7 Hooking up
It would be kind of a hassle to have all your equipment permanently attached to each other and the the power grid by wires. That's why we invented connectors. And in order to prevent hooking up the wrong types of equipment and wires to each other, we invented different connectors. For music equipment, there are mainly three types of connections: power, large signal and small signal. Power is everything that's mains voltage and what comes out of the power adapters and wall warts. Large signal means "amplified", like speaker cables. Small signal means unamplified, like the cable from a guitar to an amplifier, or between effects processors. Headphones are also considered small signal.
When it comes to connectors, not all is as it should be, though. In the past, probably because of cost, connectors have been used for both small and large signals. The infamous 1/4" jack plug, for instance. It is wrongfully being used to connect speakers to amplifiers. Why is this wrong? It's wrong because these plug were never meant for such high power. It's also wrong because small signals and large signals require a different type of cable between the connectors and the cables might get mixed up. Small signals are usually sent though shielded cables. This type of cable has a braided copper mesh, wrapped around a very thin conductor as the center, with insulation in between. The copper mesh shields most interference the signal might pick up. And because small signals don't require high currents, the center conductor can be thin and cheap. Large signals, however, require heavy gauged conductors in order to minimize power losses. Large signal are also insusceptible to interference and don't require shielding. If these cables get mixed up, you might end up with interference from your bass guitar, or power loss and possibly molten cables. Or all of the above.
The same goes for XLR type connectors, really. The audio world is pretty hard headed like that. XLRs are three pole connectors, meant specifically for small signal, balanced audio connections. Yet they are also employed as speaker connectors, with heavy gauge, unshielded cable in between them.
Another bad thing about using 1/4" jack plugs for large signal connections is the fact that they might short circuit while they are being plugged or unplugged. When the tip of the plug touches the ring shaped part where the shaft normally makes contact, it simply short circuits. Do this, even by accident, when an amplifier is running at high power and it's not hard to imagine the amp output might get damaged, or at least a fuse will be tripped, and show's over. Most 1/4" jacks are not even firmly locked into their sockets, so it can happen sooner than you think.
Yet another bad thing about those 1/4" jacks is the exposed tip that can have harmful voltages on it. A high power amplifier can easily put out 48 volts or more, which is considered harmful.
The best connectors for hooking up speakers are Speakon plugs. They are twist lock type connectors, that never expose any live contacts, and are designed for very high power. They are multi-contact (4 or 8), so hooking up a bi-amplified system can be done with a single cable.
A short overview:
|Connector type||Signal type||Application|
|1/4" jack||signal, speaker||small signal, large signal (speaker level)|
|TRS (3-contact 1/4" jack)||small signal||stage, studio|
|XLR||small signal, large signal (speaker level)||stage, studio, microphone|
|RCA or Cinch||analog / digital signal||home stereo, digital audio, video|
|Banana / 4mm||speaker||home/semi-pro speakers|
|Binding posts||speaker||home/semi-pro speakers|
|5-pole DIN||digital control signal||MIDI|
© Joris van den Heuvel 2001-2009