Manufacturer
PINNACLE^® Loudspeakers
1 Fairchild Court, Suite 140
Plainview, NY 11803
tel. (800) 346-2863, in NY (516) 576-9052
fax (516) 576-0826
www.pinnaclespeakers.com

Until recently, home-theater fans who wanted good subwoofer performance but didn't want a big box were out of luck. Sure, there are compact units that their manufacturers call "subwoofers", but at best, these are woofers: They just don't go very low or play very loud. The laws of physics would seem to dictate that low bass at high volume requires drivers with a lot of cone area in an enclosure of substantial size.

Enter the PINNACLE^® Digital Sub350, one of the new breed of compact subwoofers designed to offer the performance of much larger units. (The Velodyne HGS-10, also reviewed in this issue, is another.) To do this, the engineers at PINNACLE^® haven't broken or revised the laws of physics, but merely applied them more intelligently.

The Sub350 uses two high-excursion 12-inch drivers, one mounted behind the other; PINNACLE^® calls this configuration "compound compression". This approach allows the enclosure volume to be about half that of a comparable single-driver design. For the Sub350, additional saving in size and weight are achieved by using a Class D (digital switching) amplifier. Smaller and lighter than conventional designs, Class D amplifiers also generate less heat--a major advantage for an amplifier housed in a speaker enclosure.

The Sub350 provides speaker level inputs and outputs as well as line inputs but not line outputs; any highpass filtering of the main speakers must be done by the device feeding the subwoofer. In home-theater applications, this is not a problem: All Dolby Digital/Pro-Logic processors include high pass filters.

The unit's controls include Volume, Phase (0 or 180 degrees), Auto On/Off, and a variable lowpass-filter frequency, but the lowpass filter cannot be bypassed. As a result, the subwoofer's lowpass filter is cascaded with the surround processor's own lowpass filter, which can produce untoward interaction between the two filters.

To minimize any such interaction I set the Sub350's filter to the highest frequency (150 Hz). This resulted in a fairly even transition from the main speakers to the subwoofer, with no major dips in frequency response that I could attribute to crossover interaction. Still, the blend between the main speakers and subwoofer might have been even better if I could have bypassed the subwoofer's lowpass filter.

The response through the crossover range was more linear with the Sony SDP-EP9ES (its crossover set to 80 Hz) than with the Marantz AVP-500, which has a fixed crossover frequency of 100 Hz. With both the Sony and Marantz surround processors, the out-of-phase (180°) setting of the Sub350's crossover resulted in a more linear frequency response.

The Sub350 is finished in what PINNACLE^® calls "premium black anthracite vinyl", which sounds pretty impressive except for the "vinyl" part. It actually looks pretty good as such things go, but the people who sell genuine black anthracite shouldn't worry about losing a significant market share to the vinyl stuff.

PINNACLE^® gets some audiophile brownie points for supplying four solid-brass cone feet that screw into the enclosure, but I was unable to screw in one of the cones; this turned out to be a problem with the anchor in the enclosure. Fortunately, I found some German Acoustics cones of about the same height among my audiophile odds 'n' ends, so I substituted one of these. The Sub350 was placed in the left-front corner of my home-theater room, a location I've found to work well with other subwoofers.

Woof!
Although it is definitely compact, the PINNACLE^® Sub350 gives up little performance to the big boys. Specifications peg the -3 dB point at 22 Hz, and I'd say that's about right.

Using the ever-popular Radio Shack SPL meter and Stereophile's Test CD 3, I found the response at the listening seat to be up by 6 or 7 dB in the 40-50 Hz region, falling gently below that. At 25 Hz, the level stayed within 2 dB of the response level in the 80-100 Hz region, then it dropped by another 5 dB at 20 Hz.

I have measured a similar rise in the 40-50 Hz region with other subwoofers in the same environment, which implies the presence of a room mode. However, the PINNACLE's rise was 3-4 dB greater than the Bag End Infrasub-18 or the Velodyne HGS-10 (see reviews in this issue). This rise is noticeable on some material, giving the bass a not-unwelcome extra kick. Explosions, synthesizer bass notes, and sound effects like the lion's growl in Jumanji come across with lots of power, passing the shake-the-couch test with ease.

On music, I'd have to rate the PINNACLE's performance as merely good, not great. It certainly avoids the one-note bass that has given subwoofers a bad name in some quarters, and it goes deep enough to add useful low-end extension to the sound of most speakers, even ones that are nominally full-range.

However, bass transients (timpani, bass drum, string bass, bass guitar) have a little too much warmth and sound a bit "slow" compared to the Bag End Infrasub-18. True, the synthesizer note at the beginning of track 7 on Mickey Hart's Planet Drum (Rykodisc RCD 10206) exhibits the room-shaking quality that's the hallmark of a real subwoofer, and the varied drum sounds that follow are differentiated pretty well--just not as well as with the Infrasub-18, pedal notes in Saint-Saens' Symphony No. 3 (Philips 412 619-2). To put this in perspective, the Infrasub-18 is the "fastest" sub with the greatest bass extension in my experience; it's also much bigger, heavier, and at $1895, considerably more expensive than the Sub350.

Closer to the Sub350 in price (and even smaller in size), the Velodyne HGS-10 is the champion bantamweight subwoofer, beating the Sub350 in extension and subjective speed/tightness of bass response. However, the difference is less than that between the Sub350 and the Infrasub-18, and the HGS-10 sells for $1595--again, a significant premium over the Sub350. In the Sub350's own price range, the HSU Research HRSW12A (which has been improved since the version I reviewed in the Fall 1995 SGHT) is tough to beat, but it's much bigger.

Conclusion
Without restrictions on size and price, any competent speaker engineer can design a great sounding subwoofer. The real skill is in meeting performance expectations with a product that's both compact and affordable. In this effort, PINNACLE^® has succeeded admirably. The Sub350 doesn't deliver the tightest, fastest, or deepest bass imaginable, but subwoofers providing a closer approach to that ideal tend to take up much more space and/or cost a lot more. The PINNACLE^® Sub350 represents a good compromise among the varying requirements of size, cost performance, and aesthetics. Check it out.