- 1. Cooling
- When you are using amps that are fan-cooled and want to allow
spaces between pieces of equipment in your rack, make sure you
block the front with blank, solid (not perforated) panels. This
will allow the rack to act as a chimney with hot air exhausting
at the top, not re-circulating between adjacent amplifiers. When
you are using convection cooled amps in very high ambient temperatures,
you may find that your temperature indicators are starting to
illuminate. Typically, adding modest amounts of air movement
will enable your amp to dissipate any excessive heat and regain
its normal composure. However, if your temperature indicators
continue to illuminate, consider the following possible causes:
- 1) Insufficient air movement.
2) Overdriving of the input stage (severely into clip).
3) Very low-impedance loads.
4) High ambient temperatures.
- If you can't, or don't want to change the preceding conditions,
two possible alternatives are available to add the necessary
air movement. First, you can add fans to direct air onto any
surface of the amplifier. Second, you can space the amplifiers
in the rack using perforated panels or leaving the empty slots
open. This will allow the top and bottom covers to act as radiators.
In extreme conditions, a combination of these two methods may
be required, as would be expected for proper thermal functioning
of any amplifier.
- 2. Hum &
- 1. It is imperative that all of your electrical equipment
share the same power ground reference.
- 2. Unless you are interfacing to a microphone, the shield
of the cable should only be connected at one end.
- 3. Do not pass signal ground between electrical components
in a grounded source system.
- 4. If you wish to avoid ground loops, it doesn't matter if
you lift the input or output signal ground or your system topology,
just be consistent. Personally I prefer to lift the input signal
ground and it has always been successful.
- 5. NEVER use a ground lift adapter to lift the power ground
on a 3-wire AC cord; this is not its intended purpose. It is
better to have it SAFE than SILENT!! Look for the true source
of the noise.
- 6. Even when interfacing to an unbalanced load, it is preferable
to use two-conductor shielded cable.
- 7. Get rid of the lighting company!
- 3. Input Wiring
- 1. For all input connectivity, use shielded wire only. Cables
with a foil wrap shield or a high-density braid are superior.
Cables with a stranded spiral shield, although very flexible,
will break down over time and cause noise problems.
- 2. Try to avoid using unbalanced lines with professional
equipment. If you have no choice, keep the cables as short as
- 3. To minimize hum and crosstalk, avoid running low-level
input, high-level output and AC power feeds in the same path.
Try to run differing signal paths at 90 degrees to one another.
If you must use a common path for all cables, use a star-quad
cable for the low-level signals.
- 4. When changing input connectors or wiring, turn the amplifier
level controls all the way down (counter-clockwise) before connecting
or disconnecting input plugs.
- 5. When changing output connections, a professional dude
will turn the amplifier level down and the AC power off to minimize
the chance of short-circuiting the output.
- 4. Output
- 1. Choose carefully when selecting speaker enclosure connectors.
- 2. To prevent possible short circuits, wrap or otherwise
insulate exposed loudspeaker cable connectors.
- 3. Do not use connectors that might accidentally tie conductors
together when making or breaking the connection (for example,
a standard, 1/4-inch stereo phone plug).
- 4. Never use connectors that could be plugged into AC power
sockets. Accidental AC input will be an electrifying experience
for your equipment. But you will find out real quick if your
speakers are any good at 60 Hz.
- 5. Avoid using connectors with low current-carrying capacity,
such as XLRs.
- 6. Do not use connectors that have any tendency to short.
- 7. To maintain good bass response, use the lowest DC resistance
cable you can afford which will terminate safely in your connectors.
- 5. Speakon
- For amplifiers, the most popular termination device on professional
products has been the dual banana. However, recent regulatory
requirements in Europe have outlawed the use of the dual banana
plug and forced users to terminate speaker cables with spade
lugs or bare ends an approach that is clearly not advantageous
to the customer who wants to reconfigure his system or quickly
change out a defective product. It is possible that similar regulatory
controls will appear worldwide over the next few years.
- One solution to this problem is to use the Neutrik Speakon
connector. Most amplifier manufactures wanted to develop a system
for you that eliminated the need for specialized, time-consuming,
interface cables. The major loudspeaker manufacturers have been
using Speakon connectors for the input termination on their products
for several years now, so you can be assured of the connector's
reliability in the workplace. With Speakon connectors, you can
plug straight from the amp to the speaker, and start making those
great sounds right away.
- The Speakon connectors used on most amplifiers meet all known
safety regulations. Once wired correctly, the connector cannot
be plugged in backwards, causing the type of inverted polarity
situations that are common with banana hookups. It will provide
a safe, secure and reliable method of interfacing your amplifier
to the load.