Hi Guys
I know a lot of you are waiting for a report on the Imperial SO I'm building and a comparison to the standard Imperial. I got the first Imperial SO up and running, but what a disappointment! Something is wrong! I'm hoping someone can figure out what it is, because I can't imagine what could cause such a severe problem. If I had to guess I'd say the speaker back radiations are contained in the sealed compression chamber (like they should be). And the speaker front radiations are being delayed 180 degrees by the horn so the horn and the speaker are out of phase with each other and canceling big time. I can pump a lot of watts into this thing and no sound comes out. Here are 3 pictures that, I hope, show someone what it is that I did wrong (are you out there Steve?)
http://www.mninter.net/~kuechle/impso_1.jpgThis picture shows the front panel before the slot was cut.
http://www.mninter.net/~kuechle/impso_2.jpgThis picture shows the speaker when the front panel is removed.
http://www.mninter.net/~kuechle/impso_3.jpgHere are some graphs I took:
http://www.mninter.net/~kuechle/1.JPGhttp://www.mninter.net/~kuechle/2.JPGhttp://www.mninter.net/~kuechle/3.JPGhttp://www.mninter.net/~kuechle/4.JPGhttp://www.mninter.net/~kuechle/5.JPGhttp://www.mninter.net/~kuechle/6.JPGhttp://www.mninter.net/~kuechle/7.JPGDisregard the blue line on the graphs, its the green line that has the information.
Graphs 1 and 2 compare the new Imperial SO to the standard Imperial when driven with a sine sweep. The peak amplitude is 10 db down for the Imperial SO, which might not be too unexpected as we are comparing 1 speaker to 2 speakers, but at 30 hz the Imperial SO is 24 db down from the standard Imperial. Whats up with that?
Graphs 3 thru 7 all have the same, lower volume, sine sweep input. 3 is the Imperial SO as it should be. 4 is with the front cover removed. This is the board with the Karlson shaped slot in it. According to the graphs, this K-slot makes no difference at all! 5 is a picture of what happened when I covered up the K-slot with a solid board...higher volume by 6-7 db across the frequency range, but that nasty steep slope (looks like almost 30 db/octave to me) is still there from 20 all the way to 50 hz.
Graphs 6 and 7 are with a different speaker...pretty much the same results.
Well, I'm open to suggestions. Right now I'm thinking how hard is it going to be to turn these guys into a second pair of standard Imperials?
DanK