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It will peak more in upper mids and have less highs.

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Norman Bates

In Reply to: RE: Cutting the whizzer cone off a driver does what? posted by bcguitar on May 24, 2014 at 05:38:25

"I wouldn't like to speculate on the effects of intelligibility, but whizzer cones have an effect a lot lower than 7Khz, if you compare the response of the speaker with and without the whizzer cone, not just the frequencies where the whizzer is the sole source of sound.

Years ago I tested a Coral Flat 8A (8" driver with 160mm cone and 80mm horn shaped whizzer) with and without whizzer, and found the whizzer cone starts to have a large effect on the on and off axis response as low as 2.5Khz.

Specifically the presence of the whizzer cone reduced the on axis response from 2.5Khz to about 6Khz by nearly 3dB, but increased the (30 degree) off axis response by several dB, in other words the dispersion between 2.5Khz and 6Khz was greatly improved at the expense of some loss of on axis response.

However the on axis response without the whizzer actually had a +3dB shelf from 2.5Khz to 6Khz, which suggests the main cone of the driver was deliberately designed with an increased output in this range (probably due to decoupling rings) so that the response was balanced once the whizzer was in place.

Above 7Khz the response of the single main cone by itself disappeared rapidly, so above 7Khz the output is almost entirely the whizzer cone.

So technically the whizzer is only acting as a second separate cone above 7Khz, but between 2.5Khz and 7Khz it is still acting as a source of sound as well as a directivity modifier for the main cone, much like a phase plug would.

The improvement in dispersion is so great that at 4Khz without whizzer cone the 30 degree off axis response was 9dB down on the on axis response (severe beaming) while with the whizzer cone in place the 30 degree off axis response at 4Khz was only 1.8dB down from the on axis response... "
DBMandrake

http://www.diyaudio.com/forums/full-range/185012-whizzer-intelligibility.html

Follow Ups:

RE: It will peak more in upper mids and have less highs. - Bill Fitzmaurice 14:55:34 05/25/14 (3)
> So technically the whizzer is only acting as a second separate cone above 7Khz, but between 2.5Khz and 7Khz it is still acting as a source of sound as well as a directivity modifier for the main cone, much like a phase plug would.

Through a portion of the bandwidth the whizzer and cone will both function, the trouble is that the rear of the whizzer will be doing so out of polarity with the cone, and out of polarity with its own front wave. It's not the best arrangement for increasing high frequency bandwidth and dispersion, certainly not as good as a coax, but it's a lot less expensive method.
- RE: It will peak more in upper mids and have less highs. - thetubeguy1954 19:31:54 05/30/14 (2)
  A lot less expensive? Have you seen the $6,000 price tag of Lowther's whizzer field coils or Feastrex's $12,000 whizzer D9e TypeIII field coils or even more expensive Voxativ's $38,000 whizzer AC-Xp field coil drivers?
  
  Sorry Bill I couldn't help myself. However I understood exactly what you meant. That said, you'd think that if whizzers were that bad sonically, these manufactures would all be using coaxes instead on speakers costing $6K and up, no?
  
  I'm listening to: A Paul Simon Songbook by Bill Cunliffe & Friends
  
  Thetubeguy1954 (Tom Scata)
  
  Full-range/Wide-range Drivers --- Front & Back-Loaded Horns
  Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
  - RE: It will peak more in upper mids and have less highs. - Bill Fitzmaurice 05:33:18 05/31/14 (1)
    > That said, you'd think that if whizzers were that bad sonically, these manufactures would all be using coaxes instead on speakers costing $6K and up, no?
    
    So long as there's someone willing to pay the price there will be someone willing to provide the product. Besides, IME the more a speaker costs the less likely that someone able to afford it would know the difference between a whizzer and a squawker anyway.
    - RE: It will peak more in upper mids and have less highs. - thetubeguy1954 14:50:19 05/31/14 (0)
      You're probably right Bill...
      
      I'm listening to: Holland by The Beach Boys
      
      Thetubeguy1954 (Tom Scata)
      
      Full-range/Wide-range Drivers --- Front & Back-Loaded Horns
      Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society

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