jlossint Posted December 11, 2004 Share Posted December 11, 2004 It was stated by PWK that the back chamber should be air tight. This "tightness" should have a time constant of several seconds. If I remember right the procedure for checking this 1/ open a hole into the back chamber. 2/ Next apply a dc voltage to the driver, which will offset the cone ( i.e move it). 3/ Close the hole in 1/ 4/ Remove the dc voltage and instantly measure the dc voltage over the voice coil and measure the time it takes before the voltage is zero. (There will be voltage since the cone/voice coil is now moving towrd its resting position. Take my word, if the chamber/box is properly air tight makes a difference and this is actually valid for any type of loudspeaker. Quote Link to comment Share on other sites More sharing options...
ZAKO Posted December 14, 2004 Share Posted December 14, 2004 Jloss.....Yes but how does it sound??????? Quote Link to comment Share on other sites More sharing options...
DRBILL Posted December 15, 2004 Share Posted December 15, 2004 ---------------- On 12/11/2004 10:00:16 PM jlossint wrote: It was stated by PWK that the back chamber should be air tight. This "tightness" should have a time constant of several seconds. If I remember right the procedure for checking this 1/ open a hole into the back chamber. 2/ Next apply a dc voltage to the driver, which will offset the cone ( i.e move it). 3/ Close the hole in 1/ 4/ Remove the dc voltage and instantly measure the dc voltage over the voice coil and measure the time it takes before the voltage is zero. (There will be voltage since the cone/voice coil is now moving towrd its resting position. Take my word, if the chamber/box is properly air tight makes a difference and this is actually valid for any type of loudspeaker. ---------------- Mmmm. What did you say we would be measuring? My guess would be the "spike" caused by the collapsing magnetic field. I believe you could get similar results with the driver sitting on the bench in free air. Just a thought. DR BILL Quote Link to comment Share on other sites More sharing options...
Dylanl Posted December 16, 2004 Share Posted December 16, 2004 Rick, I am interested in how they sound. Give us an update. Quote Link to comment Share on other sites More sharing options...
jlossint Posted December 27, 2004 Share Posted December 27, 2004 Yes, your right you will be measuring the back emf voltage, generated by the magnetic field and the voice-coil moving through it. But, since the driver is mounted in the closed back-chamber of the horn, this back emf voltage will show, by its mere existance, any leaking of air. There will always be some and it will most likly be air leaking through the center spider and via the voice coil as well as through the cone material. Sorry, if I were unclear in my description. Best regards Quote Link to comment Share on other sites More sharing options...
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