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John Potis Reviews the original MicroWalsh Tall on 6moons

Monday, December 1, 2003 MicroWalsh Signature Edition Tall Speaker
Publisher: 6moons | Author: John Potis

A little History

It was 1983. My search for a “high-end” speaker took me to all the local salons to result in the purchase of my first pair of Ohm Acoustics loudspeakers. The floorstanding and remarkably full-range Ohm Walsh 4 set me back $1500 and left me one happy audiophile. They were so good that I bought a pair of the smaller Walsh 1 for another room a bit later.

Fourteen years later, it’s 1997, naturally. One of my first-ever review assignments? To evaluate the Ohm Walsh 300MkII. These speakers were larger than my first pair of Ohms, with a larger driver and cabinet, deeper bass and greater output capability. At $4000/pr, they were also more expensive.

Today my father-in-law owns a pair of those 300MkIIs, incidentally the very pair which was the subject for a little SoundStage! piece I wrote a couple of years ago. The intervening years have made two things clear: First, the Ohm Walsh300MkIIs hadn’t been completely broken in when I wrote about them. Though many things had already impressed me, I had yet to hear what those speakers really could do - this despite several weeks of riding them hard. Because their speakers are notoriously difficult to break in, Ohm now gives the buyer not a 10- or 30-day trial but a 120-day in-home evaluation period.

Second, the perspective gained over the last six years of audio reviewing has confirmed that if you had a large – or very large – room and your electronics were up to the task, those speakers are, hands down, the biggest bargain I can think of. Further playing has brought out detail I hadn’t dreamt this design capable of. The Ohm 300MkIIs create bass that will embarrass most so-called subwoofers. Their output capability exceeds what my ears can stand and they have a sweet spot as large as the room itself. Combine all that with natural soundstaging chops that compete with anything, and the result is a pair of speakers that’s a must-hear for anybody with the requisite space, and a budget that extends that far and well beyond. In many ways, these are truly magnificent speakers.

Ohm Acoustics manufactures two very different types of loudspeakers - the usual cone’n’dome variety (certain models incorporating different ideas on dispersion) and their claim to fame, a complete line of speakers using the Walsh driver based on the work of the late Lincoln Walsh. Years of refinement have created what Ohm calls the CLS or Coherent Line Source driver. Picture a typical cone woofer elongated in depth akin to a megaphone - but not quite. Now point this driver downward so that it fires into the top of the speaker’s enclosure. Sound propagates off the back of the driver rather than front, and by virtue of its open-air surroundings, in a 360-degree rather than narrow-directivity dispersion pattern.

States Ohm Acoustics on the subject: “The CLS system uses an inverted cone driver with the speaker coil driving the peak of the cone. The sound vibrations travel from the top down and out to the rim.

By using a cone material in which sound travels faster than it does in air (supersonic) and by carefully aligning the angle of the cone, the driver generates a vertical wave front, radiating sound equally in all directions like an expanding drum. Because the inverted cone driver radiates in all directions, it sounds the same in all directions.” In other words, the driver is naturally time-coherent and omni-directional. But Ohm feels that, with certain circumstantial exceptions, an omni-directional response in the treble is undesirable. Rear-wall reflections at these frequencies can become confused with the original sound and consequently blur imaging. Hence, in addition to the CLS main driver, Ohm adds a “super tweeter” mounted vertically at the Walsh driver’s top and angled inwards so as to cross its main axis well in front of the listener. This tweeter is reportedly pressed into service around 8 kHz which eliminates a crossover network anywhere near the critical 2-6kHz range where human hearing is most sensitive to discontinuities.

The tweeters are positioned such that they radiate high frequency energy diagonally across the listening area. This creates good stereo imaging over an extraordinarily wide listening area. It also allows fine adjustment of high-frequency balance via toe-in or toe-out as they naturally sound brightest when the tweeter fires straight at the listener.

With the exception of the Walsh 5 Mk2 (whose controls on the back would interfere), Ohm makes versions of all its Walsh models where the super tweeter is aimed at the ceiling instead, thus becoming optimized for rear/side speaker duty in home theater setups. Ohm finds that non-directive treble sounds more enveloping and therefore more convincing on movie effects such as rain and thunder.

