Geddes 15" Waveguide Project

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JoshK

Re: Geddes 15" Waveguide Project
« Reply #40 on: 21 May 2010, 08:36 pm »
That's smart Josh.  I'd add to that, make sure you do both out to 90 degrees--not just one or a couple axis.  That cone break up will impact the off axis performance in currently unpredictable ways unless you have fancy modeling programs and accurate driver parameters including the geometrical stiffness.  Even then, the model will not be as good as just doing the work.

Dan

Good point.

JDUBS

Re: Geddes 15" Waveguide Project
« Reply #41 on: 1 Jul 2010, 11:39 pm »
Guys, just another update.

I've changed around amplication a little...ok a lot.  I'm now using a Crown K2 on the woofers, a UCD180 amp for the mids and a 45 SET amp driving an F4 clone for the tweeters.  Had to remeasure everything as I wasn't sure of the gain levels for the UCD180 and the amp combo for the tweeters, but it was quick.  I think I have the measurement / filter creation process down to like 20 minutes or so!  :thumb:  And that's getting 40db+ confidence for each driver (minimum recommended is 20db I think).

Anyway, my system has never sounded better!  I now need to figure out a stand solution to get them up off the ground and better situated, vertically.

-Jim


Tyson

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Re: Geddes 15" Waveguide Project
« Reply #42 on: 2 Jul 2010, 12:32 am »
JDUBS,
I was talking to the DEQX engineers a while back and they suggested 2 things to get better measurements.  First, take nearfield measurements (5 inches distance, on the same vertical plane as the center of the driver, but 20 degrees off the horizontal axis - ie, 20 degrees to the side of the driver).  You have to make sure you tick the "Pause between driver measurements" option when doing this, so you can move the microphone.  Starts with the woofers, then moves to the tweeters, then to the mids, as you no doubt know.

Then, when you go to the Impulse Response page, double click on the vertical line that you'd normally manually drag to the first big squiggle.  After you double click on it, you set the larger value to 100.  This is because you have no room issues to deal with since you are doing nearfield measurements.

After that, proceed as normal.  For me, I ended up with much better sound, especially in the bass, as well as the mid/tweeter integration.

JDUBS

Re: Geddes 15" Waveguide Project
« Reply #43 on: 4 Jul 2010, 08:28 pm »
Interesting, thanks Tyson.  Do you know the reason for the 20 degree off the horizontal axis?

-Jim

DanTheMan

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Re: Geddes 15" Waveguide Project
« Reply #44 on: 6 Jul 2010, 08:03 pm »
Isn't that roughly the Geddes listening axis?  Maybe that's why?

Dan :scratch: