# Midbass under Seats in BMW 330i (e90)



## kaigoss69 (Apr 2, 2008)

Hi,

My new car is a bit more challenging as far as getting good mid- and sub bass. I have the Logic 7 system which sounds OK in the upper frequency range, but definitely lacking below 250 Hz. What I want to do is change the underseat subs and replace them with decent midbass drivers. I am looking for a midbass driver that can also play some subbass, instead of a subbass driver that can play some midbass.

I ordered some Earthquake SWS-8 subs but they look and feel cheap so I am hesitant about installing them. Anyway, I want more midbass so I was thinking about putting a midbass driver in there. The enclosure is a bit challenging, given the mounting depth of only 54 mm, but I think I can add an MDF ring and bring the depth to about 70 mm. The maximum size I think is 8".

Not sure where the L7 system crosses the subs over at, but the midrange speakers in the door are 4" so I would guess in the range of 400 Hz or so.

I will have about 150W per driver available from a Blaupunkt Plug-n-Play amp.

Thanks!


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## t3sn4f2 (Jan 3, 2007)

Talk to Andy W. on here from JBL.


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## 14642 (May 19, 2008)

We measured the output of the amp in the MS-8 BMW. As I recall, the bass is crossed over at about 80Hz, but it's 9dB higher than the output to the 4' speakers, which are crossed between 100 and 150 somewhere. Since the bass is about 9dB higher, that makes the effective crossover frequency c. 120Hz. We used those underseat drivers as midbass and added subs in the trunk, which worked great. 50 and down to two W12GTi woofers and 50-200 to the underseat midbass. 200 and up to the front speakers. The only new speakers are the W12s and some additional tweeters in the center, sides and rear. The OE speakers are quite good and are capable of easily handling the 100 watts RMS that we're using. Addiing the real sub, adding power, new crossover points and EQ are the best upgrades for that car.


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## kaigoss69 (Apr 2, 2008)

Andy Wehmeyer said:


> We measured the output of the amp in the MS-8 BMW. As I recall, the bass is crossed over at about 80Hz, but it's 9dB higher than the output to the 4' speakers, which are crossed between 100 and 150 somewhere. Since the bass is about 9dB higher, that makes the effective crossover frequency c. 120Hz. We used those underseat drivers as midbass and added subs in the trunk, which worked great. 50 and down to two W12GTi woofers and 50-200 to the underseat midbass. 200 and up to the front speakers. The only new speakers are the W12s and some additional tweeters in the center, sides and rear. The OE speakers are quite good and are capable of easily handling the 100 watts RMS that we're using. Addiing the real sub, adding power, new crossover points and EQ are the best upgrades for that car.


Thanks Andy. Kind of disappointing, that low x-over point. I cannot fathom how the 4" drivers in the doors could possibly play 100 Hz with authority. I would like to keep the DSP of the OEM system, as it is optimized for the car, and there is no good aftermarket processor available YET (hint: get the friggin' MS-8 on the market already, will ya ). So I cannot mess with the x-over points. I guess I can give the OEM drivers a shot, with some amplification, but I would guess that they will not be up to the task, given that I really LOVE midbass and I cannot get enough of it, hehe. 

I've still got some Peerless SLS 6.5's waiting to be used, but those are probably too deep for the OEM enclosures, plus I am not sure they would be a proper fit, given the low x-over point. I really loved how those sounded in my old car...

Any other suggestions on how I can add some midbass?


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## HIS4 (Oct 6, 2005)

Andy Wehmeyer said:


> We measured the output of the amp in the MS-8 BMW. As I recall, the bass is crossed over at about 80Hz, but it's 9dB higher than the output to the 4' speakers, which are crossed between 100 and 150 somewhere. Since the bass is about 9dB higher, that makes the effective crossover frequency c. 120Hz. We used those underseat drivers as midbass and added subs in the trunk, which worked great. 50 and down to two W12GTi woofers and 50-200 to the underseat midbass. 200 and up to the front speakers. The only new speakers are the W12s and some additional tweeters in the center, sides and rear. The OE speakers are quite good and are capable of easily handling the 100 watts RMS that we're using. Addiing the real sub, adding power, new crossover points and EQ are the best upgrades for that car.


What system did this BMW have? Was it Logic 7 or Individual Audio from the M3s? I thought the 8s were crossed at 250 Hz LP and the 4s were 250 Hz HP. From listening to the base system in my M3, that's what it sounds like. 

My advice to the OP is to just install the SWS-8s and see how you like it. If you're looking for loud booming bass, you're not going to get it from any sub in that location. But a lot of guys have said there is a significant improvement in going to the SWS-8s and running them from an aftermarket amp. I myself haven't tried it yet but that's the direction I was headed unless I find something better that doesn't break the bank. If your budget permits, you can also look at Alto Mobile Falstaff 8s but those are $$$ and I don't think they are drop in for the OEM enclosure.


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## 14642 (May 19, 2008)

HIS4 said:


> What system did this BMW have? Was it Logic 7 or Individual Audio from the M3s? I thought the 8s were crossed at 250 Hz LP and the 4s were 250 Hz HP. From listening to the base system in my M3, that's what it sounds like.
> 
> My advice to the OP is to just install the SWS-8s and see how you like it. If you're looking for loud booming bass, you're not going to get it from any sub in that location. But a lot of guys have said there is a significant improvement in going to the SWS-8s and running them from an aftermarket amp. I myself haven't tried it yet but that's the direction I was headed unless I find something better that doesn't break the bank. If your budget permits, you can also look at Alto Mobile Falstaff 8s but those are $$$ and I don't think they are drop in for the OEM enclosure.


Did you measure any of this? I'm going from memory, but I'm pretty sure my memory is good. There's no way the subs were crossed at 250 in the BMW I measured. 

Since the OE system is powered by IC amplifiers that make about 30 watts, the 4" speakers can play quite a bit lower than if they were driven with 100 watts. There's nothing wrong with the underseat woofers with the power they're given by the OE amp and they make great midbass drivers. UNder the seats is actually a great place for woofers, if providing good bass in all seating locations is a design objective. In the MS-8 BMW, the WHOLE stage is located up front no matter which seat you sit in and the midbass placement is an important contributor. 

But WTF do I know? I've just been doing this professionally for 25 years and work with world class audio engineers who are keen to answer my questions and help me learn.


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## HIS4 (Oct 6, 2005)

Andy Wehmeyer said:


> Did you measure any of this? I'm going from memory, but I'm pretty sure my memory is good. There's no way the subs were crossed at 250 in the BMW I measured.
> 
> Since the OE system is powered by IC amplifiers that make about 30 watts, the 4" speakers can play quite a bit lower than if they were driven with 100 watts. There's nothing wrong with the underseat woofers with the power they're given by the OE amp and they make great midbass drivers. UNder the seats is actually a great place for woofers, if providing good bass in all seating locations is a design objective. In the MS-8 BMW, the WHOLE stage is located up front no matter which seat you sit in and the midbass placement is an important contributor.
> 
> But WTF do I know? I've just been doing this professionally for 25 years and work with world class audio engineers who are keen to answer my questions and help me learn.


I didn't measure but the amp specs differ depending on which system was provided with the car. 










The base E9x M3 system is the Hi-fi system. The Logic 7 is the Top Hi-fi and the individual audio (upgraded system for the M3) is not listed. I agree that the entire stage is up front but just from listening to it everyday for a month, it does sound like it's crossed much higher than 100Hz. I don't disagree that the under seat location is great. It's just that some people are looking for the kind of bass that you get from 2-12s in the trunk from that location and realistically, that just isn't going to happen. I myself feel that, done correctly, a great SQ system could be built around subs in those locations.


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## kaigoss69 (Apr 2, 2008)

Well, I hooked up the amp and I must say the stock subs play extremely well with the added power. I got rid of some of the boominess on the low end by raising the HP filter. The midbass is very good now. I will install the SWS subs in due time and post the results.

Regarding factory x-over settings, I played some test tones and my best guess would be a setting of 150Hz.

As soon as I have completed tweaking the low end I will have to do something about the mids and highs. The tonality of the system is average at best and the staging is very poor. It is just mindboggling for me how you can have an elaborate Logic 7 DSP and not get the stage centered and lifted a bit off the dash... very poor job by Harmon indeed.


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## kaigoss69 (Apr 2, 2008)

double post sorry


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## funkalicious (Oct 8, 2007)

Andy: Would midbass drivers playing approximately 70Hz to 250Hz mounted under the front seats work well without time alignment and heavy processing for a two seat (vs. one seat listening position) setup? This mounting location would solve a LOT of midbass installation problems for me.


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## smellygas (Feb 21, 2008)

The e90 mounting locations are very frustrating. A 4" in the door makes it very hard to get decent bass extension. The maximum SPL output of a 4" driver at the usual xmax's probably cuts you off around 200-300Hz. You can forget about 100Hz, unless you're okay with high distortion and/or you're not playing at high volumes. This means your under-the-seat woofers will have to at least cover up to 200-300Hz or so. The problem is the mounting depth of the factory woofer enclosure is less than 3", which means your choices are basically a smaller driver that covers up to 200-300Hz and has so-so bass, or a shallow-mount woofer that probably doesn't do midbass up to 200-300Hz very well. Either way, I doubt you'll get thundering bass, and you'll likely require a larger sub in the trunk. Have fun.


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## El-Akeem (Feb 29, 2008)

Even when the SWS-8 look cheap, their performance in the under-seat loacation of new BMW's is quite impressive.


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## squittieri (Mar 22, 2009)

Hi Andy,

What you propose sounds the most reasonable and the best sound-for-dollar improvement I've read in any forum. I'm now living in Europe and have a 325i (E90) with the most basic audio system, the "Business CD" and four 4" "full-range speakers". It's quite inadequate. I've been reading many forums to find out what I should do to improve the system in the most effective manner and your solution of more power, subs and tweeters sounds the most reasonable if the existing components are quality items but overstretched. Getting to specifics, just exactly what do you recommend? I like all music, especially small jazz ensembles, "classic vinyl" rock and baroque music.
Thanks for your help.

Christian


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## Technic (Oct 10, 2008)

squittieri said:


> Hi Andy,
> 
> What you propose sounds the most reasonable and the best sound-for-dollar improvement I've read in any forum. I'm now living in Europe and have a 325i (E90) with the most basic audio system, the "Business CD" and four 4" "full-range speakers". It's quite inadequate. I've been reading many forums to find out what I should do to improve the system in the most effective manner and your solution of more power, subs and tweeters sounds the most reasonable if the existing components are quality items but overstretched. Getting to specifics, just exactly what do you recommend? I like all music, especially small jazz ensembles, "classic vinyl" rock and baroque music.
> Thanks for your help.
> ...


Christian

In Europe there is an OEM Alpine amplifier upgrade for your specific "Stereo" OEM system (6 speakers driven by the OEM HU) that adds not only an amplifier but also a pair of Logic7 OEM tweeters to the front doors, effectively making you system an 8-speaker sound system: http://www.1addicts.com/forums/attachment.php?attachmentid=231151&d=1222754295

A much better option for you car is to get a Blaupunkt THA555, the PnP harness for the BMW, a pair of those Logic7 OEM tweeters and a pair of SWS-8 to replace the underseat woofers. This combo will have a much better power output, much better and deeper bass, much better crossover adjustability for all the speakers and it is as easy to add to your car as the OEM Alpine version (mostly plug and play). 

This way you can get the most from the SWS-8: crossover at around 160Hz for the SWS-8, 140Hz and up for the 4" components in the front and the full range in the rear. If you really want much nicer components for your car you can replace all your OEM full range 4" with the OEM Individual Audio 4" components (4" mid, 1" tweeter separate crossover) for your front doors, the Individual Audio 4" coaxials for the rear deck and the SWS-8 for the underseat woofers. All driven by the THA555.

If you even want much more adjustability then you can get an Audiocontrol DQL-8 (and still use the Blaupunkt PnP harness for BMW to connect all the speaker inputs and outputs easier) and any 5- or 6-channel amp for a full blown high quality sound system. 

There are plenty of options for you car, all depending on what you want and want to spend.


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## smellygas (Feb 21, 2008)

I can't believe I haven't seen this article until now
2006 BMW 325i - Gary Briggs, Single Best Fabricator & Audio System Designer In the World - Car Audio & Electronics Magazine
It's the MS-8 BMW that Andy refers to above - an '06 (E90) 325i that took first place in both MECA and IASCA using the STOCK logic-7 factory speakers + their MS-8 processor (and an additional sub). It's amazing what a little DSP correction will do.

SG


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## squittieri (Mar 22, 2009)

And please have a look at this LONG read about the JBL MS-8!

JBL's MS-8. What does it do? - CARSOUND.COM Forum


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## cgm246 (Jun 27, 2011)

Nice work Andy!!!!


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