m
501
page
6
operatIng the m501
BASIC OPERATION
Turn the gain and trim controls fully counter-clockwise and check that the +48V phantom power is off.
Connect the microphone to the preamplifier and then turn on the phantom power switch on if required.
When sending a signal to a recorder that has fixed input levels, simply increase the gain until the opti-
mum recording level is reached.
When sending a signal to a recorder with a variable input, set the record level control on the recorder to
12 o’clock or midway between minimum and maximum, then set the gain on the m501 until the opti-
mum recording level is reached.
NOTE: It is important to observe proper microphone power sequencing when using phantom powered
mics. Always make sure that the +48V phantom power is turned off and discharged before connecting
or disconnecting a microphone. The red +48V LED indicates the presence of voltage at the microphone
input connector. It will go out when the +48V supply is sufficiently discharged.
uSING THE TRIM CONTROL
The trim control can be used for fine output level adjustment as well as for level riding during record-
ing. It can also add an additional 10dB of gain for a total maximum preamplifier gain of 75dB. If the trim
control is not needed for riding gain or providing extra gain, then it should be left at zero (fully counter
clockwise).
uSING RIBBON MIC MODE
Pushing the ribbon switch does three things: +48V phantom power is locked-out to prevent potential
damage to ribbon microphones, the impedance of the mic input is raised from 8.1k Ohms to 20k Ohms,
and the 48V DC blocking input capacitors are bypassed with sealed gold contact relays.
The maximum gain available on the m501 is 75dB, which is achieved by setting the gain control to 65dB
and the trim to 10dB. For recording low level sources with ribbon microphones, the m501 has ample
available gain, sufficient for even the most demanding low-level recording scenarios.
Note that if the +48V phantom power is on and then the ribbon mode is engaged there will be a
momentary delay before the m501 enters ribbon mode. This is because the m501 logic circuitry waits
for the +48V at the mic input to discharge before enabling ribbon mode. Likewise, if you are in ribbon
mode and the +48V switch is on, then phantom power will turn on immediately if the ribbon mode
switch is released. In general it is best practice to turn off the +48V phantom power before entering
ribbon mode.
The ribbon mode on the m501 is also ideal for many dynamic mics.
uSING THE HPF
The high pass filter (HPF), sometimes referred to as a bass roll-off, starts at 75Hz. This 12dB/octave filter
is optimized for minimum phase shift. The most common uses for this are in situations where low-end
rumble from mechanical sources or wind are present, to reduce excessive proximity effect, or to simply
help reign in excessive low end during recording.
