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The 3 "C's"
The 3 "C's" of sound are Connections,
The wires and patch cables you use with your system are the
glue that holds your system together. Smarter people than
you and I working for manufacturers have designed and built audio
equipment that, when properly and appropriately connected, will
deliver peak performance. The one part of the equation that you
have complete control over is the interconnection of this gear.
There are times when a piece of equipment is going to fail.
I've had brand new amplifiers out of the box not work; but normally
if no sound is coming out ... you've got a bad connection(s) somewhere.
I should define the term "bad connection." I do not
necessarily mean a cable with connectors on it that has a broken
or shorted contact. Nor do I only mean a break in a conductor
somewhere. These are easy to test for and repair or replace. Good
soldering etiquette, proper handling, and attention to strain
relief will minimize these types of problems.
The most frustrating types of bad connections that foul
up the performance of a system are ones when there appears to
be nothing wrong with the cable!
You have an output from a mixer that is a male XLR. Although
it is line level out, and uses this type of 3 pin non-shorting
connector, the mixer's manufacturer has wired the output unbalanced.
To facilitate this, Pin 1 (ground) has been strapped with a wire
jumper to Pin 2. Pin 3 of the XLR is your positive side of the
signal. This is called Pin 3 hot.
Now lets say you have an equalizer that you want to put after
the console output. This also has an XLR connector on its line
level input. However, for some reason, the manufacturer designed
and built the Eq with an unbalanced input, and they configured
their wiring as Pin 2 hot. Thus they have a jumper strap between
Pin 1 and Pin 3. This time Pin 2 has the positive side of the
Initially, you would say you're going to have a phasing problem,
but the reality is worse. The minute you take a perfectly good
male to female XLR patch cord and connect the console's output
to the Eq's input you get nothing!? You check the console without
the Eq; you check the Eq without the console; you even meter the
cable. Everything works until you combine them. Why?
The answer is not as obvious as it is frustrating. You have
dead shorted the input of the Eq. All three Pins of the XLR have
been connected together. Think about it. Pin 1 and Pin 2 are jumped
together on the mixer. Pin 1 and Pin 3 are jumped together on
the Eq. When you plugged the patch cable into both units, Pin
1, Pin 2, and Pin 3 are all shorted together .... Result: The
Eq's input will shut down and not pass any signal.
This is just one example of "inappropriate" connectivity.
Manufacturers don't help the situation. Many don't publish in
their Owner's Manual the complete details of their products. Others
have weird special case situations. Two situations come to mind:
- The standard (or as they now refer to it) Classic
Mackie 1604 mixer with all those TRS (Tip, Ring, Sleeve) ¼"
jacks on the back has a very strange quirk. The Main Left and
Right outputs are wired out of phase to the rest of the console!
This means the ring, not the tip of a ¼" TRS plug (also
referred to as a "stereo" plug), is what will receive
the positive side of the audio signal. The tip is the negative.
Mackie says if you read the fine print of the manual, this is
explained. I bought both of my 1604 consoles used with no manuals.
We found it the hard way.
- The Crown Macrotech series amplifiers have a potentially
costly condition that is less than obvious. The amps come stock
with the "P.I.P.-FX" input card in them. This card has
the TRS ¼" jacks and XLR input connectors on it. You
can use the ¼" jack with either a balanced signal coming
from a TRS ¼" plug, or an unbalanced signal by
using a TS (Tip, Sleeve - also referred to as "Mono")
¼" plug. If you buy the amps with a "P.I.P.-CLP"
input card, you cannot feed the ¼" inputs with a mono
plug (unbalanced). This connection creates a condition in the
amp which will lead to burnt up speakers. I know a person that
this happened to. Crown puts no warning on the face of the card,
but says you have to read the fine print of the manual.
THERE IS HOPE
A few manufacturers' publish documents that help you make or
choose the correct patch cables. Yamaha's Owners Manual is hard
to read (too many things lost in the translation) but full of
diagrams and How To's. Rane includes an excellent wiring chart
with all new products. EV has the P.A. Bible Series available.
My last suggestion is to talk to the people that repair this
equipment. They will tell you what you did wrong. Develop as good
a relationship with a repair technician as you did with the Dessert
Lady in the school cafeteria. You will be satisfied in both cases.
'Til Next Time,