Adding a Monsoon system to a 1992 UW4 Pontiac Grand Prix

[RPE1992GPSE]

I cut and pasted this write-up from another website. This is my own work. One day I had this idea...could I add an F-body Monsoon system to a 1992 W? Enjoy!

 

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I'm about two thirds of the way done with the Y-harness that I fabricated to connect the radio, existing body wiring, and amplifier. Most of the soldering and heat shrinking is complete. I fabricated an eight-pin in-line connector for the wires that I have to run to the dash speakers and the woofers on the rear shelf. I'll take some pictures this weekend.

 

 

In a nutshell and without any sort of diagram, this is what I'm doing:

The original six-speaker system has two 4x6 speakers in the dash, two 4x6 speakers in the doors, and two 6x9 speakers on the rear shelf. The door speakers are "amplified" by the factory unit, a black metal box about 5" by 4.75". The factory amplifier is labeled as a "low frequency amplifier" but it's not very powerful at all and it's difficult for me to determine what sort of bandpass it creates (the door speakers sound like midranges to me).

 

 

First, the Monsoon retrofit will use the original wiring to the dash speakers. These wires will be "reassigned" from the dash speakers (these have already been replaced with Pioneer 4x6 two-way models) to Delco 6 ohm front tweeters removed from 1999+ Pontiac Grand Am doors. I am going to drill holes in the A-pillars and mount the tweeters therein using 3M molding tape. I also will solder in high-pass crossovers (capacitors) to attenuate damaging low frequencies. The tweeters will be powered directly by the head unit, just like in the Firebird systems.

 

 

Second, I will run new wires from the Monsoon amplifier to the dash speakers. I will transplant the OEM connectors from the reassigned tweeter wires to these new wires to connect them to the speakers. The dash speakers will now be powered by the door midrange channels.

 

 

Third, the Monsoon retrofit will use the existing wiring to the door speakers. The factory amplifier will (obviously) be disconnected. The door speaker wires will be cut at the original connector and spliced into two of the four subwoofer output channels from the Monsoon amplifier. The door speakers will be replaced with Pioneer two-way 4x6 speakers, chosen for their favorable bass response.

 

 

Fourth, the rear speakers will be replaced with Sony Xplod four-way 6x9 units. Due to their construction, I was able to desolder the tweeter wires from the connector tabs and re-solder them to independent wires. I then soldered two wires to the now-separated woofer wires and pinned all four wires into an OEM four-pin connector, creating a four-wire "bi-amped" speaker for the rear shelf. The existing rear speaker wiring will be connected to the tweeter assemblies in the speakers, effectively creating rear tweeters powered directly by the head unit, again, just as in the Firebirds. (The tweeter assemblies already have the appropriate crossovers in place.)

 

 

Finally, I will run new wires from the Monsoon amplifier to the rear shelf speakers that will provide power from the second set of subwoofer channels to the woofer coils of the 6x9 speakers. These wires will terminate at the four-pin connectors at the speakers.

 

 

Note that I did not mention the rear midrange channels. This is because I am not using them. Grand Prixs only have six speakers at most and since I am separating the subwoofer channels, the rear midrange channels simply did not fit into my plans.

 

 

Truth be told, I still have no idea how this will sound when I'm done. It certainly can't sound any worse than the original setup. This is one of those things that you just don't know how it will sound until you try it.

 

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The stock six-speaker system sounded pretty good for what it was and how old it was. The Monsoon retrofit, however, was a MASSIVE improvement.

Edited December 27, 2012 by 1992GrandPrixSE