Dunlavy Audio Labs Signature SC-VI loudspeaker Page 3
The Signature VIs come with grain-matched platforms that bolt onto their bases. These platforms raise the speaker another 1½" off the floor. I chose not to install them on my review pair. My listening couch is about 2" shorter than a standard chair, so with the platforms installed the tweeter was no longer on the same horizontal axis as my ears. I feel that the platforms also make the speaker look far more massive than it actually is. Without the platforms, the Signature VI is less visually intrusive. Since the speaker is only 18" wide, few people who see it in my room can believe that it weighs as much or occupies as much space as it does. The Signature VI is far less visually imposing than a Sound-Lab A-3 with its side-wings, or my old Apogee Fullrange speakers.
When Robert Deutsch reviewed the smaller Dunlavy SC-IV in April '94 (Vol.17 No.4), he found that using Tiptoes improved their performance. I did not attempt to install cones or spikes under the SC-VIs, but I did put large Teflon "sliders" (for moving furniture) under them. Now, one moderately fit (I do work out three times a week), 155-lb guy could push the Signature VIs around solo. I've found that even minor (1") changes in the Signatures' placement can alter their imaging and focus. I might try Tiptoes under the VIs when I'm sure I've found their ultimate positions. Perhaps when I next have half of the CU football team up for tea, I'll ask them to help by lifting the speakers up.
The Signature VIs come with removable speaker grilles. After extensive listening, I decided that the speakers achieve slightly more precise imaging with the grilles off. John Dunlavy swears that in all his testing and listening he could discern no deleterious effects from the grilles, but in my listening tests (even blind tests) it was clear that the grilles' inner wooden frame edges do affect imaging. Also, with the grilles removed, you can admire all that lovely gray felt around the drivers.
During the six-month review period I used a wide variety of amplifiers with the Signature VIs—everything from a pair of homemade single-ended triodes with both 807 and 845 output tubes to a pair of OCM 500s. In only one case did I find a mismatch. When I combined the Jeff Rowland Design Group Model 6 monoblocks to the VIs via Synergistic Research's Resolution cables, one of the amps went into oscillation and blew its rail fuses. This problem was caused by the combination of the Synergistic Research cable's no-loss characteristics coupled with the Rowland's radically high slew rate. At extremely high frequencies the amp was effectively running into a short. When I switched on the Rowland I heard two seconds of ultra-high-frequency whine, then nothing. Its mate had no problems with this particular cable/speaker combo. Weird, huh? The problem persisted even after Rowland installed a resistive RC network on the amp's outputs. The solution was simple: change cables or amps. (This is the audiophile equivalent of "Doctor, it hurts when I do this." Doctor: "So don't do it.")
The Signature VI's impedance is benign, with a maximum value of 7.5 ohms and a minimum value of 3 ohms. Provided it can handle the low average load, a single-ended amplifier should be able to drive this sensitive (91dB/W/m) speaker without turning into a "tone control." My experiences with a single-ended amp demonstrated that, up to its limits (an spl of around 85dB at the listening position), it performed very nicely. I was especially impressed by the Dunlavy's ability to reveal the amp's liquid midrange and palpable three-dimensional characteristics. Yes, the bottom end was a bit soft and flubby, but that's the price you pay for midrange glory.
The Signature SC-VI performed very nicely with more conventional tube amps like the Manley 240 monoblocks (see my review in May, Vol.19 No.5). Regardless of what amplifiers I tried, the Dunlavy's own sonic characteristics shone through. Harmonic differences between amplifiers were not as huge as with "difficult to drive" speakers like my Apogee Fullranges, but each amplifier's "personality" was evident with the Dunlavys.
Which amp worked best? Well, what kind of sound do you like? When it came to playing large-scale orchestral pieces at realistic dynamic levels, I kept coming back to a pair of Boulder 500 AE monoblocks. When I listened to intricate pop music, I loved the Rowlands' amazing low-level detail and finesse. When listening to baroque chamber and small-group jazz, I found the Manley 240s in triode mode totally bewitching. Your own choice of amp will be determined by your tastes and pocketbook. The good news is that you needn't use megabuck amps to make the Dunlavys perform properly; even the $3500 Ayre V-3 mated delightfully well with them.
It's worth noting that while the Dunlavy is bi-wirable, I found no sonic benefits from attaching extra speaker-cable runs. John Dunlavy admitted to me that there was no sonic need for the extra five-way binding-posts. His tests showed that the Signature didn't have any back-EMF or other anomalies caused by the crossover that would be lessened by a second run of cable. Why not then just have a single set of binding posts? Marketing perhaps? The only advantage of having two sets of binding posts is that you can "bi-amp" with amps that are not bridgeable. If you own an Ayre V-3 and want to increase the horsepower feeding the Dunlavys, you could add a second amp, make a splitter connector to feed each side of an individual amp the same signal, feed each side to one of the two sets of speaker binding-posts, and voilà—one amp driving each channel without bridging.
Since the Dunlavy Signature VIs don't have protection circuits, you must be careful not to do anything rash that might trash their drivers. They are certainly not as fragile as original Quad ESLs, or even Spica TC-50s. I've done some ghastly stuff to 'em without trashing 'em. Still, care should be exercised. Turn off amps when changing input cables, avoid feedback howls, and don't turn the volume on your preamp all the way up to see if there is signal going through. I have personally done all the above without frying anything, but not without causing heart palpitations. The idea of shipping a pair of Signature VIs back to Colorado Springs to replace blown drivers could only warm the cockles of a piano-mover's heart.