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In the Forum: Horn-Loaded Speakers
In the Thread: Infinite Baffle Implementation and "Compression Sub-bass"
Post Subject: It's just one systemPosted by Scott L on: 12/15/2016
 skushino wrote:
ScottL,

It looks like the two pics you posted are of different systems, the first being slot loaded PP, and the second (full-system) showing a "traditional" IB.  You also seem to be confirming my intuitive hunch of potential sound benefits and horn matching using mild compression loading, or exhaust area < Sd.  I want to explore further.
Can you share further about your design inputs / criteria?  

For instance, the drivers I'll use are 4 x Aura 1808, Qts = 0.19, Fs = 24 Hz, 2 each in separate L + R manifolds.  These numbers differ from traditional IB drivers, but I'm not discouraged from auditioning them in an IB configuration. 

Also, what guidance, if any, wrt: exhaust area?  Your comment about observing rising Q and lower Fs using compression are encouraging.



It's just one system. I'll attempt to attach a picture here, showing the left hand side. The I.B. bass sits just behind the main speaker system.
The I.B. is just for low bass (ULF) and it is a push-push, reaction-forced vibration cancelling where the plenum housing has an exit area GREATER than 8xSD. The IB bass runs everything UNDER 60Hz.

The mid-bass is push-pull, slot load, and it sits under the big red horn. The slot exit is 1xSD, Which is 1/2 the combined SD considering it is 2 drivers per channel. I'll post another picture in  the next follow-up. Mid-bass covers 60-250Hz.

For your Aura drivers, the Qts is much too low for an infinite baffle installation. I am assuming the published specs are also the actual specs. If you mount them similar to they way I have my ppsl, you should acquire a net result increase in Qts (exactly how much, we can not be sure of?) If you are serious about your installation, you can always build the manifold first, mount the drivers, and measure the specs. The next step would be to decide how large of an air space you will need, and if you wish to e.q the response, or use a bass reflex. I do realize that in some circles bass reflex would never be considered.

Do you have the aura drivers sold through Parts express, or those that were sold through North Creek Audio?    Do you have the other t/s values as well ?
I am especially looking for Qms and Vas.

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