'03 G Sedan equipped with the upgraded "Blose Sound"

Had an Alpine 9813 pushing my stock components.

I took out my double din the other day and made my car back to stock....
Wow, the Alpine head unit made such a big difference it's UNBELIEVABLE. I felt a huge difference when I first installed it, and now that I've taken it out, it's completely re-affirmed that.

With the Alpine HU, the stock components came to life...much clearer and crisp.

Now with the stock HU, the sound is really flat and boring. Not only that, but the stock CD player is creating a weird hissing/scratching noise with my CD's that the Alpine didn't with the identical CD...weird...gotta have the dealer check that out.

So if you've got the money and your borderline on whether to change out your headunit and blow the dough on the double din....take it from me and DO IT!

 

I suspect you are merely noticing the higher level out on the Alpine.

The frequency response on a scope is identical (if lower in amplitude).

But you do want to get that fixed before you upgrade your Blose speakers and amp...

 

Actually, like el_dude said, the stock head unit has a pretty good frequency response, which is what matters if you are using seperate amps and speakers. In fact, I love the sound out of my stock unit; it is crystal clear, and very loud.

After it has been filtered through a JL 450/4 amp and into some BA Z6's, that is.

Dave

 

Yea Mikey, maybe an install issue?

 

lmao... Rashman messed up your sounds!!! haha

 

Nah, it sounds like it did before I had the head unit installed.

 

If you like your stock head unit, that's great. But it definitely does NOT have good frequency response compared to an aftermarket head unit like an Alpine. See my post from last August at the following link. I've updated the attachments showing the measured frequency response of my stock head unit since those attachments were corrupted for some reason.

https://g35driver.com/forums/showthr...716#post700716

Like MikeyMike, I noticed a huge improvement in sound quality by tossing out the head unit and replacing it with an aftermarket unit, in my case a Pioneer. Of course I also went a little farther than a simple head unit replacement, but as an intermediate step I had replaced just the head unit, and it made the biggest difference. The OEM speakers were surprisingly not that bad, and I ordered the non-Bose stereo (knowing I would upgrade, anyway).

Best regards,
Jim

 

Okay, sure. You noticed a big improvment because the first thing you replaced was the head unit. Well, when you did that, as you well know, you replaced whatever amp was powering the speakers. In your case, the amp was internal to the head unit. That's what made the difference, or at least most of the difference.

But hey, I doubt I will convince you, you seem pretty convinced of your own rightness, and it's no skin off my back either way. It's not worth removing the steering wheel controls, stock look, and integrated MP3 player for the small sound quality increase a new head unit would provide.

Dave

 

if you put your seats all the way back in the car, it increases the frequency response of aftermarket HUs. Maybe you sit with the seat slid all the way back.

 

Damn, we got some haters....

 

Ah, so THAT'S what causes that. It all makes sense now.

 

yes, it took me forever to figure that out. if you install some aftermarket grounding wires it increases your bass as well. cool huh?!?

 

Jim, if I understand the system differences accurately, the non-Bose HU seems to NOT have a balanced pre-out - it seems to have a speaker-level-amplified output only. They are not the same.

The Bose HU preouts that I have measured with an NT Instruments 30-band RTA definitely have a slight Fletcher-Munson auto-loudness curve, but above 40% or so on the volume control they are as flat as a pancake. Given that we've done this with dozens of Bose sound systems (in Infinitis, Mazdas, Audis, etc), and they all measure the same (with output level amplitude differences) I feel confident that Bose contractually requires the output of the HU used in Bose systems to be flat (other than auto-loudness). (They say Bose on the front, but Bose doesn't make them, the regular OEM supplier does.)

I will stipulate that there are sonic benefits to upgrading the OEM HU... but Bose and non-Bose are not the same, and I look forward to RTA'ing a Bose HU myself. I would expect large benefits from upgrading a HU that used an internal IC power amp, even if it was flat in response.

I suspect from your description of volume-dependent equalization that what you're seeing is the additive response of the the auto-loudness curve that lives in the preamp IC (the one that controls volume, balance, fader, bass, and treble) and whatever EQ curve they've added in. I SERIOUSLY doubt that the non-Bose HU has any volume-dependent dynamic equalization capability internally except what's in that preamp IC - it would cost too much. But it's possible that someone like ST Micro has introduced a more capable preamp IC that the user can program with their own eq settings that track volume settings.

If it's as pronounced as your graphs indicate on non-Bose HU's, then we would use a Zapco Digital Reference amp and reverse the EQ with the 10-band parametric EQ, and then use the optional remote volume **** to defeat the dynamic component. But at that point, you're right, the double-DIN option might be considered better depending on the user. Cheaper to go Digital Reference, like a 360.4, and the ****, but maybe they want other stuff too... like nav.

Since there are many cars where this is not an option (Subaru, for example) I'm glad we can still handle it...

Ken