Rational Acoustics



Oldmics
March 11th, 2009, 12:01 PM
Harry

You made the comment

"When you change the gain on an output you are shifting the crossover frequency which may lead to an out of alignment acoustic crossover."

over on the pro sound web in a post regarding a BSS 366 unit.

Would you elaborate on this?

Thanks,Oldmics

Ferrit37
March 11th, 2009, 02:44 PM
I answered over on the PSW at: http://srforums.prosoundweb.com/index.php/m/414560/16795/#msg_414560

coz' I can put images there. :)

Ferrit37
March 11th, 2009, 02:53 PM
Hey John,
you might also try these resources:
http://www.excelsior-audio.com/Publications/Crossover/Crossover1.html
http://www.excelsior-audio.com/Publications/Simulating%20the%20Directivity%20Behavior%20of%20L oudspeakers%20with%20Crossover%20Filters%20(AES123 ,%202007).pdf
http://www.excelsior-audio.com/Publications/FilterSummation/FilterSummation.html

Harry, hope you don't mind me jumpin in :)

Harry Brill Jr.
March 12th, 2009, 03:27 AM
Harry

You made the comment

"When you change the gain on an output you are shifting the crossover frequency which may lead to an out of alignment acoustic crossover."

over on the pro sound web in a post regarding a BSS 366 unit.

Would you elaborate on this?

Thanks,Oldmics

Ferrit posted a nice screen shot. The missing part of it is the phase trace. I was going to try to post a explanation but it's 3:30 am and I need to sleep. I'll get back to this as soon as I get a DSP in my hands unless Ferrit beats me to it.

PaulTucci
March 12th, 2009, 06:53 AM
Ferrit,

Bravo.
That is an eloquent way to illustrate the fact that although the electrical crossover point remains the same, the acoustic crossover point can change when the levels of the sub increases or decreases.
Thinking of this from the perspective of the electrical crossover point only is detrimental to a fuller understanding of what occurs in the acoustic realm.

Tucci

Ferrit37
March 12th, 2009, 01:49 PM
Hey Guys,
Because it's an electrical measurement its missing the "contribution" that the loudspeaker adds so the phase deviation from the filter alone isn't that dramatic, I'll try and make a measurement of a real speaker.

Ferrit37
March 12th, 2009, 03:20 PM
Hey Guys,
posted in PSW (I still can't figure how to put pictures here :( )

FILO4PRES
March 13th, 2009, 06:54 AM
http://www.youtube.com/watch?v=om8ySvIV7Fw