Monitores Phase Technology PC 1.5 y la tecnología de pistón plano de Phase Technology

Phase Technology PC 1.5 Speakers

En breve para audición en México.

by Ron Nagle & Gene Pitts

LACQUERED TO A SHINING black sheen, the PC 1.5 speakers, which their maker, Phase Technology, has sent us for review, might be classified as small monitors. Monitor or not monitor, they are fairly small in size. The letters “PC” in the model designation tell you they are from the manufacturer’s Premier Collection series.

The PC 1.5s have their front baffle tipped backward, and thus look a bit unusual, though not ugly, just not the way it’s done most often, particularly with speakers of this size. This slick look of the front, together with curved and tapered sides, gives these speakers an upscale, sleek and modern appearance. The maker describes the system’s design in a more technical way, as a shielded, bass ported or reflex, two-way design.

The tweeter is a one-inch soft dome unit, while the woofer utilizes a composite 6.5-inch RPF diaphragm which Phase Technology calls a “Flat-Piston.” Actually the woofer construction is worth a close look. Gray in color, the woofer is indeed flat out to the edges where it meets a butyl rubber surround. The radiating surface is a tri-laminate composition made by bonding Dupont Kevlar to a core made of polymer foam with a fiberglass layer covering the front surface. This is pretty advanced stuff, particularly for such a

Modestly priced system, but Phase Tech has several decades of being at the front edge of speaker driver inno- vation. They are responsible for the soft-dome tweeter, both in the invention and in the manufacture, and those

Reprinted from The Audiophile Voice Vol. 13, No. 4

The audiophile voicedomes were used in many, many famous and good- sounding speakers, most especially during the New England speaker “revolution.” Notably, Phase Tech was for a time the sole OEM supplier for the industry.

The PC 1.5 speakers are specified as having a fre- quency range of 40 Hz up to 22 kHz. Weighing in at 19 pounds per speaker they measure 13-5/8 inches tall x 7- 7/8 inches wide x 12-5/16 inches deep. The PC 1.5 is bi-wireable and rated at 4 ohms, while the recommend- ed amplifier power is from 20 to 150 watts. My review sample speakers were con- secutively numbered, 1221 and 1222. I believe the company’s giving a price for just a single speaker proba- bly will encourage home theater enthusiasts to purchase systems with an odd number of speakers, e.g. three across the front. I would like to have had some addi- tional information on the crossover design, the slopes and the components used to make them, perhaps in the specifications or as a technical note on the company’s web site.

Set Up + Time

Looking into the Phase Tech web site, I found a 28- inch high speaker stand for use with their smaller speak- ers. I have a pair of 24-inch high stands, so I phoned them, just to make certain. Their support people told me that the four-inch height difference was not critical so I placed the PC 1.5 on my stands.

Positioning the speakers in my room started out in a somewhat arbitrary fashion, while I proceeded to break them in with a local FM radio station. Let me say up front that to my ears, the break-in period produced a very large improvement in the performance. The degree of improvement was more than I have experienced in the past with similar types of speakers. The initial treble sound was bright and that soft dome tweeter was not at all that soft. The 6.5-inch mid woofer seemed slow to start and slow to stop. During this first listening period, woofer overhang was what came to my mind. These preliminary listenings were first powered by an overly expensive $8,500 KT88 tube amplifier rated at 120 watts per side; I say “overly” because of the mismatch in prices of the speaker and the amp. Following that, I used my 40-watt tube-powered Prima Luna 2 Integrated amp, and I got sound that was a bit nicer and smoother but nothing to write home about. Last amplifier in the review system was my reference Go-To powerhouse, a 350-wpc solid-state Sanders ESL. For the extended audi- tioning session, I enlisted through my long-time trusty bread-and-butter Audio Research SP9 MK3 preamp.

The Sanders powerhouse, along with another 35 hours of break-in time, provided the ticket to achieving the best performance. Apparently, the 1.5 speakers just needed that additional time. Solid state just seems to be the way to go with these speakers; what I heard was the transistor amplifier controlling the midrange and woofer frequencies more securely and the top-to-bottom fre- quency response was smoothed out to my ears.

