MJK - A Method for Designing a Compact Back Loaded Horn Loudspeaker System - diyAudio
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Old 29th September 2012, 06:21 PM   #1
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Default MJK - A Method for Designing a Compact Back Loaded Horn Loudspeaker System

Has anyone read the MJK article "A Method for Designing a Compact Back Loaded Horn Loudspeaker System (added 06/21/12)" ?
What about any builds or comments?
Other drivers that can be used?

The only reference on DIYaudio is this one: Smaller Fostex Backloaded Horns
Also: why is the MJK account "Account disabled at member's request" ?
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Old 29th September 2012, 06:30 PM   #2
mp9 is offline mp9  United States
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I read it, somewhat different approach then other designs i'm familiar with. Although the requisite corner loading does limit it's use room/placement wise, was wondering if a version for 6.5" drivers would work well with the new Mark Audio 12P driver?
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Old 29th September 2012, 08:09 PM   #3
chrisb is offline chrisb  Canada
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Quote:
Originally Posted by mp9 View Post
I read it, somewhat different approach then other designs i'm familiar with. Although the requisite corner loading does limit it's use room/placement wise, was wondering if a version for 6.5" drivers would work well with the new Mark Audio 12P driver?

probably - someone just needs to do the math - it's probably a whole lot easier to build a successful BLH than to design one (or more)
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Old 29th September 2012, 09:33 PM   #4
tsiros is offline tsiros  Greece
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I don't get the idea behind the whole thing

Is the basis of it the fact that in a normal cabinet you "get rid" of the back-propagating waves by absorbing them inside the cabinet (thus losing pretty much half the acoustic energy that the speaker driver produces) but in a BLH you design the cabinet not to get rid of the back-wave but instead take advantage of it so, in the end, you get something for nothing? ("nothing" in this case being "spend quite some time designing it" ) ?

Um

how big would a decent BLH be for a pair of 12" AN CFs ?
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Old 29th September 2012, 09:58 PM   #5
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You don't get anything for nothing in this life. All chambered back-horns are essentially more or less extreme variations on the bass reflex theme, and like all back loads, are only useful over a relatively narrow BW.

The short version is that Martin's added an internal Helmholtz resonator to his back-horn, tuned to the design / target Fh to increase the acoustic low-pass slope.

Last edited by Scottmoose; 29th September 2012 at 10:06 PM.
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Old 30th September 2012, 05:58 AM   #6
RK1 is offline RK1
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in my opinion, you will first need to:
- determine the lower frequency of operation - it determines the diameter of the outlet (it is important from the point of view of size),
- then selects the transducer,
- later determines the length of the line, and other parameters.
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Old 30th September 2012, 07:59 AM   #7
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I don't think that has much to do with the OP's question. However. Some general points:

-The first thing one normally does is to determine the requirements, budget and size constraints

-Evaluate a range of drive units that meet, or will meet, the above. Select preferred unit from shortlist

-The horn terminus size determines the lowest frequency it is impedance matched to, once boundary conditions are accounted for. Axial length and taper determines the 1/4 wave cutoff frequency. These do not necessarily have to be one and the same. Standard horn profile equations become progressively less useful the more the horn expansion is compromised / reduced.

Last edited by Scottmoose; 30th September 2012 at 08:06 AM.
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Old 30th September 2012, 08:47 AM   #8
RK1 is offline RK1
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Everything is correct (almost)
Scottmoose - Can you show me some of your designs Back Loaded Horn ?
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Old 30th September 2012, 09:09 AM   #9
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What have I said that is incorrect?

Surely. I don't want this thread to go any further off topic though since it's about Martin's box, not mine, nor is it a thread about horn design in general. However, if you want a handful of my designs, look up Frugel Horn 3 (done with DaveD & ChrisB), all of the Spawn designs (past & current) on the Frugal-horn.com site, the Madisound BK12m etc.

Last edited by Scottmoose; 30th September 2012 at 09:21 AM.
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Old 30th September 2012, 09:37 AM   #10
RK1 is offline RK1
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Very interesting.
Could you tell me something about this design.
Maybe not here (PW ?), so as not to disturb others.
Have a nice day
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