Is the DSP stereo's bass weaker than standard 10-speaker?

[iPhoneEngineer]

Hey guys,

I've been the proud owner of an M Coupe for about two months now. I've gotten the CDV out of the way, and had the car tinted, and have few complaints!

The biggest complaint is the bass performance of the stereo, which was shockingly lacking from the first time I tried it. I've done an A/B comparison with a friend's 2007 Roadster with the base stereo, and even with the top up, tracks sound great--with bass that makes itself heard.

BMW claims my stereo is operating normally, and I have heard at least one other person say that the DSP stereo actually has worse bass performance than the US-standard 10-speaker. This is shocking to me, as I heard that the DSP system was the first THX-certified stereo in a car in Europe. It also employs Carver-technology subwoofers, which seem like a great idea and should not have this problem.

Along those lines, the cones of the woofers definitely don't displace more than 0.5-1 centimeter as I have read that Carver woofers are supposed to--more like 2-3cm. In fact, when I stick my head behind the passenger seat, I hear a general decrease in bass--as though most of it is being delivered from the door speakers. Biasing the DSP settings to boost the bass helps make the system more listenable, but at the expense of bass clarity.

I would greatly appreciate hearing about any comparative experience with both systems, or knowledge of problems with the Carver woofers. Thanks!

[CFoote]

I have a 2005, so my system might be slightly different, but I have the "Jazzclub" DSP Mode set to 'on' (most people agree thats the best of the DSP settings) and I have my Bass control about 75% of the way up.

Obviously it depends on the music, but give it a shout. In 2007 they made some major changes to the stereo. 2006 and below pretty much had the same stereo since 2003.

If your friend has the same car, and your model years are the same, the only thing I could suggest would be swapping the actual amplifier unit in the trunk. Disconnect the battery before you go about doing that...

[Blind32]

I have a 2007 and the bass sounds horrible when I'm listening to the radio but when I have my iphone hooked up to AUX in, it sounds decent. When comparing stereos, try to use the same music/soundtrack and introduce it to the stereo through the same interface (CD/Aux in). Good luck and let us know what you find out.

[thekurgan]

Bass sounds pretty deep in my car, I use the Jazz setting as well, with a little trebble boost. Do you have navi? I've read here and on another Z forum, that the audio that goes through the navi to control the eq can affect the sound quality somewhat. Trying to search for that thread now.

[danlauz]

I had both car, one without NAVI and the actual one withNAVI and, definitively, the sound with NAVI is not good at all.

I have play with the setting of the base ans treble and EQU and, the net result is almost no BASS and most of the sound going to the front speaker. its much better but, never as good as my previous Z4MC without NAVY.

any other comments ?

[mousitch]

I have Nav and yes it sounds like poop. If I turn up the bass and try to crank it the amp gives out on the lows and all I get is treble. Sounds like my amp is bad. But at $1000 plus for an amp I will learn to deal with it. Plus with the headers and the Diablo's all I need is some good throttle music.

[Hoa]

i have navi in mines and after tweaking around a little, i get pretty good bass on the car. audio is not distorted at all even at max. i can hear clearly with the windows down going 80-90 in the hwy (normal speed going home )

[jumpthewire]

anyone have the specs on the various sound options?

i also use the Jazz setting and have been satisfied by it.
by no means is it amazing, but it is what it is.

[iPhoneEngineer]

Wow guys, thanks for all the replies!

My car does have the Nav screen, and I believe all cars with the "Premium/DSP" package do--because it's the only way to control the DSP.

I don't think the amplifiers are interchangeable between the DSP and non-DSP models.

What I suspected most is that the high-voltage part of the amplifier--the 30V output for the Carver subs--might be able to go bad without the rest of the amp dying. Therefore, this could be providing too little power to properly drive the subs--perhaps the same voltage as the rest of the audio system. This would result in the symptom I see…speakers that don't appear to be blown, and do move, but are really weak.

All my tests, including the A/B comparison with a non-DSP car, have used my iPhone connected to the AUX input. So, we were able to use the exact same songs with the same input, and in my experience, the bass output of his car was much better. We tested this with absolutely flat audio settings, both the basic settings and the DSP, and the difference was striking. If it comes down to it I may have to drag him to the BMW dealer with me for a demo.

