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Reviewer: Les Turoczi
Digital sources: Naim CD2 with DIN-to-RCA interconnects from Chord, Wasatch and non-commercial prototypes; Sony PCM R500 DAT deck; Sound Devices 744T HD Digital Recorder; Underwood HiFi modified Denon 3910 universal player [on review]
Analog Source: Linn Sondek LP 12 fully upgraded with Lingo, Cirkus, Trampolin etc.; Naim ARO arm; Spectral moving-coil MCIIB cartridge; ARC PH3SE phono stage; Magnum Dynalab Etude FM tuner
Preamp: Audio Research REF 1 line stage [recently retubed]
Power Amp: McCormack DNA 500; Bel Canto e.One S300 [on review]
Speakers: DeVore Gibbon 8
Cables: Various sets of interconnects and speaker wires from ARC Litz, Wasatch, Stealth Audio, Grover Huffman and experimental prototype ultra-thin gauge silver-coated copper ICs
Power: Dedicated power lines separated for analog and digital applications
Accessories: "The Base" platforms; Sound Anchor 20" Speaker Stands; Symposium Svelte Shelves, Point Pods and Fat Padz [on loan]
Room size: 14' by 23' with 8' ceiling, speakers set up on short wall; carpeted concrete flooring
Review component retail: $12,999/pr in cherry or black ash, optional finishes for surcharge
Loudspeakers come in incredible varieties. Whether based on budgetary constraints, size, driver design, visual appearance, designer proclivities or other significant parameters, it is virtually impossible for one person to hear all such products in the marketplace. Their role in converting electrical energy into sound pressure waves is a complex task, with many requirements, which need to be handled well in order to represent a viable and satisfying outcome. This approach to transduction represents one of those links in the sound reproduction chain where almost anything and everything has been tried over time - and there is still a lot of room for evolution. Selecting speakers for the long haul is thus fairly challenging if not downright daunting. I have been on such a quest for almost two years and this article will touch on my explorations with a speaker design that, up until recently, was not so commonly found in audiophile systems. I am referring to the class known as Studio Monitors. (The debate over domestic use of studio monitors in conventional audiophile applications continues and I will have a bit to say about that toward the end of this review.)
For those needing an 'instant fix' regarding these speakers, let me say this much now. The PMC IB2s are seriously evolved, highly revealing, excellent and honest speakers. They offer engaging sonic experiences, doing justice to both the music and performers while creating very gratifying listening to all kinds of repertoire. This assumes that the associated equipment is up to the task. You need to read the details that follow to get more insights and hear about the juicy stuff but at least now, you can anticipate that this story represents a very positive exploration.
The Professional Monitor Company of the UK knows a lot about studio monitors; they have been designing and selling them to the pro audio world for several years. Among the distinguishing features separating PMC designs from the many other pro brands is their choice of transmission line loading for bass propagation. This approach is found throughout their offerings, which incidentally cover a very wide spectrum of models, both at the pro level and now also for domestic use. These can be seen at their website. I have had a long-term fondness for this design ever since the time I owned IMF Reference MK IV loudspeakers in the 1970s. (That is one speaker system I truly regret having sold.)
So, here are some of the requisite details. The PMC IB2 studio monitor is a handsome and beefy three-way and stand mounted system weighing 90 lbs and occupying a space of 29.1 x 13 x 18.3 inches. The published specs show a useable frequency response of 25Hz to 25kHz, sensitivity of 89dB (at 1W, 1m) and a nominal impedance of 4 ohms. The transmission line is eight feet long and the components include a low frequency 10-inch carbon fiber/Nomex flat surfaced driver, a very special mid frequency 3-inch PMC fabric dome coupled to a high frequency 1.1 inch fabric soft dome driver. Power handling favors amps in the 120 to 500 watt range and the peak SPL at 1m is rated at 116db. Crossover points are 380Hz and 3.8kHz. The rear-mounted binding posts are arranged as three pairs of 4 mm sockets which allow for tri-wiring or tri-amping, and brass rods are provided to serve as jumpers when utilized traditionally at home with a single pair of speaker wires. The review set sent to me was finished in a beautiful rich Cherry tone but conventional studio black ash is available as well. Removable grills come with the speakers but I elected to not use them.
The IB2s are available in both passive and active forms. While I opted for the passive version, the active units come with Bryston Power Pac 300 amps directly attached to the rear panel of each enclosure. Up until recently, PMC speakers came to the US through Bryston of Canada and those company affiliations in the UK have been in place for a long-term cooperative relationship, well known to the pro audio crowd. There is now a PMC-USA distributor in California headed up by Richard Colburn [email@example.com]. Srajan discusses those details concisely in his August 2005 PMC AML-1 review.
|Speaker stands are required for proper operation and PMC does sell a 14-inch high metal version of their own design. In the early planning stages of this review, I asked Richard about that approach and he suggested that I speak with Bob Worzalla of Sound Anchors in Florida about custom stands. Bob indicated that he and James Tanner of Bryston had undertaken investigations into optimal stand height and build qualities for the IB2 and arrived at a 20-inch tall design which he recommended to me. Those were created and arrived in good time for use at chez Turoczi. Once you see the industrial quality of these Sound Anchor products, it is easy to understand why Bob has such a fine reputation for all of his offerings and excellent service. You can visit his site to see descriptions of the Four Post stands which were used in this review. I did a few small experiments of my own trying a 12" and 14" elevation and the 20" style does indeed appear to hit the nail on the head. (Placing the speaker directly on the floor, unelevated is -- duh -- totally wrong btw.)
