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Replacing Jamo System

Yahoo Message Number: 78718
My Jamo sub-amp has failed and I am not going to have it repaired. Rather I am going to replace the main Jamo unit and the MPA-101 sub-amp with a single, more up to date sound system. I do want to keep the sub speaker in the cabinet over the galley sink since it is already installed and was working fine before the amp crashed. The question is how to wire that speaker.
There is a single RCA cable from the sub-out on the Jamo amplifier, which goes into a splitter before connecting to the Jamo MPA-101 sub-amp (2 inputs). Then there are four 12 gauge wires from the sub-amp to the speakers. ????
How do I wire a single sub-woofer RCA output from a new amplifier to a four wire input at the sub-speaker?

Stuart

2005 Allure #31217

Re: Replacing Jamo System

Reply #1 –
Yahoo Message Number: 78739
Stuart

I can't describe how it was done; but, Bob Vincent at OMC installed a Sumsung 5.1 Amplifier which powers the four ceiling speakers and the woofer.
I do know that they had to splice the wires because the Samsung comes with speakers which have proprietary ends that plug into the Amp. The sound guy that works with Shaun at Davis Cabinets described a similar solution to me.

Dan 2006 Allure 31348

Re: Replacing Jamo System

Reply #2 –
Yahoo Message Number: 78740
Stuart - Sub-woofers usually have a split voice coil to handle a stereo signal (left and right channels). Two wires per voice coil make 4 wires total. It's important to phase the voice coils properly. This can be done with a single flash light battery (1.5 volts). You will also need to see the radiator (cone) of the sub-woofer. Connect the battery across each voice coil and observe the cone moving slightly inward or outward. Mark the wires +/- so the same polarity moves the cone in the same direction. Take the polarity from the battery. You connect the voice coils to your amp's output. Just make sure to be consistent with the connections. +/- doesn't matter as long as they are connected the same way on both channels. You'll now have a properly phased sub-woofer. You can parallel the voice coils to a single output if they are properly phased as described. If each voice coil is 4 ohms then a parallel connection would be 2 ohms. Make sure your amp can drive into this impedance. In a pinch you could just connect a single voice coil and let the other one float. Not proper but workable.
In some systems the left and right channels (RCA jacks) are mixed (on the input side of the sub-woofer amp) since separation in the sub-woofer isn't acoustically significant. This might be through a Y connection, single output jack or switch on the sub-woofer amp. You'll want to power both channels if you are using a stereo sub-woofer amp. You can create two feeds for your sub-woofer amp with a Y from a single RCA jack. You can create a single feed from 2 the same way. Dayton Audio makes an exact replacement for the MPA-101 at half the price. Good luck getting it all hooked up. Hope this helps.

At 08:23 AM 4/22/2012, you wrote:

Re: Replacing Jamo System

Reply #3 –
Yahoo Message Number: 78750
I learn something everyday.

As you suggested, I looked at the Dayton Audio (APA-150)and found one online for $128 including freight. I may take the easy way out for that small price and just replace the MPA-101 instead of the headache of replacing the whole system. Thanks for the heads up and the great explanation Scott.

Stuart, 2005 Allure, #31217

Re: Replacing Jamo System

Reply #4 –
Yahoo Message Number: 78757
Stuart - Glad to help out. Sharing knowledge is a great thing in our complex world where no one person can know it all. A network of brains is good. Dayton Audio's unit is an exact replacement. I did check my sub-woofer setup during the replacement and found out the factory made a mistake on the voice coil wiring. Heads up to you on that point. I used the flash light battery test to remedy the situation. Good luck and enjoy great sound. There's nothing like ghetto bass!

At 07:29 AM 4/23/2012, you wrote:
 

Re: Replacing Jamo System

Reply #5 –
Yahoo Message Number: 78770
I will remember to check the coil wiring Scott. I have the schematic CC published for reference. Thanks.

Stuart, 2005 Allure, #31217