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PMC OB1i Floorstanding Speaker Review

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PMC OB1i Floorstanding SpeakerI must confess that when Constantine Soo first approached me about a possible review of a PMC speaker system, I found myself at a loss. I personally had not heard of PMC nor had I had any recollection of ever seeing them. After he sent me the URL, I went ahead and accessed their website and had a fairly lengthy read. After doing so, I was REALLY surprised and even sort-of embarrassed at not having had previous knowledge of this company. First of all, they are English, and I have always been a fan of English speakers. Also, as it turns out, they are quite established not only in the consumer market in England, but are also highly regarded in the professional recording studio world. In fact as it turns out, according to the manual that comes with these speakers, I actually own probably as many as one hundred British import LP’s that were mastered with PMC speakers as monitors. Albums by artists as diverse as Cold Play, Peter Gabriel, Joy Division(!), Iggy Pop, Katie Melua, Kate Bush, David Bowie, (the list is seemingly endless) were all mastered with PMC’s. By the way, PMC stands for, Professional Monitor Company. ….Go figure.

The PMC line of home speakers is quite extensive. It includes the DB, TB, GB, FB, OB, and EB models, (in order of size and price). The more I research these speakers the more I realize just how steeped in European speaker design tradition they actually are. The speaker I will be describing to you in this article is the OB1i. The OB1i is second from the top of the home consumer line of full range speakers. It is a floor standing 3-way transmission line design; in PMC’s flavor, extended ATL – Advanced Transmission Line. Speakers employing a transmission line are no stranger to me. Having been in the audio business back in the days of the English IM Fried, Celestion, KEF speakers, and the American made Essence Amethyst, I heard quite a few examples of transmission line designs; all having the distinction of producing high quality bass out of rather modestly sized enclosures and having tight control over driver integration and distortion levels.

The driver complement of the PMC OB1i includes a transmission line-loaded 6 ½-inch woofer, a 3-inch soft dome cloth midrange that is mounted in its own internal enclosure, and a 1-inch soft dome cloth tweeter that is designed in partnership with SEAS, or Scandinavian Electro Acoustic Systems, which has been around at least since the 1970’s when their dome tweeter was utilized in the famous Dynaco A25’s and A50’s. The fit and finish of the cabinetry on the PMC OB1i’s is first rate. My review samples came in a handsome Cherry finish and they are also available in Oak, Walnut, and Black Ash.

Getting Started

The PMC OB1i’s arrived as a matched pair set. For the sake of doing a quick analysis of the speakers in my main room, I simply moved my electrostatics out of their position and placed the OB1i’s in the same spot. A quick listen confirmed that I would very definitely need to tweak the placement once the OB1i’s break-in was complete. I moved the PMC’s to another room in order to get this accomplished. Although the company’s representative assured me that these speakers already had some extent of play time, my initial listening impression indicated that the speakers, particularly in their bass and lower midrange performance, very likely needed to be broken in for some period of time. I opted to set-up a secondary all-solid state system to run the speakers in for a full 10 days. This seemed to have done the trick. Also worth noting is something that I have not had to deal with for many, many years in my main system: the issue of speaker grill covers. Yes, the cloth grill covers do offer some level of protection to the drivers from children and pets, and even may contribute to a speakers WAF, but definitely at the expense of sonic performance. I took them off and left them off for the entire review period.

Once broken in, I went about the task of swapping out the electrostatic speakers with the PMC OB1i’s into my main system. The initial system included an all-Conrad Johnson setup with the ET-250S power amplifier and my reference Conrad Johnson CT-5 Composite Triode line stage, and Aural Symphonics cabling throughout. Speaking of cables, I really need to comment on the connectivity options and binding posts utilized by PMC in the OB1i’s. The speaker comes with a cubby that contains 3 sets of connections so that the speaker may be tri-wired, or even powered in a tri-amped fashion. On the surface, I would applaud that level of flexibility. However, there is a caveat. The three sets of binding posts are interconnected using what appears to be a gold-plated brass jig with three U-shaped slots. This needs to be in place when you are using a single set of speaker cables with spade ends as is the case with my situation. This, as it turns out, is a very tricky and frustrating endeavor because as you loosen one set of posts to insert the spades, the brass piece makes its way out of the other two sets of posts. Also, since the brass piece is so smooth, it tends to “squirt” out of the binding post as you tighten down the posts with the speaker cable’s spade ends. The binding posts appear to be drilled for bananas, but the sets of bananas I had at my disposal were too big to fit in the posts. I therefore highly recommend the use of tri-wired, or three sets of speaker cables that are highly flexible. That way, they can all fit into the cubby area where these three sets of binding posts are located and be properly tightened into place without the need for the jig piece to connect the three sets of posts. This is especially important when first setting up the speakers and moving them around as you dial in their correct placement. The cables otherwise tend to slide right out and can cause a short.

Speaker placement, thankfully was a piece of cake. After only 3 moves, I managed to hit the perfect triangle of speaker separation, toe-in, and listening distance. Of course, it was only afterwards when I actually read the OB1i’s owner’s manual that I discovered the proper speaker placement procedure. I was happy to find that should I have simply followed their procedures for speaker placement and toe-in, I would have come to nearly exactly the same placement without the trial and error.

