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Multi-Way Conventional loudspeakers with crossovers

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Old 12th November 2012, 09:57 PM   #1
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Unhappy Desperately seeking help!!

Really hoping one of you geniuses can assist me :/. Basically, I have recently acquired a number of high quality (i think) speaker drivers and a few other components i have been saving up as i hope to build my own speakers for my DJ rig. I have :- 1X 'Richard allan HD15' 15'' 125watt RMS (no peak wattage stated), 2X 'Fane acoustics The crescendo' 10'' (No wattage or ohms stated), All three of these salvaged from a perfectly operational speaker originally used for an electric organ, also have the power amplifier/crossover circuit board and wires and such that were with it. Finally i have a 'JBL GT4-12 subwoofer' 12" 1000watt peak, 250watt RMS. I have a (at best) Basic understanding of sound, but am quite handy with DIY and electronics. Firstly i would like to know how to best assign the individual drivers to the frequencies they were designed for, I mean would i be right in thinking that the size of the driver is relative to the freqeuncy range it throws out (big for low ends, smaller for highs)? because thats what ive always assumed but after reading many forums one guy has kinda thrown me with that theory a little :/. Does anyone know how i would find out the optimal frequency ranges that each driver was originally designed for? So my plan is pretty much, Build the 15'' and the 12" into a single bass bin/subwoofer Over and under style (12 on top of the 15). Then Building two ''Top hat'' style PA monitors with the 10" crescendos, adding either one or two tweeters to each top hat. Not even got to thinking about amplifying or speaker enclosures just yet, would just like to know if i really am just opening a can of worms, extremely interested in learning more about sound engineering so figured this would be an interesting little project to embark upon, Any help that anyone can provide would be fantastic Thanks
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Old 12th November 2012, 10:15 PM   #2
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first step - find the manufacturer's parameters for these drivers (& post the links here),
then we can figure out what they're capable of...
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 12th November 2012, 11:18 PM   #3
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JBL GT4-12
Sensitivity: 93dB
Impedance: 4 Ohms
Vas: 100.45 liter
Qts: 0.43
Fs: 24.75Hz
Qes: 0.46
Qms: 6.46
Xmax 1 way: 12mm
Parameters for the R.A HD15 should be an attatchment, Ill find the others first thing tomorow, Thanks for helping out
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File Type: gif Richard allan parameters.gif (25.7 KB, 81 views)
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Old 12th November 2012, 11:59 PM   #4
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next step, download Unibox:
UniBox - Unified Box Model for Loudspeaker Design - Kristian Ougaard
and type in those parameters, the vented box alignment is proably the best place to start...
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 13th November 2012, 12:31 AM   #5
sreten is offline sreten  United Kingdom
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Hi,

Trying to meld a disparate bunch of drivers together is far harder than
well chosen drivers chosen to work with each other well and for purpose.

The RAs and Fanes are probably best used in 2 ways with a horn.
Obviously a bigger horn and cabinet for the bigger driver.

The JBL car subwoofer is exactly that : a car subwoofer.

rgds, sreten.
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Last edited by sreten; 13th November 2012 at 12:33 AM.
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Old 13th November 2012, 02:09 AM   #6
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Mind you it ( the JBL 12 inch ) might be one of the better car subwoofers; they do go quite low when put in a bigger box but using one of these on their own out in the open or a big room probably isn't the best use of the driver.
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Old 13th November 2012, 02:11 AM   #7
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Googlefoo provides some of the answers

http://www.fane-acoustics.com/downloads/CRES10M.pdf

so the Fane are a midrange driver and should be used as the PDF suggests, which means you need a pair of bass drivers and a pair of something to handle the high range.
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Last edited by Moondog55; 13th November 2012 at 02:16 AM. Reason: Add extra thoughts and waffle
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