Q.: I recently purchased a new Pyle 4340 amp. I'm getting a warble sound through my speakers and when I turn the stereo on it doesn't go away -- if anything, it gets worse if I leave the stereo on. This happens when I turn the key to accessory or run position and I've moved the ground twice with no luck. The noise even happens when the RCA cord is unplugged from the head unit. I also have a CB and when I key the mic I get a very loud piercing noise through the speakers. Also, if I talk into the mic my voice comes through the speakers. The head unit, CB and amp all have separate grounds. The CB antenna is nowhere near the stereo antenna. If I disconnect the CB it still happens. I'm using 4-gauge Kicker wires. The fuse is 16" from the battery connection and the ground is 10". The RCAs aren't running along any power wires. There's only one speaker wire running with the power wire, but it's still about 3" away. I've contacted Pyle, but they were no help.
Thanks
John Tripp
A: If it were just the CB radio modulating through your system, I'd want to check out the installation in general. This was a common problem with CB, Ham and taxi radios, but in your case the clues add up in a different way. Your installation sounds fine and the fact that you attempted a few fixes should have made you comment on changes to the symptoms, but it didn't seem to make any difference.
When you unplug the RCAs from the head unit, an installation-related problem should cause an immediate change in the character of the noise. At the very least, your amplifier is now effectively isolated from everything except speakers and power. I can rule out power problems, since if it were engine noise, you wouldn't encounter it in the key's accessory position. Also, your complaint would be a whistling noise rather than a warbling.
I suspect the warbling noise is oscillation that's limited to the amplifier itself. My experience tells me that you have a defective amplifier. Stuff happens...
Q: I recently purchased a 2007 Acura TL Type-S Sedan that comes with a stock navigation system, as well as a 5.1 Dolby Pro Logic II Surround Sound System. The stock sub wasn't giving me the bass response that I desired so I replaced it with a 10" Rockford Fosgate HE-2 sub powered by a 4-channel amp that I bridged to get the most power out of it. I bypassed the factory sub and connected an AudioLink PL-2 line output converter, which gave me engine noise at all times. I replaced it with a cheaper AudioLink line output converter. That configuration gives me engine noise at night when the headlights, fog lights or dome lights are on, and when I open the trunk. Curiously, when I open the trunk, I get a constant deep loud bass note that goes away when I open a door. What can be causing this problem and have you heard of any similar problems?
Sincerely,
Marco
Hollyweird, CA
A: This doesn't just happen in Hollyweird! Let me first say that when you are interfacing factory gear to aftermarket, there are many little conflicts that will cause problems. My first recommendation is to go fully aftermarket, "cause stock sucks!" But let's get real here, you have a severely overpriced navigation head unit and you can't justify spending on a different head unit. There is a whole world of interface modules available and more than one will work perfectly in your unique situation.
The bass note with the door open is a strange one and leads me to think either body ground problems or ground loop within the signal chain. Tie that with the seemingly unrelated engine noise and I get a picture of loop problems that can be a frustrating challenge.
First test: With the PL-2 converter in the circuit, lift the device away from the floor of the car and listen to see if the noise diminishes at all. If it does, there's a radiated noise problem that you may be able to solve just by relocating the PL-2. If that has no effect, unplug the input to the PL-2 and short the audio input wires together. If the noise stops, it's coming from the head unit.
Higher-grade interfaces will have higher levels of isolation. Try out an Audio Control DQL-8 or JL Audio CleanSweep. These high-grade products will get you closer to the answer in the shortest time compared to other options. If not, nuke the factory head unit, go aftermarket and smile -- you're better off now.