Lexicon 20 AD, 20 QUICK User Manual

20/20 AD Quick Reference Guide

THRESHUNBAL THRESHUNBAL

OVL

0 3 6 12 18 24 30 36 42 60

2 3

Getting Started

Input Connections

Balanced Unbalanced

pin Screen Screen and

1 (Shield) Return

pin Positive Positive

2 Polarity Polarity

pin Return Open or

3 Return

ATTEN reduces input level by 6dB. Use sparingly, and only on balanced input signals.

THRESHUNBAL THRESHUNBAL

1dB SCALE

ALT

PK HOLD

ATTEN

MUTE

OVL

0 3 6 12 18 24 30 36

•

–

Make sure the rear panel BALANCE switches are set to match the type of input. (IN = unbalanced; OUT = balanced) The red UNBAL light will indicate an error if there is a mismatch.

Note: Non-linearity of the potentiometer can cause the signal to become unbalanced when the level knob is set to 11:30. To correct this, turn the knob slightly in either direction until the UNBAL light goes out.

4 CHAN

EMPH

DISPLAY

RMT

LINK

VID

EXT SYNC allows you to synchronize to an internally derived sample clock, or to an external AES or Word Clock signal in the range of 4151kHz.

Note: The Word Clock input is not transformer-isolated, and requires a ground connection between the 20/20 AD and the signal source.

DIGITAL COMP/LIMITER

GAIN

100 mS

-14

-18

-10

-22

-26

-6 0

+•–

0-36

THRESHOLD RELEASE

DITHER

WIDE

20BIT

PL DN

SAMPLE RATE

48 AES WC

PRES

44.1

SPDIF

AES

LOCK

EXT SYNC

FORMAT

1S10

∞

AES / WC:

Dither types vary in spectral distribution of noise:

WIDE produces white noise HF produces noise whose

amplitude is lower than WIDE at low frequencies, but higher at high frequencies.

20 BIT has the same spectrum as HF, but with lower amplitude. Use this setting when recording to 20-bit media.

Before switching between Internal and External modes, be sure to reduce monitor volume, as some D/A converters do not mute when they lose lock.

POWER

20/20 AD

20 BIT A/D CONVERTER

Level Meters

When the compressor is OFF, the behavior of the level meters is determined by settings of 1 dB SCALE and PK HOLD.

Switches ON Meters 1 & 2 Meters 3 & 4

4-Channel

Mode

2-Channel

Mode

none

1 dB SCALE

DISPLAY

none

1 dB SCALE

DISPLAY

Press 1dB SCALE to select 1dB scale on level meters.

Press PK HOLD to cause the level meters to hold at the highest level received.

Normal

1 dB Scale

Gain Reduction

1 dB Scale

Gain Reduction

Normal Normal Normal

1 dB Scale

Gain Reduction

Normal

(Blank)

Alternate Modes

To activate the alternate modes...

press and hold ...then press one of these.





1dB SCALE

ALT









MUTE



ATTEN

4 CHAN

ALT-ATTEN will mute the outputs. The level meters will still work.







RMT

DISPLAY

LINK

DITHER

Repeat to exit the alternate mode.

VID

When the compressor is ON, pressing DISPLAY will cause gain reduction (in dB) to be displayed on the right two meters (2channel mode) or on all four meters (4-channel mode).

NORMAL

OVL

0 3

6 12 18 24 30 36 42 60

- red -

- yellow -

- green -

OVL

ALT-4 CHAN activates output of a digital sinewave at the AES ports.



ALT-DISPLAY activates remote mode/front panel lock-

1dB SCALE

OVL

-3

-6

-12

-18

-24

-30

-36

-42

-60

-1

-2

-3

-4

-5

-6

-7

-8

-9

In 4-channel mode, ALT-LINK activates a synchronized short tone burst.

ALT-ON is reserved for future enhancements.

GAIN

REDUCTION

1 2 3 4 5 6 7 8

9 10 11

out. When activated, the 1dB SCALE and DISPLAY LEDs flash and front panel controls are locked into their current settings.

ALT-DITHER activates psychoacoustically optimized noise shaping. (Disables 4channel mode, compression and mute functions.)

