I have an Alpine SWS-10D4 and when I have it wired to my amp, it only works when the two coils are wired in parallel but does not work, no audio at all, when they’re wired in series. When each coil is connected singularly to the amp I get audio, as well. Both coils work singularly.
Anyone know why this would happen?
Anyone know why this would happen?
When you series wire them are they out of phase? There is no reason you can’t connect in series. Bur if they are out of phase they will cancel each other out.
dave
dave
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I should also mention that if you wire in parallel but out of phase you should also get near nothing.
dave
dave
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Gotta teach these 'new ones' about basic electricity.
So, if you wire it with a single voice coil to the amp, then you can wire a lightbulb on the other coil and make a color organ!
The resistance of the bulb's filament will alter the driver's Q. About twenty years back, there was a brief fad of folks experimenting with adding a resistor across the disconnected voice coil of dual voice coil drivers to adjust the damping and create "dial-a-Q" drivers for their projects.
You just described Rythmik's sense coil type "servo". Unfortunately, it's subject to the same motor non-linearities that impact the driving voice coil and so is only useful as little more than a crude EQ. Better to use an accelerometer and get the cone's true motion for feedback.
Now, if you're talking about applying the Watkins' principle, that's an interesting approach.
Watkins "dual-drive" woofer as it was commercially known. It uses a woofer with two voice coils, the primary does most of the work, but at resonance when the impedance rises the second is crossed in parallel to flatten the impedance spike and effectively increase the low end extension. One of those clever ideas that works surprisingly well, but got forgotten over time because few wanted to pay the licensing fees. The actual impedances of the voice coils are significantly different to make it work the best, but you could make it sort of work with identical voice coils though it'd be a bit of a kludge. You can read the patent for it here: https://patents.google.com/patent/US3838216A/en
Just a moment, in looking that patent up, I found a spot on the 'net where Bill Watkins described his woofer, so I'll just let his own words do it:
Thanks for the work to search this - that's actually pretty clever and fairly easy to do! I can see how this saves some volume and you could build some very interesting drivers. A pitty it's not available on a wider base.
I ran a large PA that had servo sensing coils in the woofers. Circa 1990. IIRC there was a separate connection for the sense coil that went back to a processor.
Agree on the "wired out of phase" being the problem.
1. About 70 years ago, an incandescent bulb in series with a driver could provide something like loudness expansion. DAMHIK.
2. Whatever slight shortcomings the Rhythmic sensing winding may have in generating precise feedback, it provides enormous benefit compared to speakers without feedback. BTW, ordinary driver windings on a driver are pretty useless for recruiting them to provide feedback; you need much high voltage which Rhythmic, Sony, and others get from far longer (and thin wire) windings (and sometimes, also special provisions of the magnet).
3, The Watkins concept, clever as it seems "on paper", seems to be a solution to an impedance problem that bothers nobody today.
B.
2. Whatever slight shortcomings the Rhythmic sensing winding may have in generating precise feedback, it provides enormous benefit compared to speakers without feedback. BTW, ordinary driver windings on a driver are pretty useless for recruiting them to provide feedback; you need much high voltage which Rhythmic, Sony, and others get from far longer (and thin wire) windings (and sometimes, also special provisions of the magnet).
3, The Watkins concept, clever as it seems "on paper", seems to be a solution to an impedance problem that bothers nobody today.
B.
Wish this thread had existed long ago. Jim Salk's shipping me a pair of Rythmik subs I had ordered years earlier but had no space for then, though I've yet to read a disparaging word about how they sound versus other subs. https://www.rythmikaudio.com/servosurvey.html
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