PSB Synchrony One B Bookshelf Speaker and SubSeries HD10 Subwoofer

      Date posted: June 25, 2008

PSB Synchrony One
Synchrony One B: Sugg. Retail: $2000 pr USD

SubSeries HD10 Subwoofer: Sugg. Retail: $1499

Manufacturer: PSB Speakers,
633 Granite Court, Pickering
Ontario, L1W 3K1 Canada
(888) 772-0000

After a long history of Stratus  top-of-the-line loudspeakers, through the Gold and Platinum series, PSB has recently renewed its flagship line with a new name: Synchrony.  I think the intention is to bring together all the elements of acoustic design and mechanics in enclosures that employ completely new approaches to the physical and aesthetic aspects of dynamic speaker construction. It’s not often that a speaker company, especially an established brand, rethinks its whole philosophy and manufacturing modus operandi, but that’s what we have here.
Synchrony Binding Posts
Let’s start with the “boxes”, though it’s hardly fair to describe them as such. Here’s how the Synchrony brochure talks about them: “Extruded-aluminum front and back panels unite subtly curving seven-layered, hand-veneered sides into an unbelievably robust structure. Their unbroken, diffraction-free surfaces and near-total resistance to coloration-carrying vibrations yield arresting sonic purity - and smooth, beautiful surfaces utterly devoid of visually intrusive hardware.”

Now, that’s not quite purple prose, but definitely into the mauve range, and what it is saying is that the laminated wood cabinet sections are mated to the extruded aluminum baffle and rear panels by double-locking corners that make for a very rigid and well-braced box. And back to the colorful prose with respect to the speaker drivers themselves: “The double-layer aluminum front baffle sandwiches an elastometric layer that damps all unwanted vibrations, fixing the drivers in an utterly rigid, inert working surface.”

In the Synchrony One B  bookshelf model, the drivers “laminated cones sandwich fine-weave fibreglass and compressed-felted fibers into a uniquely rigid, self-damping, low-mass diaphragm for higher sensitivity and smoothness.” The cast baskets, powerful magnets, and flexible rubber surrounds add up to “error-free dynamics and longevity”, that is, large, accurate excursions to the lowest frequencies, and minimal stress on the magnetic motor system over a long life.

The tweeter is a refinement of the Stratus series design, a 25mm metal-dome design with new approaches to extending dynamic capability: “This is achieved by a lighter, stiffer, and ferrofluid-cooled voice-coil, along with a computer-optimised magnetic circuit using a high-flux neodymium magnet to maintain perfect linearity under even the highest power drive.”

The Synchrony One B   is rated for frequency response from just under 50 Hz to 23 kHz, with a lower cutoff of 38 Hz. Its rated sensitivity is 90 dB in listening room conditions, with a nominal 4-ohm impedance. Power requirements start at 15 watts, with handling of up to 150 watts rms.

The matched SubSeries HD10  subwoofer is also colorfully described in the PSB  literature (available online, of course; I must ask Paul Barton if he writes all this stuff himself!): “The challenge of subwoofer design can be summed up quite simply yet completely as follows: ‘Small, deep, loud: pick two.’ Achieving all three goals from a single design package…is on the face of it an impossible task, one that requires overturning, or at least, overpowering, the laws of physics.”

I think I’d rather precis the explanation of all this, which involves the use of high rigidity drivers and very powerful amplifiers to maintain the necessary large excursions required to accurately move air at the lowest frequencies. Such techniques were pioneered by Bob Carver at Sunfire, and we still use two of his subs as reference here at AIG. The PSB   approach mates an active driver facing forward, with sideways-opposing passive cones. The HD in the name represents High Density more than High Definition, though both can be said to apply. The HD10 weighs 38 pounds, its cabinet solid enough to allow only the drivers’ own outputs to be heard, with the passive driver motion counterbalanced to avoid any resonances or mechanical vibration beyond the deep bass output itself.

PSB SubSeries HD10 left, HD8 right
The BASH digital amplifier is rated at 750 watts continuous, with peak power of 1000 watts. Controls are provided for Level, Crossover, and Phase, with left and right RCA inputs for both regular and LFE low-level signals, and 5-way posts for speaker-level input. There is no high-pass filtered output for the latter. The subs are electronically protected from overload, and the driving of the cones from excursions beyond their capacities, by a computer optimized “smart” circuit based on real bass music algorithms.


