Making Connections

A quick glance at most recording equipment shows that a lot of different kinds of cables and connectors are used in a studio. It is often not easy to connect equipment to mixing desks. They are complex devices and it is not unusual for a large mixing desk to have over four or five hundred possible cable connection points. For that reason it is often better to use some form of intermediate device between the mixing desk and the equipment that is to be connected to it. The two most common kinds of intermediate device are described below.

The Patch Bay

A patch bay looks very much like the telephone switchboards that can be seen in old back and white films. In fact, it does pretty much the same job. In order to make a telephone call before electronic switchboards were invented one had to phone the operator. He or (usually) she would take a cable attached to your phone and plug it into a socket that was connected to the phone of the person you wanted to speak to. In other words, the switchboard acted as an intermediate connection unit.

A studio patch bay does almost the same job, even using a same old-fashioned cables! For example, we could plug the sound output ("amp") cables of a synthesiser directly into the back of a mixing desk at appropriate points. However, if we continued to do this with more instruments it would soon become impossible to tell what was plugged into what. A simple solution is to plug the amp cables into a patch bay. The reverse side of the patch bay has more cables leading from it that plug directly into the appropriate sockets on the desk. Again, we have an intermediate connection device.

A patch bay usually has 32 inputs and outputs and they are often arranged in clusters of more than one unit. Below is a typical set of patch bays:

Each of the sockets has a distinct function and will vary from studio to studio. Below is a close up of a section of a typical patch bay. In this case the section of the bay shows the outputs of one device on the top row and inputs into the mixing desk for tracks (channels) 19 - 22.

Note that the bottom row of the patch bay in the picture shows some "line inputs". Plugging into these sockets is, in effect, plugging directly into the corresponding track on a mixing desk.

A line device is one that uses a particular kind of connector, i.e. that fits into a standard patch bay, as above. The type of connector is called a 1/4-inch jack plug. They are often found on headphones and look something like this:

From the single black band it is possible to tell that the jack plug shown above is mono, whereas as stereo jack plug, such as those used for headphones will have two black bands.

Common line devices include:

• synthesisers
• effects units such as reverb and echo units
• drum machines
• electric guitars
• DAT recorders

Studio Boxes

Studio boxes are very similar to patch bays, i.e. they are another form of intermediate connecting device. However, a studio box is more likely to be used for connecting microphones, although it may also be possible to connect line or other devices.

Professional quality microphones use special three pin connectors, and a studio box will be able to accept these. They are often call XLR connectors, and the microphone cables are often called XLR cables. XLR stands for Ground, Live, Return.

The picture below shows the ends of an XLR cable:

Note that one end is male and the other end female. This means XLR cables can be connected together, rather like a daisy-chain. This is useful in cases where longer cables are required as cables can be plugged into each other in order to extend them.