Audio 2013 2: My Visit to Oswald’s Mill Audio (OMA) in Brooklyn

Audio 2013 2: My Visit to Oswald’s Mill Audio (OMA) in Brooklyn
November 17, 2013

I’ve known Jonathan Weiss since 2001, when he first began to explore the potential of music reproduction equipment as expressed by the DIY extreme, as opposed to what you find in the usual overpriced audio salons. At that time, he had some fantastic vintage RCA theater horn systems from the 1950s, driven by some Western Electric amplifiers from the 1930s. The last time I saw him was in 2008, when we used the electric winch at the Mill to lower his RCA basshorns into the back of my pickup.

Beginning around 2004, he found a calling — to take what he had discovered, and somehow make it available to the general public, which doesn’t want to learn about circuit design and speaker theory. Actually, even the DIY fanatics don’t make as much progress as one might think. Their efforts, despite some insights, tend to be not very well polished and optimized.

Weiss himself is not really an “audiophile” — he doesn’t participate in that subculture — or a tech geek. Rather, he has learned enough to find a way through the deserts of useless audio opinion, and identify the real experts. He then helps guide those experts toward creating what he has in mind. He is something like a film director, you could say, who coordinates the activities of a great many specialists to orchestrate his overall artistic vision. (Weiss was indeed a film director in the past.)

For example, early on, Weiss found Bill Woods, a now-retired speaker designer for Yorkville Sound, a major manufacturer of audio equipment for professional use. Bill Woods is what I would call a “tech geek.” He has spent his life, literally since the 1970s, experimenting with all the possibilities of horn-loaded speakers. He is probably one of the foremost experts on the subject in North America, if not the world.

However, for whatever reason, in the ten years after leaving Yorkville, and setting up his own company Acoustic Horn (, Bill Woods has never actually created a finished speaker for sale. Without Weiss’s guidance and business-building, we would never be able to enjoy the fruits of Bill Woods’ genius, except in the form of the acoustic horns themselves, which are usable only by DIY types and a minority even of those. I would even say that Bill Woods, left to himself, would not have produced something as good as the speakers he designed for OMA. Thus, I see the results as a sort of collaboration between the two.

Weiss also added his own interest in design to the mix. Weiss’s own spaces, at the Mill in Pennsylvania and his loft showroom in Brooklyn, are quite fabulous examples of architecture and interior design, which I find more satisfying than most of the stuff you see in Architectural Digest. In fact, he has had a successful side business for some time renting these spaces for commercial fashion and product shoots. (The Mill was apparently a recent site for a shoot of Ralph Lauren’s furniture line.)

Along these lines, Weiss hired design expert David D’Imperio to produce things that not only sound great, but look fantastic. Perhaps unique among all audio manufacturers, his products have been featured in major international design magazines — with no mention whatsoever of their sound, just how they look in a living room! Actually, his most recent convention showing was not at an audio event at all.

With all that in mind, I paid a visit to the OMA showroom in Brooklyn.

Let me summarize: First, this is very expensive stuff. It is for people who have vacation houses and drive luxury German automobiles. Don’t be offended if you are not in this socioeconomic class.

Second, it is also a “good value” in the sense that I don’t know of anything comparable at any price, including much higher prices. If you don’t believe me, go to the OMA showroom, and then spend a weekend later at the New York Audio Show, or Sound By Singer, where you will find all the major brands represented, at prices equivalent or higher than what OMA asks. You will probably find that the stuff at the audio show is not even in the same universe. You will probably get a sense of dissatisfaction, which would only increase the longer you spent at this game.

What I am saying is: if you think you might have an interest in introducing music into your life — what the late Dr. Gizmo called the “can opener of the heart” — and can pay for it, even if you are not an “audiophile,” then this is the place to go.

If you are a gear-fondler, then go to the New York Audio Show.

For me, I wanted to hear what was achievable. I understand the philosophy and thought process that went into it, and wanted to calibrate my own understanding to the results.

I too used to have a giant horn system, also driven by refined single-ended triodes. This was not an optimized system, and had many problems, but it did so many things right that I never had the urge to visit an audio show. I have heard that one professional veteran of over 300 audio shows recently called the OMA stuff the best he has ever encountered.

