Dahlquist DQ-12 loudspeaker
In 1976, Carl Marchisotto joined the company, designing support products for the DQ-10 including a subwoofer, variable low-pass filter, and a passive crossover. Jon Dahlquist is no longer actively involved with the company; Carl has now assumed the engineering responsibilities at Dahlquist and is the designer of the latest group of Phased Array loudspeakers (footnote 1). This new line, introduced at the Winter 1990 CES in Las Vegas, encompasses three models: the $850/pair DQ-8, the DQ-12 reviewed here, and the $2000/pair flagship, the DQ-20i.
The Phased Array technique, first used in the DQ-10, mounts the drivers in an arc with the tweeter farthest from the listener. The radiating plane of each driver will thus be at an equal distance from the listener's ears, resultingall things being equalin a time-coherent signal. Although this concept seems rather commonplace today, it was innovative in 1973. The new line of Phased Array loudspeakers shares another common heritage with the venerable DQ-10: minimization of cabinet diffraction. In both the DQ-10 and the new models, great care has been given to the shape and structure of driver baffles and enclosure.
The DQ-12 is a three-way system employing an 8" woofer, 5" midrange driver, and a 1" fabric-dome tweeter. The speaker's attractive appearance is slightly unusual and dictated by the underlying design principles. Looking at the rear of the speaker, the DQ-12 is divided into two sections: a bass enclosure, and an open-air midrange/tweeter baffle. This separation is not readily apparent from the front owing to the integral black-fabric grille. Appearing much like a standard box enclosure, the sealed-woofer cabinet is home to the 8" long-throw woofer. This woofer was designed specifically for the DQ-12 and is not found in other loudspeakers.
The lower rear of the woofer enclosure holds the fairly large terminal panel. Two pairs of five-way, gold-plated binding posts are provided for bi-wiring. If the owner chooses not to bi-wire the DQ-12, the supplied copper shorting plates are easily inserted between the two pairs of terminals. These two input pairs are staggered laterally, making it much easier to connect thick cable. The terminal panel also holds a 3 amp woofer fuse and 0.8 amp tweeter fuse. No fuse protects the midrange driver, since it is typically the most reliable component in a loudspeaker. Dahlquist maintains that the fuses should not be bypassed: the fuses are an integral part of the crossover design, and bypassing them may actually degrade the speaker's performance.
To minimize cabinet diffraction, the midrange and tweeter are mounted on a separate baffle in the open-air portion of the enclosure. This baffle is shaped like the end of an ironing board (Mrs. H's description), the edges curved to minimize diffraction. In addition, the baffle is slightly tilted back, keeping the drivers on the same acoustical plane in accordance with the Phased Array philosophy. Dahlquist says the shape of the baffle approximates the diffraction created by the human head, resulting in more accurate midrange reproduction. The rear of the open-air section is covered by a metal mesh grille.
The 5" cone midrange driver is mounted in, according to Dahlquist, a "dual cylinder aperiodic loading structure that provides controlled dipolar radiation for accurate depth of field reproduction." This is a tube about 6" in diameter extending about 7" behind the midrange, with a square piece of particle board at the opposite end of the driver. A small tube at the center of the cylinder terminates at a hole in the center of the particle board, allowing some energy from the midrange to emerge from the rear of the speaker. The large cylinder is packed with absorbing material. This design is said to provide better soundstaging and reduced distortion. The midrange driver is custom-made for Dahlquist, who then add a proprietary treatment to improve its characteristics. The driver is a pulp-based cone with two different layers of plastic material. The result reportedly possesses the best qualities of both paper and plastic: low coloration with good transient response.
The 1" fabric-dome Vifa tweeter is recessed in the baffle and mounted just above the midrange. The driver is surrounded by an electrostatically deposited fiber-like material which absorbs some of the wave before it reaches the baffle edge. This design, coupled with the baffle shape and rounded edges, greatly reduces cabinet diffraction. With all this attention to detail, however, I was disturbed to see that the midrange driver was not recessed in the baffle. Instead, its flange protruded from the baffle perpendicularly, very close to the tweeter. This arrangement seems to defeat the purpose of the elaborate diffraction-reducing schemes. Incidentally, the midrange driver appeared to be slightly offset from the baffle center, presumably to stagger the diffraction effects from the baffle edges in frequency.
Crossover frequencies are 400Hz and 3500Hz, with air-core inductors and polypropylene capacitors used exclusively. The crossover slopes fall between 6 and 12dB/octave. All crossover design is performed on an actual speaker rather than with computer simulation, as is popular today. The components are hand-wired on masonite boards, and kept away from each other to minimize interference. All crossover component selection is done by ear, not by measurement. System sensitivity is specified at 86dB, with no measurement parameters given. According to Dahlquist, however, this figure is obtained with 1W input power at a distance of 1 meter.
