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JBL GTO75.4 amp and 2-12" subs issue

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Old 04-14-2008, 12:19 AM
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Smile JBL GTO75.4 amp and 2-12" subs issue

Hey,
i have just installed my new MTX 4500 dual 2 ohm subs on the JBL 75.4 amp. My issue, is once i turn it up, the amp protects (cuts out), or it turns the light from blue to red, then back to blue. it then turns back on. I am wondering if these subs have to much draw? Would a stiffening capacitor help? I just had in 2-10" subs, and this was not a issue. The load is 2 ohm to the amp now. Any ideas?
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Old 04-14-2008, 12:44 AM
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how are you wired up? like the vc's to the amp? which configuration cause thats a 4ch amp right? one sub fr two ch? and how are the vc's wired to each other?
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Old 04-14-2008, 10:51 AM
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my front channels (1&2) are powering a pair of 5 1/4's, ands the rear (3&4) are powering the subs. the load is 2 ohm. The subs are dual 2 ohm, into series ( 4 ohm off each speaker), then parallel to the amp to be 2 ohm.
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Old 04-14-2008, 10:20 PM
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That amp will not likely do 2 ohm mono.. Thats the problem..
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Old 04-15-2008, 01:09 AM
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i would have to agree... generally when bridging two channels, especially on 4ch amps you limited to 4ohm. ill check out the amp and see for sure..
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Old 05-02-2008, 01:08 AM
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I have that amp, and it is NOT rated to do 2 ohm mono. Stereo only.

The only way you can wire up the subs, is to put the coils on each sub in series, and connect them to the amp in series, but that will give you a final load of 8 ohms.

Of course that will cut the power to them from about 200W (at 4 ohms) in half to 100W, BUT the upside, is that it will actually work.
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Old 05-03-2008, 06:00 PM
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amp will shut down around 3ohms its not made for it.Wire them to 4ohms one sub per ch

Last edited by DDnut; 05-03-2008 at 06:06 PM.
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