The Micro Walsh

The speakers under review are brand-new models and far smaller than any Ohms I’ve ever used, thus clearly intended for primarily small rooms. With its jarmulke skullcap, today’s tall version of the Micro stands just a touch over 36 inches - er, tall and measures a mere 6 x 6 inches across, parked atop an 8-inch integral square base. The diminutive short version clocks in at all of 23 inches [below]. There are no provisions for spikes of any sort. Remove the speaker’s bonnet and you find a protective perforated canister that houses the driver proper. This canister is just over 5 inches in diameter, telegraphing that the driver inside must be smaller than 5 inches across. But don’t let that fool you. Due to its unique geometry, the CLS driver has a greater radiating surface and therefore superior displacement capabilities than ordinary dynamic cones of equivalent diameter. Ohm is fairly closed-mouth, both about the soft- dome tweeter used and other details. The review pair was finished in a rich Rosewood veneer and is priced at $1000/pair. A cloth-covered version is available for $900. Ohm specifies a nominal impedance of 6 ohms, a frequency response of 45 to 20 kHz +/- 3.5dB and a sensitivity of 87 dB with a standard 2.8V input, making the Micros suitable for amplifiers between 20 and 150 watts.

Fit and finish were good, with only very few floor-standing speakers in this affordable category competing in real Rosewood livery. Close inspection revealed craftsmanship not quite of furniture-grade level but from a few feet away, the speaker looked remarkable. The only subject of doubt? The grill bonnets can’t be firmly affixed to the speaker but simply rest on top. That’s no big deal until someone brushes past them. If I owned these? I’d stow the caps away. I thought the speakers looked better without ‘em.

The speakers come with a gold sticker placed at one corner underneath the bonnet. Indicating tweeter direction, this corner must point toward the center of the listening area. Those wanting to do without the grills will probably want to relocate the sticker too, perhaps underneath the base for future reference. Sticker gone, the speaker now has a remarkably distinctive yet finished appearance. At roughly 16 lbs, the Micro is lighter than a lot of monitors, though deceptively inert. The cabinet has all the rigidity you’d expect from an enclosure with a 6-inch square footprint. When you consider that the Walsh driver excursions are vertical as opposed to horizontal like your usual cone drivers, the speaker’s entire height makes up the de facto thickness of its baffle. This is why larger Walsh speakers arrive with casters. There are no horizontal forces exerting on the speaker to make spikes or other coupling measures redundant.


The good news? These new Micros don’t take remotely as long to break in as their hoary predecessors. About 40 hours gave Ohm’s John Strohbeen and me reason to believe that they were ready for prime time, so into the listening room they went. I ended up with an equilateral triangle between speakers and listening chair which put the speakers relatively far apart but resulted in excellent soundstaging and solid center fill without toe-in. With these Ohm models, the wider you space the speakers apart, the more on-axis you sit with the tweeters. I settled on this configuration because I quite liked the overall balance, with the driver canisters’ centers not quite three feet from the back wall


What sets the Ohm Micro Walsh apart from every other sub $1K floorstanding speaker in memory? I find them unequivocally enjoyable, without any major nits to pick that would qualify my enjoyment. While better speakers certainly exist – though none in their price bracket that I’ve encountered yet – owners of the Micros, with the possible exception of ultimate bass extension, won’t feel obliged to make excuses for their speaker when compared to more expensive see-what-the-Jones-got competition. In fact, these are the kind of speakers that will make owners of certain far more expensive speakers feel rather silly.

Most amazing for a speaker its size? Bass response. Close inspection revealed a hidden bass port between enclosure and plinth that aided in cleanly extending bass to 40Hz in my smaller room. In the larger family room, the speaker was amazingly capable of satisfying bass with music, though a subwoofer will be preferred by those wishing to use the Micros in a multichannel theater system with its reliance on bass effects (and I highly recommend the Ohms for Home Theater, too). Nevertheless, even in the larger room, the Micros offered sharply defined music bass. I was halfway through Talking Heads’ Stop Making Sense DVD when I discovered that I had left my subwoofers off. Nothing about what I was hearing motivated me to get up and turn them on, either. Tina Weymouth’s bass lines were articulate, of entirely appropriate weight and rendered with complete believability. The multitude of synthetic bass generated from Steve Scales’ keyboards enjoyed equal credibility.

