- Audio Systems:
- This page will cover as many
different system configurations as possible
(until I get tired of drawing the diagrams).
Note:
The proper fusing for the amplifiers is NOT
shown. Please read the fuses and amplifiers pages of this site for tips on
proper amplifier installation. The head unit page will also give you some
important information and may help you install
your HU without murdering it. :-)
- These first few diagrams will
allow you to get a good clear look at all of the
connections on the devices which will come later
later on this page. These components will be much
smaller in the later diagrams.
This is the head unit and all of its connections.
This is the electronic
crossover.
These are the
speakers.
This is the amplifier.
- Basic System
- Head Unit,
1 Amp and 4 Speakers
- Head Unit,
1 Amp and 4 Speakers (all on amp)
- Head Unit,
1 Amp and 4 Speakers (2 subs on amp)
- Head Unit,
2 Amps and 4 Speakers (2 subs on one amp)
- Head
Unit, External Crossover, 2 Amps and 4 Speakers
- Head
Unit, External Crossover, 3 Amps and 4 Speakers
- Start of 4
Channel Amplifier Section
- Basics of 4
Channel Amplifier
- Basic System
with a 4 channel Amplifier
- A 4 channel
Amplifier system with 4 Channel Input
- 4 Channel
amplifier with Bridged Rear Channels
- 4 Channel
amplifier with Both Front and Rear Channels
Bridged
- 4 Channel amp
on front speakers, 2 channel amp on subs
- OK, Now to systems.
- The following is the most basic
system. It involves a head unit (HU) and 2 pairs
of speakers which are driven by the head unit's
internal amplifier. You can see that the battery
terminal of the HU is connected to a constant
source of power (the battery) with an inline
fuse. The accessory wire for the HU is connected
to a power source which only has power when the
ignition switch is in the 'on' or 'acc'
positions. The battery and accessory connections
will not be shown in the following diagrams but
will be the same for all of the systems. The
lines point to the speakers but the exact
connection isn't shown. The colored speaker wires
from the HU are going to be connected to the
positive speaker terminal of the speaker. The
black or darker speaker wire will be connected to
the negative speaker terminal. Of course, this is
just a generic type of diagram and you should
consult the wiring diagram which was supplied
with the HU.
- Using the HU's internal
amplifier and an
external amplifier:
- In this diagram, you see that
the front speakers are being driven from the
HU's internal amplifier and a pair of rear speakers are being powered by an external amplifier. This type of system has
very little chance of sounding good. If the
amplifier is being used because more volume is
desired and the front and rear speakers are
roughly equivalent in efficiency then the front
speaker's amplifier will probably be driven into
clipping well before the external amplifier
reaches clipping. If the HU's fader is turned
toward the rear (amplified) speakers, you may get
better sound quality (or at least less clipping
from the internal amplifier) but the image will
be from the rear of the vehicle which is
generally undesirable. Many people run tweeters
from the internal amplifier but this also
generally leads to less than optimum sound
quality. Not because the internal amplifier is of
poor quality but because it will be driven into
clipping if the output of the tweeters is to keep
up with the speakers which are driven by the
external amplifier.
- Since most amplifier are
capable of driving 2 pairs of speakers, I would
strongly recommend driving all of the speakers
from the external amplifier. (like this)
- This system has a better chance
of sounding good than the system which had the
amplifier driving the rear full range speakers. If the amplifier has a
built in crossover, you'd set the crossover for low pass and probably to about 90 or 100
hertz (if there's a choice). You still won't be
able to get very high SPL before the HU's
internal is driven into clipping but if you only
need to pick up the bottom octave or so of the audio spectrum, this
may do a good job.
Note: The remote/power
antenna wire won't be shown on the following
diagrams but you obviously have to connect it in
a real installation.
- This diagram shows how you'd
connect 2 amplifiers if the amplifiers had internal crossovers. You would set the
crossover on the top amplifier to high pass and the crossover on the bottom
amplifier to low pass.
You could adjust the levels of each amplifier by
using the HU's fader control or with the gain
controls on the individual amplifiers.
- In this diagram, we are using
an external crossover. To control the levels
between the front/high frequency speakers and the
subwoofers so that the system sounds 'balanced'
(not too much or too little of either), you could
adjust the levels on the crossover or use the gains on the amplifiers.
