Under-seat subwoofer installed: 2012 OB

31324 Views 31 Replies 9 Participants Last post by rockthebeef, Aug 1, 2013

rockthebeef

Discussion Starter · Jul 10, 2012 (Edited)

I installed the Sound Ordnance B-8PT this past weekend. I think this model is exclusive to Crutchfield and has gotten really good reviews compared to other under-seat subwoofers out on the market. It even comes with a 10 gauge installation kit for free. It was $199.99, but I got $20 off by spending over $200 (I added a $0.99 item that I didn’t even need). I haven’t heard the Subaru version, but I would bet that this thing gets louder, goes deeper, and gets lower. Don’t expect 20Hz, or even 30Hz to come out of this thing. The frequency response of this subwoofer is 40Hz-200Hz and running test tones through it verifies that.

First off, I didn’t even know if it would fit. The dimensions of the box and the area under the seat are so close that a test fit was really necessary. In the past, I’ve made cardboard models for this type of thing, but these days it’s just easier for me to test it out and send it back if it doesn’t fit. Long story short – it fits, with a very minor modification.

You must remove the seat to install this because it is that tight of a fit. Once you pull off the plastic covers that hide the seat bolts, you can then unbolt the 4 bolts. Fold the seat back into its most acute position and then lean the entire seat back against the back seat. This gives you plenty of room to work.

The modification necessary is to trim off the floor vent. It sticks out a little bit too much for the sub to sit flat on the ground.

Another test fit shows that it now fits nice and snug.

Since I was already down there I needed to find a grounding point. There is already a very handy grounding bolt underneath the carpet right between the two front seat bolts. You can pull back the carpet to reveal it. I cut the carpet because it was hot and I wanted to get out of the garage asap. I later mended the cut I made with a strip of Velcro. It will never be seen, so I’m OK with that.

I ran the short ground cable through to the hole near the drive shaft tunnel. I also ran my remote turn on wire and RCA cables to this location. Obviously that involved removing some trim panels and the radio itself. That stuff is already well documented elsewhere. You can also see the horizontal cut I made into the carpet between the two floor vents.

Next I ran the power wire through the grommet in the firewall that everybody uses. Just pull it out and drill a hole though it big enough to squeeze your wire through. I think I read somewhere that if you have the 6 speed, you will have to find an alternate location. The red arrows show the grommet reinstalled and the black wire loom that I ran to the battery. This is all routed behind the rubber barrier that’s located just to the outside of where the hood struts go. I have the rubber barrier folded up and out of the way in this picture. If you look closely, you can also see that I hid my HID ballast in there too.

Here's another shot of the wire routing (and HID ballast):

I pulled the wire into the cabin and ran it on the driver’s side of the drive shaft tunnel. Then I crossed it over to the passenger side over the tunnel and underneath the carpet. I tried to make sure that the power wire and RCAs intersected perpendicular to each other to minimize interference. With all the wires routed, here is the sub all wired up.

Couple more shots. From the front:

From the back:

At this point I bolted the seat back down and put the bolt covers back on. The seat has full range of motion. There is a very tiny piece of hardware that slides on the rail that ever so slightly touches the edge of the speaker surround as you move the seat all the way back. A couple passes and it scraped enough of the plastic speaker enclosure to clear the way for full fore-aft adjustment. We’re talking a fraction of a millimeter here – nothing to be alarmed about. Nobody will ever see the tiny scratch. It’s possible with a little more wiggling and positioning that I could have completely cleared the enclosure, but like I said, it was hot and I wanted to finish.

Here is a picture. The red arrow points to the metal piece that slides with the seat. The green arrow points to the scratch it made on the sub enclosure. Again, more judicious fitment of the enclosure could have avoided this, but as you can see it’s not a big deal at all.

With the seat back in place here is the front:

the rear:

And the side... You can access the controls here.

Tuning the subwoofer
I set the gain all the way up since I am using the remote gain control to vary the output. I know you’re supposed to set the gain to match the head unit’s output, but what does that really accomplish if you’re constantly varying the gain with the remote knob? Even when cranked I do not hear distortion with regular recorded music. 0dB test tones are a different story, but I don't listen to test tones for fun.

I set the crossover to on the sub to 80Hz, but it's crossed over even lower at the head unit (more on this later). I set the phase to 0 degrees. I played a 50Hz test tone as I moved the phase knob from 0 to 180 degrees and “0” produced the least cancellation and the loudest tone. 50Hz can still be heard through the main speakers becuase of the crossover's slope. There's always some bleed though past the crossover frequency. Additionally, I set the bass boost on the sub to "0". Too much boost sounds artificial to me. I don't believe in too much boost and smiley face EQ settings (boosted lows, attenuated mids, boosted highs = smiley face). I like natural clear sound. You will hear more music this way and your ears will be less fatiqued after long periods of listening.

After a lot of listening, I set the head unit’s HPF to 63Hz and the LPF at 63Hz as well. The stock speakers can handle this and the sub really blends best this way. A higher crossover point just sounded too boomy. This is the smoothest setting. My EQ is set flat except for one tick down at 100Hz. There was an audible hump around that frequency that needed to be attenuated.

After all that, I was able to remove enough of the bass duties away from the main speakers so that they could play louder and cleaner. The subwoofer takes over at 63Hz and sounds cleaner and louder than the main speakers ever did. The sound is nice and full and can get quite loud. It just doesn’t go down as low as a huge box in the trunk, but that’s the compromise you have to make when you want all your cargo space. Trust me, kick drums hit you in the chest a bit and basslines ooze out smoothly as you can clearly hear the bass player’s pick scraping his strings through the main speakers. In other words - no muddiness. Hip hop sounds good too as well as electronic music. I am totally satisfied with this little subwoofer.

I may or may not upgrade the speakers. It sounds quite good already. I think I will move onto leather interior next.

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