Using the 20/20 AD | Lexicon |
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Realigning Two DAT Recordings
When recording in 4-channel mode to two DAT recorders, it may be useful to record a "clapper" signal to both DATs to facilitate realignment during post- production. When you press ALT-LINK, the 20/20 AD will generate 8mS of silence, followed by an 8-cycle 1 kHz square wave burst at -12dBfs This signal is time-aligned on all four output channels. You can align the two DAT tapes on a disk audio production system by visually lining up the first edge of the burst, or you can align them audibly by subtracting channel 3 from channel 1 and adjusting the offset until the click disppears.
Digital Sinewave Generator
The 20/20 AD includes a digital sinewave generator which is accurate to 20 bits, with a dynamic range of more than 120dB. This generator is useful in testing the digital outputs. To use it:
1.Use the SAMPLE RATE, FORMAT and 4-CHAN buttons to select the output mode. (These controls are locked out in sinewave generator mode.)
2.Press and hold down 1dB SCALE (ALT)and press the 4-CHAN button. 1dB SCALE and 4-CHAN will flash to indicate that the unit will now generate digital sinewaves. The compressor GAIN knob adjusts the frequency of the sine- wave and the THRESHOLD knob adjusts the amplitude, as shown below.
2062.5 | 3000 | 5062.5 | -18 | -16 | -14 |
1500 | | 6937.5 | -20 | | -12 |
1125 | | 9000 | -22 | | -10 |
937.5 | | 11062.5 | -24 | | -8 |
750 | | 14062.5 | -26 | | -6 |
562.5 | | 17062.5 | -30 | | -3 |
375 | 187.5 | 20062.5 | -36 | -60 | 0 |
| (GAIN) | (THRESHOLD) |
| Frequency in Hz | Level in dBfs |
48 kHz Sample Rate |
1895 | 2755 | 4651 |
1378 | | | 6374 |
1033.5 | | | 8269 |
| |
861.5 | | | 10163.5 |
| |
689 | | | 12920 |
517 | | | 15676 |
344.5 | 172.5 | 18432.5 |
(GAIN)
Frequency in Hz
44.1kHz Sample Rate
3.To turn off the sinewave generator, press and hold down 1dB SCALE (ALT) and press 4-CHAN. The 20/20 AD will resume normal operation.
Note that in sinewave generator mode, only the compressor GAIN and THRESHOLD knobs have any effect. Pressing any dual-key combinations other than ALT— 4-CHAN may invoke undocumented diagnostics routines. If you accidentally get into diagnostics mode, the best way to exit is to turn the power off, then on again.
