08 XC90 Audio Bass misery...

[08volvo]

Hello Volvo enthusiasts!
I am a new user to this forum (1st post) and am working with my girlfriend's newly purchased 2008 Xc90 with Dvd, Navi., Rear A/C, and 8 speaker system. We are both about to be freshman in college so the funds are definitely limited so I'm trying to do this for her without purchasing anything too expensive (Rockford Fosgate 360 etc...) I recently put 2 12" Kenwoods in my mk3 TDI so i am passing on my entry level sub to her. (400w DUAL 2 channel amp bridged to a SVC DUAL 12" 500w sub) I wanted to build her a custom box but looked and saw on here that with Rear AC the stealth rear sub is not possible without heavy modification. I also found that if I remove the battery cover and the spare tire kit foam, the amp is a perfect fit. 12v+/- for the amp will be right next to the battery (thats a plus) but i didnt want to have to take out 3rd row or center console to wire up in the front for speaker tap/remote turn on.

My questions are:

1) Can i use a High-Low aka speaker to RCA converter on the rear speakers by the 3rd-row seatbelts to get a tap for the amp? Or will these cause distorted signals from the Eq. (looks to be grey/grey-white and orange/orange-black wires.)

2)If so, where could i run the remote wire? Personally I was thinking to the 12v Accessory plug in the back to keep trim removal and wiring simple.

On top of this, if i dont have a remote sub control, should I get one? Or what is suggested to delete the rattly ass bass in the speakers in the doors while still being able to use RCA converter? Any suggestions are welcome and correct me on anything I have missed or am mistaken on.




Thank you all,
Adam

[08volvo]

Bump

[okar]

Hey Adam.

It's been a while since your post, but in case its still useful, I'll drop my 2 cents. (I'm brand new here and seems sad how many posts remain completely ignored)

I added an amplified Nakamichi 12" ported subwoofer and you wouldn't believe how simple and good it was. I did tap the signal from the rear speakers and the sound is great. Those are only tweeters but they have a passive crossover in place, so the singal they receive is full-range.
From there the cable just drops a few inches down to where the battery is located so it was a very short cable without the need to take out a single screw. I used a hi-lo that generates a remote signal when it senses sound, so with that and the battery right there, there was no need to even look at the front of the car ever. The sub has its own crossover so there was nothing else to do but adjust and enjoy, so the entire setup was done surprisingly fast in about an hour.

Regards,
Oscar.

[08volvo]

Hey Adam.

It's been a while since your post, but in case its still useful, I'll drop my 2 cents. (I'm brand new here and seems sad how many posts remain completely ignored)

I added an amplified Nakamichi 12" ported subwoofer and you wouldn't believe how simple and good it was. I did tap the signal from the rear speakers and the sound is great. Those are only tweeters but they have a passive crossover in place, so the singal they receive is full-range.
From there the cable just drops a few inches down to where the battery is located so it was a very short cable without the need to take out a single screw. I used a hi-lo that generates a remote signal when it senses sound, so with that and the battery right there, there was no need to even look at the front of the car ever. The sub has its own crossover so there was nothing else to do but adjust and enjoy, so the entire setup was done surprisingly fast in about an hour.

Regards,
Oscar.

Oscar, i greatly appreciate the response. I have been putting this off due to not knowing how the sub would sound tapped from the rear tweeter. Do you know which exact make RCA converter you purchased? I would love to be able to do this for her.
Thanks,
Adam

[okar]

Sure, it's a Pyle PLVHL70 I got from Amazon. I'm sure you can find something better, this one doesn't look like the best quality item but it does the job.

I did wait a long time just like you since I didn't know what to expect and also got no reply from other forums. When I got the sub I started just investigating what it might involve and ended setting it all up. You can use a plastic pry tool to take out the rear speaker grilles, and you'll see the speaker itself will come with them. I unhooked the connector and did my tap easily. Then got the cable in there and it immediately came out at the bottom near the battery.

I didn't know the wire codes so I just tested a bit: once the sub was on, a couple of seconds of music showed me the polarity was reversed. Once I got left and right working together, I cranked up all the bass at the head unit (with low volume) and used the subwoofer level at the minimum, so I could be able to hear them both about the same level. At that point just raise and lower or even turn off the sub to see if it's working with or against the door speakers. Consider your OEM speakers a system and your sub another one. The idea is to find out just by listening, if they work better together or alone. If you hear more bass with either system alone, the polarity is reversed. If they add up, it is correct.

Once it was all wired right I went back to the head unit and, with the subwoofer turned off, I started with a flat eq, some well known music, and cranked it up. I then lowered the bass so the door speakers could handle it better. Then cranked it up a bit more and repeat. When it was as loud as they would handle it without distortion, I lowered the volume to something comfortable (not low but not loud either) and started rising the subwoofer level (on the amp) until it filled in nicely. You'll need to play with the crossover so that there are no gaps. A very well known piece of music is key for this. Typically the crossover should end up around 100Hz so start there. The amp level has no typical setting as it depends entirely on the voltage provided by the hi-lo and the amp's sensitivity.

Finally, when the sound was balanced, I fiddled with the mids and highs on the eq according to what I felt was needed. The result is a very strong bass that doesn't interfere with the main full-range speakers in the doors, and because the bass on the eq is a bit low, they don't rattle or distort at all. In my case everything reaches its peak at about the same time. Your subs are more powerful so they will still have quite some headroom.
As Volvo uses fiber optic to interconnect components and provides no dedicated subwoofer output nor level, the only practical way to go futher than this is to replace everything, including head unit. Still, this kind of setup is can be surprisingly balanced and powerful. Almost forgot, make sure to set the fade level to what you like. Because the sub is wired to the rear speakers, you won't be able to move the front/back balance without messing the whole thing up.

Now, about the remote for the sub... that's a dark topic, I hope no one gets offended. Any audio professional (not car audio installer) will tell you that once a sound system has been properly aligned, there is no need to move any levels or settings ever again (unless any component or environment variable changes). Only basic bass or treble knobs should be used to compensate for example for old records or each person's taste. Any such change in eq must happen prior to the amp levels, otherwise the crossover points will move and the entire alignment will be no more. Remote level controls exist (even in really good car audio brands) only because they sell, and rely on most end-users' ignorance about audio. I guess it's something that happens everywhere, in most fields. End users are not expected to be experts, just to have money.

I'm not sure how experienced you are in audio, I hope this long post wasn't too much details you might already know. On the other hand any more questions I'll be glad to help if I can.