Things To Know - Violectric HPA V181 User Manual

Things to know ...

The HPA V181 offers balanced and unbalanced inputs.
Which advantages do balanced signals offer ?
In contrast to unbalanced signals, balanced signals are carried by two
wires (plus ground/shield). In the transmitting device, a balanced signal is
created by generating an inverted original signal (180ˆphase shifted). The
"hot" wire carries the original signal (a), the "cold" wire the inverted signal
(-a). In the receiving device, the balanced signal is processed by a
differential amplifier, which detects the difference between both: (a) – (-a)
= 2a.
On its way between devices, the useful signal can be affected by
interference (s). Interferences however are in phase on both wires and
fed to the differential amplifier as well. Again, the amplifier detects the
difference between the interference contents: (s) – (s) = 0. Thus - in an
ideal situation - all interference on the signal path is eliminated.
Like mentioned above, the balanced signals are fed to differential
amplifiers. From there - now being unbalanced - they get to the
switching contacts of the cinch inputs. If a plug is inserted here, any
balanced input signal possibly present is interrupted. I.e. unbalanced
signals fed to the cinch inputs have priority.
These signals are fed to buffer amplifiers - for left and right channel
separately - which also provide the PRE-GAIN setting.
Why are discrete signal paths important ?
Twin op-amps are the most common design for operational amplifiers,
i.e. two amplifier circuits are integrated in one device. If left- and right-
channel signals are processed simultaneously by such a device,
interaction between both cannot be excluded. This interaction is
admittedly diminutive, but should be avoided whenever a different design
offers the possibility.
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