Control description and operation – Drawmer 1969 Vacuum Tube Compressor Pre-Amplifier User Manual

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W ith the exception of the Aux preamp section, both channels of the 1969 are identical
and may be used independently or linked for stereo operation. In both the linked modes,
only Channel 1 compressor controls are functional and serve as the stereo master. In
Stereo Link mode, both channels track together to avoid the inevitable image shifting
that would occur if the two channels of a stereo signal were treated independently.


Source Select:

This rotary switch selects the compressor input source. The

Line and Mic inputs are via the rear-panel XLRs while the
Aux input is available on the front panel. The two Mic
positions offer an input with or without +48V phantom
powering, with a red LED lit when active.

Note: if the Aux input is to be used at the same time as a Mic input, it is
recommended that the Mic input be processed through the upper channel
and the Aux input through the lower channel as this minimises crosstalk
between tube amplification stages sharing the same envelope.

Phase Reverse:

This will invert the phase of the selected input signal.

Use of the Phase Rev feature is usually required in multi-
mic situations where phase anomalies or arrival time
discrepancies need to be compensated for. It is advisable
to check for mono compatibility when using phase reversal
within a multi-mic arrangement.


The signal path incorporates a switchable high-pass filter

which may be set to 50Hz, 100Hz or Off. Its use is to
attenuate low frequency signals that might otherwise prove
troublesome, eg. traffic rumble or stage vibration.


Determines the input level above which gain reduction will

be applied and may be set in the range -20dB to infinity.
Because the compression system is based on the Soft Knee
principle, the onset of compression is progressive, so no
Ratio control is necessary.