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Reviewer: John Potis
Analog Source: Rega P9 turntable, RB1000, Benz Micro MC Silver, Rega Super Elys & Garrott Bros Optim FGS cartridges
Digital source: Pioneer DV-535 DVD player/ Bel Canto DAC2
Preamp: Shindo Partager
Power amps: Bryston 7B ST monos, Art Audio Carissa
Speakers: Ohm Acoustics Walsh 4 with 4.5 mk.2 upgrade, Horning Perikles
Cables: JPS Labs Superconductor interconnects and speaker wire, DH Labs D-75 digital; power Cords: JPS Lab's Power AC, Analog AC, Digital AC and Kaptovator power cords, ZCable's Heavy & Black Lightning cords
Powerline conditioning: Balanced Power Technology 3.5 Signature Plus with ZCable Heavy power cord
Sundry accessories: Vibrapod Isolators and Cones, Ultra & Heavy Z-Sleeves
Room size: 12' by 16' with 9' ceiling
Review component retail: $2995

I've written about them so many times that I almost can't bear to do it again - those Ohm Walsh 4s that I purchased for myself in 1983. I wrote about them in 1997 when I reviewed the Ohm Walsh 300 Mk 2 loudspeakers. I wrote about them again when I reviewed the tiny Ohm Walsh Micros for 6moons in December of 2003 and here I am writing about them once more. I guess it's true, we never do forget our first. And indeed, they were my first. My first quality pair of loudspeakers. I bought them after an exhaustive search through both magazine reviews and HiFi store auditions. But I remember like it was yesterday - that feeling that I just had to hear them before I bought anything else. Unfortunately, since Ohm Acoustics went factory-direct in 1998, most audiophiles today won't get the same opportunity. That's too bad.


Those Ohms of 21 years ago were different and worked unlike any speaker I was able to hear. Early Ohms utilized what they called the Walsh driver developed by the late Lincoln Walsh. This driver looked like an elongated cone that faced down into the speaker cabinet and radiated sound in a 360° pattern off the driver's rear via the speaker's open architecture. Modern Ohm Acoustics speakers feature what Ohm calls their CLS driver - a refinement of the Walsh. Most notably, the CLS (Coherent Line Source) is much more efficient than the original Walsh driver. Go here for a detailed discussion of the CLS.


Another thing that makes the Ohm speakers unique (then and now) is that they are almost a 1-way speaker. The CLS driver handles frequencies from the bass through about 10kHz, at which time they (finally) hand off to a (metal) dome tweeter. In doing so, they remain completely free of all known deleterious effects of crossovers usually located in the all-important midrange. Coherence is the natural by-product of one driver doing most of the talking - or singing as it were. So are phase coherence and time alignment.


Getting back to the 4s, when I sold them after about 6 years of ownership, they didn't go far. I sold them to my father-in-law where they enjoyed regular use until about three years ago. Then the drivers finally fell victim to UV induced cancer of the surrounds (Ohm estimates the life of today's surrounds at about 30 years). At that point, my father-in-law owned three pairs of Ohms. A pair of circa 1985 Ohm Walsh 1s upstairs; the aforementioned 4s in one room on the ground floor; and a pair of the larger modern Ohm Walsh 300 Mk IIs in another room on the same floor. (Ohms enjoy tremendous popularity in my circles. My brother-in-law owns a pair of Walsh 200s as does my assistant at work - a pair of restored Walsh FRS-11s.)


After a little research, I discovered that Ohm would replace those rotted surrounds for $300, which my father-in-law had them do. I also learned something else of interest. Not only could Ohm repair the speakers but they could also fit the enclosures with modern Mk II versions of the same driver. If that wasn't cool enough, what really got my juices flowing was that they could fit the 4's enclosures with the larger drivers used in the Walsh 300 Mk II -- the subject of a piece I wrote for SoundStage! a few years ago. And if that wasn't enough, one could upgrade these 20+ year old speakers with the very best driver Ohm makes, the driver designed for their flagship, the Walsh 5 Mk II. Is that radical or what? Not only could this company keep a vintage pair of their speakers on the road, but they could upgrade them to their current state of the art. Contrast that with companies that can't retrofit this year's improvements into last year's speaker.

Following my being so impressed with Ohm's tiny Micro Walsh speaker last year, I decided it was time to revisit the larger Ohms. After some haggling with my father-in-law, I reacquired my long-lost Walsh 4 cabinets with an eye toward upgrading the drivers. But to which ones? The big Ohm 300 Mk IIs are too much speaker for either of my current listening rooms. With true 20Hz of bass and lots of it, they overwhelm all but the largest rooms for which they are designed. But what about the driver designed for the Walsh 5 MkII? It's the exact same driver used in the 300 MkII save for a series of three-position frequency-contour switches located on the driver's rear. One 3-position switch each adjusts the level of low bass, mid bass, midrange and treble. In a nutshell, the low bass controls are designed to vary the bass output for larger or smaller rooms. The midbass control is largely to compensate for room boundary and corner effects, the midrange attenuator to accommodate personal tastes and the treble pot to compensate for reflective/absorptive surface conditions.


Did I dare dream of shoehorning a pair of Ohm's best drivers into my room? Think of all that bass. Think of all the untapped headroom. In my smaller rooms, that driver would be assured of never breaking a sweat. An e-mail to Ohm's president John Strohbeen, with a description of my room and a request for a suggestion for my best option was answered in short order. Strohbeen was sure that the Walsh 5 Mk II driver was just my ticket. Ohm refers to this option as the "4.5.2 upgrade".


