VNE Vacuum Tube Compression Amplifier
HAZELRIGG INDUSTRIES
13
Figure 2. VNE front panel controls and indicators
CONTROLS (see Figure 2.)
Threshold (1)
The Threshold control adjusts the point where compression begins. With the control all the way
down, there is no compression and the VNE operates as a straight amplifier. As the control is
turned clockwise, the amount of compression increases. This can be monitored on the Gain
Reduction meter, or by ear.
Input switch (2)
The input switch has 3 positions: Bypass, In, and HPF. While in Bypass, audio comes into the
VNE, then immediately goes back out without going through any internal circuitry. In the ‘In’
position, audio will go through the amplifiers and compression circuitry. In the HPF position, a
high-pass (low cut) filter is inserted in the sidechain. This makes the compression less bass-
sensitive and may be useful on sources that have a very heavy bass content. The roll-off of bass
sensitivity is a very gentle curve (about 6dB per octave) and has little effect above 150Hz. When
the VNE is powered off audio will simply bypass.
Output Signal Indicator (3)
The bi-color LED (8) displays output directly from the secondary of the output transformer,
through an isolation amplifier. Ideally, the indicator should show green while recording signal.