Composition of a Rack system

Beginning in the 1980's, many guitarists started using more complex amplification systems. Not satisfied with just pedals, they began using typical recording studio effects for live performances due to their versatility and reliability with respect to floor pedals. These effects could not be transported one by one because of the risk of being ruined (they are quite delicate), and if you used two of more of them, it required alot of time for setup and connection. They were therefore inserted into special containers, called "flight cases", for protection and were already internally connected by cables. This formed the so-called rack system (normally just called rack), which is composed of the case and the various units. The models of cases are identified by their ability, which can go from one contained unit (1 unit case) to particularly large cases (20 or more contained units). The units are attached to a special grate and can be accessed by opening the front panel, while the rear panel is generally devoted to the connections.
What can be put in a rack? Not only the effects. For someone who uses either a combo or header and speaker type amplification, only the effects are inserted into the case. But for someone who uses a rack preamp and power amp, they should keep the power amp in a separate rack because it could cause unpleasant noises, but also because of its weight (especially if the valve type). For someone who often plays live and is always changing locations, has an higher risk of dropping or hitting the case(s) should opt for models in shockproof cases, which have an internal 5 cm layer of expanded foam (similar to polystyrene) that can absorb hits and vibrations. The units are attached to an internal block which can be suspended by a system of springs or rubber bands. Good ventilation is always advisable, because some pieces of equipment generate a large amount of heat, in particular preamps and power amps. A good ventilation system can be obtained by inserting some small fans (such as those for computers which don't give humming problems), and leaving some space between the normal units and those that generate heat, even if these are normally equiped with their own cooling fans.
For the connections, you should keep the Midi and audio electric cables separate. For instance the feed cables can be gathered and put along the inside of the cases, the cables that carry the audio signal to the opposite side and the Midi cables in the middle. To gather the cables you can use special cable holders in plastic (those used by electricians) that prohibit the cables from falling out of the case. It is also useful to label the various cables to avoid wasting time when looking for a certain cable. The audio cables should be of the best quality because it is useless to spend thousands for a good rack system and then to use cables that cost a few dollars. A low cost cable can cause frequency lose to the audio signal, ruining the sound.
Finally lets look at surge protection systems. Assuming that the electrical outlets are wired correctly, it is always best to use a protection and filtration system for electrical current (called power conditioners), that guarantee the regular flow of electrical current to the equipment, even if there are sudden voltage changes. Some of these can also filter any noises coming from high and low frequency signals that may be present. Take the electrical current seriously, because most equipment are very sensitive to sudden voltage changes.
All the setups that we will see should help you create your own personal setup: its important to not copy exactly a scheme, but to get useful advice on how to use various equipment in the best possible way.

Examples of Rack setup
Lets look at our first setup using the basic system, which is composed of a preamplifer, the effects and power amp. This setup uses two preamplifers and we therefore have the possibility to use one or the other in order to have two different types of preamplification, which is chosen using a programmable Patch-Bay. The purpose of the Patch-Bay is to address one or more output signals from the same piece of equipment, that were taken from the various inputs and chosen one by one based on the program of that machine. The typical operation of this type of equipment is seen in figure 1.

The two preamps send their signals to the two inputs (in 1 and in 2) and, depending on the program (generally made by Midi) are chosen and sent to the out, which will send the signal to the effects. The two send-returns are used to insert a compressor and an equalizer (or an exciter, recording equipment that checks the range of preset frequencies). Whether to insert it or not is also programmable. There may also be an output for the control of external equipment.
In the next page we will talk more about this system.