Before we can get the noise out, we have to detemine how the noise is getting
into your system. There are various troubleshooting
techniques to get to the root of the problem, but I recommend learning one
method and sticking to that method. Begin at the amplifier. Unplug the RCA
cables and insert "Muting Plugs" in their place. A muting plug is simply a
dead short. You can make your own muting plugs on a budget by going to Radio
Shack and purchasing a pack of 8 Phono (RCA-type) plugs (Part Number 274-321)
for $2.99. If you are planning on a career in audio, then check out the
professional Right Angle RCA Phono Plugs from Monster Cable Products (Phone
415-840-2000). I have a been using the same set of Monster heavy metal muting
plugs for the past 8 years and they still look new.
Begin making your muting plugs by soldering two small wires to the RCA Plug.
One wire is connected to the center pin and the other wire is connected to
the outer circular connection. Then strip the remaining ends of the small
wires and solder them together. Attach the barrel and that's it. This is one
of the most important troubleshooting devices in your tool box.
With your muting plugs in the input of your amplifier, the signal level is
zero volts. As we all know, with zero as a multiplier, the result must be
zero. For instance if your amplifier is providing 15 dB of gain, the speaker
output of the amplifier must be zero volts. If you hear engine whine with the
muting plugs in place, then the problem lies with the amplifier, speaker
wires, passive crossover elements, or the speakers themselves. If you don't
hear engine whine with the muting plugs in place, then the problem lies with
the deck, processors, or signal cables.
IF YOU DON'T HEAR THE NOISE
Remove the muting plugs from the input of your amp, insert the RCA cables,
and relocate the muting plugs to the opposite end of the RCA cables. Is the
noise back? If so, then the cables are picking up the noise. If there is no
noise, then plug the RCA cables into the inputs of the deck/changer. If the
noise is back, then the deck/changer is the problem. Just to make sure,
temporarily relocate the deck/changer to the Amp. Connect with very, very
short RCA cables. Is the noise back?
IF YOU HEAR THE NOISE
To determine if the source(s) are the problem, you'll need to substitute a
quiet source. Can you find a Sony Walkman or Discman? Add the appropriate 3.5
mm stereo to Dual RCA adapter and see if the system is quiet with the Sony
portable player. If it is, then your deck and/or changer is the problem. If
the system is noisy with the portable player, then the problem lies in the
feed.
IF YOU HEAR NOISE WITH PORTBLE CD PLAYER
Normally we'd use a balanced signal system to solve the porblem. This requires three items: 1)
Balanced Transmitter, 2) Balanced Transmission Line, and a 3) Balanced
Receiver.
Start by eliminating your present signal cables and selecting small twisted
pair cables such as the MicroLoop XLN cables from Monster Cable Products
(phone 415-840-2000). This type of cable should always be used in high noise
environments.
IF YOU HEARD THE NOISE WITH THE MUTING PLUGS ON THE AMP's RCA INPUTS
Speakers use coils of wire and coils of wire can easily pick up noise. This
is how the original telephone worked. Also passive crossover elements use
coils of wire. Crossover coils can couple noise from any wires or conductive
surfaces. Also speaker wires are simple coils of wire that are unwound. They
also become an antenna for noise. The noise gets into the amp and you hear it
in the speakers. For the final test, connect a test speaker on the amp with a short
speaker wire. If you hear noise, it's time to check your amp.
This is a rough guide to get you started on how to get rid of the noise in your car audio system. I don't have time right now to finish off this topic, but I'll have it done this winter break of 99.
Hope this helps.
