Alto EQU231VU-MKII V2 User manual

www.altoproaudio.com
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!Version 1.0
MODEL: EQU231VU- MKII V2
Revised on Jan,2010

CONTENTS
1. Introduction...................................................................................................................1
2. Specification.................................................................................................................2
3. Block Diagram..............................................................................................................3
4. Schematic Diagram.....................................................................................................4
5. Wiring Diagram............................................................................................................8
6. PCB Layout.................................................................................................................9
7. Test Procedure...........................................................................................................13
8. Exploded View & Mechanical Parts List.....................................................................17
9. BOM List....................................................................................................................19

The EQU231VU-MKII V2 Graphic Stereo 31-Band Equalizer/VU meter*2 is an extremely
musical and flexible Graphic Equalizer, based on many years of experience and designed
to provide a permanent precise equalization to musician, performer, and studio engineer. It
can be used wherever is requested to modify the frequency “contour” of a sound and can
offer a solution to many common sound problems and allows the user to use the creativity
to obtain nice results in terms of sound characterization.
The EQU231VU-MKII V2 Graphic Stereo 31-Band Equalizer/VU meter*2 Features:
Constant Q circuitry with a 3% center frequency accuracy
Control range +/-6dB/+/-12dB selectable
Active balanced and unbalanced input and output connectors
Variable input level control
Signal clop pilot
Ground “LIFT” switch to disconnect signal ground from chassis ground
Power off automatic bypass function
Line voltage selectable robust and compact design
Manufactured under QS9000, VDA6.1 certified management system
1. Introduction
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Type EQU231VU-MKII V2 2*31-Band: 1/3 Octave, ISO spacing(2H series)
Slider Travel 20mm with positive centre detent
Range +/-6dB or +/-12dB selectable
Active balanced XLR and 1/4'' TRS
Unbalanced RCA
20k Ω(bal.)
15k Ω(unbal.)
Maximum input level 14 dBu
Active balanced XLR and 1/4'' TRS
Unbalanced RCA
Output impedance ＜600Ω
High pass filter 40Hz(12dB/Oct)fixed-button type
Low pass filter 16KHz(12db/Oct)fixed-button type
Frequency response 20 Hz to 50kHz at -1.5dBu
THD+N% ＜0.01% (@1kHz, all VR at middle position)
S/N Ratio 110dB
95V -120V AC -60Hz
220V-240VAC -50Hz/60Hz
Consumption 18W
Dimension 483(W)*220(D)*88(H)mm (19''*8.66'*3.5'')
Power supply
Input impedance
Output connections
Input connections
2. Specification
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3. Block Diagram
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4. Schematic Diagram
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5. Wiring Diagram
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6. PCB Layout
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EQU231VU-MKII V2 Finished Product Test
Test Instruments
1. AP (Audio Precision)
2. Dual-track oscilloscope
Instrument setting
1. Set proper AC input voltage
2. Connect the output signal of AP to the input of EQU231VU-MKII V2
3. Connect the output of EQU231VU-MKII V2 to the input of AP
Adjustment according to following procedures
1. Set the potentiometer of 31-band EQ in center, set the input level at 0dB, all buttons out
2. Turn input level to maximum, the output level +12dB+/-1dB, and the distortion shall be
0.003%+/-0.001%
3. Set INPUT LEVEL at minimum, the output level shall be -12dB+/-1dB, and distortion shall be
0.006%+/-0.001%
7. Test Procedure
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4. Adjust the input level so that the AP output is 0dB, the frequency response is as following
10Hz ~ 22KHz +/-2dBu
5. Adjust the input level so that the AP output is 0dB, press the HI-pass button and the frequency
response is as following
6. Adjust the input level so that the AP output is 0dB, press the low pass button and the frequency
response is as following
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7. Press EQ button down, keep RANGE out and the LED indicates +12, adjust slide buttons to
maximum and minimum, measure the frequency response independently and the curve shall
be as following
8. Turn off the AP input signal and set input level as maximum, the AP setting is as following, now
it shall be no more than -82dB
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9. Turn on the AP input signal, and set the input level at maximum, theAP setting is as following,
the maximum non-distortion level is +28dBu+/-1dB and distortion is 1%
10. Now, the S/N shall be no less than 110dB
11. Connect AP input and output to Channel 2,repeat steps 1~10
12. Input a 0dBu signal, adjust the INPUT LEVEL to 0dBu, and AP output shall be 0dBu.Now it
shall indicate 0dBu on the Vu meter
13. All slides shall be set in center and all buttons out before shipping
~Test Completed~
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8. Exploded View & Mechanical Parts List
MODEL No: EQU231VU-MKII V2
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S/N Part No Description Specification Qty
1 MB03477 Chassis EQU231VUMKII 1
2 MB03220 Rear panel EQU231MKII 1
3 MC00578 Top cover EQU231MKII 1
4 MA04798 Front panel EQU231VUMKII ALTO 1
5 HC00015 AC socket (S)315-B(with AC selector) 1
6 TC00212 Fixed voltage transformer PT-231-II-230V 1
7 MG00127 Color screw M4*8 2
8 MG00042 Black plated screw M3*10 2
9 NI00315 Pwer switch 5*5*9(inner3.3*3.3) 8
10 MG00061 Lback plated screw M3*10 12
11 NI00501 Adhesve cushion 12.7*3t(SF-004) 4
12 HK00327 K-PCB P-131VU 2
13 HI00026 Power SW RA12KKATO F2P 1
14 MG00025 Black plated screw M3*6 24
15 MG00041 Black plated screw M3*6 20
16 ME00016 Color nut 4mm 1
17 MF00038 Spring washer ψ4*ψ7*1t 2
18 MF00048 Outer fear washer ψ4*ψ8*0.5t 3
19 HK02058 K-PCB P-EQU231VUFP-II-DIP 2
20 HK02063 K-PCB P-EQU31EQ-II-DIP 2
21 HK02065 K-PCB P-EQU31PU-II-DIP 1
22 HK02066 K-PCB P-EQU31PU-II-1-DIP 1
23 ND00340 Dust cover 344*37 2
24 HK04116 K-PCB P-EQU231SW-II-DIP 2
25 NI00002 Plastic nut Hexψ7/16''*G20/15*4.8
26 MI01998 Fixed bracket EQU231MKII 1
27 NC00131 T-wood washer 1*ψ11.3*ψ15.3 red 4
28 MJ00808 Power mixing plate WL3-32T 6
29 MG00247 Copper column M3*0.5PH*10 total length 16 3
30 MG00408 Copper column M3*33*0.5PH total length 39 3
31 MG00241 Copper column M3*30*0.5PH total length 36 3
32 MG00512 Copper column M3*12.5*0.5PH total length 17mm 3
Mechanical Parts List
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