LavryBlue 4496
Operation
16
B.) SETTINGS
The MicPre has a number of internal settings, which can be accessed by removing the top cover (please see
“Opening the LavryBlue” Page 20).
Configuring the output for Balanced or Unbalanced operation-
the outputs can be configured for
Unbalanced operation by placing the jumpers U6, U7, U8, and U9 on the appropriate pins. They are located
next to the male output XLR connectors.
Please note that the polarity is Pin 2 “+” on the input
connectors, so configuring the outputs for Pin 3 active unbalanced operation would result in the
polarity of the output signal being inverted with most microphones.
Lavry Engineering would therefore
recommend when configuring the output for Unbalanced operation to use the “Pin 2 active” setting, and
wiring the cables that plug into the MicPre outputs accordingly.
The “Left” or “Right” refer to which two of the three pins the jumper is placed, as viewed facing the front
of the 4496 while looking towards the inside of the back panel.
Analog Output Mode
U6
U7
U8
U9
Balanced output (as shipped from factory)
Left
Left
Left
Left
Unbalanced Output – Pin 2 active, Pin3 to ground
Left
Right
Left
Right
Unbalanced Output – Pin 3 active, Pin2 to ground
Right
Left
Right
Left
Phantom Power disabling-
In the special case of vintage condenser microphone that have their own power
supply, it may be desirable to disable the Phantom Power when using the “Condenser” setting on the front
panel switch. There is a jumper (U101) near the middle of the PC board towards the front panel for this
function. It is labeled “Phantom” and the “Off” position disables Phantom Power completely.
Optimizing for longer cable lengths-
near the “Phantom Power” jumper is a second jumper (U80) labeled
“CMMR.” The default setting of this jumper is “On” for cables up to 200 feet long. To optimize the input
for cables longer than 200 feet, the jumper can be moved to the “Off” position. The “Off” position will
work in either circumstance, but using the “On” position for cables less than 200 feet in length does
improve the noise rejection of the input.
C.) SPECIFICATIONS
Distortion
-
Measured at 100Hz, 1kHz, 10kHz, &20kHz:
Gain setting 40- 0.001%
Gain setting 60- 0.005%
Noise
-
Input referenced noise at gain settings from 40 to 70dB:
Input shorted
-128dB
150 Ohm source -126dB
Gain
-
Individual stepped analog control with 21 to 70 dB’s gain in 1dB steps for each channel.
Pad
-
Front panel switch for 10 dB Output “Pad” controls both channels. Does not affect input level.
Inputs
-
Two channels of electronically balanced XLR inputs wired for Pin 2 “+” (non-inverting), Pin 3 “-”
(inverting). Input impedance matching for Ribbon, Dynamic, and Condenser microphones. Front panel
switch controls both channels. Absolute Maximum input +3V.
Outputs
-
Two channels electronically balanced XLR o4dBu nominal level. +24dBu Maximum
Output Level (+14dBu with Gain Pad “on”).
Wired for Pin 2 “+” (non-inverting), Pin 3 “-” (inverting)
operation. Can be configured for unbalanced operation using internal jumpers.
Phantom Power +48V
-
Available on the input XLR connectors, only in the “Condenser” setting. Dual
regulation provides exceptional inter-channel isolation.
