Larry Greenhill

It didn't seem like such a big deal. After all, when designer Kevin Voecks added a passive radiator to the bottom of Revel Loudspeakers' powerful <A HREF="http://www.stereophile.com/loudspeakerreviews/90">Ultima Sub 15</A> subwoofer, no one expected that the resulting 6dB increase in bass output below 35Hz would be so audible. However, Revel's sophisticated double-blind listening tests (described in my review of their flagship <A HREF="http://www.stereophile.com/loudspeakerreviews/96">Ultima Salon</A> full-range loudspeaker in the March 1999 <I>Stereophile</I>, revealed that a big change had occurred. With now twice the radiating surface, the modified Sub 15 produced significantly deeper, more powerful bass.

Makers of powered subwoofers fall into two camps: those that fit a high-powered amplifier and a single, large woofer into a relatively small, unobtrusive enclosure; and those that build two or more 10" woofers and an amp of moderate power into a larger, heavier enclosure.

Harry Partch (1901-1974), composer and inventor of musical instruments, delighted in generating deep bass. Finding most standard orchestral instruments wanting in that department, he built the huge Marimba Eroica, which he described on his <I>A Glimpse into the World of Harry Partch: 27 Unique Instruments</I> (LP, Columbia MS-20576):

It's common to read ads for new audio hardware that crow about "revolutionary" breakthroughs in sound performance, and that's how Velodyne crowed about their new Digital Drive DD-18, servo-controlled, powered 18" subwoofer. The ads suggested that the DD-18 can be digitally equalized to one's room with a resultant in-room frequency response of 20-200Hz, &#177;3dB.

Unless you've been on active duty in the Middle East, you're aware that Mobile Fidelity Sound Lab is back in business. During <I>Stereophile</I>'s Home Entertainment 2003 show in San Francisco last June, <A HREF="http://www.stereophile.com/musicintheround">Kal Rubinson</A> and I played hookey to visit MoFi mastering engineer Paul Stubblebine's recording studio, at 1340 Mission Street. As we sat spellbound, Paul played the original four-track, &#189;", 1-mil master tape of Stanislaw Skrowaczewski and the Minnesota Orchestra's legendary 1974 recording of Ravel's <I>Bol&#233;ro</I> and <I>Daphnis et Chlo&#233;</I> (footnote 1). Stubblebine fed the four discrete channels from the specially modified ReVox reel-to-reel deck to a modern surround system. The master tape produced the cleanest, purest sound I had heard in a long time.

&#201;mile Durkheim (1858-1917) once wrote, "The less limited one feels, the more intolerable all limitation appears" (footnote 1). Although directed at the paradoxical observation that suicide rates are higher in newly prosperous countries than in those mired in poverty, his comment applies equally well to subwoofers.

All high-end audio companies turn over their product lines periodically. Even those amplifiers I have depended on as references go out of production. Although my reference amplifier can remain a part of the reviewing sequence, readers won't be able to purchase a discontinued model and get the results I describe. Thus I am compelled to get a review sample of a new amplifier or speaker, and hope for the best.