So, I showed up and we enjoyed some time together.

Weiss is a vinyl fan, and has some wonderful turntables. They are very good, but not necessarily better than some other wonderful turntables from other makers. Also, some people are just not vinyl people, including most people who want a system they can just turn on and listen to without being too fussy-fussy. I like vinyl too, but I also like digital, and decided that I didn’t want the complexity of both for now. So, I am a digital guy for the time being. (Hint: get the Metrum Octave and listen to it for at least one full year.)

The amplifiers from OMA are very, very good, but somewhat in the now-longstanding tradition of ambitious single-ended triode amplifiers as expressed by other makers such as Kondo/Audio Note. I personally have found that the DHT SET road is the most satisfying. But, you need very high efficiency speakers for this.

Thus, OMA’s biggest contribution is on the side of speakers. I am amazed today that 99% of all “audiophile” speakers are the basic “monkey coffin” cones and domes in a box that have defined the industry for the last forty years. This is fine for general consumer stuff, but, no matter what the price, you can only get so much out of a 5″ cone midrange and a 1″ dome tweeter, and it isn’t enough, in my opinion, for even modest ambitions. It’s just the physical nature of the elements involved. OMA only makes speakers with horns. Even the smallest model, the Mini, offers the kind of pop and sparkle that only horns can provide, while still being compact enough even for a small apartment.

However, I found that I was most satisfied with the larger AC-1 and of course the top-of-the-line Imperia. Indeed, if anything, I found that my suspicion that I would not be satisfied by anything other than a mid/bass horn in the 100-600hz region to be confirmed. The AC-1 was good, but personally, I would be unsatisfied eventually, having owned big basshorns myself in the past. Thus, the Imperia was the one that really floated my boat. It costs as much as Porsche’s best cars — and, if you are the kind of person who buys the Turbo S models, it would add more to your lifestyle and enjoyment than any automobile.

Following Bill Woods’ vision, OMA uses only conical horns, This is the simplest imaginable horn, and also, arguably, the best. Anyway, Bill Woods thinks so, and he has been professionally designing his own horns for nearly four decades, while also listening to pretty much every vintage item ever made, including RCA prototypes that were never produced. The big advantage of the conical shape is, first, constant directivity. What this means in practice is that the speakers sound good throughout the room. You don’t have to sit in a “sweet spot,” which is a big issue with many horn speakers which “beam” their high frequencies into a very narrow channel.

However, there are a lot of constant directivity horn designs. Variants of the conical constant-directivity horn are the industry standard now for prosound use, and have been at least since the Altec Manta-Ray horns of the late 1970s. (Audiophiles are still stuck on tractrix and “Le Cleach” designs however.) The other advantages of the conical approach are many, but have to do particularly with the first two inches or so of the horn. This is the part of the horn that influences the higher frequencies most directly. Think about how a horn sounds not at its lowest frequency extension, but the highest. Obviously, a very clean and direct shape at this point will tend to lead to the most “clean and direct” sound, which is indeed borne out in practice. After many experiments, Bill Woods abandoned all horns with a “transition zone” in the throat, as is common with some “waveguides” today. Most all commercial horns you see, including constant-directivity designs, have a complicated and, in my opinion, misshapen throat area. This serves no purpose, and only introduces problems. This is also why I have abandoned typical “radial” horns and also vintage multicells. They all have convoluted throat sections. Just think about how it acts at the upper frequency ranges, 2000hz on up. In practice, I have used these horns and they sounded like doodoo — compared to my vintage IPL horn from roughly 1936. (I used the RCA MI-9595 radial horn with the RCA Ubangi bass horns, and also the Altec 1005 multicell, in a biamped Altec A5 system that was in my workshop. Both were not that great, IMO, and I no longer own either.)

For me personally, I am a DIY builder. My visit confirmed what I have long suspected, which is that I am happiest either with headphones, or a full-on horn rig. What a bizarre place to end up after these years of audio interest. I would build my own full-on horn rig, which wouldn’t sound as good as the Imperia which has been optimized over years by one of the best speaker designers alive today. But, it would sound good enough for me, and I wouldn’t have any urge to visit the New York Audio Show.

