Why do all Passive radiators sub setups sound like crap?

Discussion in 'Archived Threads 2001-2004' started by Billy Gun, Dec 27, 2001.

  1. Billy Gun

    Billy Gun Stunt Coordinator

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    Every one I've ever heard sounded really "Muddy" and "Boomy".

    Are they all that way, or do you think the ones I heard weren't crossed correctly or setup right?

    Why use a passive radiator anyway....why not use a regular port? Or is the passive radiator a compromise for the box not being big enough?

    ???
     
  2. Dustin B

    Dustin B Producer

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    The Stryke HE-15 cube sub that uses 3 passive radiators per driver is supposed to sound great. Although many argue that the ported HE-15 design sounds better than the PR one. But I have no experience comparing the same driver in a ported and PR enclosure so I won't make any statment either way.

    But to answer your question, from my understanding the reason you use a passive radiator over a port is with high excursion drivers in small enclosures. The smaller an enclosure the longer a port has to be to tune to a low frequency. Also the larger the diameter of a port, the longer it has to be to tune low. Drivers that move a lot of air require a large diameter port to allow air to flow freely. Too small and the air a high excursion driver moves will cause port noise.

    So a small box and a driver that moves a lot of air would mean a suitable port would be too long to fit in the box. For example the Stryke HE-15 cube is 24" on all sides. That driver should really have an 8" diameter port. For an 8" diameter port to tune an enclosure of that size to 18hz it would have to be 71" long. Not exactly going to fit. Where as multiple passive radiators with long enough strokes and the right mass can tune the HE-15 cube to 18hz.

    Hope that helps.
     
  3. Tom Brennan

    Tom Brennan Screenwriter

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    Billy---The ServoDrive Contrabass is argueably the best direct radiating sub made and it uses 2 18" PRs (and 2 15" drivers). The Contrabass crushes any sub I ever heard and also has the low distortion and high output to keepup with basshorns, quite a feat. The PR is a substitute for a vent in designs where the intended vent would be too large or long. They are used in both small (Sunfire) and large (Contrabass, JBL L220) systems.
     
  4. Billy Gun

    Billy Gun Stunt Coordinator

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    A velodyne sub in particular which I know is a great name brand sounded really bad and another one I think was a Klipsch....but like I said, they may have been crossed too high or not setup correctly....
     
  5. Jack Keck

    Jack Keck Second Unit

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    This is way off topic, but I've had a pair of Pold Audio main speakers for about 22 years that sound great. Back then, all we had were mains, and we liked them.
     
  6. Billy Gun

    Billy Gun Stunt Coordinator

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    Where can I find info on the ServoDrive Contrabass?
     
  7. TerryC

    TerryC Stunt Coordinator

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    You listened to two subs. That is sure a far cry from all PR subs as mentioned in the tread title. PR subs can and do sound very good.
     
  8. Tom Brennan

    Tom Brennan Screenwriter

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    Billy---www.servodrive.com ServoDrives are prosound subs but there are people who use them at home. They work on a completely different principle than dynamic drivers with magnets and voice coils; they use a rotary electric motor to drive the woofers through a belt and driveshaft. Thus huge excursions are possible without the compression and distortion of long-stroking dynamic drivers. Pretty neat and a real "slap your head" idea. The designer, Tom Danley, has the most original mind in loudspeaker design since the heady days of the 1930s when guys like Hilliard, Lansing, Wente, Fletcher, Thuras and Voight were working. I heard a pair of planar speakers he made that had 2 long diaphragms that swung together back and forth like the doors in a saloon in a western movie, sounded great.
     
  9. Billy Gun

    Billy Gun Stunt Coordinator

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    Thanks for your input everybody.
    Oh.....and Have a happy new year Terry C. [​IMG]
     

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