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      02-13-2010, 12:17 AM   #18
808MGuy's Avatar

Drives: 2009 E90 M3
Join Date: Jun 2008
Location: Oahu, Hawaii

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Just a few observations from my short experience with the SWS.

Originally Posted by ********* View Post
Is the SWS-8 upgrade for me?

The upgrade is for those looking for an improved low to mid-range sound output. SWS-8s WILL NOT produce ground shaking bass. This is simply because of the size of the SWS-8 woofer. The SWS-8s are 8" shallow mount woofers that can only travel so far. They have a hard time hitting frequncies below say 60Hz. If you want hard hitting bass, bass that will make drivers next to you stare, you need a 10" or 12" trunk sub in a proper enclosure.

From my current experience with tuning my system, the SWS8 gives me usable output down to about 35Hz. From there the output drops off very fast. Do they hit hard? Well it depends on your defenition of hit hard but for most people I would say no. Do they give you full sound above 40 Hz? Yes.

Should the underseat subs be in stereo or mono?

The underseat subs should be run in stereo because they are responsible for most of the mid-range frequencies. They can be run in mono, however better sound quality can be reached in stereo.

Since I'm running mine at 80Hz and below, stereo separation is not that big an issue. I would like to run them in stereo but don't have the power at 4 ohms to do it.

How much power/what amp to get?

A 2-channel amp with 150W-200W RMS per channel is ideal for the SWS-8's. However, you can easily power them with a more powerful amp as long as the gains are set properly/not too high. A monoblock amp can also be used as well but keep in mind that they will sound better in stereo.

Based on the rating of my amp, I'm running 500W mono to the pair so 250W each and they seem to be fine even at very high volume.

Amp Settings?

Make sure the gain is all the way down before starting up the system. Turn the gain up slowly until you hear distortion and back off a few clicks. You should run the gain low for a week or two to break-in the subs. The factory L7 amp low passes the sub outputs at 150Hz. The SWS-8s have a difficult time hitting anything below 60Hz. So High-passing your amp at 60Hz should make the sound a bit cleaner/less distorted.

I still think crossing at 60 Hz is a bit of a waste. Of course, if you're going to use the SWS as dedicated midbasses then sure because you have a sub to take over after that but there are better drivers suited for that purpose since the SWS doesn't sound so good above 125 Hz either.


Spacers are needed between the SWS-8s and the factory underseat enclosures in order to provide enough clearance for the slightly taller SWS-8s. < This is a must! Another spacer can be placed between the grill and the carpet. Some leave the grill off and others just use the spacer. Some even put the spacer and the grill under the carpet. In some situations, the spacer and grill need longer screws to secure them to the enclosure. (e.g. The spacer is on top of the carpet and then the grill is placed on top of the spacer.) You can either make your own or buy a set from one of the member on the forums.

I did the trimming the ribs method as well as installed a foam/rubber gasket between the enclosure and the SWS. That lifted it up enough for me not to have to use a spacer.

Why do the side skirts rattle with the new SWS-8 upgrade?

The underseat enclosures are ported into the side skirts. The increased movement of air from the more powerful SWS-8s create the rattling effect. Nothing can really be done about this. You could try blocking off the ports, however you will lose significant space and therefore decrease sound output. In short, blocking the ports is not recommended.

I haven't heard mine rattle yet even at high volume. I did not block the ports and I didn't use any sound damping material in the enclosure.
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