Crosstalk; Peak Led Light-Up Level; Distortion Factor; Equivalent Input Noise - Yamaha MG12/4FX Service Manual

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Table 3.6-1 [dB]
EQ control
HI
MID
LO

3.7 Crosstalk

Setting the fader to the nominal position and each input channel ON switch to ON, and turning the PAN control shall be
-50dBu or (BAL control in the case of ST CH INPUT) counterclockwise fully, the level of the leakage to ST R OUT less
when the output level of ST OUT is +20dBu.
Also turning the PAN control clockwise fully, the level of the leakage to ST L OUT shall be -50dBu or less when the output
level of ST R OUT is +20dBu.

3.8 PEAK LED light-up level

In the state 3.1, each LED shall light-up when a signal specified as below is fed to the MIC input.
Table 3.8-1 [dBu]
INPUT
MIC
3.9 Meter LED lighting check
PEAK LEDs lights up, when ST output level reachs +17.5 ±2dBu.
0 LED lights up, when ST output level reachs +4 ±2dBu.
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Operate the fader and check that LED light up in order from "-20" to "PEAK".

3.10 Distortion Factor

In the signal routes of the Table 3.3-1 to 3.3-6 indicated with q to !0 (expect er), set the VR and Fader of INPUT and
MASTER to the Nominal Position, and set the GAIN to the position specified in the Table (except PHONES).
Then, feeding each 20Hz, 1kHz and 20kHz signal, the distortion shall be less than 0.1 % when the output signal level is
+14dBu. At the C-R OUT (L/R), setting the Level Control to the 12 o'clock position, feeding each 20Hz, 1kHz and 20kHz
signal, the distortion shall be less than 0.2% when the output signal level is +3dBu.
In the route q, check every OUT when the signal is fed to CH1, and check only the ST L OUT when the signal is fed
＊
to CH2 and other channels.
In the route w, turning the PAN/BAL control to L fully, the distortion shall be less 0.1%, when the ST L OUT signal level
＊
is +4dBu.
In the route e, check only the ST L OUT and the ST R OUT.
＊
3.11 Maximum Output
In the state 3.1, the distortion factor shall be less than 1% when the output level is +24dBu at ST L OUT and ST R OUT,
and +20dBu at GROUP1/2 OUT, AUX SEND, EFFECT SEND and C-R OUT.
The distortion factor shall be less than 1% when the output level is +7.5dBu at PHONES (L/R).
In measuring the ST L OUT, the ST R OUT and the GROUP1/2 OUT, set the PAN or BAL Control to L or R fully
respectively.

3.12 Equivalent Input Noise

In the state 3.1, connect between the CH INPUT MIC terminals (2pin-Hot and 3pin-Cold) with 150 ohms, the noise level
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obtained at ST L OUT shall be less than -43.5dBu.
If it is over than -43.5dBu, calculate the input converted noise level (= noise level - channel gain) and it shall be less than -
127.5dBu.
Connect between the ST INPUT MIC terminals (2pin-Hot and 3pin-Cold) with 150 ohms, the noise level obtained at ST L
.
OUT shall be less than -39.5dBu.
If it is over than -39.5dBu, calculate the input converted noise level (= noise level - channel gain) and it shall be less than -
123.5dBu.
(Use a 12.7 kHz, -6 dB/octave low pass filter when measuring noise.)
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EQ GAIN Applied frequency
MAX
10kHz
MIN
MAX
2.5kHz
MIN
MAX
100Hz
MIN
PEAK LED
-43 ±2
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Variaion width
+12 ±2
-12 ±2
+15 ±2
-15 ±2
+12 ±2
-12 ±2
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MG12/4FX
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