Recording - August 2015 - 60

By Paul J. Stamler

Part 8: Cables-The Forgotten Component
The last several articles in this series have talked about microphones: their theory and practice, what I chose for the Ottoman
Underground session, and their use in stereo arrays. The next
component in the signal chain is the mic preamp or console, right?
Actually, no; the next component is the microphone cable,
which connects the mic to the preamp, console or interface. And
while there are many factors in recording that are esoteric and
complex, the fact remains that for most recordings, if the mic
cable isn't working, you've got nothing. So this installment of
First Steps is about mic cables, how they work (there are some
subtleties) and how to keep them working-for a long time.
How long? Well, you should know that the average lifetime for cables used and abused at live gigs has been estimated at six months. Back when I was just getting started in
serious recording umpteen years ago, I bought my first goodquality cables from the local pro audio store. They were
Neumann cables (which are now sold under the Gotham
brand), and I bought five of them: two each of the 25' and
50' lengths, and one 100'. The latter I cut into six pieces
16.6' apiece, and soldered on new XLR plugs...
And I'm still using them. All of them. I've had to re-solder a
couple of the XLR plugs over the years, but I've never had to
discard a broken cable. Why? Because I treated them right.
This article will talk about how to treat cables right. I'll start
by talking about how audio cables are constructed.
What's inside
A professional mic cable has a minimum of three conductors inside it, sometimes more. The two principal wires are in
the middle, usually twisted into a tight spiral (Figure 1); these
carry the actual audio signal from the microphone, along
with the phantom power that drives the mic's head amp (if
it's a condenser or active ribbon mic). The two conductors
are called Hot and Cold; they're inevitably stranded, which
means that instead of being solid chunks of metal, they're
divided into many fine metal wires. This helps make the
cable flexible.

Not always, though; some cables use a separate Ground
wire, wrapped in with the Hot and Cold wires. In these cables
the Ground wire carries the ground connection (duh), while the
shield is connected to ground only at one end: typically the male
plug, which plugs into the preamp.
Cables with two or three internal wires, as I said, have them
tightly wound around each other. The idea behind this is that, if
the cable passes near something which radiates hum (like a
power transformer, or an electric motor, or a power cable carrying lots of juice) the hum source's magnetic field will induce
identical noise signals in the two closely-wrapped signal wires.
There's another wrinkle: some cables use two separatelyinsulated wires for the Hot conductor, and two more for the
Cold, which makes for an even more intimately wrapped bundle in the middle of the cable (Figure 2). In my experience,
cables like this-called Star-Quad® by Canare and Belden,
Neglex® by Mogami-never have separate Ground wires; they
carry the Ground connection in the shield. Star-Quad construction takes the usual twisted pair of signal wires a step further:
Figure 1. A good mic cable has the Hot and Cold wires
tightly and evenly twisted.

because the two Hot and two Cold wires are so well intertwined
with one another, an induced noise signal has the best chance
of being identical in Hot and Cold. We'll find out next month,
when we discuss mic preamps, why this is a Very Good Idea.
In a cable with two or three internal signal wires, the insulation
on them is always color coded, with Hot and Cold often colored
red and black, or black and white (the Ground wire, if present,
is often green). Star-Quad cables are similarly color-coded; the
two Hot wires are typically white, while the two Cold wires are
blue, as shown in Figure 2.
Pin 2 in a standard XLR connector is reserved for Hot, Pin
3 for Cold, while Pin 1 is Ground. On the connectors, the

You should know that the average lifetime for cables used and
abused at live gigs has been estimated at six months...
The third conductor is the shield, which surrounds the two
audio wires and helps keep interference out. In some cables
(like my Neumanns) this is made from more fine strands that are
wrapped around the central wires in a spiral; in many other
cables the strands are braided together in a tight weave. In most
cables the shield is connected to the ground pins of the XLR
plugs, and acts as the ground conductor from the mic to the preamp, console, or audio interface. The shield also carries the
ground for the phantom power supply.
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RECORDING August 2015

pins will be numbered for reference, and of course the female's
numbering will be the reverse of the male's; see Figure 3.
This color coding and numbering makes it easy to properly connect
Pin 2 on the female end to Pin 2 on the male end, and Pin 3 likewise
to Pin 3. If you connected the female's Pin 2 to the male's Pin 3, and
vice versa, you'd have a cable that flipped the signal's polarity. That's
occasionally a useful thing to do, but you don't want it to be a surprise.
Some audio pros carry a polarity-flipping cable in their kit, but it's
always prominently labeled, so they won't use it by mistake.

Table of Contents for the Digital Edition of Recording - August 2015