Manley CORE - Page 11

11
CALIBRATION / INTERNAL ADJUSTMENTS* (connued)
i) CALIBRATION OF VU METER:
1 - Feed a balanced sine tone @ 1 KHz, +4dBu (1.228V RMS) from an audio tone generator/oscillator into the LINE INPUT XLR.
2 - Use your audio analyzer and/or, set your voltmeter to read volts AC and put it at the output of XLR “OP1”. Start bringing up the
Input level aenuator unl you have +4dBu (1.228V RMS) at the output XLR “OP1”. This will be the same level as the input signal from
oscillator (unity gain)
3 - Use the VU meter select switch to read “OP1”. Adjust VR16 (OP1 ZERO VU) so that the meter reads “0” VU.
4 - Use the VU meter select switch to read “GR”. Adjust VR11 (GR-ZERO) so meter reads “0” VU.
ii) CALIBRATION OF ELOP
®
COMPRESSOR:
1 - Make sure the output level at XLR “OP1” is sll set for +4dBu, and the meter reading for “OP1” is “0” VU.
2 - Move your voltmeter (Volts AC)/Audio Analyzer to read the output XLR “OP2”.
3 - Use the VU meter select switch to read “OP2”.
4 - Adjust the OUTPUT GAIN control for an output level of +4dBu (1.228V RMS) at “OP2”. Meter reading for “OP2” should be “0” VU.
5 - Switch IN the COMPRESSOR.
6 - Adjust VR6 (GR-AUDIO) for a gain reducon of 6dB at “OP2”. (The output XLR “OP2” will read -2 dBu).
7 - Use the VU meter select switch to read “GR”.
8 - The VU meter should read -6. If not, adjust VR9 (GR-METER). Verify that VU “GR” and audio are within 0.2dB of each other.
9 - Repeat steps 6 to 8.
10 - Switch out the COMPRESSOR by switching it to BYPASS.
iii) CALIBRATION OF PEAK LIMITER:
1 - Make sure the output level at XLR “OP2” is sll reading +4dBu, and the meter reading for “OP2” is “0” VU.
2 - Turn OFF your audio generator/oscillator temporarily to complete next step.
3 - Switch your voltmeter to read Volts DC. Locate test point TP13 on the front panel PCB and use your voltmeter to check for a voltage
reading of +9.0VDC (± 0.1VDC). Adjust VR15 (LIM REF V.) So that TP13 reads 9.0 VDC. Locate test point TP14 verify a voltage reading of
-9.0Vdc (± 0.1VDC).
4 - Locate test point TP20. Check for a reading of -4.4VDC (± 0.3Vdc), Adjust VR12 (LIM CV) so that TP20 = -4.4 VDC
5 - Turn audio generator/oscillator back on.
6 - Make sure the output level at XLR “OP2” is sll +4dBu, and the meter reading for “OP2” is “0” VU.
7 - Move the liming control to “MAX”. Peak limiter red LED indicator should turn ON (± 1.0dB). Decrease oscillator output level by 2dB.
The LED indicator should turn OFF.
8 - Return the liming control back to “MIN”. Restore oscillator output level back to +4dBu.
9 - Use the VU meter select switch to read “GR”.
10 - Increase the oscillator output to +21dBu. The Peak limiter red LED indicator should turn ON (±1.5db). Decrease oscillator output
level by 2dB. The LED indicator should turn OFF.
Note 1: if you do not have enough output level coming from your oscillator, then increase the signal level coming into the CORE by adjusng the
INPUT LEVEL ATTENUATOR control. Bring up the input level aenuator unl you have a reading of +21dBu at the output XLR “OP2”.
Note 2: The Manley CORE Peak limiter secon was designed to automacally “kick in” according to specic output levels at the main output “OP2”.
When the LIMITING control knob is set at MIN the LIMIT threshold will be at +20dBu (± 1dB)
When the LIMITING control knob is set at MAX the LIMIT threshold will be at +3.5dBu (± 0.5dB)
*Experienced Technicians Only
The calibraon procedures menoned
here are to aid in the servicing of the
unit. They should only be aempted by
a skilled technician. These adjustments
should not be aempted by the user
without experience. Trimming these
potenometers without the correct
understanding will result in poor
performance of the unit.
INTERNAL GAIN JUMPER ADJUSTMENT
The factory default seng (+10dB gain dierence between LOW and HI) has the
internal jumper (JP2) connected to the pin marked ‘50’. For higher gain (+20dB
gain dierence), remove and replace the jumper (JP2) so it is connected to the
pin marked ‘60’.
50dB GAIN
(factory default)
60dB GAIN