I believe there are only two possibilities here, and your information is helping to figure out which one is the case:
1) The DSP stereo's bass really is worse than the standard US stereo
2) The DSP stereo's carver sub amplifier is prone to a failure mode where the subs no longer receive enough voltage for proper bass performance, but is superior to the base stereo when working correctly.

Here's a great thread about the different audio systems. My understanding is that the US models only came with either the HiFi (also called 10-speaker) or the Top HiFi (also called Premium Package sound/Nav/DSP). My friend's car is the HiFi.

http://www.zpost.com/forums/showthread.php?t=63030

Thanks again!

[thekurgan]

I have the Carver system and no navi, it is DSP enabled, just not controlled via the nav screen. I've got no issue other than having to loctite the sub attachment screws.

[iPhoneEngineer]

OK, good to know! Now, is it possible to have the nav screen but no Carver/DSP?

[Blind32]

Originally Posted by Hoa

i have navi in mines and after tweaking around a little, i get pretty good bass on the car. audio is not distorted at all even at max. i can hear clearly with the windows down going 80-90 in the hwy (normal speed going home )

Would you mind posting up your setttings? Thanks

[Hoa]

i did this adjustment in a few mins so im sure it can be improved.

[dekaliber]

I have a navi on the M and I don't think it's that bad. I have all EQ and DSP settings off. IMO, the less electronics between the signal and the speaker, the better.

I don't remember it being all that different from my 3.0si, which did not have Navi, but did have premium sound.

I don't know. It's a sports car with a sweet engine and very little concern for dampening outside noise. (In fact, don't the 3.0si coupes have a sound generator to funnel in engine noises?)

[iPhoneEngineer]

Agreed…no desire to dampen outside noise. I'm disappointed with the bass when the car is parked with the engine off--at "flat", it seems substantially biased towards midranges and treble.

Good info; I'm going to push back on BMW that something is indeed wrong. The unfortunate bit is that it seems that a fair number of other people report poor bass on the DSP/premium sound system, and that may mean this failure is fairly common yet hard to definitively notice because the subs do move to some extent.

At this point the most valuable input would be from anyone who has done, or could do an A/B comparison between a DSP and standard HiFi model, if you have access to both between you and a friend…my test is clear, but I could easily have an ailing amplifier.

[dekaliber]

Just a gut impression, so probably not all that accurate, but my sense from using the aux-in from my ipod on my 3.0si (standard hi-fi, no DSP) and the M (navi, w/ DSP) seems to be that the bass is actually stronger in the M, if only by a little, especially in the low low frequencies. EQs were flat in both cases.

It would be hard to get a dealer to act on this though, unless the difference in frequency response is very pronounced, or if there is some noticeable artifact that is indicative of some sort of failure. Does the audio distort significantly at high volumes? I'm not sure where the sub is located, but it might be worth digging around to see if there's an issue with the connections. Of course, this starts getting into work that the dealer should be doing.

One way to start might be to get a SPL meter and play some sweeps to show conclusively that there is an enormous dropoff in signal after, say, 200 or 150 Hz. I wouldn't think that the small drivers on the regular speakers would produce anything appreciable that low.

[iPhoneEngineer]

dekaliber, thanks a bunch for your input. That is what I would expect--the Caver subs should be pretty effective!

The audio does distort significantly at moderate volumes if I use the audio corrections to bring in what I would consider a "flat" amount of bass response. I haven't tried cranking it up when flat, because the treble and midranges are plenty powerful and clear.

Good point about the SPL meter and frequency sweeps--that sounds like a good way to proceed in coaxing action from the dealer. I won't be happy until they either fix it, or are willing to state that the DSP system has demonstrably inferior bass performance to the base stereo.

On another note, is it possible to be assigned to a different service advisor, or is that linked to the VIN or something?

[jumpthewire]

friend of mine offered to run a sine & measure the SPL & EQ outputs-
ill report back with findings

[Z4Murder]

i keep my stereo on the jazz settings, i think it sounds incredible for a stock system.

[Blind32]

Originally Posted by iPhoneEngineer

...Good point about the SPL meter and frequency sweeps..

There's an app for that...

Sorry had to

and if there isn't, you should make one. Call it the Carver BMW sub tester!

[ZStig]

ive always enjoyed the subs in my carver/navi combo

[Alpha Bravo]

Jazz DSP actuaaly hurts my ears with the top on, had to put DSP off to lessen the bass on my system. Altough turning DSP jazz and up the treble give good sound for certain genres of music....boom boom boom