Yamaha MW12 Service Manual page 31

3.11 Distortion Factor
In the signal routes of the Table 3.3-1 to 3.3-6 indicated with q to !0 (except 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 r, check only the ST L OUT and the ST R OUT.
3.12 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, AUX1 OUT, AUX2 OUT 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.
3.13 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 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.
(Minimize the LEVEL VR other than the measurement channel. Noise is measured with a 12.7kHz -6dB/octave
low pass filter.)
3.14 Residual Noise
In the state 3.1, set the Fader and Level Control of all input CH to MIN and set the all Assign switch to OFF.
Then, the noise level shall be less than the level specified in the Table 3.14-1.
* In measuring the C-R OUT and the PHONES, set the ST Fader to MIN.
(Noise is measured with a 12.7kHz -6dB/octave low pass filter.)
Table 3.14-1 [dBu]
Fader/VR STEREO OUT GROUP OUT
MAX -78.0
MIN -100.0
3.15 PHANTOM
Connect a 10kΩ (1W or more) load resistance between the pin 1 and 2 of the MIC and short-circuit between the
pin 2 and 3.
Turn on the PHANTOM switch (LED shall light) and the voltage between pin 1 and 2 shall be within +35 +/-3V.
3.16 Preparation of delivery
Factory set
• EQ Gain control
• PAN,BAL,PAN/BAL control
• Other VR control
• FADER
• Lock-PUSH switch
• ON/STANDBY switch
AUX OUT
-80.0 -75.0
-100.0 -100.0
: CENTER
: CENTER
: MIN
: MIN
: OFF
: STANDBY
C-R OUT
-72.0
-87.0
MW12
31