Revel Performa M20 loudspeaker
Revel's Performa M20 mates the 1" aluminum-dome tweeter from the F30 with a 6.5", full-range version of that speaker's magnesium-alloy inverted-dome midrange unit. Both units are made by Revel. The woofer uses a 1.5"-diameter voice-coil edge-wound with flat wire on a Kapton former to maximize the amount of conductor within the magnetic gap. The pole-piece is vented for better cooling and lower compression, and fitted with a flux-shorting ring to reduce modulation distortion. A diecast basket is used for maximum rigidity, and the seamless dome is terminated with a surround of butyl rubber, chosen for its linear excursion capability. The tweeter is cooled with ferrofluid and uses both a flux ring and an underhung voice-coil to minimize distortion.
The use of lightweight metal-alloy diaphragms for both drive-units is said to ensure true pistonic operation within their passbands. The crossover is set at 2.2kHz, and "high-order" filters are used. Rotary controls on the rear panel adjust the woofer's output for free-space, stand-mounted conditions, or for use on a bookshelf, and shelve the tweeter up or down by up to ±1dB, in 0.5dB steps.
The M20's cabinet is constructed from 1" MDF, finished in real-wood veneer, braced to maximize cabinet-wall rigidity, and out of the box is fitted with three bulbous feet of cast aluminum. When the speaker is used with Revel's matching open-frame stands, these feet are removed and fitted to the base of the stand. The M20's front baffle has rounded edges to optimize diffraction. Even so, the speaker looks a little over-square in its proportions, which generally implies a somewhat compromised horizontal radiation pattern. Electrical connection is via a single pair of high-quality binding posts beneath the rear-facing, 2.25"-diameter reflex port, the latter flared to reduce wind noise.
The overall impression is of a well-engineered, well-crafted speaker that—especially considering its weight—you'd expect would sell for quite a bit more than $2000/pair.
I initially set the Performa M20s up on their 27"-high stands, but after some experimentation with positioning in the room, replaced these with Celestion's 24" Si stands, the single pillars of which were filled with lead shot and sand. The shorter stands fleshed out the midbass—due to the fact that the woofers were now at more different distances from the three adjacent room boundaries—and put my ears exactly at tweeter level. However, listening to pink noise revealed that the M20s began to sound hollow if I sat up so that my ears were above the top of the cabinets. If in doubt, use Revel's stands.
Footnote 1: Dr. Kal subsequently raved about the F30 in the May 2000 Stereophile.
Footnote 2: Barry Willis' two-part report on this visit is available on-line.