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Multi-Way Conventional loudspeakers with crossovers

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Old 15th August 2006, 09:36 PM   #1
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Join Date: Aug 2005
Default one final check...

Ok so I have revised the plan many times and decided on this:
1 x Neo3
1 x Neo8
2 x Dayton RS225s-8 (8")
1 x Dayton IB 15"
The enclosure below will be filled with sand although without the exploded view you cannot see that it is hollow but it is.
I have done several prototypes with the Neo8 in this enclosure type and it produces pretty good results from 300hz to 16khz with no peak at 11.5khz. With the proper x-over it should be about +-1.5-2db from 300-12000hz with the exception of the 3db dip at 1240hz, which btw irritated the heck out of me, it wont go away! Ive tried various radiuses in the center, and various angles on the wings, its alway there. anyway, any ideas on what is causing the dip at 1200hz?

The main reason for this post is to let anyone chime in with any problems that you think I might encounter, any design flaws that you notice, or any suggestions on anything.

The final design criteria/methodology:
-dipole, the neo's were designed for it so there it is, also if the upper octaves are di- then the woofers should be also. This means that the dayton 8's were a bad choice! In comes the IB15", it will pick up where the 8's fall off.
-Thick walled and sand filled, nuff said.
-"Floating" drivers, none of the drivers will touch wood. The neo's will be sanwiched between a thick fibrous material, for prototype I used the stuff you put under furniture.
-Neo8 centered at listening height with neo3 above, this gives more versatility(seated,standing) and keeps the daytons closer to the center line. The neo3 will be crossed above 8khz, probably around 11khz so will get little signal with most music.
-Symmetrically waveguided dipole, this was an idea I had and the neo's are the only speaker that allow this to happen due to the fact that they are the only drivers that are symmetrical front and rear. The effect of this is should be much closer to true dipole behavior and im curious how that will sound with my concrete walls. The waveguides provide amazing bass extension for the neo8 which allow a low order xover between the datyon and neo. And interestingly, the dayton peaks at the same frequency as the neo dips. Yes I planned that one
-I will eq the 15 as needed, or supplement with my 18" for ht and let the 15's handle music.
-Finish, will be a mixture of piano lac and veneer, glossed to the max.
-Crossover will be 3-way passive with active sub. I have a built in mono-sub amp/crossover on my receiver however eventually I want a stereo sub amp maybe a pro amp? Any suggestions here would be greatly appreciated as I have yet to research the ins and outs of amp selection and availibility.
-Crossover will be mounted in a small decorative box on top of U-frame of 15" with a glass lid to make it visible- it will be vented.

Well that's probably enough, heres the Solidworks pic:
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Old 16th August 2006, 10:22 AM   #2
rho is offline rho  Belgium
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Location: Peer, Belgium
Quote:
any ideas on what is causing the dip at 1200hz?
Maybe the room you are measuring the speakers in?
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Old 16th August 2006, 05:38 PM   #3
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Quote:
Maybe the room you are measuring the speakers in?
Sorry, should of mentioned SW and gated measurements were used at various mic distances, heights and speaker placements.
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Old 16th August 2006, 06:14 PM   #4
rho is offline rho  Belgium
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Just a guess: Maybe the distance from the neo8 to the top of the speaker has something to do with it.
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Old 16th August 2006, 07:08 PM   #5
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Quote:
Originally posted by rho
Just a guess: Maybe the distance from the neo8 to the top of the speaker has something to do with it.

hmmm...

I dont know if that matters for gated measurements. However on the flat baffle the dip is at 2khz and the flat baffle is the same height as the test baffle with the radiused throat and the neo is placed approximately the same distance from the bottom. The neo8 w/o baffle does not exhibit any major dips however it rolls of steadily from about 2600hz down to around 700hz(sloped response).

It is starting to seem like the throat geometry is causing the dip.

Any waveguide experts here who can comment?
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