Coaxial drivers...

[454Casull]

Say you have a 1" tweeter inside a 8" woofer - will the moving 8" cone modulate the sound of the tweeter? I imagine the larger cone swinging 10mm around p-p should do something to the highs coming from the center...

[rcavictim]

Absolutely! The low frequency wavefront emanating from the woofer cone will consist of layers of denser and more rarified air. The speed of sound is faster in denser air than in rarefied air so the sound from the tweeter at shorter wavelengths will get bunched in packets following the low frequency activity. I think you would have to use a two tone generator test to hear the effect though.

[454Casull]

But the speed of sound in the air would keep changing, correct? the woofer goes back and forth, and the sound pressure goes down and up...

Would you say that this effect is measurable and/or discernable by ear?

[Volenti]

Originally posted by 454Casull
But the speed of sound in the air would keep changing, correct? the woofer goes back and forth, and the sound pressure goes down and up...

Would you say that this effect is measurable and/or discernable by ear?

The only time I've noticed this is when there is a large volume of very low frequencies occuring (typically car audio with bass levels 20-30db louder than the rest of the spectrum), I haven't heard it occur in normal listening levels in a system a balanced frequency response.

Talk into a large desk fan at close range to hear what it sounds like.

[454Casull]

Originally posted by Volenti


The only time I've noticed this is when there is a large volume of very low frequencies occuring (typically car audio with bass levels 20-30db louder than the rest of the spectrum), I haven't heard it occur in normal listening levels in a system a balanced frequency response.

Talk into a large desk fan at close range to hear what it sounds like.

I don't think the "talking into the fan" effect is the same, because some sound passes through while much of it bounces off the fan blades...

[robertwb70]

I have the Adire 10.1s-the woofer cone moves so little I wouldn't think this was a concern-and it certainly doesn't sound like talking into a fan...never has

and then there's the fact that the tweeter is also horn loaded

I'm not sure if this is the line/type of speaker you had in mind but it's the first coaxial(home use) that comes to mind...probably because I have a pair

[Volenti]

Originally posted by 454Casull

I don't think the "talking into the fan" effect is the same, because some sound passes through while much of it bounces off the fan blades...

I was merely giving an axample of where I've encounted higher frequency sound being noticeably modulated by high levels of lower frequencies, it does sound similar to talking into a fan, and unless he has a system that can reproduce ~20 hz at 130db it's the only way he's going to experience it.

[johninCR]

If someone runs accross a coax driver that will do 130db at 20hz, please let us know because I want some.