73Corvette

I replaced door speakers and rear speakers with Kicker plug and play replacements... add the Peripheral PXDP PXHGM4 Chevrolet Corvette 97-04 iPod Adapter, the 30 Pin Bluetooth Reciever and did a LOT of sound deadening... The system is now quite capable for most of our listening in our 04 vert... is it KILLER...no. Does it sound fair...yes it does... I have three other vehicles with KILLER stereos and I can still live with the OEM HU with the above listed upgrades. Just Sayin

GCG

Definitely there's something wrong. The headunit swap should have been a satisfaying upgrade in itself, without having to touch the OEM speakers, as it has been noted above.

In addition to that, replacing the twiddlers with quality speakers should have taken this up to another level of performance, and not remain inferior, as a whole, when compared to the OEM system.

As mentioned above, your new headunit should have plenty of adjustments and more than enough EQ settings and controls, but I would try to begin with an interface between the new headunit and the OEM system as clean as possible to minimize corrections. To that effect, I would restore to factory default any audio settings changed in the headunit and tweak the adapter interface first.

You said that "highs were missing and bass was flat". The PAC ROEM-VET1 has built-in adjustment potentiometers to get the highs just right. I would suggest to begin there.

Regarding bass, here are a couple of suggestions:
1) Make sure the OEM C4 plug is connected to the PAC ROEM-VET1 harness, otherwise you'll have no real bass.
2) Also, make sure your BLUE WHITE from radio is connected to BLUE on the PAC ROEM-VET1. If your installer wired "blue white" to "blue white" instead, your door subs will not turn on and then no real bass neither.

If this takes you to where you want to be, within reason of course, then it's time to go ahead and play with the headunit's adjustments if you feel like it

GCG

The C5 OEM speakers do not include real tweeters. Bose calls "twiddlers" their plain-cone speakers that act as "tweeter/mid range"

CorvetteBob52

That's why I swapped out all the speakers for real tweeter/woofer combo's by Rockford Fosgate's plus they can handle up to 100 watts each.

axman

The adjustments don't ADD anything. They just filter out parts of the signal to whatever speakers are attached to them. When they are properly adjusted, you shouldn't know they are there.

Check the Amazon reviews:
https://www.amazon.com/PAC-ROEM-VET1...=1&*entries*=0

"Factory Bose EQ cannot be retained, optional tweeters are needed to maintain high frequencies"

"Installed the unit and my front Factory Bose speakers had NO highs!
I did get it figured out and you do have to adjust the potentiometers for the front speakers - these units are NOT plug and play! The settings from the factory are too high (booming) and do not allow the tweeters to operate on the front speakers."

Once you upgrade your head unit, your limitation on sound quality becomes the stock speakers. If you get a new head unit, you need the ROEM if you want to use your existing amps.

In the C4, the Bose setup seemed amazing. Unfortunately, in my C5, the Bose seemed to sound muffled. I didn't want to upgrade the Bose speakers either, but the Kicker upgrade was easy, relatively cheap, and I am very very happy with the Pioneer / Kicker combo.

I actually upgraded the speakers BEFORE the head unit since they were easier. It made a huge difference, and it would have been fine as-is. Later, I upgraded the head unit to get digital audio and a backup camera.

ZO6 cracker

How do you like the headunit for using your GPS. Are you happy with it

lewislgZ06

Good information GCG. I installed a Kenwood single din KDC-X500 over the winter and mine sounded immediately improved. I took my time connecting the PAC ROEM-VET1 to the stereo wiring harness. This is very critical. Sounds like the OP's could possibly be wired incorrectly.
I spent about as much time adjusting the sound as I did on the installation, but it sounded great with the factory bose speakers.
I later installed an amp and sub and now my stereo kicks azz.

GCG

Exactly! There's no reason for the OP's results to be any different than yours. It seems something is not right here.

Congratulations on your upgrade!

zeevette

One issue not addressed; what are you using for your source? If it's not unconverted digital, it'll sound muddy. CDs, USB flash drives/iPod/phone, with digital cable, not the mini-plug. I don't like wireless, myself, though some don't mind. My Z's so loud, a fancy stereo would be wasted, but on my X1, without the optional (f*ck BMW) connectivity I have to use a flash drive to get good sound with variety.

AlaJoe

When we got our vette it already had an aftermarket head unit in it. It sounded horrible much like you described. It was hooked up with the pac roem-vet1 interface to the bose speakers. I checked all the wiring and it appeared correct. I still though could not believe that a bose system was supposed to sound this bad. I then went and bought a Metra XSVI-2004 and installed the same radio with it. Talk about a difference, It sounded great! It was night and day even the retained accessory power worked.

In a nut shell an aftermarket head unit properly hooked up should sound just as good as the factory head unit.

tentuna

If I remember correctly Polk audio with separate dome tweeters and crossovers. Cut the mounting plates from 1/2 ply & it sounds great

73Corvette

I do like Polk speakers they are awesome...

seattle

I installed a Kenwood from DD several years ago. I had DD pre-wire it. The bass did not sound right and we discovered the harness was wired incorrectly. We corrected that and it sounds decent. Maybe check all your wiring to be sure something wasn't done correctly.

GCG

I suggested couple of things along that line, above in Post 22

lewislgZ06

BOUT X

Good luck I have same head unit tried using stock Bose speakers could not get the sound to sound right. I ended up buying Memphis Audio speakers OMG sounds like I am at the studio listening to whoever is playing crisp & Clear.

Pops

DNFC5

I recently installed a Kenwood DDX393 I received from Dennis a few weeks ago. I used the Pac ROEM and all the stock Bose amps and speakers.
After carefully making all the connections and double checking everything many times, I powered it up. To my dismay it sounded terrible, nasal, thin, muddy, every thing bad you could imagine.
I spoke with Dennis who was very patient and helpful. We decided to try a new PAC unit. So a few days later I swapped out the PAC and it still sounded crappy. Mind you I had to turn the adjustment pots on the PAC way Dow just to keep the unit sounding reasonable.
Well tonight it all clicked with me. I realized that the initial setting on the Kenwood crossover had the front speakers set to cut out the lower frequency on the front speakers. Well duh, that's where the subs are!!! So I set the high pass crossover for the fronts to "through". Now I went back to the pots on the PAC and dialed up the bass and HOLY CRAP now we are rocking!!! So after two weeks of being frustrated, imagine my relief.
Do yourself a favor and use the JL audio tools app and use it to tune the EQ and it gets even better. Then set the EQ to be the same across all the sources and tweak them from there as needed.
Are the stock speakers perfect? No. Could changing them out improve the overall sound quality? Most likely.
I just figured my experience might help someone else. These radios have so many settings in them you can get lost quick. I'm sure I can keep tweaking to perfect it, but I'm just glad I got it figured out.
Hope this helps.

DNFC5

By the way use the link in post 19 to understand the JL Audio tools app and how to use RTA meter.

Forcedvert

I had crappy results with an alpine head unit connected to the Bose amp and speakers in my 2004 gmc, all so I could have an iPod interface, (I was told buy the counter guy it will be much crisper than Bose head unit) it did not!!! I tried adjusting all the audio settings and it still sounded hollow. I took it back to the installation shop and the installer told me that's how they sound with a Bose amp and speakers, he said I would have to spend a couple grand (amp, sub woofer, speakers) installed, to get the sound quality better than factory Bose head unit. I left it alone and sold truck, I will be following this thread,,, because I would not mind a modern head unit in the Vette but don't want to go backwards in sound quality again.

Tuco

After all the great things said about them I have no idea why anyone would look anywhere else.