I would really like to add a subwoofer to my factor stereo system. A buddy added one in his car (not a vette) by taking "signal" from his rear speakers and feeding the speaker level inputs of an amplifier. This was bridged and fed a 12" free air sub in his hatchback. and sounded wonderful. He turned the bass down on his stereo head unit, and then adjusted the gain up on his amp to turn up the bass. This keeps the bass from the factory speakers, yet allows the system to really come alive!

Would this same approach work on my Z? I'd but the amp and the 12" free air sub in the spare tire compartment. Thoughts??

 

Depending on the amp, you may or may not be able to take the signal by taping into the speaker wire of a rear speaker. My Kicker can do it but not all can. IMO the signal will not be very clear using this method but since you are using the stock head unit it's probably the only alternative. Why use a free air sub when you can make a box for the rear compartment? Id take a sealed sub over a free air any day of the week.

 

Should I use the spare tire compartment as my "sealed box"?? I could make a plate (to fit the opening) for the speaker, cover it with high-grade automotive carpet, and mount it over the compartment. ??

 

This is exactly what I did in my previous '01 Coupe. I plan on reinstalling the same thing into my '04 Z.

I used a 12" JL Audio Sub mounted in a 5/8" thick MDF "Plate". Thicker is better but I didn't want it to sick up too much. I beveled the edges with a router and covered with black carpet. This doesn't give you a 100% sealed enclosure due to some slight air leakage at the carpet. But I found it good enough to produce very good results. I also used high-strength steel fencing material to make a protective barrier for the speaker - under the carpet. I can take some pictures of what I did if you like.

Also, I tapped into the wires coming out of the factory head unit to get a pre-amplified signal. I think I have documented somewhere, what color wires from the head unit were used. There are also commercially available adapters that will give you a pre-amp output from your factory head unit.

Tapping off the rear speakers using a line-level converter is a typical method for obtaining a pre-amp output to your amplifier. However, Bose applies some type of equalization in their amplifiers that may not be appropriate for your sub. I'm not completely sure but I don't think that the rear speakers of the Vette receive the lowest bass frequencies due to this Bose equalization. You want a full-range signal or at least all bass frequencies sent to your Sub amp. Then you can use the amp's built-in crossover (if it has one) or an external passive crossover to tailor the output of the amp to your specific sub.

 

You are correct, tapping into the rear speakers in the ZO6 will only give you "mid-range" bass and NO low-end bass. Tried that on mine and it sounded like crap, had to connect through the front speakers instead. Also, I know Mike (on the forum here) sells mdf boxes for around $200 and that includes the sub/subs. I did this install for less than $500 and that includes the box, subs (MB Quarts from Mike), amp, and install. All I can say, is that it sounds SWEET and now I have bass to go along with the factory BOSE. You may find alot more information in the audio section of the forum too... I know not everyone knows about it: http://forums.corvetteforum.com/zeroforum?id=20

 

I have a midrange Alpine amp and a 10 inch Kicker sub. I put the sub in a shallow box and rested it flat in the trunkwell. It only sticks about 2 inches above the lip or the well so I don't really lose any space inside the trunk and get superior sound.

 

I added a Bazooka 10" subwoofer and amp to my rear speakers, fits perfectly in the rear center compartment:) I adjust the base at the bazooka vs on the dash, LOVE IT!

 

I did somthing similar. I added an ampified SAS bazoka and placed it in the center compartment. The signal had to be obtained from the front speakers. I only recieved a mid signal from rear speakers and was unable to obtain bass signal from behind reciever. Had similar system in my c5. The main difference was that the c5 had a sub signal behind the reciever. I had it done by professionals 2years ago, that I've been using for over 10 years that are the best. Anyways it still sounds great in the car and can be made loud enough for the car next to me to feel. If you want to set car alarms off as you drive by or have quarter flipping compititions, you would need more extensive of a system. The tube cost me about $300 back in '98, install was $50, I couldn't imagine driving without it.