PSB Synchrony One B/SubSeies HD10 Frequency Response

Let me say off the top that this is one of the flattest-measuring speakers in my experience, pretty much +/-1 dB from about 100 Hz to beyond 10 kHz in our Pink Noise Sweep (PNS, the more squiggly curve at top), and close to that in the Summed Axial Response (SAR) that tracks it very closely, only down a dB or so from the contribution of the -30-degree curve seen below.Looking at the lower curve group, we see 0, -15, and -30 degrees off axis, with a 4th squigglier curve (I didn’t smooth it on purpose) showing something not discussed previously, the effect of a rubber plug for the speaker’s rear port supplied to help deal with some room conditions, and recommended for use with a subwoofer added to the system. It can be seen that the insertion of this “bung” (as B&W  like to call it) reduces bass output by a quite uniform 2-3 dB below 150 Hz.
Without it in play (or stop, as is the case here), bass response of the Synchrony One B  is quite flat to about 80 Hz, down only 5 dB at 50, and -10 dB at about 34 Hz, very good for a bookshelf design.

At the other end of the frequency range, we see excellent dispersion of the tweeter, very smooth crossover behaviour (2200 Hz), and absolutely no evidence of driver lobing. The smooth upper rolloff at 30 degrees off axis accompanies virtually perfect dispersion within the normal listening window.

Looking at the other end of the range again at the subwoofer measurements, we find curves taken at the same volume setting, but with the crossover set to its Full, Mid, and Low positions, top to bottom. It can be seen that the HD10’s extension is to 25 Hz, below which it rolls off quickly. The Full position provides more energy above 50 Hz, that below shelving, which may work well in some rooms with a lot of deep bass gain. The Mid position reverses this, providing the most energy between 25 and 50 Hz, while the Low setting simply provides the range between 25 and 55 Hz. These settings, and those in between, should provide plenty of latitude for matching with speakers. In my room, the 3/4 position of the Crossover control was optimum, especially with the port blocked. Buyers of this system will have lots of fun experimenting, and the bass tones on our Test & Reference CD  may be helpful.

PSB Synchrony One B Impedance/Phase
Looking at the Impedance/Phase curves, we see at top, impedance between 7 and 10 ohms from 100 Hz up, with another dB of rise above 5 kHz. The lowest point is near crossover, 4.5 ohms. Also worth noting is the behaviour in the bass region, the 2 curves with and without the rubber port blocker inserted. The two rises at 30 and 85 Hz indicate the ported performance, while we find a single larger one at 60 Hz with port blocked. Finally, this difference can also be seen in the electrical phase curves below, which also indicate a crossover phase change of +/-30 degrees, quite benign for a smaller 2-way design. These speakers will be quite easy for any amplifier to drive, and as noted elsewhere, did quite a nice job with the Shanling MC-30 single-ended tube receiver.

All in all, the measurements of this full-range system are superb, and it would be more than a surprise if it didn’t reproduce music with accuracy and authority.


I spent quite a bit of time auditioning these speakers here, and in the acoustically optimised room at Lenbrook’s Pickering ON headquarters. I also talked at length with chief designer Paul Barton about their design criteria and process. All I can say is that the result totally justifies the effort put into this new PSB  series. They are very sweet and accurate in nature, and provide quite amazing deep bass for their size. With a sub they make a superlative full-range system.

The Synchrony One B  has a very musical quality that make them exceptionally easy to listen to, even at high levels for long periods of time. Low distortion has a lot to do with this, and something they share with the simultaneously reviewed Paradigm Signature S1s. With such superb audio reproducers, differences are very subtle, and I will offer a direct comparison presently. And there is a special magic that small monitors offer that is seldom matched by large full-range speakers. I hear that magic in spades - in speed, in timbral truth, in dynamic power, and, finally, in sheer musical involvement and enjoyment with these Synchrony speakers, a new achievement from a great Canadian speaker maker.

Andrew Marshall

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