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METERS
VU Meters Display the RMS signal level of the selected monitor source, and the peak indicator
illuminates red when the peak threshold has been exceeded, which is roughly 3dB before the clipping
point.
DIM
Engaged when either the Dim or Talkback switch is depressed, Dim reduces the volume of the monitor
source between -6dB and -30dB adjusted with the Dim Level control.
POWER
We obviously saved the best for last. If this rear panel switch is not pressed then the 5060 is maximally
“green” and exhibits its absolute lowest noise floor. However, for any of the previously described
features and fun controls to have any significance, the POWER switch should be pressed. If nothing
happens when the switch is pressed and not one LED even winks at you, then you may also want to plug
in the Power cord too.
A Note on Distortion
The human hearing system is a remarkably complex mechanism and we seem to be learning more
details about its workings all the time. For example, Oohashi demonstrated that arbitrarily filtering out
ultrasonic information that is generally considered above our hearing range had a measurable effect
on listener’s electroencephalo-grams. Additionally, Kunchur describes several demonstrations that have
shown that our hearing is capable of perceiving approximately twice the temporal resolution that a limit
of 20 kHz might imply. His peer reviewed papers demonstrated that we can hear temporal resolution of
approximately with 5 microseconds (20 kHz implies a 9 microsecond temporal resolution, while a CD
at 44.1k sample rate has a best-case temporal resolution of 23 microseconds).
It is also well understood that we can perceive steady tones even when buried under 20 to 30 dB of
noise. And we know that most gain stages exhibit rising distortion at higher frequencies, including
more IM (intermodulation) distortion. One common IM test is to mix 19 kHz and 20 kHz sine waves,
send them through a device and then measure how much 1 kHz is generated (20-19=1). All this hints
at the importance of maintaining a sufficient bandwidth with minimal phase shift, while at the same
time minimizing high frequency artifacts and distortions. All of the above and our experience listening
and designing suggest that there are many subtle aspects to hearing that are beyond the realm of simple
traditional measurement characterizations.
The way in which an analog amplifier handles very small signals is as important as the way it behaves
at high levels. For low distortion, an analog amplifier must have a linear transfer characteristic, in other
words, the output signal must be an exact replica of the input signal, differing only in magnitude. The
magnitude can be controlled by a gain control or fader (consisting of a high quality variable resistor
that, by definition, has a linear transfer characteristic.) A dynamics controller - i.e. a compressor,
limiter or expander - is a gain control that can adjust gain of the amplifier very rapidly in response to
the fluctuating audio signal, ideally without introducing significant distortion, i.e. it must have a linear
transfer characteristic. But, by definition, rapidly changing gain means that a signal “starting out” to be
linear and, therefore without distortion, gets changed on the way to produce a different amplitude.
Inevitably our data bank of “natural” sound is built up on the basis of our personal experience and
this must surely emphasize the importance of listening to “natural” sound, and high quality musical
