Vandersteen 2C loudspeaker John Atkinson May 1989
Following my reports on 13 mainly inexpensive loudspeakers that have appeared in the last four issues of Stereophile, I thought I would give myself a treat this month by reviewing the latest incarnations of two models that have stood the test of time: Vandersteen's 2Ci and Celestion's SL600Si. An interesting pair, I'm sure you will agree, as they represent to a T the prevailing design philosophies in their countries of origin. Both benefit from high-quality speaker stands, in fact both contributed to the development of such stands by demonstrating the need for them. Both are equipped, and intended, to be used bi-wired or bi-amped. But from there on they differ. The three-way Vandersteen uses apparently relatively conventional drive-units. It achieves an extended bass response through use of a variant of reflex-loading, and features careful time-alignment of the drive-units, first-order crossover slopes, and polarity-correct driver connections in order to achieve optimal time-domain performance. On the intended listening axis, the speaker should present waveforms with their shapes preserved.
The strange thing is that when it comes to performance, the two models actually approach each other from opposite ends of the design spectrum. But I precede myself.
Vandersteen's Model Two loudspeaker was introduced in 1977 and in one form or another has remained a bestseller since then. Along with KEF's R105, also launched in 1977, the Vandersteen Model Two was one of the first loudspeakers to feature minimum-area, carefully profiled baffles, optimizing lateral dispersion and eliminating the effects of diffraction from the baffle edges (footnote 1). The 2C has been the subject of a program of continuing improvement, Vandersteen being one of the first US companies to invest heavily in FFT and TDS measurement techniques. In its last incarnation, the 2C which first appeared in 1984, the speaker was very favorably reviewed by Anthony H. Cordesman in Stereophile Vol.9 No.6. The latest Ci version features an improved midrange unit, but is otherwise very similar in its general design philosophy.
One factor in the speaker's success has been the fact that the Vandersteen purchaser gets a lot of loudspeaker at the price, and a reason for that must be the unusual styling. Apart from the oiled-wood-veneer top and bottom caps, the entire speaker is surrounded by a black jersey-cloth "sock," held into a conventional rectangular form by four 1¼" rods that form the speaker's "corners." The enclosure proper can thus be just painted black, allowing the money saved on veneer to be spent on the things that count—those that produce the sound!
Underneath the sock, rigidly fixed between the rods by the bottom panel and horizontal braces, is an asymmetrical bass enclosure, 23" or so high and 13.5" wide at the rear, tapering to just over 9" at the front, which is only just wide enough to carry the woofer. This driver is constructed on a diecast basket and features a conventional half-roll surround and an 8" curvilinear cone fabricated from a plastic material termed by Vandersteen "polycone." At the enclosure's rear is a large, 10" actively driven pulp cone, this the "Acoustic Coupler" and mass-loaded with what appears to be a wooden disc over its dust cap. On the top of the bass bin is fixed the small, 6"-wide enclosure that carries the 4.5" plastic-cone midrange unit. This sub-cabinet is slope-fronted to bring the acoustic center of the driver in alignment with that of the woofer.
The midrange drive-unit is also constructed on a diecast basket and is cooled with ferrofluid. It has an unusual surround, this flat rather than the usual half-roll, and a result of the research program that resulted in the sophisticated midrange driver featured by Vandersteen's 4A loudspeaker. It is said to better absorb traveling waves in the cone material. The final driver is a 1", ferrofluid-cooled fabric-dome tweeter, mounted in another small enclosure on top of the one for the midrange and surrounded by a blanket of felt that reaches as far as the frame of the midrange driver. Along with the fact that all the front edges of the baffles are radiused, this will lower the level of interfering reflections from obstructions in the tweeter's acoustic environment.
All the cabinetwork is constructed from "Multi-Fiber," a wood product said to be more dense and stable than particle board, and resonances are said to be sufficiently well-controlled that they cancel rather become additive. Electrical connection is via two pairs of 4mm sockets on a rear panel, one for the woofer/acoustic-coupler combination, the other for the mids and highs, next to two wirewound pots that offer a degree of control over midrange and tweeter levels. (I would recommend the 2Ci owner rotate these over their full travel a few times every couple of months to ensure that the electrical connection between wiper and track remains good.) The crossover is constructed on a double-sided Mil-Spec printed circuit board and features first-order slopes. Audiophile-quality components are used throughout, including air-cored inductors and polycarbonate, polypropylene, and IAR capacitors in the signal path; IAR Wonder Solder is used exclusively. The crossover includes phase- and impedance-compensating networks to minimize the change of impedance with frequency, thus presenting the amplifier with a basically resistive load.
System & Set-up
Each 2Ci was attached to the dedicated stand produced by Sound Anchor of Florida with two bolts, the actual contact between speaker and stand being via three small ball-bearings which fit into recesses in the stands' top pieces. These triangular stands are impressively solid, and even though Richard Vandersteen says that the less expensive Vandersteen stands give 95% of the Sound Anchors' sonic performance, I would urge 2C owners to go the whole hog.
In their excellent and informative handbook, Vandersteen recommends placement of the speakers parallel to the rear wall and at least 12" away from it, with the side walls at least 24" away. After some experiment, the speakers were positioned some 24" from the rear wall, 60" from the side walls, and some 6' apart, firing straight ahead. The side walls to the front of the speaker are basically dispersive rather than reflective, being faced with bookshelves. Due to the time-coherent nature of the design, the vertical listening axis is very important. With the 2Ci raised some 6-8" above the floor by its stand, the listener's ear must be between 35" and 39" off the floor. If that is not the case, then the stand spikes must be adjusted to bring the listener on to the optimal axis.
Footnote 1: See Ken Kessler's interview with Richard Vandersteen in Vol.11 No.6, June 1988, for the full background of this design.—John Atkinson