The DQ-12 is physically much more complex than a standard box speaker, with its metal-mesh rear grille, baffle-mounting hardware, unusual front grille, and midrange/tweeter baffle. Overall, I found the DQ-12's appearance quite attractive. Construction and build quality appear good, but with the woofer enclosure falling short of the workmanship found in other competitively priced loudspeakers. The corner joints, for example, are not as tight as one sees on enclosures where these edges are visible. (The integral front grille, however, being wider than the bass enclosure, effectively hides it from view.) Knocking on the woofer enclosure revealed a somewhat lively tone.
During the weeks before auditioning the DQ-12s, I had been listening to B&W 801 Matrix Series 2 loudspeakers with the same component complement (except for the Classé DR-5). After breaking in the DQ-12s for about 20 hours, I sat down for some serious listening. Once the DQ-12s' optimal placements were found, I inserted the four spiked feet supplied with each loudspeaker.
Quite early in the listening session, I realized that the DQ-12s do some things exceptionally well, while having several weaknesses. Although all components, especially speakers, have good and bad sonic attributes, this range seemed especially wide in the DQ-12.
I was immediately impressed by the speakers' ability to throw a convincing soundstage. On recording after recording, the DQ-12s revealed a surprising sense of depth and presentation of spatial information. The soundstage was wide, extending beyond the speaker boundaries, and had a remarkable sense of envelopment, especially on naturally miked recordings. Instrumental outlines were focused and had a feeling of air and space around them. Images appeared between the speakers at precise locations without being overly bloated. Listening to Friday Night in San Francisco, a live recording of acoustic guitars (John McLaughlin, Paco De Lucia, and Al DiMeola) in a fairly large hall, I was able to hear the size of the room, position of the guitarists, and other spatial clues with clarity and precision. Naturally miked orchestral music took on the appropriate size of the ensemble and recording space. Vocals were anchored in the center of the soundstage, apparently disembodied from the speakers. These characteristics gave music through the DQ-12s a very pleasant, open, "unboxy" sound.
I found, however, that slight lateral head movements tended to shift the center image. This phenomenon has been dubbed the "vertical venetian blind effect" by JGH. After finding the best head location in the listening chair, it was not a significant distraction to maintain that position. (My listening chair places the listening axis 36" above the floor.)
Although the DQ-12s did not approach the B&W 801s or my other reference, the MartinLogan Sequel 2s, in spatial definition and soundstage transparency, their performance in this area was surprisingly good for a mid-priced dynamic speaker.
Another impressive aspect of the DQ-12's performance was bass extension and weight. The tonal balance was full and robust; coupled with the soundstaging, this gave the DQ-12 a "big" character. Low frequencies were reproduced with authority and a sense of ease. Even on the Dorian Pictures at an Exhibition (DOR-90117), performed on pipe organ, the DQ-12s did not sound thin or anemic. Although the lowermost octave on that recording (16Hz32Hz) was only hinted at, the balance was still satisfying and conveyed the LF extension of the instrument along with the musical intent. The mid to upper bass region, however, was somewhat bloated and tubby, obscuring LF detail. Acoustic bass lines in jazz recordings tended to be sluggish and smeared. This had the effect of removing the "bite" from plucked double bass, and reducing the feeling of rhythm and bounce.
Overall, the bass presentation tended to be overly warm and ripe. My criticism of the somewhat slow and ill-defined midbass is not just in relation to the B&W 801s, which excel in this regard: a comparison with the similarly priced Thiel CS1.2s revealed the latter to have a faster, more articulate LF presentation, though the CS1.2s did not match the LF extension of the DQ-12s.
There appeared to be a resonant peak in the mid/upper bass that was particularly noticeable on solo piano, especially Dick Hyman Plays Fats Waller (Reference Recordings RR-33CD). Certain left-hand notes could clearly be heard to "stick out" and hang longer. This coloration was not readily audible on all music, but when it could be heard, it was inescapable. Female vocal took on a slight chestiness in the lower registers, perhaps due to this same coloration. Beyond this region, however, most of the midrange was remarkably smooth and uncolored. Female vocal in the upper registers did not excite this resonance and was clean and pure, except for an exaggerated sibilance (more on this later). Male spoken voice (Sam Tellig's announcement on the Stereophile Test CD) was clear and natural, except for the chestiness noted. My first inclination is to attribute this midbass coloration to a cabinet resonance. I suspect that subsequent measurement of the DQ-12 with DRA Labs' MLSSA, Stereophile's speaker and room analysis system (footnote 2) may reveal something about this coloration.
With these praises and relatively minor criticisms, we now come to the DQ-12's most serious liability: a bright, forward, analytical treble. During the listening, I had to force myself to listen past the brightness of this speaker to hear its many attributes. When audio component manufacturers err in the tonal balance, why is it nearly always on the bright side? Live music doesn't sound sizzly, etched, and forward. Why do so many speakers? This question dogged me during the review. It is unfortunate that this otherwise excellent speaker is compromised by an overly aggressive treble. It seems that when the designer got so much right with the DQ-12soundstaging, bass extension, coloration-free midrange (aspects difficult to achieve, mind you)he could have gotten the treble balance correct; it's a much easier thing to control.
