[ctrlz]

Based on some tips here, I went ahead and swapped one of the rear side speakers for a 2 ohm (advertised) coaxial JBL I had leftover from my last car.
The short of it:
The Bose speaker went back in because it was louder by about 6-8 dB (I measured that) and had fuller sound (my opinion).

Hardest part of getting the side panel off was removing the lower seat cushion. I tried multiple ideas mentioned here and elsewhere. I really did not want to shatter the plastic inserts which lock the seat down. I ended up using a 2' pry bar and coming in at about a 45 deg angle through the open door. Push the bar until it contacts the U-shaped metal loop. Then you can pry it and it will pop. It is very hard to get a grip or leverage against this fastener, but this worked for me.

With the Bose speaker out I noted it to have a voice coil resistance of 3.6 ohms, which kind of surprised me as I thought it would be closer to 2. I checked with two DVM's. Bose uses a paper diaphragm with a plastic center dome (kind of like a tweeter area I guess). The effective diameter is 4".

My JBL speaker has a VCR of 2.7 ohms. There is a 1" dome tweeter on a pillar with a slide switch for 0 or +3 dB. The woofer area is plastic with an effective diameter of 4.5". Based on these specs I had expectations of louder sound and boosted high end in particular. I set the slider switch to the +3 position for my A/B test.

So, with a stock Bose on the left and JBL on the right I put on some mono audio (Beatles Hard Day's Night in mono). Pretty obvious from the get go that the Bose was louder and had fuller sound. The tweeter on the JBL was crisp, but the mids were lacking and the effect was scratchy. It probably was hitting a bit higher than the Bose, but it didn't sound good, so I did not try to measure the spectrum. I fired up the SPL meter and noted the Bose was 6-8 dB louder than the JBL. Went back and forth with the balance and kept the meter in one place and it was consistently reproducible.

The Bose went back in and the JBL went back in the basement. I think the JBL would be the better speaker with proper amplification. The Bose is probably getting better efficiency from the lightweight paper cone and probably a less rigid surround. In my last car I was able to throw some power at the JBL and it sounded great. In the role of "rear fill" in the Camaro, the Bose sounded better to me. I was hoping for a 3 dB boost with the JBL, not a 6 dB cut.

I know my car would sound better with DSP, amplifiers, and aftermarket speakers all around. But that was not the point of this experiment.

And I did check to make sure both 6x9's on the back deck were working. Those speakers are really underutilized/underpowered in that position, but they were working fine.

[Camarentino]

I feel you. I just changed out all my speakers and was a little disappointed to be honest. Better clarity and highs but gave bass as a result. There is no quick fix for sound system on these cars without big $$$

[ctrlz]

Originally Posted by Camarentino

I feel you. I just changed out all my speakers and was a little disappointed to be honest. Better clarity and highs but gave bass as a result. There is no quick fix for sound system on these cars without big $$$

Hey, it was an experiment, and it just seemed like a step backwards to me. Yes, i think the nice tweeter in the JBL's gave crisper highs, but the mids were way gone and I did not like the effect.
I just wanted to post my impressions here, because on paper this looked like a solid idea.
Thank you for the positive support, Camarentino.

Now, where are all the naysayers with comments like, "You should have wrapped your ears in aluminum foil for a proper test!"?

[Petrol Head]

Modern car stereos are pretty much engineered as one complete system. Swapping out speakers piece meal isn’t going to give you much of any reference point, good or bad. If you don’t like the Bose system you kind of have to go from the amp forward and replace everything, all speakers, new amps, a processor that eliminates bass roll off as you turn up the volume, and full range audio to the rear deck 6x9s. It’s expensive and you need to tear half the car apart to do it right.

Upgrading Factory systems sucks these days. I did a lot of car audio in the late 90s-early 2000s. Things aren’t even close to the same.

[SomeGeoffGuy]

Did you know what the sensitivity rating of the JBL speaker is? That will tell you a lot about how it handles power relative to volume. The problem is that the sensitivity of the Bose speaker is probably not listed in the service manual, so it will be really hard to make a comparison.But you might need 99 or 100 dB to match the Bose

-Geoff

[ctrlz]

Geoff, I know the advertised sensitivity for the JBL's, 92 dB at 1 W 1 m. The problem is that rating is always BS. They never tell you at what frequency they are measuring that SPL. So it might be 92 dB at 8000 Hz and 82 at 800 Hz for a coaxial speaker.

[SomeGeoffGuy]

Originally Posted by ctrlz

Geoff, I know the advertised sensitivity for the JBL's, 92 dB at 1 W 1 m. The problem is that rating is always BS. They never tell you at what frequency they are measuring that SPL. So it might be 92 dB at 8000 Hz and 82 at 800 Hz for a coaxial speaker.

I know it doesn't mean a lot, but it should get you in the ball park at least. I just looked to see if Klipsch makes car speakers (they don't). But they make home speakers in the 100 dB range and it is a legit rating - it takes hardly any wattage at all to get them LOUD on my home system. I am not sure of any other manufacturers who make stuff in that range, though.

If you were 6-8 dB short and the JBL's are at 92, then you would need around 99dB to get a match. not sure if anyone is making that or not.

-Geoff