LaChapell Audio 503 500 Series EQ - Manual (Page 3)

583E Controls:
Input Gain Control
Output Gain Control
Mic/Hi-Z Input Select
Phantom Power
20dB Input Pad
Polarity Reverse
Hi-Z Input
High Frequency EQ Band
Mid Frequency EQ Band
Low Frequency EQ Band
EQ Assignment Select (Auto Patching)
Input Gain Control: Provides variable control
over how much input source signal is driven onto
the vacuum tube. Specifically, this control is posi-
tioned after the Jensen input transformer and just
before the 12AX7 tube. Think of this control as
your “throttle” for tube coloration/harmonics
(distortion).
Phantom Power (48v): This toggle provides a 48
volt supply of DC current for all condenser micro-
phones. Each 983S is calibrated to exactly 48V
during final assembly.
20dB Input Pad (-20): When engaged, micro-
phone input source signal is reduced by 20dB.
Specifically, this action occurs before the Jensen
input transformer.
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 ap-
proach effectively minimizes the gain coming
from the Jensen input transformer while drasti-
cally increasing the character of the vacuum tube
(this is only possible with the microphone path).
Polarity Reverse: Reverses the polarity of the
output line level signal.
Input Select: Alternates between rear panel mi-
crophone XLR input or front panel ¼ Hi-Z input.
Each position defeats the other.
Hi-Z Input: The Hi-Z input stage is transformer-
less and operates with an input impendence of
100Kohm. It cannot make use of the -20dB pad.
Output Gain Control: Provides variable con-
trol 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.
High Frequency Band: Fully variable sweep
range; 2.5kHz to 20kHz. Q value of 1 at +8dB
Mid. Frequency Band: Fully variable sweep
range; 325Hz to 5kHz. Q value of 1 at +8dB
Low Frequency Band: Fully variable sweep
range; 30Hz to 400Hz
EQ Assignment Select: Auto-patches the EQ
to run independent or as part of the preamp
output path.
Pre + EQ: In this mode, the EQ section is
internally routed to serve the preamp’s output signal;
effected signal is sent out the left bay output jack.
Independent EQ: In this mode, the EQ section
is available as a completely independent module. The
corresponding rear/right side XLR connectors are
now active allowing you to use the EQ on any exter-
nal souse while the preamp remains available on the
left bay. In this mode, think of the 583E as two mod-
ules.