LavryBlue 4496
Operation
7
5.) SELECT DITHER & OPTIONAL NOISE SHAPING for 16bit or 20 bit modes.
Dither, ABC-1 and ABC-2 are grouped together (similar to Word Length).
•
α
coustic
β
it Correction™
is dither plus psycho-acoustic enhancement of the converter’s
dynamic range for word length reduction to 20 or 16 bits. (Some describe this as getting more than
16 bits performance with a 16 bit word length.)
• ABC-1
provides a gentler enhancement curve.
• ABC-2
provides a more aggressive enhancement curve.
• NOTE: Setting the position of the internal DIP switch position to “ON” changes ABC-1 and ABC-2 to
less aggressive curves. Please refer to the SETTINGS SECTION on pages 10-11.
6.) METER FUNCTIONS
The meters on the M•DA-824 display the “digital level”- or in other words the
peak level
of the signal after
it has been encoded by the A-to-D converter. This means they are extremely accurate, and will reflect
adjustments made to the analog input trimmers. This also means that there is no way to show actual signal
level above “0 dB” or “Full Scale Digital” (all bits “On”). The MAX lamps indicate that this level has been
exceeded, but not by
how much
. This is why the lamps from –5 dB to 0 dB are red- to indicate that with
typical audio signals you are approaching the level where a loud peak might be “clipped” by exceeding 0
dB. It is desirable to record as loud as possible without exceeding 0 dB and thus making the MAX lamps
light. So don’t be afraid to “record in the red” of the M•DA-824’s meters, but it is best to avoid lighting the
MAX lamps. See “Saturation Modes” (sections 3&4 above) for ways to record higher levels without
“clipping.”
7.) PEAK-HOLD-
Enabling this function will indicate and “hold” the highest peak level. The peak that is held can be reset by
quickly activating the front panel switch.
8.) REFERENCE METER BRIDGE-
In this mode, the range of the M•AD-824’s meters are “expanded” around the reference level so that each
lamp indicates approximately
0.2dB of input level change
above or below the reference level.
To use this mode you need an analog audio reference tone source (1 kHz for example). The tone needs to
be at a level that corresponds to the AVERAGE level of the music source. This “average” level will
typically be in the range of 10 to 20dB’s below analog PEAK level of the music program. For those with
VU meters, this would typically be “0dBVU.” For those without VU meters, that have a PC interface with
fixed “+4” level outputs, the equivalent would be a digital tone at a level 14dB below 0dBFS routed to a
pair of analog outputs that are feeding the M•AD-824’s analog inputs. (The digital level “0dBFS” is
sometimes referred to as digital “clipping” level)
Before applying the tone, use the “Select/Set” switch to select “Reference.” An illuminated pair of lamps
(Left and Right channel) indicates the reference level between -10 and -20dB on the meters- they will be
near the middle of the meters’ range. Toggle “SET” to move these lamps to the desired reference level (-10,
-12, -14, -16, -18 or –20dBFS as indicated by the scale printed on the meter of the M
AD-824).
Apply the tone to the analog inputs of the M•AD-824. If the top lamps of the meter are lit, it means that the
analog input level is ABOVE the meter range, and if the bottom lamps are lit the level of the tone is
BELOW the range.
Use a small screwdriver to adjust the front panel 20-turn pots to bring the input level “on scale” and the
lamps will appear to move up from the bottom or down from the top until they coincide with the selected
reference level. This indicates that you analog reference level (“0dBVU” for example) corresponds to the
digital reference level of the M•AD-824. You can also set the level above or below the reference mark for
reference levels between the available marks (for example, five lamps below “–10 reference level” would
be “-11dB”). Remember each lamp is ~0.2 dB’s of level change in reference mode.
