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REAR PANEL CONTROLS 

 
 

AC INLET  The 901 accommodates a standard IEC power cable.  The IEC inlet 
contains a built in RFI filter. 

LINE VOLTAGE SELECTOR    To change the line voltage use a small screwdriver to pry 
open the voltage select door.  Carefully remove the voltage select cam and insert with the 
desired voltage showing.  Use the table below for voltage settings and fuse values. 

 

CAM SETTING 

LINE VOLTAGE 

FUSE VALUE 

110Vac 

100Vac 

120Vac 

 

.25A SLOW  

220Vac 

220Vac 

230Vac 

240Vac 

.125A SLOW  

 

WARNING:  The Model 901 is capable of delivering over .5 Amperes of 
current to the headphone jack.  The nature of the TRS jack allows for the ring 
to be shorted to the sleeve when the plug is partially inserted.  If the plug is 
left partially inserted and there is a high amplitude signal on the output of the 
amplifier the line fuse will blow.  Always replace the line fuse with the proper 
type fuse or damage to the amplifier can occur.  Note that this fault condition 
will not harm your headphones. 

DIGITAL IN SELECTOR  The digital input selector switch selects either AES or S/PDIF 

and

 

optical signals.  When the switch is set in the S/PDIF/optical position either input can be 
used but only one can be used at a time. 

Summary of Contents for Grace 901

Page 1: ...el 901 HEADPHONE AMPLIFIER OWNERS MANUAL PO Box 204 Boulder CO 80306 tel 303 443 7454 fax 303 444 4634 email info gracedesign com web www gracedesign com Revision A November 2001 Copyright 2001 Lunatec LLC ...

Page 2: ...find the latest owners manuals and other technical documents at http www gracedesign com documents docs html MODEL 901 FEATURES Balanced XLR analog inputs Unbalanced RCA analog inputs AES SPDIF and TOS LINK digital inputs High current output amplifier drives 8 Ohm loads 24 position level attenuator with 05dB channel matching Internal linear power supply High current low noise torroidal power trans...

Page 3: ...NUATION POSITION ATTENUATION 24 0 16 16 8 32 23 2 15 18 7 34 22 4 14 20 6 38 21 6 13 22 5 42 20 8 12 24 4 46 19 10 11 26 3 50 18 12 10 28 2 60 17 14 9 30 1 GAIN RANGE The gain range switch provides an extra 10dB of gain for monitoring 10dB signals or use with low sensitivity headphones With the LEVEL CONTROL at maximum the LOW gain position provides 10dB overall gain when using the analog inputs W...

Page 4: ...he sample rate is determined by a frequency comparator not by the sample rate bits in the digital data This ensures that the proper DAC filter settings are used even if there are erroneous sample rate bits in the signal Sample rates of 44 1 48 88 2 and 96kHz are directly indicated 32kHz is indicated when the 44 1 and 96 LEDs are both illuminated OUTPUT JACK The two output jacks are wired in parall...

Page 5: ...odel 901 is capable of delivering over 5 Amperes of current to the headphone jack The nature of the TRS jack allows for the ring to be shorted to the sleeve when the plug is partially inserted If the plug is left partially inserted and there is a high amplitude signal on the output of the amplifier the line fuse will blow Always replace the line fuse with the proper type fuse or damage to the ampl...

Page 6: ...de to 10dB Boost Mode to 20dB FREQUENCY RESPONSE 0dBu out 25dB 22Hz 120kHz 0dBu out 5dB 12Hz 260kHz 0dBu out 3dB 4Hz 600kHz MAXIMUM OUTPUT LEVEL 1kHz 50 Ohm load 23dBu 10 9Vrms 30 8V p p INPUT IMPEDANCE 40K Ohms balanced 20K Ohms unbalanced OUTPUT IMPEDANCE 5 Ohms DYNAMIC RANGE 0dB gain 50 Ohm load 116dB 10dB gain 50 Ohm load 121dB CMRR 3 5Vrms in 10dB gain 75dB DISTORTION THD N 10dB gain 10dBu ou...

Page 7: ...6 NOISE FLOOR 0dB gain 22 22kHz 95dBu 0dB gain A weighted 102dBu POWER REQUIREMENTS 115VAC 16A 230VAC 08A ...

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