| Tokyo
Ko-On Denpa
2CP-2511 Stereo volume control.
One important feature of a dual audio-taper
attenuator (volume control from here on) is how well
it tracks: that is, how closely matched the two channels
are to each other.
No volume control has perfect tracking: one channel
will always be a little different from the other. Even
well-trained ears are only sensitive enough to notice
a difference of about 1dB, though, and for the average
person the minimum noticeable difference is more like
3dB. It's no surprise, then, that the least expensive
volume controls have a 3dB tracking specification.
With
potentiometer type attenuators, the tracking spec will
only be given down to a certain level. A common spec
is 3dB down to -40dB. 40dB is a factor of 100, so such
a pot is guaranteed to have its channels within 3dB
of each other down to the point where the pot is attenuating
the signal to 0.01×. Below that point, the channels
can be badly mismatched and the pot will still be within
spec. The reason pots are specified this way is that
manufacturing errors build up over the range of the
pot's travel. It's much harder to make a pot with good
matching down to -60dB, for instance. This spec is a
good indicator of a pot's quality, since it reflects
on the accuracy and repeatability of the manufacturing
process.
The
channel unbalance for the TKD 2CP2511 is less then 0,5
dB at -60dB. This is almost as good as a stepped attenuator.
The 2CP2511 achieves this through it's special design.
In parallel to the main resistive element there are
6 laser trimmed resistors.Each channel is trimmed for
perfect balance and perfect logarithmic behavior.
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