Another set of conditions require some discussion prior to moving on to the "how do they sound?" section. It involves coupling the speakers to the Sound Anchor stands. Bob does provide small 1 ½"diameter, 3/32" thick Blue Dot flat Sorbothane discs which he recommends placing between the bottoms of the enclosure corners and the tops of his metal stands. This is where I started, naturally. After playing with speaker placement and connection variations, I felt the need to explore that enclosure-to-stand interface. My gut reaction pointed me toward finding a way to make a more direct, solid coupling at this physical level. Peter Bizlewicz of Symposium Acoustics was next on my list of people to call. I have known Peter for a long time and many close, trusted audio buddies happily own various forms of his products including Roller Balls, Symposium platforms etc. After a long phone chat about the physics and acoustics of this issue, it was decided that Peter would send along some of his Svelte Shelves, Point Pods and Fat Padz for my explorations. This loan was quite fortuitous as will be described later.
Once unboxed, placed on the stands, wired up and casually positioned in my room, the IB2s were given a steady diet of music from either the FM tuner or CD player as a way to help the break-in process. I am amazed at just how long you can play raucous bagpipe music at loud volumes before neighbors start asking questions. Trying to form an early opinion about any component is usually an iffy thing at best so I avoided that temptation for a while. After a few solid days of run-in playing, I did switch over to some actual normal music and sat listening for a short stretch. It was clear, even with this non-optimized arrangement, that these speakers had dynamics. It would take lots more adjusting to get speaker placement and other tweakings to fall into place, but this early taste set the stage for what ultimately turned into rewarding and involving listening.
The plan was to try the rule of thirds for speaker positioning in my 14" x 23" x 8" room. In the past, this has met with variable success but it was a logical beginning. The dynamics, energy and vitality were easily discernible, but deep bass, spatiality and dimensionality were lacking. As several alternate placements were tried, things clearly improved by moving the speakers closer to the front and side walls. Untoeing generated surprisingly good results and ultimately the speakers came to rest in an almost straight-out facing mode. Now the bass, overall tonality and spatial performance really started making sense. Spiking the stands did the usual good things for bass solidity, but also helped the sense of focus, texture and the ever elusive disappearing act. Every room and set of components will be different enough that trying unorthodox configurations should be more the rule than exception.
Concern about how the speakers interfaced with the Sound Anchor stands still needed sorting out. In addition to early listening with the Blue Dots as noted above, I also used slightly thicker, spongier Sorbothane pads. Too much life was sucked out that way, so those units did not remain in place for very long. The benefit of having multiple formats of Symposium Acoustics devices revealed profound and positive results. The Point Pads, which are thin, flat devices approximately the size of a standard thick credit card were substituted for the Blue Dots. There was an immediate improvement. I fiddled with the positioning of these pads relative to the stands and bottoms of the enclosures for a few days. A pad under each of the front corners, with a third along the rear enclosure edge at the center seemed quite good. The Fat Padz were then substituted in several varied locations, but the best results were again obtained using three of them, as before at the front corners and rear center edge. Because the Fat Padz, as their name implies, are considerable thicker than the Point Pods, I was slightly concerned that the overall speaker height was now getting beyond the limits of where my ears registered in the listening chair. The final trial employed the Svelte Shelves, one directly under each enclosure and this yielded the most cohesive, balanced, airy sound of all. I used this configuration for the balance of the evaluation period and felt very good about the finessed sound coming from the speakers, the stands and the shelves. The Fat Padz and Point Pods would, however, serve well elsewhere, especially under the CDP and REF1.
One final frontier needed tackling. The three pairs of binding posts on the back of each IB2 enclosure were ostensibly created for studio implementation. My speculation is that in a pro application, there is a practical or convenience consideration which puts a preference on banana plugs for speaker wire terminations. That would be a neat way to attach six wires without having a lot of fuss. We audiophiles tend to look down our noses at banana jacks and plugs for our stuff however. PMC anticipates the connection needs of domestic users by providing cylindrical solid brass rods as jumpers between all of the binding posts. Notably, these PMC binding posts are beefy, having an oversized diameter, which will challenge standard spade lugs. Using my Stealth Audio speaker wires even with their expandable spade lugs left me feeling uncertain about the solidity and effectiveness of the connections.
|After trying many different ways to making this work, I decided that the PMC-provided jumper rods needed to go. Initially I tried simple 12-gauge stranded copper wire threaded through the upper two pairs of binding post holes and then wrapped the wire tail around the lower most post, to which my spades would be connected. While this did allow for a more direct mechanical connection, the sonic properties were essentially unchanged. At least, I felt better about the physical integration of speaker wires and binding posts. After a bit of reflection, I decided to use this same hookup approach but with other forms of wire. Searching about further, I found that the Parts Connexion folks in Canada had a nice range of wire available at good prices so I ordered a few alternates. Moving to 12- gauge solid copper from FIM provided a slight improvement (not a night-and-day difference, mind you) but a sense of better controlled power transfer. Things felt more solid but this was hard to define exactly. The best choice turned out to be 18-gauge solid core 99.99% silver wire from DH Labs. Now the sound benefited from greater dimensionality and image specificity, tighter and extended bass response and an improvement in overall timbral balance which collectively meant this was a good thing. The rest of my evaluation work utilized this setup. The bulk of the listening happened through my resident ARC REF1, the McCormack DNA500, the Naim CD2 and, to a smaller extent, via vinyl on the Linn Sondek rig. Other gear was substituted over time, but that represented short bursts of exposure.|
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