How many engineers have seen neat and well-documented wiring in new
studios? Probably a fair number. How many have seen neat wiring in
five-year-old studios? Not many engineers have, because it is almost
impossible to build studios, no matter how neat and well-documented,
that retain the same level of organization and coherence after several
years in the real world of last-minute remotes, unexpected equipment
failures and format changes made without notice to the engineering
department. It seems almost impossible to stay ahead of the game, but
Allow enough space in the rack to
provide for any future expansion, whether it is adding another station
to the facility or accommodating a new format. Clear Channel Hartford rack room by Scott Frances and
courtesy of the Lawrence Group Architects, St. Louis.
Expansion will happen. I have never seen a studio or studio facility
that didn't need to be expanded within a year or so of its
construction. Provide plenty of room for expansion by running extra
wire and cable pairs, by allotting additional space for equipment and
for wiring blocks, and by providing additional capacity in the entire
Pull more pairs than needed from each rack or cabinet to the wiring
block area in each studio and from each studio to the rack room. Order
cabinets and racks large and deep enough to accommodate new source
equipment, new satellite and remote equipment, and especially new
computers. Size generators, UPS units and HVAC equipment to handle
additional loads. Save space in the building for future studio areas.
Size the rack room to accommodate additional racks, but resist the
temptation to let the current wiring expand to fill that available
Use only smart wires. Don't wire a studio using anything but AES-3
compatible cable. AES-3 requires a twisted-pair cable impedance of
110Ω while traditional analog twisted-pair is typically 30Ω
to 40Ω. Analog wire should not be used to carry an AES signal more
than a few feet. Even if your current need is for analog audio only,
the AES cable does it no harm, and will be in place when and if your
station makes the digital transition, which will become more and more
likely as digital equipment prices continue to fall and performance and
ease of use rises. The good news is that 110Ω cable is quite
common and is available in single pair, multiple pair or snake cable
and microphone-tough cable in wire sizes as small as 26 gauge. All
Ethernet cable (CAT5, CAT5E and CAT6) cable is rated at 100Ω,
which is within the AES-3 audio specification. Ethernet cables are
available in 4-, 8-, 12- and even 25-pair configurations, which today
are cost-effective compared to traditional individually-shielded,
twisted-pair cables. CAT5 is available with overall shields too,
although balanced, line-level, low-impedance audio does not usually
Multiple-pair, twisted-pair, 110Ω ribbon cables rolled in a
tough jacket — and even shielded — are also available.
These can be quickly and easily mass terminated to connectors or bulk
Label the wires clearly. My first experience with heat-shrink labels
used white pieces of heat shrink mounted on plastic tabs, like
cartridges on an ammo belt, that could be loaded into a modified IBM
Selectric typewriter. While they were expensive and time-consuming, the
level of professionalism they brought to my wiring generated many
positive comments. Today there are improved versions of this that are
quicker and cheaper.
Personally, I use sheets of self-laminating laser printer labels
that will fit on most cables of less than 1" diameter. I have settled
on four fields on each label to indicate where each end of the wire
goes, what type of wire it is and the color. The first two fields are
for troubleshooting, and the last two are so that my crew doesn't put
the label on the wrong wire. Color-coding can be a great tool; just be
sure that none of your installers is color-blind.
Various methods exist to create neat
and practical labels, some of which are quite advanced and offer bar
codes to simplify accessing data. Photo by Don
Danko, CBRE CBNT.
Whenever possible, use wiring blocks. Traditional telephone-type 66
blocks are easy to find, offer lots of accessories and can be purchased
from stock from several telecom and electronics distributors. Keep in
mind that CAT5-rated 66 blocks should be used for AES-3 signals. ADC,
AVP, Krone and others make excellent, high-density, high-reliability
wiring blocks designed for professional and digital audio.
Keep the wiring blocks neat. Allow enough room to mount all the
blocks needed for the current installation and include space for
several spares. Because shielding is usually not needed for balanced,
line-level analog audio or for AES-3 digital audio, cross-connects on
punch or other wiring blocks can be unshielded twisted-pair cable like
the phone company uses. Using this type of cable helps keep punch block
areas and walls neat and uncluttered. CAT5 cross-connect wire is also
available. Not terminating shields increases the density of punch
blocks, too. There is almost never any need to carry shields through
punch blocks, and the user throws away ⅓ of the block's capacity
trying. If using a shielded cable, remember to terminate only one end.
I prefer to make a pigtail of all the shields and solder or
crimp-connect it to a ground bus bar running near the blocks. Bring the
permanent cables in behind the punch blocks, or permanent in one end
and cross-connects out the other, so that permanent and cross-connected
wiring is as separate as possible.
I have reluctantly decided that wiring channel, such as that made by
Panduit, is a mixed blessing at best. Never mount a wire-trough channel
upside down. As soon as you remove the cover, all the wires fall out.
If you mount it sideways, put a wire-tie anchor inside it every so
often, or anchor a Velcro wire-tie instead so the wires can be held up
and to the back of the channel, out of the way of the cover. Another
drawback is that the first time a cable has to be added in a hurry, the
wiring channel covers tend to get removed and then not put back
afterwards. Instead, use metal or plastic D-rings. Use the plastic ones
that have a little seam that you can thread wires through without
having to pass the end through each ring. They also have screw holes to
anchor them down. Placing one about every foot and in corners will keep
wires organized but not inaccessible — and there are no covers to
lose. When appearance is paramount, like running wires that are in
public view, opt for the wiring channel.
There is no such thing as too much documentation, a point that
cannot be stressed heavily enough. Because I usually work with a crew
of several people, I generate lots of documentation. In addition to the
layout sheets I mentioned earlier, I generate a wiring and
cross-connect list for each wiring block plus a wire running list for
each room. That way I have created essentially a complete virtual
studio on paper. Once this is done it's easy to go back and verify that
the crew actually ran the wires as they were intended. It also serves
to verify the documentation. It's easy to create documentation in a
spreadsheet, database or forms program. I'm planning to document my
next studio project in HTML, complete with hyperlinks for the
cross-connects. The advantage is that it can be viewed on any browser
and easily modified — with the right passwords.
Good old-fashioned written documentation is not yet obsolete,
either. Take a big three-ring binder and use tab separators for each
studio and sheet protectors for each page. Mark the revision date or
number on each page, so it is obvious which version of a page is out of
date. Generate and give the client multiple copies of the documentation
and multiple copies of any digitally-stored documents too. Keep copies
for yourself. Stations lose paperwork easily during ownership or
engineering personnel changes.
Test, test and test again
Before a studio is finished, ring out every wire and every
cross-connect, either with an ohmmeter or a cable tester. Test cables
for continuity, shorts and polarity. Some wiring blocks will have
trouble with AES cable, due to the larger insulation required to make
the higher cable impedance, and the engineer may need to punch the
occasional wire down twice or take other remedial action.
Jocks and production people can't use features they don't know
exist, and who better to show them than the installer himself? Show the
program director and the production director everything the studio will
do. Make sure they are happy with how it works. This is often the last
chance to ensure that the studio's users' needs have been met.
This is an exciting time to be building studios. While the pressures
to keep costs down are great, and the flexibility and features desired
of a modern studio are many, the tools for accomplishing these goals
are plentiful. With proper planning and wiring techniques, the
experienced installer can build first-class studios that will also pass
the test of time without busting the budget.
Patton is president of Michael Patton and Associates, Baton
Rouge, LA. Contact him through www.michaelpatton.com.