Send & return

The entire preamplification system is based on the global volume control of the output section, that, should be on the preamplifer or a multi-effect unit, depending on their position in the signal path. Any type of rack or pedal effect should work on the sound after the signal is preamplified.
Using the send-return, the sound passes into the effects through the preamp, which then returns it to the output of that same preamp, where the volume output level is checked (graphic A). If instead the effects are in series after the preamp (called a cascade system ), the output level of the last piece of equipment in the signal path will control the overall volume (graphic B).

The send-return is a good system for the connection of effects inside a preamplifer. We have already mentioned this system in the amplifers section, which contains both the preamp and the power amp in a compact block.
Analyzing the signal path, we see that the sound should reach the power amp complete with all its origional characteristics. The effects should be inserted, according to their type, in different points: compressors, distortors, equalizers must be placed before the preamp, with the environmental effects (chorus, delay, reverberation, etc,) after. The send-return is used for maintaining the analogical signal, mixing with the digital effects. The send-return tries to influence the analogical nature of the sound as little as possible. Not all digital equipment have good A/D-D/A converters (analogical/digital - digital/analogical), and connecting it in line after the preamp could negatively influence the sound (i.e. lose of certain frequencies or "consuming" sound dynamics). We will therefore look at how the various types of effects behave with the send-return.
We first of all check the impedance of the job: pedals are usually prefered for low level signals (the output of the guitar), while rack effects are prefered for high-level signals, even if some can be adapted to work with both types of signal. Pedals and processors cannot coexist in the same send-return, because there is an increase in ground noise and a decrease in volume. It's possible that a preamp can have two send-returns: in this case we connect one to the pedals (for low level signals, i.e. -10db), and the other to the rack processors (+4db). Be careful of the fact that the two send-returns are independent and not stereo. In this case they must be adapted to a stereo signal. The low level send-return usually works before the EQ controls, leaving the signal treated by the first send-return unchanged. In a majority of the cases, we find one send-return in the preamp that has a selection switch to regulate two values (-10db or +4db): select the first one for pedals and the second for rack units.
There is also a control that regulates the effects sent, something that is very useful in fine tuning, because some effects have different settings than the "standards" mentioned above. The connections can be made in series, in parallel or both. If you are unable to have both, you need to know if the connection is in series or in parallel, because this has a big influence on the sound. It is therefore worthwhile to read the instructions.

With this system the signal is divided into two parts: one that travels through the preamp to the output, the other comes from the send and is sent to the external processor, which after being enhanced is sent back to the return. At this point the signal can be mixed with the original using a special control (mix, effect, etc.). It's very important that the return signal to the amplifier is only the one effected: therefore reset the dry signal control (direct) on the external processor, seeing this is already present on the preamp and is therefore useless to have another.

The entire signal is sent to the processor using the send-return in series. After being made, it returns to the preamp: in this case the difference of the balancing is managed by the dry and level controls in the processor.

We can divide the processors into two categories:

• Effects that process the entire signal, such as the Distorter, the Compressor, the Equalizer, etc., that are connected between the guitar and amplifier or to the send-retun in series, because they work on the body of the sound in real time.
• Effects that mix a portion of treated signal with the original, such as the Flanger, the Chorus, the Delay, the Pitch transposer, the Reverb, etc. These should be connected in parallel because they work on the circuits of time delay. Some higher quality processors (Eventide, TC Elet.) have such a high A/D-D/A procession that it doesn't negatively influence the dry signal, and therefore can be put in series with the send-return or even in cascade after the preamp and before the power amp.