Hey everyone. I have the 2004 Bonneville GXP with an 8 speaker Monsoon stereo system. I believe my Monsoon amp is blown because now I only get sound (minimal and no midbass) from 4 of 8 speakers, my tweeters in the front doors and the rear 5-14" door panel speakers with the volume cranked all the way up. There is absolutely no sound coming from the front 6-1/2s or the rear 6x9s in the rear deck. I tested the front 6-1/2s and rear deck 6x9 speakers using an outside audio source and they are not blown so I am sure it is the Monsoon amp.

So after doing a lot of research I have made the decision to completely scrap the Monsoon system and upgrade to a complete MA Audio system (minus the HU). So far I have an MA Audio HK602C component system for the 6-1/2" front speakers and the front door panel tweeters, an MA Audio HK502C component set which I'll use just the 5-1/4" woofers for the rear door panels and keep the tweeters from that set as spares, an MA Audio HK6902 pair of 6x9" 3-way speakers for the rear deck, an MA Audio MA412BX 1000 watt dual 12" sub enclosure, and an MA Audio 1000 watt mono block amplifier. The subs will be wired in parallel at 2 ohms and hooked to the mono amp for maximum output power.

This is where its complicated to me. So now I just need a head unit and an additional 4 channel amp i believe. I have OnStar and Steering wheel controls. Therefore, I would need the Metra Axxess GMOS-09 OnStar Amplified GM with "Dock-n-Lock" Harness to replace the HU and retain these features including door chimes and RAP (radio turns off after opening driver side door and ignition is off). Is this correct and has anyone had success?

Then do I run my tweeters and rear panel speakers from the head unit then run the head units front and rear preamp outputs to a 4 channel amp to push the front 6-1/2s and rear deck'* 6x9s? Then I could use the 4 channel amp RCA outs to daisy chain to the mono amp for my subs? I'll probably need an additional battery but it would be well worth it.

So is what I am doing basically bypassing the Monsoon amp therefore I could just unplug it? That thing is so confusing because it seems to control so many things in the car.

Please help me out if you have experience upgrading Monsoon systems in Bonnevilles.

Thank you.

Well I scrapped the Monsoon system in my 02. I also scrapped the OnStar and door chimes. I have no need for any of that crap.

I replaced the HU and all the speakers with Kenwood equipment, and amped it all with a 4-channel Kenwood.

To do this my sound guy ran all new wiring from the HU location to the Monsoon amp location. He then clipped wires and spliced in the new wires, bypassing the need for the amp. The new HU and speakers all functioned properly this way. Then he just wired in the amp.

If I was in the states I'd take pictures of everything so you could see how he did it.

What part of Illinois are you in?

While MA Audio is decent stuff, there'* better stuff out there and there is absolutely no reason to stick with only one brand on a variety of components.

I would not run anything off the head unit; I would run them all off of independent amps. You may need more than one amp to make it sound good given the number of speakers you have. I'm going to guess a 4 channel for rear deck and rear door, a 2 channel for the front components, and a mono for the sub. You could get away with a 5 channel amp instead of the 4 channel to reduce the number of amps, but a good set of components needs a good amp.

I would be willing to meet up with you so you could hear what my Regal'* sound system sounds like and see how I got everything running so you could get an idea of what a very good SQ system sounds like if you haven't been in the car audio arena for very long.

As for the monsoon amp, your best bet will be to scrap EVERYTHING. That includes wiring, head unit, monsoon amp, everything, and start from scratch. This is what I'm going to need to do with the monsoon system in the 2000 Regal I just bought.

He doesn't need multiple amps for the interior speakers. They can all run just fine off of one good 4-channel amp. The only reason to do such a thing is for SQL comps.

Hell, my setup off one 4-channel sounds freaking amazing. Two amps is all you need. One for the interior speakers, and one for the sub/*. Anything more than that is just overkill

The reason I am using MA Audio is because they are free. I know the President of MA Audio. I also work for an online consumer electronics store, I just don't know anything about monsoon systems at all. I blew the amp and starting looking at everything and was amazed it'* like they made them way too complicated.

I could run all 8 speakers off of one 4 channel which would put each channel at a 2 ohm rating. Knowing the industry and exaggerated wattage ratings, even on the best brand names, honestly I could probably get a 4 channel which was 100W RMS x 4CH and be just fine like Mouse said and then daisy chain to the mono amp. I'll bypass the amp by using quick connects (a no no lol) so i can retain the factory harnesses.

i have a 2005 GXP also with Monsoon
You lost me when you said you wanna scrap the Monsoon amp, then why do you need GMOS-09? just for OnStar? do you actually use it?

I would really hate to see you go through the hassle of doing something that was never done before, i couldnt find anyone with an aftermarket HU, Monsoon & GXP when i did mine, took me over a month to get it working...

are you sure your amp is not working? also if you're sure about that, wouldnt be easier to buy a used amp online? im sure you can find one from Morad off ebay, i think this would be a much easier way

i cant help you with bypassing the amp, because i never did it before

if you end up keeping the monsoon (which what i recommend), the stock speakers/monsoon amp would sound totally different, when i installed my first HU JVC KW-NT1 i was really shocked with how good it sounded, i couldnt believe this was coming out of them same speakers and amp

the GMOS-09 will work for a monsoon system, but theres a wiring problem from Metra, its an easy fix, just one wire must be cut (other than the brown loop), the GMOS-09 will keep your stock chimes, warnings, and onstar coming out of the driverside speaker, just like factory

you will also need a PAC harness to get your steering wheel controls to work, harness number will depending on which aftermarket HU you're buying.
you will also need an antenna adapter, VW style
last thing is you have to trim thr dash cavity behind the deck, it was easy, just take your time
i have tons of pics, threads & info about a GXP aftermarket install, feel free to ask me anything

at the end my point is, the Monsoon system sounds like *** when connected to the stock deck, you will notice a major change in sound/bass when you install an aftermarket unit on stock speakers/amp, not saying aftermarket speakers are not good, but just ask yourself if you need it first

If you can get a powerful enough 4 channel amp, then yeah you can make it happen. I usually run front components that need quite a bit of power and prefer as little distortion as possible. Overpowering them generally does the trick. I'm feeding my Polk DB5250 components with 170W RMS each.

Free is good, lol, and your 4 channel idea is excellent.

What are you thinking as far as sub(*) go?

I don't know the math behind my setup, but I know I can turn my stuff louder than I can bear and there is no distortion. Britt and Brian both have heard my setup, and can vouch for me.