Let’s get into quizzical, quizzical

Longer term listening reveals the personality of this transducer. The very first thing that jumped out at me was dispersion. Here I’m referring to the Phase Tech PC 1.5’s ability to generate a wonderfully wide sound stage. Throughout my listening sessions with the 1.5, no matter where I moved them I was able to adjust the

speaker’s position to construct a very con- vincing panoramic per- formance. Some part of this phenomenon is due to the speaker’s rel- ative immunity to the effects of room bound- aries. Unusually, the serial number plate is on the bottom of the speaker, instead of the back, and it refers to the PC1.5 as a “book- shelf” speaker. Indeed, itwillfitonalotof bookshelves or into a lot of bookcases. However, because of the rear ported design and the deep cabinet profile, it didn’t seem a good idea to position them very close to a rear wall. It is my normal practice to always give any speaker plenty of room to breath so that I may listen in a totally unaffected way.


Somewhere at one of the many hi-fi shows, someone gave me a demo disc that I used a lot at one time. The title is Best Audiophile Voices Selection and it’s on the Premium Records label (PR27905); it is a compilation of 14 different female vocalists. I just rediscovered it sitting on my shelf, and it is perfect for this review. There are two tracks on this disc that I think can tell us more about the PC 1.5 than pretty well any other test or demo CD. Understand that my critical reference is the sound of a human voice and most of the time it is a female voice.

Track 13 on Best Voices... is titled “When You Say Nothing At All” from the album Alison Krause & Union


The longer I played the PC 1.5s, the better they seemed and I’m not certain at this point that this improvement process has come to an end. The PC 1.5 can play very much louder than I normally care to listen and they seem to prefer big and powerful amplifiers. Of course, these speakers do have limits, like most any speaker. For example, they can be overdriven, and the

would project her voice more from the diaphragm and chest, it would convey a broader and warmer range of emotion, at least for me. Perhaps another way to say this is that she still could hit all the notes but would give more meaning if she projected more. Having said that, I still really enjoyed her performance via the Phase Tech PC 1.5 speakers. This track has some demanding seg- ments, the vocals with a lead and a back-up voice, plus the crisp steel transients from the lead guitar. All these ambient details came to you courtesy of Phase Tech, a testament to the speed and pitch delineation of the PC 1.5 design.

Track 8 is “Marisa” by Dave’s True Story. On this selection, once again I was drawn in by the clean, clear dimensionality of the lead voice that the PC 1.5’s places directly in front of me. There is a clarity that enables me to hear and hang on to her every intake of breath as she crafts each phrase. A deep bass guitar line provides a gentle foundation of chord changes that echo and sup- port the vocal line that rides octaves above it. At the bridge, a tenor saxophone passage fills my room, each note surrounded by an envelope of echoing air.

My long-standing bass reference is the recording of Albinoni’s Adagio in G minor by Gary Karr and Harman Lewis on pipe organ. Recorded in a large cathedral in Japan, of all places. Gary Karr’s Amati bass fiddle, tran- sitioning the scales from low bass to upper midrange, has to be the ultimate test of any woofer’s accuracy of timbre as well as the crossover interface between the woofer and the midrange. Any mismatch between woofer and midrange will be instantly apparent. It is a difficult thing to reproduce all the vibrating wooden warmth and rich yet sad-sounding harmonic overtones of this instrument correctly.

Sound stage can then fall into confusion. I think they work best on small-scaled compositions like a classical string quartet or a jazz ensemble of moderate size. I also like them with my usual reference the human voice. No, they are not perfect, as every once in a while, some slice of the frequency response stepped up or down a decibel or two, catching my attention. On a hard- sounding CD, the treble response of these speakers will quickly tell you just how bad the recording is, and weren’t unforgiving in this. One system matching suggestion for the PC 1.5s would be to get a good tube pre- amp and feed its output into a no-nonsense solid-state amplifier that provides lots of drive power. In my esti- mation, that would be the best way to take care of the tweet and the woof halves of these speakers. It’s what I did.

At this stage of the speaker buying game, there are lots of good choices out there in this segment. However, this system is more than merely reasonable if you calculate two times the price.

No hay comentarios: