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Folks,

It's that time of the year, when there is an itch you much scratch! This time, the victim will be the bmw under seat subwoofer.

Egads! That's not a subwoofer! It's a midrange woofer sold to idiots as a subwoofer!

Without going into this debate, there is a narrow selection of replacement speakers to choose from for the F22.

The usual suspects are of course, the Eton, which is copied by Rockford Fosgate. Focal is another suspect, but doesn't fit too well. Then there is the GHOST sub. And then the Jenhert.

I am not going to count SWS. It's mid range is non-existent.

As the subwoofer upgrade is at best a marginal improvement in sound, the ROI for a sub upgrade is a silly investment, if you paid full price for the above offerings.

But now a new offering has reared its ugly head. The GRS B200-2 ASD speaker. At under $300 for a pair, $150 per speaker, the ROI gets interesting.

Apparently this speaker looks suspiciously close to the German Engineered GZCS 200BMW-SW from Ground Zero.

Keep in mind that you'll need to upgrade your amp before you consider 2-ohm loads. I have a Focal/ZED amp so I am not worried.

Pictures will be coming soon and an evaluation of the woofers performance.

Take care friends!

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Here they are!

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Great Replacement Speakers! It is what it is!

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forgot to install! Comes in handy for this project.

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Nominal Diameter 8"
Power Handling (RMS)100 Watts
Power Handling (max)200 Watts
Impedance 2 ohms
Frequency Response 25 to 2,000 Hz
Sensitivity 96.8 dB 2.83V/1m
Voice Coil Diameter2"


Thiele-Small Parameters

Resonant Frequency (Fs)64.6 Hz
DC Resistance (Re)1.82 ohms
Voice Coil Inductance (Le)0.47 mH
Mechanical Q (Qms)3.38
Electromagnetic Q (Qes)0.66
Total Q (Qts)0.55
Compliance Equivalent Volume (Vas)0.61 ft.³
Mechanical Compliance of Suspension (Cms)0.21 mm/N
BL Product (BL)5.63 Tm
Diaphragm Mass Inc. Airload (Mms)28.3g
Maximum Linear Excursion (Xmax)5.5 mm
Surface Area of Cone (Sd)240 cm²

At this price, who cares!

[ThipNg]

Subscribed as I am considering the GRS as well.

I've purchased their satellite speakers, but haven't installed them yet. Still researching amp options.

[fancyfl1ght]

Originally Posted by ThipNg

Subscribed as I am considering the GRS as well.

I've purchased their satellite speakers, but haven't installed them yet. Still researching amp options.

Looks impressive, with impressive specs! Unbelievable price too! Let me know how that goes.

I am of course bias about amps. Check my Focal FDP 6.900 amplifier. This thing is a Steve Mantz designed amplifier. I will say no more.

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Here are some shots I took installing the remote sub switch.

Step 1 remove the accessory tray on the right side of the steering wheel.

Step 2 remove left driver side bottom strip.

Step 3 pull up the rear bench seat and snake wire to the trunk.

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Here is a shot of the remote sub control installed and turned on. The OEM sub sound so good I don't want to install the GRS!

What a dilemma!

Maxed out the bass just for fun to try to see it clip. Darn light never turns red! This amp has real pulling power!

[ThipNg]

So are you saying that the stock Subwoofers are actually pretty good when powered by good amplifier? That's good news.

You should install the GRS' anyways to see if they're better.

[fancyfl1ght]

Originally Posted by ThipNg

So are you saying that the stock Subwoofers are actually pretty good when powered by good amplifier? That's good news.

You should install the GRS' anyways to see if they're better.

When the bass is maxed out, the OEM subs are are shaking the the side view mirrors, the rear view mirrors.

I can't wait to see what the GRS subs will do!

I've done the traditional 80Hz crossover, which is the lowest the Energy coaxials are rated for. Anything below goes to the OEM subs.

In fact, I will be posting videos of the mirrors shaking just for fun!

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Just because I am curious, I used a kitchen food scale to determine the weight of the subs. The OEM subs came in at 26.45 oz. The GRS subs came in at 50.26 oz. Wow! Good sign. Almost double the weight of the OEM woofers.

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The unthinkable that would stop most people in their tracks! But I am not most people. Heh heh heh!

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Wood working tools come in handy for this upgrade!

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Slides right in!

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Have you used 45 lbs feet of torque on your seat's bolts? You don't want your seat flying around after your sub installation. Have fun, but be safe!

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OEM vs GRS subs

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Ready to rumble!

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True Love is one of those tunes that gives the subs a major work out. The OEM subs are loose compared to the GRS. GRS sounds tighter and hits harder that the OEM subs.

GRS wins. OEM subs looses.

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If there ever was a bass track to punish subs, this song is it. GRS, again very tight and hits hard. You feel like the bass player is under the seat plucking away. Detailed, less muddy.

OEMs again muddy and muddled.

GRS Wins. OEM looses.

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Slightly more complex bass rhythm. GRS able to capture more details than OEM. GRS has a slight edge on this song.

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In this little experiment, I've learned a lot more about my amp and how it works with an upgraded and inexpensive under seat sub woofer.

Is it a dramatic improvement? No it isn't. The OEM subs are that good! They are enough for most listening situations with a high quality after market amp.

Am I disappointed with the GRS? No they are great! For the price paid and overall incremental improvement in sound, they are worth every penny. The difference tends to be more subtle such as better defined sound when listening to a bass guitar. Mid-bass is improved as well.

It goes back to my original point, which is that paying too much for an under seat woofer is not a good idea.

I am of the opinion that eventually, I will need to add a digital signal processor to get the most from my Hertz and GRS speakers. Most likely a Helix Pro DSP or Audison.

But for now, I am pleased with the Hertz/GRS/Focal amp combo.