LACHAPELL AUDIO MODEL 983M
5
CONTROLS
CONTROL DETAILS
• TUBE DRIVE: TUBE DRIVE controls how much of the source signal is fed to the vacuum tube. Higher
levels will drive the tube harder and result in more harmonics. Think of this control as your amount
of tube coloration/harmonics (distortion).
• LEVEL: Provides variable control over line level signal strength. Think of this control as your source for
clean gain. Typically, this control is used to establish the desired line level after the input gain has
been set but it can work interactively with the TUBE DRIVE for a wide array of tonal possibilities.
• 48V: The 983M features TRUE48™, a dynamic phantom
power supply that provides a 48 volt supply of DC current
for condenser microphones. Unlike other phantom power
supplies, TRUE48 provides a full 44-48V of phantom power
regardless of the source resulting in more headroom, lower
distortion and quicker transient recovery.
• HI-Z INPUT: The Hi-Z input stage is transformerless and operates
with an input impedance of 100Kohm. The input pad has no
effect on the Hi-Z input.
• 20dB INPUT PAD (-20): When engaged, the microphone input
source signal is reduced by 20dB.
• POLARITY REVERSE: Reverses the polarity of the output signal.
• MUTE: Output level mute. The MUTE LED will illuminate red when the channel is muted.
• VU METER: This detects the microphone input signal (not output level). The LED is calibrated to
detect input signals as low as -50dBu. When +4 is illuminated, it indicates that line level has been
achieved. The Clip LED is intended to be a warning that clipping may occur if output signal
strength is pushed further. It is calibrated to illuminate when the output is d23dBu into a
40kohm source. It does not necessarily indicate that the output stage has reached its limit.
• HIGH-PASS FILTER (HP): Select no fi lter (center position), cut at 50hz (down position) or cut at 150hz
(up position).
• LOW-PASS FILTER (LP): Select no fi lter (center position), cut at 5Khz (down position) or cut at 10Khz
(up position).
• POWER SWITCH: Master power rocker switch. LED will illuminate red when power is on.
CREATIVE TIP:
For near transformer-less sound,
consider engaging this pad
function and compensate for
the loss of gain by increasing
the input gain control. This
approach effectively minimizes
the input transformer gain
while drastically increasing the
character of the vacuum tube
(this is only possible with the
microphone path).
TUBE DRIVE
CONTROL
VU
METER
HI-Z
INPUT
TRUE48
PHANTOM
POWER
POLARITY
REVERSE
LEVEL
CONTROL
HIGH-PASS
FILTER
LOW-PASS
FILTER
-20 dB
PAD
CHANNEL
MUTE
AC
POWER