Operator`s manual

MODEL CS 208 v2

OPERATIONAL & APPLICATION NOTES

MAY 2003

Inputs:

XLR In: Transformer balanced input. Nominally Pin 2 high. (Pin 3 - low, Pin 1 - ground).

Channel Power: To conserve current consumption, switch off unused channels. Do not switch

during recording.

Mic Power Select: Mic power off. For example, dynamic and radio microphones. T-power / AB

power = Unbalanced microphone powering, nominally Pin 2 is positive, for use

with unmodified European microphones. XLR must be reversed for ‘red dot’

microphones. Phantom power = Balanced powering, positive DC voltage on

both Pins 2 and 3, normally set for 48v (See application note AN 2C v.2).

Do not switch to 48 volt with 12 volt phantom microphones.

Phase: This affects audio phase only (ie: does not control the T-power polarity).

N (normal) = Pin 2 high. R (reverse). It is important that the phase of the

microphones are matched to avoid phase cancellation. Absolute phase

throughout the system should also be maintained.

Mic / Line: Up = Mic, Down = Line. 40 dB pad.

Pad: 15 dB pad, effective in both mic and line positions.

For typical SPL (sound pressure levels) pads are not necessary due to the high

system headroom. The use of pads will degrade the signal to noise ratio if used

within the range of the microphone gain trim. 40 dB pad may be used for

balanced line level signals.

HP1: Pre transformer filter (100 Hz, 6 dB/oct) for use where very high level, low

frequency signals may saturate the transformer and pre-amplifier. In general,

because of the very high saturation point of the Jensen Transformers (-6 dBu at

20 Hz), this filter is rarely necessary.

HP2: Is a post preamp filter. (70 Hz, 12 dB/oct) Sharp roll-off below 70 Hz to reduce

microphone handling noise and other low frequency disturbances. It is

recommended to use this for dialogue recording as the bandwidth of interest

normally exceeds 100 Hz.

EQ: Hard bypass switch does not affect H.P. filters. EQ-H.F. = (High frequency ,

shelving response) Used to increase / decrease ‘brightness’ of signal. (eg: to

reduce sibilance.) EQ-M.F. = (Mid frequency) Center frequency variable from

500-5 kHz. (eg: May be used to increase ‘presence’) EQ-L.F. = (Low frequency,

shelving response), may be used for a more gradual tapering of low frequency

signals.

ABCD: Assigns channel to ABCD mix busses.

‘L’ & ‘R’ indicate pan pot and monitor assignment.