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Kick Bin Design Idea B&C 15ndl76

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luthier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 09 January 2019 at 11:57pm
Been playing around with the design a bit more. This is the best I've got so far, any suggestions on how to either make the design more compact or increase the low end down to 100hz (ideally 80hz) would be fantastic!





Also, I'm having issues with excursion below 105hz, I've also been playing around with porting but simming a flat response I only get down to 95hz flat and have excursion issues at 105hz again. Also with the port I lose about 1db overall sensitivity.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote corell Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2019 at 9:24am
12,5 l backchamber and 1,1 l frontchamber is very small for a 15", nearly impossible imo. Also i see its not a bandpass horn design anymore. Could you post a rough sketch of how you would fold the new idea?
On another note: a linear ("conical") expansion  in one plane and two parallel sides in the other plane (as nearly every wooden box) is simulated as parabolic ("par") in hornresp.


Edited by corell - 10 January 2019 at 9:25am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2019 at 1:40pm
Thanks for the advice Corell, I'm still planing on making it a BPH as a FLH would be to large for my requirements. I'm still learning hornresp and really trying to translate my theoretical knowledge into the software. It's not exactly the most user friendly software I've used.
need to reach 400hz not 300hz. I've been able to do this with a relatively short horn but I'm loosing all my low end between 100hz and 140hz. I've tried adding a port to compensate but I can't seem to control the xmax and loose significant sensitivity. 

If I make my S1 smaller I get a better result but anything under 300 seems to get hornresp angry. I imagine it's down to the compression ratio. I wonder If anyone uses a phase plug to correct this in a bph or just a very small throat.




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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2019 at 1:42pm
On another side note I've checked and with a 102db sensitivity for my B&C15ndl76 500w I should match perfectly to the Sonitus mr8xt with it 105db senitivity and 150w rms. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2019 at 4:16pm
Let's start with simulating a single segment horn and incorporate directivity, without that you're only seeing half the story really.

What makes you say you've got an excursion problem, because I'm pretty sure that you shouldn't have one.

Best regards Johan
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Post Options Post Options   Thanks (1) Thanks(1)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2019 at 4:24pm
As a note, to get up that high (and more) F1 use a phase plug in the low section of theirs boxes. A bloody big one on some of the Res.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 12 January 2019 at 7:10pm
Originally posted by mobiele eenheid mobiele eenheid wrote:

Let's start with simulating a single segment horn and incorporate directivity, without that you're only seeing half the story really.

What makes you say you've got an excursion problem, because I'm pretty sure that you shouldn't have one.

Best regards Johan

Here's a look at the directivity, I was a bit shocked about the spl increase between 200hz and 400hz, but I couldn't see any lobes in the directivity pattern.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 12 January 2019 at 7:26pm
Currently trying to decide if I should go back to my original plan of a target response of 102db -3db between 100hz - 300hz. Im thinking I could potentially eq between 300 - 400hz on the mr8xt.

Here's the sim of the MR8xt:


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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 12 January 2019 at 9:31pm
So I've now increased the horn length pretty much doubling it, but it is starting to produce the results I wanted to see. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2019 at 11:32pm
So I have spent a bit of time on Solidworks drawing up the B&C 15ndl76, it still needs a bit of work, primarily on the cone, but it's close. The purpose of this was to determine the displacement of the driver in the chamber before the first horn section. 

Here's a few pictures of the process.





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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2019 at 1:49am
Starting to try and model the horn now, already feeling my 720mm horn path is too long! 

Could anyone shed some light on the S1 section? I'm planing on getting the 125mm segment length chasing down the back of the cabinet as I really don't want to make it any deeper! 





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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2019 at 1:50am
I'm aware my chamber volumes are far too large at this point! 
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