations
Ohm’s John Strohbeen deserves high praise for continuing to improve his speakers and pressing them to perform to very high levels of coherency and naturalness.

In short, if you’re searching for a speaker that provides wonderful coherency and tonal balance, is not fussy about positioning or amplifier power, and that will provide a credible stereo image regardless of your position in the room you need look no further than the Ohm MicroWalsh Tall SE.

In small to mid-size rooms the MicroWalsh Tall SE will be difficult to beat. And if you have a large room and require higher output with more bass extension, there are other models in the Ohm line that will fill the bill.

Ohm speakers are sold factory direct, with a 120-day satisfaction guarantee, so there’s little risk in enjoying a pair for a few months.

Once heard, most people would buy the Ohm MicroWalsh Tall SE for its outstanding imaging abilities alone. Happy Listening!

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