I came to the conclusion that either this tonal balance sounds good to the designer, or perhaps the company is catering to perceived market demands. During my days selling hi-fi (and a good deal of mid-fi), I learned that neophyte audio consumers often prefer a bright, lively sounding speaker to one with a natural HF response during a brief audition. The speaker that jumps out and demands attention is, unfortunately, all too often the one that ends up in the customer's living room.
At any rate, the entire upper-octave region seemed shelved up, as opposed to having a narrow peak at a particular frequency. Cymbals, violins, and other instruments with substantial HF content became aggressive and forward. Sibilance assumed a much too prominent level in the presentation. The piano on the Fats Waller CD took on a "clangy" quality in the upper registers. Tape hiss had a whitish, bleached character. This overly etched rendering was highly detailed, however, and may appeal to some listeners. To my ears, the HF presentation imparted a trace of cold sterility to some music. Acoustic guitar took on a steely character, while violin sounded edgy, especially at high levels.
The excellent Chesky recording of Johnny Frigo with Bucky and John Pizzarelli, Live From Studio A, features both instruments, and is a good example of this. This recording showed no trace of harshness through the Thiel CS1.2s or the B&W 801s, but became less involving through the DQ-12s as a result of their aggressive treble. Throughout the auditioning, the elevated high-frequency presentation was inescapable and evident on nearly every recording. With recordings possessing little treble energy, however, the DQ-12s were very enjoyable. Perhaps this rising treble response contributes to the DQ-12's remarkable sense of openness.
Exacerbating the treble problem is the fact that the DQ-12s will probably be used with moderately priced solid-state amplifiers and CD players, not VTL 225 monoblocks and a Wadia 2000. I suspected that matching the DQ-12s with solid-state amplification would be the wrong choice. Indeed, driving the DQ-12s with an Adcom GFA-555 confirmed this. The Adcom's slightly brittle upper-octave textures did not help the DQ-12s' treble presentation.
LP playback, which I generally prefer to CD, became even more desirable with the DQ-12s, and somewhat mitigated the stridency noted. To put this bright presentation into perspective, I would not characterize the DQ-12s as "run screaming from the room" bright (footnote 3), but the elevated HF response is a constant reminder of the speakers' presence. I should add that my listening room is less bright than most living rooms and tends to render a softer presentation. Furthermore, the other components in the signal path could not be considered bright or forward.
Comparing the DQ-12s with the highly regarded and similarly priced ($1090/pair) Thiel CS1.2s threw into sharp relief the DQ-12s' strengths and weaknesses. Though the 1.2s had a much more laid-back presentation and a "smaller" sound, their treble balance was much closer to what one hears from live instruments. In addition, the 1.2s had a faster, more articulate bass reproduction, although sounding leaner throughout the entire lower registers. Furthermore, the CS1.2s' midbass lacked the resonant coloration of the Dahlquist.
The DQ-12s, however, had a fuller low-frequency presentation, despite the coloration noted and lack of bass detail. The DQ-12s presented more dynamic impact and punch than the CS1.2s. Soundstage width and depth were superior through the DQ-12s, but the CS1.2s had more precise focus of instrumental outlines, though within a smaller soundstage. In addition, most of the DQ-12s' midrange region sounded less colored than the CS1.2s'. After a long listening session with the DQ-12s, however, the CS1.2s' smoother tonal balance was welcome, despite the latter's shortcomings.
Finally, I felt the CS1.2s' presentation of detail drew me into the music, while the DQ-12s' overly detailed rendering was thrust at me, reducing my ability to forget I was listening to a speaker instead of music.
If it weren't for the bright and analytic upper octaves, the DQ-12's Achilles Heel, I could more enthusiastically recommend this speaker. Instead, I must offer only a guarded recommendation, but a recommendation nonetheless. The DQ-12 does many things right, qualifying it as a high-end contender despite its treble presentation. In some areas it offers performance exceptional for its price: an open, airy soundstage, excellent spatial presentation with a feeling of envelopment, satisfying bass extension, and a relatively uncolored midrange. My other criticisms, apart from the treble, are the speaker's sluggish and overly warm low-frequency character, and a mid/upper-bass resonance.
Some listeners may not be as put off by the treble presentation as I was, and may enjoy the highly detailed rendering. I find that my ears tend to be a little less tolerant of overly bright components than the average person's. I therefore suggest that shoppers for mid-priced loudspeakers add the Dahlquist DQ-12 to their list of speakers to audition. At this price range, however, the DQ-12 faces stiff competition from the Thiel CS1.2, Vandersteen 2Ci, Spica Angelus, and Acoustat Spectra 11. Matching the DQ-12 with a laid-back tube amplifier would enhance the speaker's attributes and ameliorate some of its liabilities.
Overall, I recommend that the DQ-12 be auditioned, with the potential purchaser deciding if the speaker's considerable strengths overcome its flaws.Robert Harley
Footnote 1: Followjg his departure from Dahlquist in the mid-1990s, Carl Marchisotto founded first Alón Loudspeakers, then Nola Loudspeakers.John Atkinson
Footnote 2: See Stereophile, Vol.13 No.2, February 1990, p.118.
Footnote 3: This is Dick Olsher's description of components he feels are excruciatingly bright.