Hello, My name is Allen, in Tennessee

Matthew J Poes

Staff Writer
Staff member
Joined
Oct 18, 2017
Messages
1,830
A wide sweet spot is not something I've experienced with any CD. I am always able to locate the speaker immediately - even on said JBL's that I absolutely loved.

I have no problem with waveguides. I like them paired with traditional drivers like Amphion and JWM Acoustics use. These are modest waveguides that don't have the issues with the sweet spot I usually experience.
I think maybe you just haven't heard the best modern CD designs. Old CD horns used diffraction slots and this caused harshness and a bit of distortion in the highs. Modern CD's have either smoothed the diffraction slot (JBL knuckles) or removed it entirely (Gedees and Seos).

If you look at the article I linked you can see that it's just a matter of physics. The constant directivity behavior allows a far wider and more even sweet spot than could be possible otherwise.

Having said that, it seems like most people set up their CD speakers incorrectly. To create this effect I'm mentioning your listening axis has to be about 22 degrees to the outside of the center axis. If you don't do that then by the laws of physics you will actually make the sweet spot much worse.
 

AudioThesis

Member
Joined
Oct 30, 2017
Messages
73
My AV System  
Preamp, Processor or Receiver
Dayens Ampino
Main Amp
MastersounD Evolution 845, Compact 845, Dueventi
Additional Amp
Dayens Ampino Integrated, Dayens Ampino Monoblocks
Other Amp
North Star Design Blue Diamond Integrated Amp
Universal / Blu-ray / CD Player
North Star Design Magnifico
Front Speakers
Rosso Fiorentino Volterra, Fiesole
Other Speakers or Equipment
Usher Be-10, T-515; Sonner Audio Allegro Unum
Video Display Device
Sony XBR-75X940C
Other Equipment
North Star Design Supremo, Venti, Intenso, Incanto
The problem with the paper is that the image is 'falsely centered'. What I mean by that is the imaging is not truly centered. This is akin to setting the balance 2-3 steps to the right in your car and getting a 'center image'. All you have done is kept the response similar within that range but it doesn't take into account the time issues. While they do mention this issue as shifting the center image, it isn't simply fixed by smooth frequency response over a wide area.

I mean this as no disrespect to the author of that paper and I think he has a good writeup for why it will work for the majority of people, it doesn't do anything except address the center image stability... only a part of the whole when it comes to a stereophonic experience. To be fair, one should expect the center image to shift the same way they shift (i.e., move to the left and center follows you). This is normal. What isn't normal is when you move to the left and the entire soundstage collapses and all you hear is the speaker you are closest to - again, not just center image, but the entire soundstage.

CD and horns aren't the only design with this issue. Planars and electrostats also suffer this fate, but it is a caveat that you accept when you buy. The difference is, the CD/horn can still work VERY well in a HT application, where the planars and electrostats simply don't hold up over a wide area.

For what its worth, I do think that is an awesome effect for CD's.
 
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