Carlspeak Posted February 16, 2009 Report Share Posted February 16, 2009 Attached is a WT3 plot of a Snell Model A speaker. The xover has been modded a bit with updated xover parts.Note the high woofer box Qtc of 1.4. A second, sister speaker meas. 1.5. Perhaps the high Q was by design to compensate for the woofer being mounted facing into the cabinet at the bottom of it.Beyond the woofer portion of the crossover, there is a lowering of impedance down into the claimed 4 ohm range for all of the mid and tweeter portioin of the total frequency response. Also note phase is in the plus/minus 10 degrees band throughout the same range. Nice performance for a dated design.Snell_A_1512_doc.doc Link to comment Share on other sites More sharing options...
Pete B Posted February 17, 2009 Report Share Posted February 17, 2009 Attached is a WT3 plot of a Snell Model A speaker. The xover has been modded a bit with updated xover parts.Note the high woofer box Qtc of 1.4. A second, sister speaker meas. 1.5. Perhaps the high Q was by design to compensate for the woofer being mounted facing into the cabinet at the bottom of it.Beyond the woofer portion of the crossover, there is a lowering of impedance down into the claimed 4 ohm range for all of the mid and tweeter portioin of the total frequency response. Also note phase is in the plus/minus 10 degrees band throughout the same range. Nice performance for a dated design.That is odd, are you sure that none of the connections to the woofer have a highresistance due to corrosion or something? Small came up with a volume-bandwidth-efficiency factor K and it peaks for a Qtc of about 1.2 in sealed systems. Most puristswould complain about the poor damping associated with a high Q, however, I've always felt that this was not well founded especially considering the high Qassociated with room resonances. I'd be interested to see the woofer XO schematic ifyou happen to trace it out. It is also interesting that a high Q provides some bafflestep compensation since there is broad peaking well above resoance.Do the woofers have Alnico or ceramic magnets? Link to comment Share on other sites More sharing options...
Carlspeak Posted February 17, 2009 Author Report Share Posted February 17, 2009 The woofer is Italian made RCF L12P48 with ceramic magnet and modded cone. Sorry, I don't have the woofer xover schematic, nor do I have the speakers any longer. Link to comment Share on other sites More sharing options...
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