The input impedance of the icOn TVC is strongly dependent upon the load im-
pedance and selected attenuation. The worst-case input impedance occurs
with no attenuation selected, in this case the input impedance will equal the
load impedance plus the copper losses for the unity gain connection.
The icOn
TVC should not be used with loads lower than 10kOhm.
As soon as the signal is attenuated (which is the way the icOn TVC will be oper-
ated in most cases most of the time) the input impedance rises and is ultimately
only limited by the inductive and capacitive reactance of the primary winding
near the outer edges of the audio band. In the midrange the input impedance of
the icOn TVC can become VERY HIGH, with a 10kOhm load and 14dB attenua-
tion selected the midrange input impedance will approach 250 kOhm. Hence, in
the subjectively critical midrange, the loading of the source is drastically low-
ered, resulting in most cases in drastically lowered distortion from the source.
The limit of the input voltage to the icOn TVC depends upon the exact fre-
quency and also the source impedance. For a source impedance of 600 Ohm
and the unity gain connection a maximum level of +20dbU (7.75V RMS) is per-
missible above 40Hz before distortion becomes problematic, at 20Hz +14dbU
(3.875V RMS) are permissible. It should be noted that if the specified level is ex-
ceeded no damage as such will occur; the device will simply start to show in-
creased distortion. This distortion will only happen at very low frequencies and
consist of very low order harmonics, which are usually considered subjectively
harmless. So while potentially reaching several percent THD at low frequencies
for a severe input overload. In most cases even such levels of distortion will be
inaudible or at the very worst musically quite benign.
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ABOUT THE INPUT
icOn Smart TVC preamplifier