In the smaller dedicated two-channel room, the Micros had even greater authority. Only truly extended material like Electronica or Reggae would require a subwoofer. The very lowest notes were MIA, granted, but down to the electric bass’ lowest fundamental or around 40Hz, the Micros were completely self-sufficient. The opening bass note on “Humpty Dumpty” from Aimee Mann’s Lost In Space [SuperEgo SE 007] had both the heft and transient authority that I look for, without bloat or artificial lower-midrange ripeness. Ditto for the ambitious bass line from the CD’s title cut.

While the diminutive Ohm Micros offer superb bass for the ears, they are obviously not pant-flappers or wall-shakers. They couldn’t quite manage the wall-flexing power required to give Bowling For Soup’s Drunk Enough To Dance [Silverstone/Jive 01241-41819-2] the drive that other, much larger speakers do. Nevertheless, they did an almost unbelievably good job with songs like “Tea In The Sahara” from The Police CD Synchronicity [A&M CD-3735] and ZZ Top’s “Rough Boy” from their Greatest Hits [Warner 9 26846-2]. Both songs resulted in loud and satisfying bass that energized the room.

The Micro Ohm’s midrange is superb in this class of speaker and very good by any definition. Highly detailed and uncolored, its full-bodied mid-bass and lower midrange differentiate the Ohm’s presentation from that of competitively priced mini speakers. Those stand-mounted monitors tend to favor midrange detail over all else and can’t generate the body and warmth of the Micros, with a psycho-acoustic side effect being that body and warmth can, at first blush, make a speaker seem not quite as transparent or detailed. The Micros easily stand up to any minis with their meaty presentation that’s accomplished, solid and beautifully fleshed-out.

Female vocals sound relaxed and effortless and indicate a slight sweetening of the upper midrange. Compared to much more expensive speakers, the Micros seem to shave off a touch of leading edge in this region. When the Micros are used with good associated equipment, the result is a relaxed sound that pleases with easy-going silkiness. When used with the receivers that will be their likely mates, I imagine their forgiving nature as God-sent. Anyway you slice it, the Ohms add up to a grain and glare-free presentation that is free of any edge.

That easygoing nature continues right along to a perfectly married treble that’s smooth, sweet and very forgiving. In this regard, these speakers remind me of the Morel Octwin loudspeakers that I reviewed for SoundStage! earlier this year and which sell for about 9 times what the Micros demand. As you would expect, the Morel tweeter is more extended and highly detailed, but the two speakers do have very similar personalities, making them eminently suitable for fatigue-free extended listening.

It is this sweet and forgiving nature that makes the Micros sound particularly good once the volume control is cranked up. Contrary to other speakers in this class that manage composure at polite volumes only to become rough, ragged and abrasive once their limited threshold of civility is breached, the Micros maintain their poise like much more expensive speakers. With decibel peaks in the mid 90s – something well beyond most their competition – the bass remains articulate and capable of energizing the room while the midrange remains unchanged: Smooth, clean and relaxed. The soundstage stays put and does not get in the listener’s face. Ditto for the treble; at high volume levels, it retains composure and never threatens with hostility. If this were the end of today’s Ohm Micro story, it’d be more than good enough. But we haven’t even touched upon what makes the Micros so special yet: These speakers are omni-directional, remember? If you haven’t lived with a pair of omnis, you don’t know what you are missing. Period.

First, while controlled-directivity speakers may offer predictable benefits for the seated listener, omni-directional speakers invite everybody in the room to join the fun. You may find that the sweet spot loses its appeal as you move about the whole room enjoying a full stereo-spread if not quite pinpoint imaging. We’ve all walked past a pair of monopoles only to hear the closest speaker first. You observe its volume increase in intensity as you approach. As you pass, its output decreases and you discover yet another sound source ahead as you approach the second speaker - and never mind the hideous timbral changes. Not so with omnis. Walk by the pair and it’s as though you were crossing a soundstage. No increasing and decreasing intensities, no drastic shifts in tonal balance, just a smooth changing of perspective as you seemingly walk by performers on stage.