It's generally, but not always, easier to use the
crossover's level controls. In this
configuration, since we are using a single set of
RCA cables, you'd have no control over the levels
of each amplifier from the head unit. Some
crossovers have a third input which would allow
you to connect the other set of RCA outputs (from
the head unit) to the crossover (into a subwoofer
input jack). This would allow you use the
fader to adjust the levels between amplifiers.
- In this diagram we see that we
have a seperate amplifier for the front, rear and
low frequency speakers. We are using both sets of
RCA outputs from the HU. The RCA patch cables go
to the front and rear inputs of the crossover.
The front outputs of the crossover go to the
amplifier which drives the front speakers. The
rear outputs go to the amplifier which drives the
speakers in the rear deck. The crossover's
subwoofer output goes to the subwoofer amplifier.
On most crossovers, the fader will still operate
through the crossover which would allow you to
balance the levels of the front and rear speakers
from the head unit. Many crossovers mix the low frequencies of the front and rear input signals and send both of them into
the subwoofer section of the crossover. This
makes sure that you have low frequency output no
matter what the fader position.
Multi-Channel
Amplifiers
- Multi-channel amplifiers are
essentially the same as a stereo amplifier except
for the fact that they have more than 2 channels.
Now this may seem fairly obvious to some people
but you must remember that this site is designed
for people who are new to car audio. This section
will (hopefully) clear up any misconceptions or
confusion about multi-channel amplifiers in
general.
- Generic 4 channel amplifier:
-
- Basics:
- As you can see on the 4
channel amplifier below, there are 4
input jacks and 4 sets (+&-
terminals) of corresponding speaker
output terminals.
- There is also an input
selector which allows you to use only 2
inputs to drive all 4 channels without
having to use all 4 input jacks. When the
switch is in the 2 channel input
position, only 2 inputs (1 right and 1
left) are required to drive all of the
channels. When the switch is in the 4
channel position, all 4 channels have to
be driven seperately and are independent
of each other.
- You can also see that
there are 2 crossover selector switches.
They allow either pair of channels (front
or rear) to play either a full range
signal (which will pass the entire input
signal to the amplifier section), a high
pass signal (blocks out the low
frequencies) or a low pass signal which
blocks out the high frequencies but
allows the bass to play through. Now
these are the simplest of built in
crossovers. They don't allow you to
select the crossover point or slope. Some
amplifiers allow you full adjustment of
all parameters but for this example, I
chose to only show this type (read: I was
too lazy to draw anything fancier). On
this amplifier, the front 2 channels are
set to high pass. The rear channels are
set to low pass and the input selector
switch is set to 4 channel which means
that all 4 channels will have to be
driven individually (all 4 input jacks
will have to be used).
- Basic System:
- In this diagram, you can see
that one set of pre out jacks from the head unit
are connected to the front inputs of the
amplifier. To allow all 4 channels to be driven,
the input selector is set to 2 channel. The front
channel crossover is set to high pass. The front
channels are used to drive a pair of coaxials.
The rear channel crossover is set to low pass and
the rear channels are being used to drive a pair
of subs. In this type of system, the relative
output levels would have to be set with the gain
controls on the amplifier.
- 4 Channel Input:
- In this diagram, all 4 input
channels of the amplifier are being driven
independently. The input selector is set to 4
channel. Everything else is the same as the
previous diagram. This setup would be a little
better than the previous diagram because you
could adjust the relative levels of the coaxial
speakers and the subs through the use of the
fader control on the head unit.
- Bridged Rear
Channels:
- This diagram shows the rear
channels bridged. When bridging an amplifier, you
must make sure that the total impedance of the
speakers is not too LOW for the amplifier that
you're using. If you're confused about the
impedance of multiple speaker loads, try reading
either this link
or this link.
- Both Front and
Rear Channels Bridged:
- This diagram shows how you
might use the amplifier with both the front and
rear channels bridged. You can see that the rear
preamp output channels of the head unit are
connected to the 4 channel amplifier AND the
input selector is set to 2 channel AND BOTH
crossovers are set to low pass. The front pre
outs of the head unit are connected to separate
amplifier which is being used to drive the
front/high frequency speakers. The relative
output levels of the high and low frequency
speakers would again be adjustable through the
fader control of the head unit.
- 4 Channel amp on
front speakers 2 channel amp on subs:
- This diagram shows how you
could use the 4 channel amplifier on the high
frequency speakers and a second amplifier on the
subs. Note the crossover settings on each of the
amplifiers.
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