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.