Solid State Logic X-Logic Series Rack Mic Amp Module, MIC Section E, Line Section F, A-1

X-Rack Mic Amp Module

A. The Mic Amp Module

A.1 Connection

The rear panel of the module carries the Mic (‘IN’) and Line input (‘LINE’) XLRs along with a single output (‘OUT’) XLR. The Line input and output operate at a nominal level of +4dBu although the gain of the Line input can be varied by a front panel control. Also contained on the front panel is an additional mono Jack socket for a high impedance Instrument input.

A.2 Operation

The X-Rack Mic module contains three seperate input amplifiers; a Microphone amplifier, an Instrument input and a Line input, any one of which may be selected at any one time. A set of High and Low Pass filters are also provided.

A.2.1 MIC Section E

Normally, the Microphone input on the rear of the module will be selected (‘LINE’ and ‘INST’ switches released); pressing the ‘INST’ switch selects the mono jack instrument input on the front of the module. This is a very high impedance unbalanced input intended to be used with guitar pickups etc. To help alleviate ‘hum’, a ground lift (‘GND LFT’) switch has been provided which places a 1k2Ω impedance in series with the sleeve of this connector and audio ground in the module. The gain of these inputs is continuously variable between +12dB and +75dB.

The impedance of the Microphone input can be varied between ≈1k2Ω and ≈10kΩ by selecting the ‘IMP IN’ switch and adjusting the ‘Z’ control. This allows the connection of line level signals to the Microphone input if required, and provides an alternative input impedance for some dynamic microphones.

The ‘PAD’ switch reduces the signal level of both the Microphone or Instrument inputs by 20dB. Phantom power, for microphones requiring this, can be switched on using the ‘+48V’ switch. Please note that X-Rack units prior to serial number XRK0110 are not normally enabled for +48V. However, a field retrofit kit (629620XR) is available for these units. Any in-warrantyX-Rack units can be upgraded free-of-charge; for units out of warranty a charge will be made. Please contact your local distributor to order this kit, if required.

Note. Please note that connecting a microphone to the X-Rack Mic module with phantom power switched on is not advised as it may cause damage to either the microphone or the input stage of the X-Rack module. Take care not to connect line level sources (keyboards etc.) to the microphone input with phantom power switched on as this may damage the output stage of the connected unit.

A.2.2 LINE Section F

XR621
MIC		E
INST
IMP
IN	Z	HI
LO
+48V
PAD
+12	dB	+75
LINE		F
LINE
-20	dB	+20

Ø

HF

9 6

30 4

IN

50 KHz 3

LF

160 300

60

IN

30 600

OUTPUT

REC

L

SIGNAL

REC

R

INSTRUMENT

GND

LIFT

The Line input on the rear of the module is selected by pressing the ‘LINE’ switch. The gain of this input can be varied by ±20dB from the nominal 0dB.

The Ø (Phase) switch reverses the phase of the selected input.

Page A-1