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Old 20th September 2013, 08:05 PM   #1011
xrk971 is offline xrk971  United States
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we both felt that they were possibly the best speakers we have heard
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Old 20th September 2013, 08:11 PM   #1012
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Old 20th September 2013, 08:41 PM   #1013
Dave R is online now Dave R  United States
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Originally Posted by xrk971 View Post
It helps to provide a smoother frequency response.

If you had just one length, it would be double the amplitude of the green without the red to balance it.
Thanks. The pictures and those comments help.
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Old 21st September 2013, 12:29 AM   #1014
Coen is offline Coen  Netherlands
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The foamboard arrived yesterday and i'm well on my way making my first speaker. Decided to try a 50cm in foam first, but already have the plywood ready for the second one. Hope to finish it this weekend!
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Old 21st September 2013, 01:34 AM   #1015
xrk971 is offline xrk971  United States
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Coen,
Very nice work, looks great. Nice kitty you have there.
Looking forward to first sound.
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Old 21st September 2013, 03:07 AM   #1016
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i'm well on my way making my first speaker.
Now if you could only sleep in your own bed. That couch looks nice, kitty included, but...

Hey I've been there. My honey now accepts my hobby.
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Old 21st September 2013, 06:05 PM   #1017
Coen is offline Coen  Netherlands
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Now if you could only sleep in your own bed. That couch looks nice, kitty included, but...

Hey I've been there. My honey now accepts my hobby.
That's my lovely assistant who's fallen asleep on the couch.. she was actually quite usefull in holding down the foamboard strips waiting for the glue to dry, but it did get a little late.. (2am)

Waiting for the front part to dry now and thinking about how to attach it to the wall

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Coen,
Very nice work, looks great. Nice kitty you have there.
Looking forward to first sound.
Thanks, it turned out pretty good, first time i used a glue gun.
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Old 22nd September 2013, 04:51 PM   #1018
howardg is offline howardg  United States
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One thing I wonder about on a practical vs theory level is why a bunch of small mouths apparently end up acting like one big mouth? Since the low freq. cut off of a horn is supposed to depend in large part on the circumference of the mouth, one theoretical guess might be that you would have a bunch of trumpets sounding, instead of a tuba.

I can imagine how a wavefront could be divided up and then recombine at multiple mouths. But then also if there are different path lengths, then what is recombining and how and when? Maybe the spikes in the FR graphs partly show constructive and destructive interactions outside the horn mouths.

Maybe the small cornu horn segments are more resonant-like a TL-than a horn? What is the average the path length on a 24" cornu? Something like 20"?

The wall would extend the horn, sure, but Cal's cornus made good sounding 60hz or so bass in "free air" outside at DIYFEST.

Of course all practical size horns for the home are not big enough to act like an ideal horn in the lower bass range, and so are so compromise between a horn and a pipe utilizing standing waves.
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Old 22nd September 2013, 07:40 PM   #1019
hajj is offline hajj  Lebanon
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New idea alert!
(please note that this idea came to me in the middle of 2 day marathon to write a 50-page financial report... not the best of situations)

How about a BVR type cornu?

A BVR is like a horn loaded bass reflex box, and according to Scottmoose and David from planet10 (who coined the term BVR for Big Vented Reflex) is very good at accommodating different drivers with somewhat differing T/S parameters but similar Sd's.
IIRC it works so well because it seems to influence the T/S params of the drivers to the extent of minimizing their influence on the enclosure's behaviour (remember 50-page report, not the sharpest writing right now).

In practice this would mean a bigger chamber volume and a much shorter horn.

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Old 22nd September 2013, 10:17 PM   #1020
xrk971 is offline xrk971  United States
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Howard,
The 24 in Cornu has an unfolded longest horn path of 1.44m IIRC. That is consistent with 60 Hz 1/4-wave freq. The size of the mouth as a radiator is taken into account by the AkAbak sims so the influence of mouth size is in there. As BLH's go, the Cornu is one of the few with an expansion ratio >> 10. It is 25 in fact and this accounts for its ability to get +10dB to +12 dB gain in the bass region without taking up a huge amount of room on the floor.
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