This article originally appeared in the January, 2018 issue of Pro Sound News. Innovations is a monthly column where different pro audio manufacturers are invited to discuss the thought-process behind creating their products of note.
U.K. loudspeaker manufacturer PMC has always been a design- and engineering-led company. Perhaps it was inevitable that creating the newest, most affordable member of PMC’s professional range would prove more involved than the compact dimensions of the speaker itself would suggest.
The challenge was this: Could the PMC engineering team—whose previous most affordable compact nearfield retailed for over U.S. $5,000 a pair—produce a simple, easy-to-use monitor that would provide a more affordable introduction to the sonic benefits of our ATL designs, yet still offer the features that won PMC its reputation in high-end professional studios, mix facilities and mastering houses? Namely (to use the points most commonly made by our customers): high-resolution, accurate and natural-sounding audio; an extended, dynamic bass response; clean, undistorted mid-range and natural-sounding highs with a wide "sweet spot"; together with a highly consistent tonal response at all output levels, conferring the ability to create finished work at speed that translates accurately to any playback system, small or large.
And ... could this new speaker be brought to market for $3,000 or less?
Designing to a price can be relatively straightforward—but no one at PMC wanted to resort to the tactics used by many manufacturers when creating an entry-level product: making a smaller, "meaner" product, using much cheaper materials and components, omitting all the innovative features, or accepting a less impressive performance. Apart from reducing the size of the new speaker, none of these other approaches was ever going to be acceptable in a PMC design.
In fact, even making the result.6 smaller required a great deal of engineering. The Advanced Transmission Line (ATL) lies at the heart of all PMC speakers, from small to large, but it is not a technology that lends itself to being scaled in a straightforward manner. The bass-loading effect is produced by a tightly engineered combination of bass driver, loudspeaker cabinet and transmission line working in combination; if one of the elements changes materially in size or construction, the design has to be re-engineered from scratch. Since it was clear from early in the design process that the speaker would feature a newly designed bass driver and cabinet, the ATL had to be rethought from first principles, with a newly designed absorptive lining with different geometry, and then custom-tuned with the new cabinet and bass driver.
These days, some companies save money when designing loudspeakers by employing cheap drivers. They then use a built-in DSP section to tweak the compromised responses and crossover and bring the output back to something approaching a reasonably acceptable tonal balance (albeit at the expense of resolution and a natural sound). PMC has never taken this approach—where DSP is used, it is always sparingly, to obtain an extra few percent of performance from a design that is already well engineered, and not to salvage a poor one.
For the result.6, our team soon realized that at the projected retail price of the speaker, there was more to be gained by reinvesting the cost of a DSP section in other aspects of the design. The potential complexity of a menu-driven DSP system also seemed an ill fit for the "simple and approachable" concept we had started out with for the new speaker, so we chose to sidestep DSP completely. Instead, we used our engineering experience to create a sophisticated, high-order, pure analogue crossover.
User options are streamlined to a ±10 dB Trim control on the rear panel. The result.6’s Class D amplification was also new, optimized by means of extensive measurement and performance analysis sessions, together with double-blind listening tests, during product development, and mechanically isolated from the cabinet in the finished monitor by custom-designed mounting hardware. Some aspects of the result.6 driver designs, such as the natural-fiber cone in the LF driver and the HF dispersion grille, took the designs used in the proven twotwo nearfields as their starting point, but even these elements were refined for the new speaker rather than being adopted wholesale in their original twotwo form.
Perhaps the most visually distinctive aspect of the new speaker is the treble driver’s finned surround. This was another new development for the result.6, engineered to eliminate cabinet edge effects that might have arisen due to the centrally placed treble driver. The fins not only block the reflections from the cabinet’s edges, which, left untreated, would cause comb filtering and a smearing of the HF response, they also enhance the treble driver’s already generous HF dispersion, greatly reducing the difference in the on- and off-axis response and making for the usual generous PMC "sweet spot."
The result.6 represented another milestone for PMC: it is the first speaker to benefit from our new in-house laser measurement system, which enables us to accurately measure the displacement of the drive unit cone and therefore optimize its performance when coupled to the transmission line loading it. This was particularly useful while finalizing the design of the ATL in the result.6 and integrating it with the cabinet and LF driver, and will be used on all PMC designs in the future.
As is frequently the case with new designs, the name of the product was one of the last pieces of the puzzle, but it arrived pretty quickly. When we considered it, the ethos of the product—which can actually be applied to all PMC professional products—seemed to be about getting to finished results faster. And of course, it had a 6-inch bass driver.
The result.6 contains a lot more engineering than is apparent from its size, but far from being a cut-down version of an existing PMC product created to hit a price point, it’s one we can be as proud of as we are of our larger designs—and it retails for U.S. $2,950 a pair. In both respects, I’m happy to say that we, as engineers, got the result we wanted too.
Oliver Thomas followed his father, PMC co-founder Peter Thomas, into the loudspeaker design business after obtaining his engineering degree and experience in other industries. He is now head of design at PMC.
PMC • pmc-speakers.com