The best monopole speakers may offer certain things to head-in-a-vise sweet spot listeners that these Ohms can’t replicate - but these Walsh speakers are designed for those who want to enjoy their music while they live their life. And that, friends, you do not do from a chair. And while it may seem silly to even consider such a thing, the power response of omni-directional speakers promises even better sound when listened to from the adjacent room - that’s a fact! One thing that monopoles in this price category will never offer to the seated listener is omni-polar soundstaging. These speakers disappear completely, leaving only a stage of musicians, something unheard of in this class. And for those in the small rooms for which the Micro was designed, this is especially important because the Micros conjure up a spaciously deep and wide soundstage starting well behind them. Such depth of field is sometimes related to a reticent tonal balance but not here. Most omnis can pull this trick regardless of tonal balance - it’s a product of dispersion patterns. For all intents and purposes, the Ohms are capable of completely obliterating the rear wall. And when the music calls for them to do so? They can remove the sidewalls, too, leaving only an extraordinarily deep and wide perspective on the music.

Try “The Heart Is A Lonely Hunter” from Dave Grusin & Peggy Lee’s One Of A Kind [GRP-D-9514] and observe the beautifully natural soundstage and Grusin’s piano placed deep at stage right. Notice the Ohms’ natural beauty on the piano, rich in body and nuance and completely surrounded with syncopating space. Then there are Ron Carter’s subtle acoustic bass lines, taut yet inconspicuously supporting the music until the end of the song where it stands out in very detailed tonality. Violins are smooth, with just enough detail to sound like massed strings rather than a dumb mass of strings. Beautiful. “Birk’s Works” from Dizzy Gillespie’s New Faces [GRP-D-9512] demonstrated fine instrumental textures and contrasts. Gillespie’s trumpet, Kenny Kirkland’s piano and the tenor and soprano saxuosity of Branford Marsalis combine for a sonic obstacle course through which the Micros sailed with ease.


Going into this review, the most pressing question was one I wanted answered for myself. 20 years ago, the most musical speaker my budget could locate was the Ohm Walsh 4. By today’s standards, it sounds dated and colored but since Ohm has no dealer network, I was left to ponder whether the modern Ohm Walsh speakers had kept up with technology or were stuck in a circa 1983 time warp. If you own Ohm speakers and are wondering the same thing – or considering a new pair – you should know that indeed, Ohm has kept up with them Jones. They still produce some of the most over-achieving speakers around. Their speakers combine uncommon listenability with some of the most musically natural and distinctly non-HiFi, non razor-edged soundstaging extant, coupled to the transparency and colorless performance of some of today’s better dynamic designs.

The Ohm Acoustic Micros are superb speakers and class-leaders. By combining excellent sonics and a most room-friendly size and appearance with what Ohm refers to as Full Room Stereo, Ohm Acoustics has produced a superb example of state-of- the-art budget speaker design. As a reviewer accustomed to gear costing multiples of what Ohm Acoustics asks for the Micros, it is my greatest pleasure to borrow our Editor’s blue seal and bestow onto them 6moons’ Blue Moon Award for transcending class and expectations in the $1000 loudspeaker category.

Peter Aczel, currently Editor and Publisher of The Audio Critic, says Ohm started in 1971. According to Strohbeen, he’d know since he was one of the original founders. Unlike any other company I can think of, Ohm still fully supports every product they’ve ever made. Two years ago, I bought newly reconditioned drivers for those 20-year old Walsh 4s. They also take trade-ins no matter the vintage. Periodically, they refinish those trade-in cabinets, install the latest/greatest drivers and offer them for sale at attractive prices. Without a doubt, these guys go the extra mile to serve their customers past and present and are very serious about what they are doing.

Think about that next time you open up your wallet. You can spend your money with manicured and flashy designers who go out of business periodically only to resurface with a whole new look and an entirely different philosophy of design. Or you can spend it with a company whose track record for quality design and customer support makes no excuses. Don’t then underestimate the importance whereby Ohm regards all of its past and present customers. Ever since they went factory-direct in 1998, past customers have become Ohm’s mainstay, for repeat as well as referral business. Hence the first thing Ohm did in 1998 was to upgrade every single speaker in its lineup. Boy am I glad that I didn’t stay stuck in a time warp and revisited this company in 2003. Like Magnepan, Ohm is one of the unsung heroes in the high-value, high-performance speaker sweepstakes.