M•AD-824
Quick-Start Guide
6
2.)
It is easiest to feed the reference tone to the MAD module before switching to
REFERENCE mode to establish what level it will appear on the MAD meters. For
example- Use a tone at “0 dBVU” from an analog source or “-12 dBFS” from a
digital source feeding a DA converter. Without changing the output level of the
device feeding the MAD analog inputs or the trimmers on the MAD, make a note of
the level of the tone as displayed on the MAD meters. For this example, we will use
“-12 dB.”
3.)
The indicated level of the tone has to be in the range of “-20” to “-10” to use the
REFERENCE mode. If it is not, you may need to use another analog level as your
reference level (+3 dBVU analog , or -8dBFS digital for example). Choose a level
that you can accurately meter or duplicate at a later time.
4.)
Select the REFERENCE mode, and set the reference level to the dB level established
in (2) above. Our example is “-12 dB,” so you would click the toggle switch in the
SET direction until the reference marker lamps are next to the -12 label on the MAD
meters. When the setting reaches “-20,” it starts over again at “-10,” so it may be
necessary to click the switch in the set direction repeatedly to get it back to “-12.”
5.)
There should also be two other lamps illuminated on the MAD meters which
represent the input signal level. Please note that you do not have to use the reference
marker’s level as your reference level. Each lamp above or below the reference mark
represents 0.2 dB’s of change, so by counting the number of lamps above or below
the reference marker, you can establish the reference level for an “in-between” level
such as “-13 dB.” Using our example where the reference mark is at “-12,” this level
would be indicated by the lamps that are between the “-30” and “-20” label on the
MAD meters, which is five lamps below the “-12” lamp.
6.)
Because the level established using music program in step 1 (above) represent the
loudest level without “clipping,” it would be advisable to use the lower of the two
channels as the reference level. For example, before further adjustment, the meters on
the MAD module show the reference tone at one lamp above -12 on the left channel,
and one lamp below -12 on the right channel. If you lower the left channel to one
lamp below -12 (or -12.2 dB), the channels will be balanced and at a level that did not
cause clipping.
7.)
Some further experimentation may be necessary to “fine-tune” the setting. By using
the REFERENCE mode to make the adjustment, it is both easy to change in a
calibrated manner and easy to reset to a known level.
8.)
One last note- it is possible to turn the trimmers down on the MAD module and
create a situation where the analog outputs of the device feeding it “clip” or distort
before the signal reaches “0dBFS.” With the trimmers turned all the way “down”
(counterclockwise) the maximum input level of the MAD module is very close to
+24dBu, which may be up to 6 dB’s hotter than some analog outputs are capable of
outputting. For example- if the maximum output level of your analog device is
+18dBu, then “0 dBVU” or “-14dBFS” would correspond to “-14” on the MAD
meters to match the maximum analog level to digital clipping level. In this case, the
trimmers would be closer to the middle of their adjustment range.
PEAK HOLD FUNCTION-
Enabling this function will indicate and “hold” the highest peak level on the meter. The peak
indication that is held can be reset by quickly activating the front panel switch when the
MAD is normal mode (after exiting the programming mode).
