This might help:
JOHN MAROVSKIS
Already in 1970 John Marovskis from the Bronx (New York) designed his extraordinary Janis W-1 subwoofer. The story goes that he made some 50 cabinets before he arrived at the excellent sonic performance of his system which has a flat frequency response from 30 to 100 Hz. (-3dB). He designed an electronic crossover module with a 60 Watt amplifier to go with the handsomely finished cabinet. He called this elelctronic crossover unit with amplifier, Janis Interphase with a fixed crossover frequency of 100 Hz. Both low pass and high pass sections filtered with 18 dB slopes. Later he designed a smaller Janis W-2 to add to his catalog, and also another version of the Interphase. The crossover frequency was fixed at 100 Hz. The Janis Interphase filtered the low pass section (Janis W1 or smaller W2) and the high pass section (satellites) with slopes of 18 dB per octave.
Another, most important feature of the Interphase modules was the continuous variable phase adjustment of the subwoofer (0-180º) in order to achieve a seamless and harmonious integration of subwoofer and satellites, independent of the subwoofer's position in the room.
Dutch importer Jan Endenburg told in an interview that he had read about the Janis W-1 system in 1970 in an article written by Bert Whyte (published in AUDIO) and when he was in New York he called John Marovskis asking where he could hear the Janis subwoofer. Marovskis asked Jan Endenburg where he was calling from. "I am in New York", Endeburg said. John Marovskis invited him to his home and demonstrated the systems set up with Quad ESL loudspeakers. That is how Endenburg's firm Engasound became the importer for the Netherlands. It was Jan Endenburg who explained to me the importance of phase and he pointed out to me that optimum phase coherence could also be obtained by using a 12dB low pass for the Janis W1 and a 6dB high pass filter for the satellite speaker as was achieved by the than cherished and famous Symmetry Electronic Crossover. But I found that the 18 dB slopes were much cleaner and also the Symmetry did not have this variable phase.
JANUS INTERPHASE + SUBWOOFER
Once in a while you read a rather negative review about the Janis subs. But these are always written by people who do not know how to use the Janis sub woofers. They make the mistake of using high current amplifiers (NAD, Rotel, Bryston, etc.) that get their power out of the large toroidal transformer instead of large capacitors. Toroidal transformers cannot deliver enough current and are soon exhausted because they need to deliver current directly out of the AC mains. In the past I have tried a Tandberg power amplifier for the satellites. They did not match at all. The sound of the Janis Woofers became realistically impressive only when using amplifiers that really go with the nature of the Janis Interphase. For instance when an Amcron power amplifier was used to furnish the power to the satellites. The Janis worked also perfectly well with mono blocks from French manufacturer Elipson. Just to mention some historical units. If you combine the Janis Interphase with the right amplification then the music will get its impact and slam. Not only when playing Tchaikovsky's 1812, but any record from your collection.
In recording studios in Hilversum (The Netherlands) Janis Subs were used in the nineteen seventies en eighties. Below the frequency response curve of the Janis W-1 (from the literature provided by John Marovskis).
Another favorite bass system from the past was the Hartley sub woofer which was combined with de Decca Ribbon high frequency unit and the Quad electrostatic speakers (ESL). Impressive as well. (See: The Decca London Ribbon Horn Tweeter.)
Also:
http://mail.audiokarma.net/forums/showthread.php?t=273268
