Audio Upgrade Follow-Up
Questions and Answers, Part 1

> Saw your page on the GP stereo modifications and had one question. Did
> you take the rear 6x9 signals from the trunk (after the amp) and then
> convert them to line level or did you take the signal before the
> amplifier and then amplify it or did you take the signal before the
> amplifier then put it to a line level converter then amplify it?

I took the signal for the rear speakers from before the amp, ran them through line converters, and then amplified that signal. All speaker wires in the stock system (before or after the amp) carry speaker-level signals. If you look at the original schematic on the page you'll see that the inputs to the stock amp are wired in parallel with the wires that feed the front and rear full-range speakers. Also remember, that the rear 6X9 signals in the stock system are NOT full range. They come straight out of the amp from under the glove compartment. That amp has a low-pass crossover built into it, so the 6X9s only get bass frequencies.

The 6X9 signals as they are only good for driving woofers and cannot be used for driving full-range speakers.

I tried to stress that if you're going to the trouble of adding an aftermarket amp, then just get rid (electrically) of the stock one. It can only add distortion and other unwanted characteristics.

> Oh, and I never knew they put the amp under the glove compartment. This
> I gotta see. And I don't have the courage to put the 4in speakers in
> the door. I started to do it, but it seems like it was impossible to
> pull the panel off and I just didn't feel like breaking my GP!

You mean the 5 1/4" in the doors? The 4 inch drivers (full-range) are in the rear deck.

I know what you mean about being concerned to tear a new car apart. It was easier for me, since I've done a fair number of stereo installs in the past. Funny thing is, 36 hours after I drove the car home, The rear seats, door panels, etc. were leaning against my garage walls. You get over the fear. As long as you are reasonably handy and you trust your abilities, go for it!

The door panel is pretty easy, you just have to pry it out. Gently, of course. It also helps if you put tape on your prying tool so that you don's scratch any paint or mar the panel itself. I would recommend one of those panel removers that they sell at the car dealers, or at Crutchfield. It's only about $8. They're nice and wide and spread the force over a large area. Much better than a screwdriver. Actually, the prying part is very easy... once you get an edge started. The start can be a bit difficult, depending on how tight your panel was installed at the factory. The harder part CAN be (doesn't have to be) is releasing the control panel that holds the power window/locks switches from the door panel. Take your time there.

> I modified my car a little. Added an amp, and an Infinity subwoofer
> with the signal from the rear through a line converter. The bass
> however is disproportional to the rest of the system, most likley
> because of the seperate amp. I think the 6x9 lines are power limited.

So you took the signal that used to go the 6X9s, ran it through line converters, and then went into the amp? Sounds reasonable. A lot of people have done the same thing because it's very convenient. The problem that I see though, is that we don't know what frequency the stock amp that feeds the 6X9s is crossed over at. That makes it difficult to predict the performance, so it's more of a hit or miss.

I agree that the bass could be disproportionate. Can you lower the level on your new amp? Also, you probably don't need the 6X9s anymore. Are they still wired in? Remember that a sub can push enormous amounts of air around in the trunk cavity. This air pressure can actually interfere and muddle the sound of the stock 6X9s.

> I replaced the 3/4 inch tweeters with Infinitys. They are a bit better,
> but the original ones aren't bad at all. I would prefer a larger fuller
> range speaker for those tweeters but the size would have to be larger.

I'm confused. How did you replace the tweeters without taking out the door panels?

Another thing to remember is that the tweeters and the 5 1/4" drivers in the doors are wired in parallel without a crossover. If you upgrade the tweeters, and keep the stock wiring without adding a crossover, you will force the tweeters to try to reproduce low frequencies as well as the highs. This won't help the sound quality.