|   Question on Channel Separation | RickM
Jul 12, 2001 9:16 AM | | I am just curious, does anyone know what "channel separation" is? I see it listed as a pre-amp specification, but what does it mean? And what is concidered the "normal?" |
| Answer on Channel Separation | Kursun
Jul 13, 2001 12:23 AM | | Separation is a measure of inter-channel signal leakage. The amount of leakage varies with frequency. Generally the amount of leakage is higher at high frequencies. If no frequency is stated, it's generally at 1 kHz.
The factors that lower the separation of components may differ. A turntable cartridge, an FM tuner, a cassete deck, a multi-channel home theatre decoder (DD, DTS), an amplifier, all have different factors regarding separation.
The resulting leakage is similar to the case when you play a CD and switch the amp's input selector to an unused input, turn the volume all the way up (careful!) and listen to the leakage from the cd player. This is another form of leakage.
To measure separation, I think, you short the input of one channel by a dummy plug, and apply signal to the other channel. Then you measure the signal output at both channels. The output of the unused channel usually contains a very small amount of the signal that is applied to the other channel. The separation specification is stated as the relative level of attenuation in db, with respect to the active channel. Ideally the measurement should be taken at all the frequencies within the pass-band and plotted.
Mono-block power-amps are said to have superior separation. But in this case separation is limited by the source. In this age of digital audio separation figures of close to 100 db can be expected. But any figure 50 db and up should be OK.
How important is the separation specification? It gives us clues about how well the amp is built. It is a form of distortion. Since it's frequency dependant, it is of non-linear nature. It also degrades signal to noise ratio. It's not one of the most important specifications, but shouldn't be disregarded either.
P.S. Everything I have stated above should be taken with a bit of salt, as I am not an electrical engineer! :-) |
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