If you aren’t going to have horns, then you will have cones of some sort. Right away, you are dealing with lower efficiency and thus the need for more power, which makes my beloved DHT SETs more problematic. Also, you have all kinds of complexity regarding crossovers and such. Some people come to appreciate the problems of this, so they go the fullrange or wideband driver route. The problem here is that you are giving up more efficiency, more dynamic range, and have more and more technical problems because it is not so easy to make one cone driver make music all by itself. (I used to have some Fertin 8″ field coil fullrangers in an open baffle, assisted by a Fostex bullet tweeter on top and twin 15″ woofers on the bottom. It was about as good as a cone speaker could be, and people told me so. I sold it.)

This brings us to headphones. I use the not-very-impressive Sennheiser HD600. You give up a lot when you go to headphones, from real speakers making real sound.

But, you gain a lot too. Headphones are superefficient, so, just like big horn speakers, the power limitations of DHT SET amplifiers are no longer an issue. They are single-driver fullrange, so no crossovers, multiamping or integration problems, including phase, dispersion, cancellation, lobing, and all the other issues that emerge when you have multiple drivers trying to act like one. Of course, they don’t bother your neighbors or your wife, don’t fill up your living room, and don’t have an issue with room resonance and damping. You just pay your $350, put them on your head, and focus your attention on electronics instead. Actually, you can focus your attention on the rest of your life — a big horn system, particularly a multiamped one as I made in the past and would make again, is a 10x greater commitment of time and energy than a nice headphone rig. It typically takes about three or four years of tweaking to get it right, and even that assumes that the basic building blocks are good to begin with. For me, maybe it is a retirement project.

One reason I write this is to help people bring great music into their life, without wandering in the desert of “audiophile” confusion. I want to show what I consider the simple and pure path to emotionally satisfying sound. Actually, this is also what inspired Weiss to create OMA and its line of products.

If this sounds interesting, and you can afford it, go there.

If you have a normal-size bank account, consider the Bill Woods-designed Unity U15 or Unity U215 speakers from Yorkville, available for about $2400-$3000 per pair new including shipping (try eBay). You might even be able to find a pair used, for 50%-60% of the new price. Biamp with a big solid-state amp on the woofers, a SET DHT amplifier on the horn, and a passive upstream line-level crossover on the SET amp. First-order is fine, around 300hz. I would cut out the woofers around 70hz and add a sealed subwoofer. You can use something like the Behringer amplifiers with included digital DSP for the woofers and sub. Even this plug-and-play approach takes a little technical skill. You have to learn what a “passive line level crossover is,” whether you have a source to drive it, and how to make one.

I wish that Tom Danley, the Other Great American Speaker Designer Besides Bill Woods, would release a home-audio version of the Danley SH50. I would aim for a 100hz cutoff, better than 104db efficiency, 8 ohm or higher impedance, and lower power handling (40 watts or under), which would allow shallower crossover slopes and perhaps the use of different drivers such as the coaxial compression drivers from BMS that Danley uses on some of his largest creations. The stock SH50 is also pretty good of course, but it is around 97db/w/m, which is really too low for SET DHT amps. Lower efficiency doesn’t matter much when you are using 2000 watt prosound amps, and it allows Danley to EQ-up the lower end, pushing extension to 50hz although it is really a 100hz horn geometry. I would even consider (sacrilege!) adding a supertweeter, which would eliminate the need for most constant-directivity EQ on the tweeter, thus allowing more efficiency and also cutting the tweeter out before it starts to go into breakup modes around 12kHz. For all these reasons, I don’t think I can recommend the SH50 in its stock form unless you also use a higher-power amplifier around 20 watts or more. That eliminates SET DHTs, but could still be done with push-pull DHTs, however, something like a PP 300B or even PP GM70, if you are a little nutz. Otherwise, I’d consider something like the Hypex NCore, with the caveat that I have never actually heard a “Class-D” amp that sounds good.