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Section 4
Connections
For guitarists this is the most common of wiring schemes.
The cable used is normally a single lap spiral screened
(typically 95% braid) coaxial cable, with a PVC insulated
outer and conductive PVC inner surrounding a multi-
stranded copper core. Typically this type of cable is often
marketed as 'instrument' cable. The best cables however,
are double screened; they have a 95% braid outer screen
and a 100% conductive foil inner screen. The outer braid
rejects RFI (as it forms a Faraday Cage) and the inner
screen protects against EMI.
The problem with these cables are that they are susceptible
to noise, because unbalanced cables do not reject noise like
balanced ones do. Lap spiral screening is pretty poor, and
although the double screened cables easily, and audibly beat
the pants off of lap spiral screened cables the unbalanced
configuration just isn't the best. Also these cables may
suffer signal loss over large distances (> 20ft).
On the plus side these cables are easily available and are
pretty much bog standard when it comes to connecting
guitar's and their associated gear. However, make sure you
invest in some good cables.... cheap ones use pathetic lap
spiral screens...Ill be mentioning this again!
Unbalanced Stereo 0.25" & 3.5mm
TRS Jack
A typical configuration found with unbalanced, lap spiral
screened, with 2 PVC insulated multi-strand copper cores.
This sort of connector and cabling is often found on
headphones, and in the case of 3.5mm jacks on PCs. On a
PC the line in, line out and speaker outs will all use this
configuration. Whilst a higher quality cable can be used it
inevitably isn't due to the width of high quality cable
exceeding the maximum permitted by the 3.5mm
connectors. As this cable is rarely used where audio quality
is paramount it is unusual to find high quality cable being
used – even with 0.25" jacks.
© Copyright 2000-2002 Barry S. Pearce et al.
Balanced Mono XLR
Typically found connected by lap spiral or 95% braid
screened cable, with 2 PVC insulated multi-strand copper
cores. This is the most common of balanced wiring
schemes. It is used by microphones, mixing desks, FOH
snakes in large theatres etc etc. Its use is extremely
widespread. For the most part the wiring scheme is
standard, but one or two equipment manufacturers have
been known to use different schemes, although these days
that is rare. Often sold as 'microphone' cables these cables
offer fantastic noise rejection and may be used on extremely
long runs before preamps are necessary. XLR connectors
may used freely interchanged with TRS connectors for
balanced applications without conversion.
These cables are also the type used with DMX based
lighting controllers and dimmer packs. Pays to have a few
extra of these about at a gig.
Balanced Mono 0.25" TRS Jack
This wiring scheme is gaining popularularity, and in the
past has been used less than XLR connectors. It is
theoretically identical to the balanced mono XLR cable. In
fact, given the same spec cable the actual use of connector
(either TRS or XLR) will be irrelevant in terms of audio
quality.
Thus,
TRS
interchanged
with
XLR
applications without conversion.
Although it is possible to wire a 3.5mm jack in the same
manner it is extremely unlikely – again due to cable size
constraints. I must say I have never seen a balanced
application using a 3.5mm jack.
connectors
may
used
connectors
for
balanced
freely
24
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