070-09091 Rev 1

20/20 AD Quick Reference Guide

3 + 4 1 + 2

V ~

Using the Compressor

0dB

-3dB

-6dB

-8dB

-10dB

-12dB

-14dB

-16dB

THRESHOLD

-18dB

-20dB

-22dB

-24dB

-26dB

-30dB

-36dB

1.50:1

1.20:1

1.14:1

1.11:1

1.09:1

1.07:1

1.06:1

1.05:1

1.04:1

1.03:1

1.02:1

3.00:1

1.50:1

1.33:1

1.25:1

1.20:1

1.16:1

1.14:1

1.12:1

1.11:1

1.10:1

1.09:1

1.08:1

1.07:1

1.06:1

4.00:1

2.00:1

1.66:1

1.42:1

1.33:1

1.27:1

1.23:1

1.20:1

1.17:1

1.16:1

1.14:1

1.13:1

1.11:1

1.09:1

4.00:1

3.00:1

2.00:1

1.66:1

1.50:1

1.40:1

1.33:1

1.28:1

1.25:1

1.22:1

1.20:1

1.18:1

1.15:1

1.12:1

4.00:1

2.66:1

2.00:1

1.71:1

1.55:1

1.45:1

1.38:1

1.33:1

1.29:1

1.26:1

1.23:1

1.20:1

1.16:1

PUSH

AES

SYNC

GAIN

4.00:1

2.50:1

2.00:1

1.75:1

1.60:1

1.50:1

1.42:1

1.37:1

1.33:1

1.30:1

1.25:1

1.20:1

WORD CLOCK IN

OUT

4.00:1

3.33:1

2.40:1

2.00:1

1.77:1

1.63:1

1.53:1

1.46:1

1.41:1

1.36:1

1.30:1

1.24:1

PUSH

4.00:1

3.00:1

2.33:1

2.00:1

1.80:1

1.66:1

1.57:1

1.50:1

1.44:1

1.36:1

1.28:1

4IN3

UNBAL

BAL

4.00:1

2.81:1

2.28:1

2.00:1

1.81:1

1.69:1

1.60:1

1.52:1

1.42:1

1.33:1

PUSH PUSH

4.00:1

3.50:1

2.66:1

2.25:1

2.00:1

1.83:1

1.71:1

1.62:1

1.50:1

1.38:1

2IN1

4.00:1

3.20:1

2.57:1

2.22:1

2.00:1

1.84:1

1.73:1

1.57:1

1.44:1

UNBAL

BAL

PUSH

4.00:1

3.00:1

2.50:1

2.20:1

2.00:1

1.85:1

1.66:1

1.50:1

To minimize the audibility of compression artifacts, use ratios from the unshaded portion of the table.

Dynamic Range Compression

Start with compressor GAIN set between 4 and 6dB.

Set THRESHOLD between

-18 and -36dB.

Set RELEASE to 100 mS.

Shorten the time constant for percussive program material and lengthen it for voice.

Overload Protection

Press PK HOLD and 1dB SCALE. Set input so that peaks read approximately -4dB.

Set compressor GAIN to 4dB.

Set THRESHOLD to 0dB.

Start with RELEASE set to 100mS and adjust it for the program material

Recognizing Machine States

Flashing Machine State Comment

1dB SCALE and ATTEN Outputs muted. To unmute, press and hold 1dB SCALE and press ATTEN. 1dB SCALE and 4-CHAN Sinewave generator mode To exit, press and hold 1dB SCALE and press 4-CHAN. 1dB SCALE and EMPH Diagnostics mode To exit, turn 20/20 AD POWER off, then on again. 1dB SCALE and DISPLAY Front panel lockout To exit, press and hold 1dB SCALE and press DISPLAY. WC or AES External sync source selected Connect the appropriate sync source or use EXT SYNC to

but not present select Internal Sync (neither WC nor AES lighted).

48 and 44.1 AES sync source not present AES sync source must be within 41-51 kHz range.

or out of range

Continuously Lit

WIDE, HF and 20BIT Psychoacoustically optimized 4-CHAN, DISPLAY, LINK, compressor ON and ALT-MUTE

noise shaping activated are disabled. To exit, press DITHER.

3 Oak Park • Bedford, MA 01730 USA • Tel 781-280-0300 • Fax 781-280-0499