Echo Audio AUDIOFIRE 12 Manuel du propriétaire télécharger pdf (Page 50)

Appendix C: An Introduction to Digital Recording

are matched, any noise added to the minus component will still be approximately

the same as that picked up by the plus component and will be subtracted out by the

input amplifier. Your Echo product uses this type of output.

Balanced signals connect with either XLR connectors or TRS (tip, ring, sleeve)

connectors. Your Echo product uses XLR connectors for microphones and TRS

connectors for connecting balanced (and unbalanced) line level signals.

The three sections of a TRS connector are used to transmit the three components of

a balanced signal (T = plus, R = minus, S = ground).

Dynamic Range

Dynamic range represents the difference between the maximum signal that can be

recorded and the “noise floor”, or level of noise with no signal present. A system

with a high dynamic range will be quieter than one with a lower dynamic range.

Dynamic range is a very important specification, and your echo product uses

converters that have very high dynamic range.

Theoretically, a 24-bit system has a dynamic range of 144dB and a 16-bit system

has a dynamic range of 96dB. Two questions immediately come to mind:

1) Why does my Echo product only have a dynamic range of 110 to 114dB?

2) For mastering 16-bit CDs with a dynamic range of 96dB, isn’t anything

more than 96dB just overkill?

First, today’s analog-to-digital converters typically produce a full-scale input

voltage with an input of +7dBu. If they were to have 144dB of dynamic range, they

would have to be capable of resolving signals as small as –137dBu (7dBu –

144dBu) or approximately 10 nano-volts. That’s 10 one-billionths of a volt!

Transistors and resistors produce noise in this range just by having electrons

moving around due to heat. Even if the converters could be perfectly designed to

1 2 ... 45 46 47 48 49 50 51 52 53 54 55 ... 59 60

Pas de commentaire

Echo Audio AUDIOFIRE 12 Manuel du propriétaire Page 50