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[Ivan Beaver]

Hi Chris, the idea of doppler shift, as put forth in this situation is a myth. A persistent one that has roots in magazine articles, (I got mine from an article based on work done by Cerwin Vega), and perpetuated on the interwebs. Basically the 100hz and 4k sum. Just like all sounds in nature. If you have a piccolo player on stage at symphony hall, and 20 marching drummers with bass drums come across the stage, the piccolo sound will not shift with the drum beats, it will simply get added to. Same with woofers stacked near hf, the sounds sum. Being in the same horn, or even on the same component will make no difference to this.

I know this because I was corrected by Tom Danley. He says the only thing relevant to this is when you get loud enough to distort the air.

I am surprised that Ivan did not weigh in on this, but maybe it was because it would be defending the competitor. 

There are lots of bad facts or ideas that float around in our industry.

Part of the problem is that most of the actual users don't know enough to be able to pick out good ideas from bad.

So when somebody they respect says something-they just keep on repeating it-and furthering the "belief" as if it were fact.

And manufacturers presenting false ideas does not help either.

I have often wondered if some of the marketing guys sit around and say "Let's do "this" and see if anybody catches it".  Let's show them how bad it is, and yet if presented in the proper way-people will somehow think it is good-------

I better stop now

[Stephen Kirby]

Hi Chris, the idea of doppler shift, as put forth in this situation is a myth. A persistent one that has roots in magazine articles, (I got mine from an article based on work done by Cerwin Vega), and perpetuated on the interwebs. Basically the 100hz and 4k sum. Just like all sounds in nature. If you have a piccolo player on stage at symphony hall, and 20 marching drummers with bass drums come across the stage, the piccolo sound will not shift with the drum beats, it will simply get added to. Same with woofers stacked near hf, the sounds sum. Being in the same horn, or even on the same component will make no difference to this.

I know this because I was corrected by Tom Danley. He says the only thing relevant to this is when you get loud enough to distort the air.

I am surprised that Ivan did not weigh in on this, but maybe it was because it would be defending the competitor. 

Jack, I recently read a paper from John Meyer where he described the summation of pressure waves in air and I understand that different sources won't affect each other.  As in the type of co-ax driver where the woofer cone acts as a wave guide for the HF driver.  But those of us who remember trying to sing though the same amp the bass was playing through in '60s garage bands (many used the 2nd channel of any amp available for another instrument or microphone) remember the gargley sound.  I had always thought of this as intermodulation distortion.  That is the higher frequency signal modulated or distorted by the lower frequency signal.  But IM is a different thing, and the effect I remember gets called Doppler distortion.
Not having one of the hornless coax drivers to play with, I'm wondering what happens in the cross over region when the HF driver is producing sound and the LF driver is modulating that same sound with some LF component.  Seems a good reason to limit the excursion or LF extension of the woofer.

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