Floor Loudspeaker Reviews

Exactly five years ago as I write these words, I reviewed an elegant-looking and elegant-sounding tower loudspeaker from Canadian manufacturer PSB: the Imagine T3. Priced at $7498/pair before it was discontinued, the T3 combined three woofers, each housed in its own vented subenclosure, with a 5.25" midrange unit mounted above a 1" tweeter.

As I write these words I am listening to a pair of PSB's new Synchrony T600 loudspeakers, which cost $7999/pair and were designed, like the T3, by a team led by PSB founder and chief acoustic designer Paul Barton. Also like the T3, the T600 houses each of its three woofers in its own vented subenclosure, married to a 5.25" midrange unit and a 1" titanium-dome tweeter, again with the midrange unit mounted above the tweeter. But there, the similarities end.

The most obvious difference is that, whereas the Imagine T3 featured a gracefully curved, veneered enclosure formed under pressure from MDF laminations, the Synchrony T600 is a conventional-looking tower with a gloss-finished, rectangular–cross-section cabinet made from MDF and an aluminum-clad front baffle. While the T3's three 7" woofers featured cones of compressed felt and fiberglass, the T600's three 6.5" woofers use cones of woven carbon fiber, allied to rubber surrounds and cast-aluminum baskets. The midrange unit's cone is also formed from woven carbon fiber, and the new drive units are said to offer low levels of distortion, due to each incorporating a Faraday ring, a shorted turn, a long voice coil, and symmetrical magnetic drive.

PSB claims that the crossover between the midrange unit and the tweeter, set at a relatively low 1.8kHz, is "the most advanced amplitude-perfect Linkwitz-Riley 4th order crossover that PSB Speakers has ever utilized, featuring high-voltage poly film capacitors and oxygen-free interconnect wire for complete driver control." The crossover frequency between the midrange unit and the woofers is specified as 450Hz, with third-order Butterworth high- and low-pass filters. However, this crossover frequency applies to the topmost woofer: As shown in the "Measurements" sidebar, the lower two woofers roll off at successively lower frequencies. Each woofer is reflex-loaded with its own back-panel port. Two rubber plugs are supplied with each speaker so that one or both ports can be sealed to compensate for problematic room acoustics. Electrical connection is via three pairs of five-way binding posts at the base of the rear panel. Jumpers are provided to allow tri- and biwiring or tri- and biamping.

The T600 sits on two metal outrigger bases supported by custom IsoAcoustics feet based on GAIA II isolators. These feet act as low-pass filters, reducing the coupling of the loudspeaker's higher-frequency cabinet vibrations to the floor.

System and setup
Each speaker's front baffle ended up 131" from the listening position and 81" from the wall behind it, toed-in toward the listening position. The woofers of the left Synchrony T600 were 31" from the LPs that line the nearest sidewall; the right-hand speaker's woofers were 43" from the bookshelves that line its sidewall. When I sit in my listening chair, my ears are 36" from the floor, a couple of inches below the center of the Synchrony T600's midrange unit. I didn't use the magnetically attached grilles. With all three ports open on both loudspeakers, the lows sounded powerful—indeed, excessive. After some experimentation, I inserted rubber plugs into the bottom and top ports on the right-hand speaker and the left-hand speaker's top port. This yielded the smoothest transition between the low- and midbass regions.

The music source was my Roon Nucleus+ powered by either an HDPlex linear power supply or its own switching supply. An MBL N31 CD player/DAC or an Ayre QB-9 Twenty D/A processor (footnote 1)—this kindly loaned me by reader Charles King when we met at a celebration of Art Dudley's life in July 2021—were fed audio data over my network or via USB, respectively. Amplification was provided by a pair of Parasound Halo JC 1+ monoblocks. I didn't use a preamplifier. The speakers were single-wired, first with AudioQuest K2 cables, later with AudioQuest's relatively new Robin Hood cable.

Listening
Once the setup was optimized, I started the critical listening with the test tone files I created for the Editor's Choice CD (Stereophile STPH016-2), as I always do with my loudspeaker reviews. The dual-mono pink noise track sounded smooth with an uncolored midrange, with, however, some upper-bass emphasis. The image of the pink noise was appropriately narrow and stable with no "splashing" to the sides at any frequency. The balance didn't change appreciably as I moved my ears a little lower, but a slight vowel character was apparent if I sat up so that my ears were just above the top of the speakers.

The Synchrony T600s reproduced the 1/3-octave warble tones on Editor's Choice down to 40Hz with the 160Hz warble a little too high in level and the 100Hz and 80Hz warbles slightly lower in level than adjacent warble tones. The 32Hz tone was reinforced by the lowest room mode, the 25Hz warble was still audible at my usual listening level, but I couldn't hear the 20Hz tone. The warble tones sounded clean, which implies low distortion.

The half-step–spaced tonebursts on Editor's Choice spoke cleanly and evenly down to 32Hz, the frequency of the lowest one. Listening to the enclosure with a stethoscope while these tonebursts played, I could hear very little liveliness on the sidewalls. Some midrange resonances were audible with the stethoscope on the back panel, but the fact that this panel faces away from the listener should reduce the audibility of any resulting coloration.

Test signals done with, it was time for music. I have always loved Brahms's two piano concertos, not only for their heroic scale but also because of their richly melodic scoring. A recent discovery, courtesy of Roon and Qobuz, was Lars Vogt's performances of these concertos with the UK's Royal Northern Sinfonia, Vogt leading the orchestra from the piano (24/48 FLAC, Qobuz/Ondine). The second concerto sounded rich and warm on the PSBs, and the double basses and the piano's left-hand register were reproduced with appropriate weight. The sound of the piano had excellent leading-edge definition, and the Synchrony T600s were sufficiently transparent that I was able to hear the hall's reverberant signature in this rather dry, flat-perspectived recording, so that I could sit back and enjoy Vogt's perhaps overly dramatic interpretation.

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Footnote 1: Stereophile hasn't reviewed the QB-9 Twenty but we did review Ayre's original QB-9 in October 2009.