Re: Which tube expert can do custom works?

John Byrns wrote:

What does the presence or absence of buffering have to do with the level at which mixing is done?

As the OP already pointed out he said impedance not level.

Crosstalk only becomes an issue if a single
input must feed more than one bus, in which case a buffer serves a useful purpose. What does buffering have to do with "noise issues"?


Two things. Mixing at high impedance introduces more noise so it is better to mix a relatively low impedances. To drive a relatively low impedance you need a buffer.


Second, the buffer is after the fader and pan pot and it directly feeds the mix bus. Therefore, all the buffers, used or not, contribute noise to the mix bus. 8 buffers adds 9dB of noise. The normal way to minimise this is to include a channel cut switch after the buffer which switches the bus feed from the buffer to ground.

Cheers

Ian
.

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