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From: FRANCISCO%FILIP0.LIPUC.RCCN.PT@CUNYVM.CUNY.EDU (FRANCISCO FRAGA)
Newsgroups: rec.audio.high-end
Subject: Subwoofer For ESL63
Message-ID: <11177@uwm.edu>
Date: 19 Apr 91 12:40:27 GMT
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Approved: tjk@csd4.csd.uwm.edu
Originator: tjk@csd4.csd.uwm.edu

I am still trying to match a subwoofer to my Quads ESL 63 and
I have built this week end a dipole subwoofer using an Hartley
24" speaker as published by  Speaker Builter (thanks, Ray).
The first results were encouraging, but I have several doubts
and advice would be welcome.
        In this project the high pass section of the crossover is
passive (6dB/octave) and as the  ESL 63 bass roll-off
is 3rd order below resonance one gets a 24 dB/octave filter.
But the crossover frequency of the ESL is difficult to establish.
The frequency of the impedance peak is level dependent, so it can't
be considered as cross frequency. From the sine wave frequency reponse
the crossover seems to be about 50Hz but from the 1/3 octave pink noise
published data it seems to be 63Hz. What is the correct answer?
        Another question about double speakers subwoofers. Mirage M1,
and Celestion 3000 system, e.g., use two opposing bass speakers. Are they
operated in electrical phase and /or accoustical phase? When one of the
speakers cone approches towards the listener the other aproaches or
stands off from the listener?

........................................................
Francisco A. F. Fraga
Dept. Physics
Univ. Coimbra
3000 Coimbra PORTUGAL tel. 351-39-34668 fax 351-39-29158
FRANCISCO@FILIP0.LIPUC.RCCN.PT