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CD Equalization achieved--passively!

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Brian Cheney

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    • http://www.vmpsaudio.com
CD Equalization achieved--passively!
« on: 25 Apr 2006, 02:49 am »
Since CES I have been working on a method for achieving CD EQ passively.

As most VMPS'ers know, the Constant Directivity Wave Guide (CDWG) distributes the same amount of energy over a 180 degree angle, which leads to an audible rolloff effecting extension and dynamics beginning sooner than theorized (10kHz in my first designs, 7 kHz now).  

Since the rolloff is a characteristic curve and not a shelf, boost must be applied at 6dB/oct at the frequency where the CD has its greatest effect.
I have managed to do this passively, by both de-horning the tweeter (suggested by Bruno B) and simple changes in the first-order crossover.
For those with DIY tendencies we will supply the necessary parts at no charge along with the CDWG. The new crossover will be supplied with the 626R, RM 30 and RM 40 for now.

So, no electronic equalizers, controllers, digital processors etc. required.  We now have flat frequency response with 180 degree dispersion and no lobing or other anomalies off-axis.  I don't think this has ever been done before. The sound is extremely natural, present, and with excellent imaging and 3-D soundstage.

Enjoy!!
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HAL

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CD Equalization achieved--passively!
« Reply #1 on: 25 Apr 2006, 03:02 am »
Is the CDWG for the QSO-626R available?  Have a pair here ready for CDWG upgrade with the XO mod.
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ka7niq

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CD Equalization achieved--passively!
« Reply #2 on: 25 Apr 2006, 04:55 am »
Is there a waveguide for us RM 40 spiral creatures yet ?
Since you cant "de horn" a spiral, is it going to be possible to passive eq it like a FST ?
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ctviggen

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CD Equalization achieved--passively!
« Reply #3 on: 28 Apr 2006, 08:12 pm »
Brian, I'll take the new stuff for my Rm40s and Rm30C.   Put me on the list!
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ctviggen

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CD Equalization achieved--passively!
« Reply #4 on: 28 Apr 2006, 08:14 pm »
Oops.  I guess I should say, Put me on the list as long as the list occurs after my honeymoon is over (May 22).
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warnerwh

CD Equalization achieved--passively!
« Reply #5 on: 28 Apr 2006, 11:47 pm »
Congratulations Bob! Hope you have a nice honeymoon.
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John B

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CD Equalization achieved--passively!
« Reply #6 on: 30 Apr 2006, 12:18 pm »
The 626R-CDWG w/passive equalization is in da house!  B brought over my speakers yesterday, and after a bit of fine tuning we sat down to enjoy some classical, jazz and blues SACDs and CDs.  I didn't think the CDWG series of speakers could sound much better than they already are, but B has done it again.  I hesitate to say this, because it's such a cliche in this community, but the music from these ribbon monitors sounded down right LIVE.  I got the same sense of real world "presence" of the music that I get from hearing the music live in the small clubs I go to in the bay area.  A stunning acheivement in speaker design...a big thumbs up to Mr. Cheney.  :mrgreen:
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Woodsea

CD Equalization achieved--passively!
« Reply #7 on: 30 Apr 2006, 12:34 pm »
Put me down for a pair of 626's and one LRC CDWG.
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