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Multi-Way Conventional loudspeakers with crossovers

Cross over help for a newbe
Cross over help for a newbe
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Old 25th October 2010, 08:22 AM   #1
KiwiDon is offline KiwiDon  New Zealand
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Join Date: Sep 2009
Default Cross over help for a newbe

Hi All,
I have just found some Jbl MR25 speakers,one with a missing woofer.I had some Skytronic 130mm woofers sitting around.After fitting them found the not very loud and no bass.Me thinks with the Jbl woofers being 4.6 ohms and the new speakers 8 ohms ,something is out of balance.Can anyone give some help designing a new crossover? Thanks Don

New woofers
Surplustronics - Wide Range Kevlar 5.25" 100W RMS
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Old 25th October 2010, 03:41 PM   #2
DougL is offline DougL  United States
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Join Date: Feb 2004
Location: Wheaton IL.
In general, successful driver replacement requires a careful match of Fs, Qts, Re and efficiency. Anything else is a complete redesign, with a measuring mike, simulation software and all new crossover components.

I have 4 successful speakers designs and I would not attempt what you are doing.


Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well)
Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus
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Old 26th October 2010, 07:48 AM   #3
KiwiDon is offline KiwiDon  New Zealand
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D'oh!-Thanks anyway.
I wasnt looking something that flash. just a little more bass than what im getting.thanks Don
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Old 28th October 2010, 07:36 PM   #4
Inductor is offline Inductor  Portugal
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Location: Cascais
Hey, Kiwi.
You can not compare the two mid/woofers (different SPL/different impedance/different specs), with out any more data/specs available (no specs).
Now, what you have is impedance of Re=7Ω on the new woofer (902402).
The JBL (76431) is Re=4,6Ω. There is an impedance mismatch that will bring your low frequencies down for a couple of dB's (1). Plus, your JBL speaker is 87 dB SPL... and your new woofer (902402) is 84,8 dB SPL (2). All together, less output from n1 plus less output from n2. You are engineering a nightmare. Good luck here
Madalena Iglsias "Ocaso" (1970)
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