MartinLogan CLS loudspeaker Jack English part 2

...and now, the CLS IIA
Upgrading a pair of CLS IIs to IIA standard costs $150. If you are marginally competent technically, you can install this upgrade yourself. If not, your dealer can do it for you. Of course, the electronics can be shipped back to M-L for upgrading. The IIA upgrade consists of snipping out one component (for each unit) and soldering in a 9" piece of wire. The IIA has a bit more midrange energy and detail than the II. This change moves the sound of the CLS back toward more of the midrange immediacy of the original CLS I.

Though there is a $2520 "upgrade" available for the I, the CLS IIA is not an updated I. The only thing that isn't changed in the upgrade from a I is the wooden frame—everything else is replaced! The diaphragms, electronics, and transformers are all new. In short, the CLS IIA is an entirely different speaker and should be treated as such.

Considering it an upgraded version creates problems. For example, the CLS I could be effectively driven by a high-quality, low-powered tube amp. The impedance curve ran from 4 ohms at 20Hz through 32 ohms at 1kHz to 2.2/2.3 ohms at 18 to 20kHz. The impedance curve on the CLS IIA has less swing or variance over its range—it's nominally rated as a 4 ohm speaker—but it dips to a low of less than 1 ohm at 20kHz! With a low-powered tube amp this will result in a noticeably attenuated top end. Even higher-powered tube amps like the ARC Classic 120 will tend to attenuate the extreme upper frequencies.

Wrong amplifier matches have led to complaints often inappropriately directed at the speakers. If you hear a pair of CLS IIAs and there is no treble, they are probably being driven by the wrong amplifier. If a pair of CLS IIAs are inserted into a system that had been fine with CLS Is, it's not certain that the performance will be as good using the same electronics or cables. For example, both Pfeffer and Cooledge found the VTL 225 to be a poor match with the IIs, although the amplifier more than satisfied the stated power requirements and had been able to mate well with the CLS Is.

For the CLS IIAs to perform optimally, therefore, great care must be exercised in the selection of a matching amplifier. While MartinLogan addresses this question in terms of rated amplifier power, that is inadequate. Where low-powered tube amplifiers may have been ideal choices for the CLS I, solid-state amplifiers from companies like Krell and Classé may actually be a better match in a number of situations with the IIAs. Your dealer and MartinLogan should be able to provide more meaningful guidance on this issue.

Setup, etc.
Let's take a bit of time to review some mundane issues often overlooked by reviewers and yet of paramount importance to prospective purchasers. Given the track record of any new panel speaker in general and electrostatics in particular, reliability is often suspect. With more than seven years of actual production under their belt, MartinLogan's designs have cleared this hurdle with aplomb. Their products are reported as indeed being reliable and trouble-free, so much so that they now offer a three-year warranty at no charge. The purchaser simply completes and returns the certificate of registration within 30 days of purchase.

The packaging and shipping of the product is equally trouble-free. My CLS IIAs arrived in two cartons, one each for the speaker panels and the electronics. One electronics module is connected and fastened to each speaker panel. To complete the setup, the enclosed feet are affixed, speaker cables connected, and power cords plugged in. The final step is to properly position the speakers. M-L suggests locating them at least 2' from any wall and very slightly angled toward the listening position. That done, you're ready to go!

Not quite, of course. Remember, the CLS IIAs are electrostatic speakers and require a significant amount of time for the panels to properly charge, as well as a significantly longer period of time to break in. The more important factors here are the established reliability of the product, the integrity of the packaging, and the ease of unpacking and installing the speakers. All in all, a very straightforward and professional job with the consumer in mind.

Another important factor for the consumer is the care with which the CLS User's Manual has been put together. For the impatient there is a section entitled "Installation in Brief" to help you get set up and playing in the shortest amount of time. This section is the very first portion of the manual, not buried in an appendix or at the end, as is so often the case. For those with more patience, the manual includes a concise historical chapter giving proper credit for the electrostatic design to people like Rice & Kellogg (Bell Labs), Arthur Janszen (KLH), and Peter Walker (Quad). This is followed by an easy-to-read chapter on the electrostatic concept.

Only after providing all of this information on the evolution of the electrostatic design does the manual begin to discuss MartinLogan's unique contributions: the curvilinear line source (CLS) panel geometry (the CLS is still M-L's only full-range electrostatic speaker), the vapor-deposited film diaphragm, and transducer integrity. Appropriate cautions are provided on the speakers' use and maintenance. Seven pages of text are then devoted to room acoustics and proper speaker placement. There is even a section on recommended recordings. This is an excellent, instructive manual.