2nd 90-degree bend: where is it?
Quote:
Originally Posted by
Lee in Montreal
The tall gap at the back is a cost cutting measure. Instead of using a 60" tall rear panel, it is only 48" tall.
I did not mean the tall gap at the back. I meant the SCOOP itself, it is the 2nd 90-degree bend.
I also did not mean to suggest that You integrate a boom box. I meant that what You remember as the sound of the Waldorf may be the sound of the dbx and the Bertha combined.
Ruediger
Yes, there is a math equation
Quote:
Originally Posted by
louped garouv
Lee,
Is there a math equation for determining/optimizing the back chamber's volume for a particular driver?
The phase at the rear of the speaker is shifted by pi which corresponds to 1/2 wavelength.
At the frequency where the horns length is 1/2 wavelength the total shift is 2 pi or 1/1 wavelength, which is zero under steady state conditions.
Down to the frequency where the horns length is 1/4 wavelength and up to the frequency where the horns length is 3/4 wavelength the sound from the speakers front and from the horns mouth will add to each other, below and above they will subtract from each other.
For a scoop the frequencies might be 40 Hz, 80 Hz and 120 Hz. The rear chamber should function as a low pass below 120 Hz and should block frequencies above 120 Hz.
There is a paper from D.B.Keele about how to design a horn from the drivers TS parameters. The calculations are for a front loaded horn. The front chamber of the front loaded horn is the rear chamber of the rear loaded horn, and the rear chamber of the front loaded horn has no counterpart in the rear loaded horn (is infinite).
The Keele paper is in the technical references thread of the general audio discussions forum.
Ruediger