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grace design m801

mk2

owner’s manual

nal present. In contrast, there will almost always be an audible click if turning the gain control while
a signal is present. This is because the gain control, being a stepped control, will make an instanta-
neous change in amplitude when turned, which creates a transient signal.

EQUIPMENT NEEDED

•

DC Volt meter with at least 1mV sensitivity

•

Plastic alignment tool or a small screwdriver.

•

#2 phillips head screwdriver

PROCEDURE

1. Remove the 14 phillips head screws from the top lid but leave the lid in place.
2. Turn on the preamplifier and allow to warm up for at least 45 minutes. (go get a nice cup of

coffee and do some stretches)

3.  Set all of the preamplifier gain controls to minimum (fully counter clockwise).
4.  Set all +48V, polarity reverse, pad, and ribbon mode switches to OFF
5.  Remove the top lid and locate the DC offset test points TP7 and TP8 (figure 3) on the channel

to be adjusted. Place the Volt meter probes into these holes and note the DC Volts. It should

be in the range of +/- 0.02V.

6. Rotate the gain control to maximum (fully clockwise) and note the DC Volts.
7. Locate DC offset potentiometer VR1 and rotate it for a reading that matches the minimum

gain reading. +/- 0.005V.

8. The objective is to get the minimum gain offset and the maximum gain offset to match as

closely as possible.

9. The input offset does drift with temperature and having the lid off will allow the circuitry to

cool. It is advisable to replace the lid and let the preamplifier warm up again (about 20 min-

utes) and then re-check your adjustments.

R29

R31

D15

R19 C16

D16

+48V

C15

C18

R24

CAL

R34

R36

R37

C37

R39

R58

TP1

TP2

GND

TP3

TP5

R21

C17

D10

R23

R25

R27

R32

D11

C29

C35

R38

C36

R45

TP9

D13

C41

R48

R49

R50

R51

R52

D18

R54

C46

R55

R56

R57

R59

C44 J4

C47

-18

-15

R7 R9

TP8

R18

TP7

C22

R22

C25

R30

R28

R35

C38

R44

C39

R53

D19

C45

E -

C10

R17

C19

R11

R13

R15

VR1

C14

R46

C49

C11

-15V REG

+15V REG

R16

TP6

TP4

C13

C21

C24

C23

METER

CAL

R10

VR2

R14

R12

C20

C28

C26

C32

R41

C33

C34

U10

C40

U11

AUTO

+10dB

D12

C42

R43

D17

D14

TP10

+5V

+15

+18

R20

C48

R26

C30

R33

C27

C31

R40

R47

R42

GAIN

C43

OFFSET

+48V

OFFSET

AT211 Rev

VR1

DC OFFSET CAL

TP7-TP8

DC OFFSET

TEST POINTS

+10dB GAIN / AUTO

VR2

PEAK LED CAL

figure 3

- offset test point and peak LED adjust trimpots

Содержание m801mk2

Страница 1: ...Owner s Manual Rev A All contents Grace Design Lunatec LLC 303 823 8100 www gracedesign com 8 Channel Microphone Preamplfier ...

Страница 2: ...pabilities of the m801mk2 Also please do not hesitate to contact us directly if you have any questions comments or concerns with your new m801mk2 microphone preamplifier Thanks for reading and happy recording The Grace Design Team Contents Welcome 2 Important Safety Information 3 GENERAL 3 SAFETY MARKING SYMBOLS 3 SERVICE INFORMATION 3 Front Panel Controls 4 Rearpanel Connections 5 Installation 6 ...

Страница 3: ...uitable for continuous operation Weight 12 0lbs 5 44kg SAFETY MARKING SYMBOLS CAUTION READ ACCOMPANYING DOCUMENTS This symbol located on the equipment and in this manual refers to important instructions Read this manual thoroughly before operating this equipment WARNING ELECTRICAL SHOCK HAZARD This symbol located on the equipment and in this manual indicates the potential for electrical shock haza...

Страница 4: ... the filter capacitors discharge As well even if the phantom power is switched off the LED will illuminate if voltage is being fed from an external source i e when using a direct split in a remote recording application D PHASE REVERSAL SWITCH The phase reverse switch reverses the absolute polarity of the music signal at the input of the preamplifier The switch illuminates green and provides power ...

Страница 5: ...reamplifier Fuses are two T800mA 250V 5mm x 20mm Time Delay Fuses B XLR MIC INPUT CONNECTOR Input connections are made via female XLR con nectors with pin 2 positive pin 3 negative and pin 1 ground 48V phantom power is supplied on pins 2 and 3 C XLR OUTPUT CONNECTOR Output connections are made via male XLR con nectors with pin 2 positive pin 3 negative and pin 1 ground D PARALLEL XLR OUTPUT CONNEC...

Страница 6: ...quire any extra ventilation 4 Rack screws are included in the box AUDIO CONNECTIONS Microphone input connections are made via female XLR connectors with pin 2 positive pin 3 nega tive and pin 1 ground 48V phantom power is supplied on pins 2 and 3 Output connections are made via male XLR connectors with pin 2 positive pin 3 negative and pin 1 ground If the output is to be used unbalanced pin 1 shou...

Страница 7: ...ophones by boosting the gain by 10dB while disabling 48V phantom power and increasing the input impedance Before activating ribbon mic mode make sure the channel s gain is fully down counter clockwise and 48V phantom power is off Now simply press the ribbon switch and turn the gain control upwards until the proper recording level is achieved If you press the 48V phantom switch while the ribbon swi...

Страница 8: ...he generator preamplifier then the level meter 8 Adjust the generator output level so that the preamplifier output level is at 16dBu 4 88VRMS or another desired red threshold level If the proper level can t be reached adjust the preamplifier gain control 9 Locate VR2 see figure 3 p 9 on the channel 1 audio circuit board and adjust until the peak LED is between green and red Repeat this procedure f...

Страница 9: ...te DC offset potentiometer VR1 and rotate it for a reading that matches the minimum gain reading 0 005V 8 The objective is to get the minimum gain offset and the maximum gain offset to match as closely as possible 9 The input offset does drift with temperature and having the lid off will allow the circuitry to cool It is advisable to replace the lid and let the preamplifier warm up again about 20 ...

Страница 10: ...eighting 130dB 40dB gain 150Ω source 22 22kHz 125dB 40dB gain 150Ω source A weighting 128dB 20dB gain 50Ω source 22 22kHz 117dB 20dB gain 50Ω source A weighting 120dB 20dB gain 150Ω source 22 22kHz 117dB 20dB gain 150Ω source A weighting 119dB GAIN RANGE Default Mode 18 64dB 2dB steps Ribbon Mode 28 74dB 2dB steps PHASE DEVIATION 40dB gain 40Ω source 75Hz 45kHz 3 CROSSTALK Any Channel 40dB gain 1k...

Страница 11: ...ve workmanship without charge provided the customer has appropriate proof of purchase and that the product has its original factory serial number Customers within the US are responsible for all inbound freight charges to Grace Design s facility while Grace Design will pay for return freight charges via ground service Customers outside the US must contact their distributor for warranty product retu...

Страница 12: ...grace design m801mk2 owner s manual 12 Manual Revisions Revision Page Change Date Initials A all initial release 11 08 18 edg ...

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