FCFIFRAGA%CIUC2.UC.RCCN.PT@CUNYVM.CUNY.EDU (FRANCISCO AMARAL F FRAGA) (07/31/90)
I would be very much interested in hearing about the Velodyne subwoofer mentioned in the description of Gary Gibson system. Is it a dual stereo subwoofer or a central mono one? I have heard several experiments of ELS63 with subwoofers and I was not fully pleased. The best I heard was with a pair of Janis subwoofers, but unhappily the quality of the system was spoiled by a poor quality active crossover. (It was an old model and it didn't match the valve preamplifer and amplifier with which was being used). If some one has experience or information of home building subwoofers and matching active crossovers for Quad ELS63 I would be quite pleased to hear about. I own a pair of these electrostatics and, in spite of conflicting opinions about that matter, feel that they need some help in the bass. However, after hearing for some brief moments to a friend Roland Research Model 5 driving them, may be it is the Audio Research D70 II that needs some help! Francisco Fraga -------------------------------------------------------- Francisco A. F. Fraga Dept. Physics Univ. Coimbra 3000 Coimbra PORTUGAL tel. 351-39-34668 fax 351-39-29158 FCFIFRAGA@CIUC2.UC.RCCN.PT
bill@vrdxhq.verdix.com (William Spencer) (08/02/90)
in article <5447@uwm.edu>, FCFIFRAGA%CIUC2.UC.RCCN.PT@CUNYVM.CUNY.EDU (FRANCISCO AMARAL F FRAGA) says: > I have heard several experiments of ELS63 > with subwoofers and I was not fully pleased. [...] > If some one has experience or information of home building subwoofers > and matching active crossovers for Quad ELS63 I would be quite > pleased to hear about. Check out _Speaker Builder_ #6/89. The system described has two very interesting features: * Dipole type subwoofer. This helps solve the integration problems of matching dipole main speakers. Interesting, since dipoles are not known for bass. However there are advantages: the driver operates at free air resonance and the polar response is different. The author of the article used a single Hartley 24" driver. I could see using multiple low cost 15" woofers instead to get the required "cubic inches" of air movement. The cabinet (open back) was only a bit larger than the driver and rolls off at 6 dB per octave below 100 Hz due to baffle cancellation. The author claims the efficiency is high. * Use of combined electronic and acoustic rolloffs for the crossover. This could be useful in any subwoofer system. The Quads roll off at 12 dB per octave below 80 Hz. The elecronic crossover adds 6 dB/octave to provide a combined 18 dB/octave slope at 80 Hz. The subwoofer side uses an 18 dB/octave filter using Old Colony filter boards plus the 6 dB/octave boost below 100 Hz to compensate for the baffle cancellation noted above. The 6 dB filter for the mains only provides a small reduction in the Quad's workload but it still helps. More signifigant, the filter is passively implemented so none of your main tone need pass through excess circuitry. The above info should help with one of the most common questions on the net. I'm planning on some dipole experiments myself soon (not for Quads :-). bill S.
alan@syacus.acus.oz.au (Alan Stewart) (08/02/90)
FCFIFRAGA%CIUC2.UC.RCCN.PT@CUNYVM.CUNY.EDU (FRANCISCO AMARAL F FRAGA) writes: >I would be very much interested in hearing about the Velodyne subwoofer >mentioned in the description of Gary Gibson system. Is it a dual >stereo subwoofer or a central mono one? >I have heard several experiments of ELS63 >with subwoofers and I was not fully pleased. The best I heard was A review was done in Hi-Fi Review last year (I will find out what month) for a dipole subwoofer system especially designed by Celestian for the ELS63's. The dipole bass system matched the nature of the sound radiation pattern from the Quad's more accurately than other systems on the market. Alan