Hi, fairly new to Hummers and this forum...just got my 2007 H3 about a month ago. I've already swapped out the changer head unit for an Alpine IXA-W407, and I've purchased a JL Audio Stealthbox (I do have the Monsoon system FWIW). Eventually the rest of the stock speakers will come out as well, but first I need to put in a new amp to run the Stealthbox, and I'd like to use a single 5-channel amp to run everything. So, where to put such a beast? I was thinking under the driver's seat...I don't want to put it in the back or anywhere too visible. The thing is....there's not a lot of room there, and with the seat in my usual driving position, it's going to be sticking out from under it in the back. I THINK that's probably OK. Any thoughts? Most of the decently-powerful 5-channel amps are 18-20" long which won't fit. However, Alpine's PDX-5 is only about 11" on the longest side, and about 2.5" high, which should just fit. I think. Any thoughts on this? Better ideas for an install location?

My second question is...I want to use the OnStar mic for Bluetooth...I don't care about OnStar, I am not going to subscribe, so I really just need to know which wires going into the OnStar unit are the mic wires. I haven't been able to find that anywhere...anyone know?

Thanks in advance...

jds

 

Can't help you with the OnStar mic question, however I was thinking the same thing so if I ever look into it I'll let you know.

For the amp, I would say just screw it down into the monsoon panel. I mean if you're already in the business of wanting to gut your OnStar system whats a few screw holes in the monsoon panel in the cargo area?

 

Well, I'm not positive since I haven't opened up the rear yet, but I was under the impression that the Stealth Box would take up the available space back there. I believe the Monsoon amp and sub are there now..is there really that much extra room back there?

 

I have an update on the OnStar mic issue. I did find some references to it on the net...the gray wire and bare wire (covered in black electrical tape) going to pins 9 and 10 of the smaller OnStar connector are the mic wires. However, it's an electric mic and needs a DC bias, provided in the OnStar box. I read that someone successfully spliced into these wires, leaving them attached to the Onstar, and it worked. So I tried it, but the results are...well, they're unusable. However I know I did some stuff wrong...for one thing the Alpine plug is actually a stereo plug, and the Radio Shack plugs I got were mono. Two lines from the mic, why do I need stereo, which should be three wires, right? So I'm showing some ignorance here. If the Alpine mic is a 2-wire device but uses a stereo plug, which of the three sections are the wires connected to?

Unfortunately I cut up my Alpine mic to use the plug, only to find these extremely thin "wires" that I really couldn't use. Oh well, I guess more experimentation is due. But, in case anyone else is looking at this, it does appear to be the gray and electical-taped wires that go to the mic.

 

I'm not sure how much room you'll have left to be honest, but I'd guess not alot. I would say wait and see, and if you don't have alot of room left mount it to the back of the rear driver side seat. Worse comes to worse you can throw a blanket or something over it when moving heavy things that will sit on the amps.

 

So is it safe to say that people hate the idea of squeezing it under the driver's seat?

 

I'm just not a fan of that, I don't like the idea of shoving something with the potential to overheat in a confined space.

 

That's a good point. Although, there should be some airflow through there, as it's open, but there won't be much room between the top of the amp and the bottom of the seat. Hmmm...anyone know if a PDX-5 gets hot? Some amps do, some don't.

 

Update on the OnStar mic thing. I disconnected the mic wires from the OnStar module, thinking that perhaps all the noise and feedback was the mic getting biased now by both the Alpine and the OnStar, and indeed it did help...no more noise, no more echo. However, the mic audio is extremely quiet now. Way too quiet. I wish there were a way to crank up the mic gain on the Alpine, but there isn't, as far as I know. I'm starting to think this mic is simply not a match. Ugh...looks like I'll be buying a new Alpine mic and pulling all the ceiling panels to route it to where the OnStar mic currently resides. Not really my idea of a fun time :-(

 

Well this post may be too little too late because you may have already ran everything but If you buy the external mic for the bluetooth why not just mount it with the bracket it comes with above the Rear view mirror? Normally they (well, the pioneer and sony mics) come with clips that can be clipped to the edge of the headliner and you can run the mic wire right inside the edge of the headliner along the wiondshield and down the A Pillar. Sometimes its helpful to put 1/4 inch loom around the wire so it stays tucked above the head liner. ...Just a thought.

About the amp: I wouldnt mount under the driver seat just because if it does stick out (or even if it doesn't) the RCAs and other wires could be kicked by passengers' feet. RCAs can break or power cables pulled out. I wouldnt worry so much about over heating as I would the wires getting kicked.
If you can mount it on the back of the rear seats go for that, you will just have holes in the plastic. Just be sure to use some big threaded screws (like drywall screws). The plastic is relatively soft and easy to strip out. Unfortunately there just arent many good places to put a big amp in the H3.
If you could, I would look into getting something like the Arc Audio Mini amps. They tiny and have plenty of power. They arent really cheap but they could fit under front seats quite easily.