SDR 24/96

Metering and Setting Record Levels

A professional analog recorder has meters that indicate 0 VU at a +4 dBu nominal signal level. Generally you can record peaks 10 to 15 dB above that before distortion becomes objectionable. This 10-15 dB range above the nominal level is called “headroom.”

On digital recorder meters, zero represents the full-scale digital signal level, 0 dBFS for short. 0 dBFS is the hottest signal that a digital device can handle, with no headroom to spare. When a digital signal reaches 0 dBFS for more than a sample or two, the resulting distortion is uglier than scraping your fingernails across a chalkboard.

24 TRACK/24 BIT DIGITAL AUDIO RECORDER

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To get the get the best sound from the SDR24/96:

1. Turn ALL INPUT on.

ALL

INPUT

2.Ask the talent to play or sing as loud as they will be performing during the session. While watching the SDR24/96 meters, adjust the console’s tape outputs so that the signal peaks cause the red overload indicators to come on occasionally. Then, back off the tape output level slightly. This insures the best fidelity and the widest dynamic range in the recorded signal and leaves you a little headroom to accommodate the talent’s enthusiasm. Keep the signal levels as high as possible without overload, because recording at lower levels reduces resolution and dynamic range. Nonetheless it is always better to be conservative and avoid the risk of overload than to try squeezing the last ounce of dynamic range from the signal.

3.Alternately, if you have a tone generator or a sound source with a constant volume (you can hold down a key on a synth), turn All Input on and send the tone to all 24 tracks of the console. Adjust the output levels to read 0 VU on analog consoles, or around –20 dBFS on digital consoles. If the SDR24/96 meters read –15 to –20, you’re in good shape. This leaves enough headroom for most popular music, but if you’re recording acoustic music, jazz, classical, or narration, you may want to leave a little more. When the talent starts to play you may have to make some final tweaks to get everything just right.

4.After adjusting the tape output levels for each console channel, follow your console manufacturer’s instructions for setting the console tape return levels.

With analog I/O, a +22 dBu signal at the SDR24/96 inputs and outputs corresponds to 0 dBFS inside the SDR24/96. So, if your console has a nominal output level (0 VU) of +4 dBu, there is 18 dB of headroom before you hit the maximum record level on the SDR24/96. It also means that your console must be capable of putting out at least +22 dBu without distortion so the console

 

dBu

 

equivalent

OL

+22 dBu

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+20

4

+18

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+15

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+12

15

+7

20

+2

25

–3

30

–8

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–13

40

–18

50

–28 dBu

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SDR 24/96