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Old 29th October 2011, 06:04 PM   #1
Zero D is offline Zero D  United Kingdom
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Question Multiple Bandpass designs ?

I was looking at Elbert's nice looking build in here Completed build, for inspiration.. & in particular this screenie

I've seen similar internal partitioning in other designs, & wondered "if" they & the holes could be considered in some way/s, a multiple bandpass type of arrangement ? I know Elbert's design is a Closed Box design, but even so might there be some internal tuning interactions occurring ?

Also what about a ported version with similar etc innards ?
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Old 29th October 2011, 09:50 PM   #2
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I think you mean "Karlson" for a multi-resonant design!

I was wondering the same thing too - if there are any repeating dimensions inside the interior partitions. But can't matter too much due to dimensions, locations, etc.

But I recently asked about cardboard cones. Replies did not give me much sense of closure.

But sound from inside probably can leak out through our thin cardboard cones. Who knows????? For sure it can leak out through ports.

I am sometimes surprised at the lack of intuition in the implementation of mammoth internal bracing when just a few braces bridging the centers of opposite sides would do the trick at a fraction of the weight and fuss and less loss of internal volume too.

HiFi aspirations since 1957. Currently working on motional feedback again... the final frontier in audio

Last edited by bentoronto; 29th October 2011 at 09:53 PM.
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Old 30th October 2011, 10:29 AM   #3
Zero D is offline Zero D  United Kingdom
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Originally Posted by bentoronto

I think you mean "Karlson" for a multi-resonant design!
Hi, no not really, but i see what you were thinking

Rather boxes with more than 2 tuned compartments, either behind and/or in front of the driver/s.

Using Elbert's example, his box is divided into 11 internal compartments, & each one is ported into the adjoining ones. I realise the modus operandi wasn't to port/tune in that way, but my thoughts were that it "seems" to amount to that ? In which case i'm wondering what overall effect it has, compared to an empty box with driver/s ?
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Old 30th October 2011, 05:27 PM   #4
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Default Bracing

I had been thinking the same....

Bracing should not impede airflow, unless it is intended to affect tuning... in which case it would be mor ethan just bracing, and presumably ports and their dimensions would enter calculations, as well as the many connected volumes.

Clearly this rather solid bracing will impede airflow.

If he made more or larger holes, much better airflow could be eachieved without reducing stiffness.

If the builder is happy with the result, good for him!
If the box was modelled as a simple single volume, I'd be surprised if the measured response and output, etc matched the predicted and actual stats for a cabinet without impeded airflow.

Another issue - the sheer amount of wood must have reduced the internal volume of this cabinet by over 10%, which must also affect the end results, unless the builder made the cabinet sufficiently large by included the lost volume in his calculations.

It would be very interesting to model such a complex cabinet, abnd the tunings could be quite special, I look forward to more information!

Regards, Ben
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Old 30th October 2011, 06:27 PM   #5
freddi is offline freddi  United States
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Raymond Rodden's patent shows what I think is a three chamber BP4 with two equal volumes in front of the sealed rear chamber and a "Karlson-slot" divider for the two front chambers. A hole or vent is placed on the outside of the outer chamber. Its not intuitive what that divider would do as I'd guess it to be ~transparent at low frequencies (?) I've built an 18" klam projector and watched the wings bend on drumbeats so it may provide some load.(?)

Speaker housing - Google Patents

my 18" toy klam has a regular front chamber and high tuning compared to a regular BP4
Click the image to open in full size.

Last edited by freddi; 30th October 2011 at 06:29 PM.
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Old 31st October 2011, 03:47 PM   #6
Zero D is offline Zero D  United Kingdom
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Originally Posted by salzburgsoundsystem

It would be very interesting to model such a complex cabinet, abnd the tunings could be quite special, I look forward to more information!
Me too, if Anyone could do that though ? Seems quite a task !

@ freddi

Thanks for the Patent link & info
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