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PostPosted: 28 Oct 2013, 09:29 
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Joined: 28 Oct 2013, 09:16
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Hi, I'm new to this forum.
I'm considering making a 3-way acoustic boxes and speaker 10 inc. boxes will have an approximate volume of 95 liters, which keep a rear bass reflex system. The anger woofer mounted on the bottom, the middle range in the middle and upper tweeter. My question is this:
You can mount inside the box to cushion system back wave of the woofer?, Below the frequency of the waves bass reflex output from the port without problem, the resonance frequency bass reflex comes into phase with the woofer, but for higher frequencies have thought of putting a grid-like structure lined with foam cubes phono absorbing, so that the wave of media passes up is find a great superfiecie attenuating foam.
Someone has set up something similar?
Thank you.


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PostPosted: 28 Oct 2013, 17:46 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi Daniel and welcome to the forum. I'm not exactly sure what you want to do but I would suggest you post the question on the forum at Parts Express and the one on audioroundtable.com

Both sites have a lot of speaker builders and they may have done something like you want to do.

Good listening
Bruce

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PostPosted: 29 Oct 2013, 02:53 
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Joined: 28 Oct 2013, 09:16
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thanks for your information, i atteched a simple draw of the structure, perhaps with the draw is more easy to see te idea.


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PostPosted: 29 Oct 2013, 06:19 
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Attachment didn't show :confused:

(You have to upload them before hitting "reply")

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PostPosted: 29 Oct 2013, 06:35 
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i`m sorry i upload the file again


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PostPosted: 29 Oct 2013, 17:50 
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Thanks!

I see a couple of caveats:

It's best to completely seal off the woofer from the midrange and tweeter. Even if you don't blow the voicecoils off the magnet poles, you will push the cones into a non-linear range otherwise.

I've built rear-firing port cabs before and they have to be positioned *perfect* to get the bass enhancement, or the bottom end gets all boomy and mushy.

Cheers!

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* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
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PostPosted: 30 Oct 2013, 10:18 
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Joined: 28 Oct 2013, 09:16
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thanks geek, the midrange and the tweeter is shielded, the rear part of both speakers are completly closed.
of course the bass-reflex is calculated for 34 hz. But really is important the position of the tube?
there are any special possition for the bass-reflex tube?
thanks again


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PostPosted: 30 Oct 2013, 16:48 
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Hi,

Not really, but behind the woofer seems to be the most accepted position as the air has less distance to travel.

The important thing is the length and diameter of the tube, as it sets the resonance. Too small diameter and it'll "chuff" on bass transients, so as large of diameter as practical befor going negative in length in the math.

Cheers!

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* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


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PostPosted: 31 Oct 2013, 09:38 
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Joined: 28 Oct 2013, 09:16
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thanks Geek. of course the resonant frecuency of the bass reflex (lenght and wide dimesion) is calculated to extend the frecuency response of the woofer, that allows to extend the low range of the complete system.
But my question is refered of the constuction of the structure build in the midle of the box, the square grid shape lined of foam with piramidal, for decrease quickly the waveform produced by the woofer in the rear side.

i think, the ideal enclosure must not be a reflexive space, because that creates a lots of interaction of waves inside the box, that is the reason of increase the surface of piramidal foam with this structure, similar as a heat dissipator used with electronic devices with the hot.

somebody constructed something similar?


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