Replacing Speakers w/ Bose... Keeping Stock H/U and Amp? GMT-360


Original poster
Jul 7, 2012
Still a newb at the GMT-360... but not new to GM, or cars in general. Disclaimer: I also am not very good when it comes to electrical bits.

Background: I upgraded the stereo system in my 1998 Grand Prix by simply replacing the speakers. I went with the lower end Alpine speakers in the 5.25" door spots, same in the 6x9 rears, and in the rear deack 4" spot, some Pioneers that an F-Body guy recommended. It works amazing with the stock amp. I looked for speakers with low level RMS response (like 2-45 rangeish kind of stuff) to work with the stock H/U and amp. The results were awesome. Night and day. Most people think I have an amp and subs in that car. It has good highs and mid range punch. Of course without subs, it is not particularly good for recreating the takeoff rumble of the space shuttle, but it hits hard. IIRC, factory spec was 8 ohm and I went with 4 ohm speakers. It is definitely louder than stock as well.

I was hoping to do the same the 9-7x.... but the more I read, the more I am confused. I really don't want to get into doing an amp and subs with this thing, as I do use the cargo area frequently for transporting crap work. Right now, I almost always have the volume in the 1/4 top of the range, especially with FM/XM. Even in the Saab, it sounds quiet below 75% volume or so. In the Grand Prix... GM designed it so that certain speakers only received bass - IIRC the 6x9's in the rear deck. Did they do anything like that with the rear door speakers in the GMT-360?

I tried a google search to find the impedance of the speakers with Bose, but saw several different answers. What are they really? Front and rear?

Also, I have now seen a few people say not to bother with the speakers on Bose unless upgrading the entire sound system. Can someone explain why? - remember I am not an audiophile or stereo guy. Can I just get some low-mid level speakers like I did with my Pontiac and see some improvement?

Normally I just do go-fast mods, but as I spend more and more time in a vehicle I end up wanting to upgrade the audio. I do have a JL 6 channel 450 watt amp sitting around doing nothing, as well as some 5.25" Alpine components. But like I said... I'd prefer not to get into that on this truck, because I do use it for work, and don't want to limit my cargo capacity at all.

Newb out.


Nov 18, 2011
GS_Geoff said:
Also, I have now seen a few people say not to bother with the speakers on Bose unless upgrading the entire sound system. Can someone explain why? - remember I am not an audiophile or stereo guy.


Photo courtesy of Black LT

Those are the speakers in the bose systems. The little guy is in the dash, the middle guy is in the back doors, and the big jupiter looking thing is in the front doors. Each of these speakers were designed to play a specific frequency range. Because of this, the audio signals that each receives are not full range signals. The signals are filtered so that the little guys don't play low end bass, and jupiter doesn't play highs. The bose radio sends a full range signal to the bose amp, and the amp filters the signal.

The main issue with speaker replacement only is that the bose amp has non-adjustable crossover points. That makes it next to impossible to get a full range signal to the doors. The bottom line is, if jupiter was replaced with a coaxial, the coaxial would only play the frequency range of jupiter, so the coaxials tweeter would be more or less a decoration. The rear door speaker gets a midrange signal, so it doesn't play lower end or higher end frequencies. If a coaxial was used there, it wouldn't sound its best either.

Let's say that you decided to replace the bose amp to get around that. You'd have to get an interface to convert the high level, full range outputs from the bose radio to low level rca outputs. There are interfaces for both versions of bose for around $120. I've read some complaints that when using them, the amp gain had to be cranked up for "better" volume and that inducted noise which could be heard through the tweeters.

To get around that, you'd have to get a head unit. And if you want to keep chimes/retained acc power, you'd need an interface. If you did this, you would not need the interface mentioned above.

On top of all that, getting aftermarket speakers to fit in the bose door speaker mounting pods isn't fun.

I've seen a few posts where the bose front doors and dash speakers were replaced with components, and the bose amp was kept. The woofer got the signal that jupiter did, and the tweeter got the same signal that the dash speaker did. I haven't heard one in person so I can't vouch for how good they sounded in real life.

Also I never read the Saab shop manual. All of this is based on the TB/EV bose systems.

Black LT

Dec 4, 2011
It's been a while since I had mine apart. I had to make an adapter to make a 6.5 fit. I can check what size the stock ones were, but I seem to remember thinking if I was to just do the speakers - I think someone makes an 8" woofer - might be easier than 6.5.

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