Of the 4.5.2 upgrade Ohm's website says, "This upgrade gives you deeper bass, extended dispersion in the treble, over twice the dynamic headroom and controls to match your room and listening tastes. The kit includes:


1.) Two new Walsh 5 Mk-2 drivers on special mounting boards for the Walsh 4 cabinet.
2.) Two new grills to fit the larger drive.
3.) Two new input boards with gold-plated binding posts.
4.) Two new vent adapters to tune the cabinets lower."


I placed my order. In no time my new goodies arrived. Ohm's packaging is first-rate and, with the exception of the protective plastic bags, biodegradable. They come so well protected that I can't imagine their products incurring shipping damage very often. As promised, I found everything listed plus some new mounting hardware. All I needed to supply was a screwdriver for prying and a hot glue gun for installation of the binding post boards.
The hardware they sent along was unnecessary as I was able to use what came with my speakers (which looked better too). The first (and easiest) thing I did was slide the vent adapters right inside the existing vents at the speaker's bottom. They are wrapped with foam and slid right inside where the foam held them snug. After that, it only took a few moments to unscrew the driver mounting assembly, remove the old driver, disconnect it from the crossover which is mounted on the inside of the speaker input board and set it aside. From there I proceeded to carefully remove the speaker's stuffing, putting it aside for later re-insertion. Then came the scary part - the removal of the old crossover, level controls and inputs, all located on one board. I was a little concerned about damaging the enclosure but I needn't have been intimidated because it popped loose with a little prying of a screwdriver. With the aid of a hot glue gun, installation of the new binding post board was a snap. All the crossover and filter components are mounded inside the grill of the Walsh 5 Mk II driver rather than on the board.


After the reinstallation of the speaker's stuffing (requiring a little more hot glue), it came time to install the new driver proper. The Walsh 5 Mk II came mounted on a board of the same dimensions as the top of the speaker enclosure. As the Walsh 5 Mk II driver has a much greater diameter than the old one, it could not be dropped into the cabinet as was its predecessor. Rather than dropping down into the enclosure as before, the new driver is seated on top and then secured by the aforementioned hardware. This necessitated the removal of all the mounting bolts from the enclosure. Through the use of long bolts and a series of locking nuts, I was able to adjust the original hardware to make it appropriate for its new task (look inside your Ohms to see what I mean). This process took as much time as everything else combined. All in all, I spent about an hour and a half on the whole project and never broke a sweat.

The new black grills looked great but I really like my old brown ones. So I boxed up the blacks and put them away. I got out a jigsaw and in the most ungraceful of ways, enlarged the openings of my old grills to accommodate the larger driver [see below]. The elegance with which they now adorned the newly upgraded speakers completely belied the mess I knew was hidden underneath. I was very pleased. I even found the new contrasting black accent (the driver's mounting plate) somewhat chic.

When I was done, I had restored/upgraded a pair of speakers (that in 1983 cost me $1500) with a new set of drivers that run $2995 for a product roughly the equivalent of the Ohm Walsh 5 MkII that sells for $5,000. Does Ohm protect the value of your investment or what?
Setup
At the time of writing, I've had the Ohms up and running for nearly 5 months. I learned from experience (namely, my review of the Walsh 300 MkII) that Ohms (particularly the larger ones) require real break-in time. I
think this pair is ready for the prime time but I won't be surprised if they keep getting better.


I've kidded to friends that if I tire of the rest of the speaker, I'll low-pass filter them and use them as subwoofers. With ca. 25Hz bass extension, these speakers will embarrass a lot of so-called subwoofers both in terms of quality and quantity. I keep the low-bass switch in the middle "0" position no matter the room. In very large rooms, one would set them to the highest position to match the output of the big Walsh 300 MkII.
Removing the speakers to the smaller of my rooms does necessitate a decrease in the speaker's mid-bass response. Here I position its filter to the most attenuated position (the "-" mark). For the sake of utter neutrality, I should probably do the same for the deep bass but I like the added foundation I'm getting. It's much akin to bumping up the subwoofer (low-passed at about 40Hz) just a notch or two. It sounds good and it's fun. So sue me.
In either of my rooms, I keep the treble setting at "0" - the middle position. If your room is particularly live or dead, one of the other two settings may be appropriate. Here's the surprising part: In the larger of my rooms I position the midrange control to the lowest output setting, in the smaller room the middle "0" setting. Even stranger is the fact that in the larger room, placing the midrange control at the "0" setting results in what sounds like a midrange suck-out. The sound gets a little hootey, a little blunted and reserved as though in need of a boost through this region. Male vocals in
particular take on a hooded quality. Initially this caused me some frustration because increasing the output (to the "+" setting) made matters worse. When I tried the reduced setting out of desperation, everything settled right in. Strange? Kinda. But my living room is difficult and that's the beauty of being able to tailor these speakers to their environment. When I was done, the Ohms worked better in that room than any speaker I've ever used in there - bar none. And they work fantastically in the smaller dedicated listening room.


In my smaller room, the speakers ended up about 30 inches into the room. Particular attention needs to be paid to ensure that the acoustic environment behind the speakers is fairly symmetrical as they are, after all, omni-directional. In my case, I started with a tall ficus tree (well, the trunk of one) behind one speaker and a shorter and much leafier tree behind the other. The ficus trunk gave way to the much more reflective wall behind it, which caused image focus to skew toward that speaker. Rather than remove the decorative trees, I threw a small piece of acoustic foam into the corner to create acoustic symmetry. Due to their adjustability, the Ohms are fairly easy to place for such a full-range speaker. As usual, final placement was based on obtaining the quickest, most powerful and most delineated bass.