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3.2 Rear Panel Connections
3.2.1 Send/Return Loop
The system consists of 2 separate Loops. It allows creation of effects path in either
serial or parallel configurations. The individual channel volume controls determine the
signal strength at the send jacks. The range is ... to +10dB. The output impedance is
4.7 kΩ. To use the Send/Return Loops, connect the "Send" to the "return" or "input"
or "in" of the effects unit. Be sure to adjust the input level of the effects unit to the
amplifiers level. Most effects units have led bar or other level control devices. The
Output of the effects unit must be connected to one of the return jacks, parallel,, or
serial. If you use the parallel return, then the signal can be mixed to the original
signal via the rear panel mounted "Volume" control.
3.2.2 Parallel or Serial
Which is better for you? Read on. There are 2 ways to handle effects signals. The
serial loop interrupts the signal path of the Einstein and the signal is sent to the
processor, becomes processed, then sent back to the serial return into the power
amp. Digital effects units often digitize this signal once received, then process the
signal, convert it back to analog, then send it to the amp. This is called ADA (analog
digital analog) conversion. It is necessary for digital effects units digitize your guitar
signal so that the processor can read and understand signal. Your tubes, however,
need an analog signal to operate, so the processor converts the signal back to analog
before it goes back to the amp. Generally, even in highest quality effects processors,
this causes a change in the original signal, typically a loss of tonality and warmth, also
noticeable as a "harder" sound. When you use the serial loop for an effects unit like
this, then your signal will have been ADA converted at least once. Tone junkies and
vintage freaks alike will more than likely have hives developing by now. But - as
always, there is a better way. Use the Parallel loop and the Volume control in the rear
determines how much effect signal is being added to the original signal, which now
still flows through the amplifier. There is always an analog connection between the
send and return jacks; a parallel loop! Important: You must set the mix control on the
effects unit to 100% wet when using the parallel loop. Otherwise there will be nasty
phasing problems resulting in unsatisfactory tone. The signal portion that is
unaffected by the mix control in the effects unit would reach the amplifier at a
different time due to the cabling, and cause phasing cancellations.
3.2.3 Top 5 Reasons for dynamic losses in the effects loop
Many different factors can be responsible for loss of dynamics, aside from those
mentioned in 3.2.2 (ADA conversion). A vital point that often leads to frustrationis a
maladjusted output level of an effects unit. If the output level is too high, the unit will
cause unwanted distortion in the power amp. If it is too low, then the rig
will not sound punchy and might get lost in the band sound. When used in the serial
loop, the output of the effects unit determines the ultimate drive signal strength of
the power amp. The output level should be matched to give the best possible sound
with all channels without over driving the power amp section. (Unless this is desired
for power amp distortion) Headroom adjustments of 10% are usually sufficient.
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