The Sound

For those of you that have already read my review of the Conrad Johnson ET-250S power amplifier, you already have a preview as to the sound qualities of the PMC OB-1i’s. The sonic qualities I consistently heard through various iterations of my system suggest that the PMC OB-1i’s are quite capable of delivering a clean and resolute sound space, as long as the speaker grills are removed and set aside. Particularly noteworthy is the fact that despite being a 3-way design and therefore having 2 crossover points, I did not hear any irregularities in response nor anything untoward to suggest that there was anything amiss in the crossover frequency regions. This is admirable for a speaker of this size and price class. Imaging was expansive in depth and width, while not quite as crystalline-clear and transparent as with my reference electrostatics. That said, what the PMC OB-1i’s do phenomenally well is to deliver an image of a vocalist or soloist that is much more believable in size and scale when compared to my large panel speakers. For instance, intimate recordings of vocal and acoustic guitar by Sting, Katie Melua, and Dave Cousins come across as more believable in terms of sizing that contributes to an overall you-are-there factor. The PMC OB-1’s deliver a superb midrange and upper bass performance. Male vocals, even those that are closely miked, sound natural, clean, without any sign of honkiness or heaviness that can sometimes be heard in designs where the crossover region is smack dab in the male vocal range and the two involved drivers tend to interact. In the case of the OB1’s, the crossover points are at 380Hz and 3.8kHz. The interesting thing about the OB1i’s design is that there are really no crossover “regions” per se. They are true crossover points where the crossover filters at a rate of 24dB per octave. A steep aggressive slope such as this is uncommon and in the case of this particular speaker design, greatly contributes to the subjective uniformity and consistency of the midrange. Clearly, very special attention was given to the tuning of the midrange unit which is also mounted in its own enclosure within the speaker. Conversely, with such aggressive filtering in place at 380 Hz, the rather diminutive 6.5-inch transmission line-loaded woofer unit can be tuned to deliver its best below 380 Hz without any concerns of frequencies above that. I can definitely confirm that indeed, the OB-1’s deliver excellent, clean, well-defined, fast and punchy, bass response. In my room, the response seemed to begin to roll-off at roughly 60Hz or so. However, what they lacked in quantity of the lowest bass registers when compared to my dedicated subwoofers, they more than made up for the quality of the bass they did produce. Indeed, this is a solid bass performance that belies the woofer’s diminutive size and overall cabinet footprint.

These babies can rock.

Playing LP’s from the laundry list of artists that use PMC speakers for their mastering process proved to be a real blast. The OB1i’s deliver dynamics and decibels that my full range electrostatics can only dream of delivering. In fact, LP after LP, CD after CD, of everything from Bowie, to Cold Play, Gabriel, Joy Division, New Order, early Genesis, early Yes, the Who, were all a joy to listen to on these speakers. They have just enough of that English politeness, from lack of a better term, to allow the music to emerge and to downplay the distortion and nastiness that some of these recordings have when being played through hypercritical speakers like electrostatics. This does not mean that the PMC OB1i’s are seriously lacking in resolution and detail. Quite the contrary, they deliver a very specific and detailed image. They do not deliver the level of detail of a full range electrostatic, but these errors of omission are quickly dismissed when immersed in what they can, and do, achieve. There was more head bobbing, foot-stomping, knee slapping, and air jamming going on in my listening room during the PMC’s visit than in any other time in recent memory. In short, they are very forgiving of not-so-great recordings and therefore are fun to listen to on many of the LP’s and CD’s in my collection.

Summary

Choosing a speaker for your stereo system is a very personal choice. As the transducer at the end of an audio chain of considerable sonic neutrality, it should reflect as nearly as possible your preferences, desires, and prejudices of what your in-home sound system should sound like to your ears. The best any speaker review can offer is insight as to whether the speaker commits any real sonic errors, as well as provide some subjective description of the speaker’s overall top-to-bottom consistency.

To that end, I most certainly recommend that if your speaker budget is in the region of $7,500 per pair, these are a must-listen. (The current pricing of the OB1i is $7,999 per pair. Our apology for the outdated MSRP during initial publishing of the Review. -Ed.) At that price level, there is always going to be compromise and you are certainly not going to find “perfection”. However, the PMC OB1i’s are a speaker that offer rock solid performance, excellent workmanship, and their own particular British flair for the sonic truth that made the review process hugely entertaining.

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2 Responses to PMC OB1i Floorstanding Speaker Review


  1. Bill Armstrong says:

    You say these are a big room speaker.
    My listening room is 12 x 13 x 8.
    How do you think they’d work in a room that size?

  2. Martin says:

    I’m a bit late with a response but in case it is of interest to anyone….. my room is 17 x 13 x 8 and you need to leave the door and ideally the windows open to get the best sound from the PMC OB1i speakers. If you can’t do that, or introduce other acoustic control measures, you may be disappointed.

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