Adcom GFA-565 User Manual Download Page 12

when  the  amplifier  is  carelessly  operated  well  beyond  its  limitations.  Other  types  of 

protection  circuits,  beyond  the  methods  used  in  the  GFA-565  amplifier,  such  as  current 

limiting, etc., usually result in deterioration of the audio performance of the amplifier.   

 

While  the  GFA-565  will  operate  dependably  in  every  normal  situation,  no  amplifier  is 

impervious to abuse. There are conditions which must always be avoided if the amplifier is to 

operate  reliably  and  if  triggering  of  protective  devices  is  to  be  avoided.  The  preceding  is 

particularly true of amplifiers which have extremely wide audio bandwidth, such as ADCOM 

amplifiers. Among the undertakings which must be avoided, if damage to the amplifier or to 

the loudspeakers being used is to be prevented, are actions such as connecting the inputs 

or  outputs  to  or  from  the  amplifier  while  the  amplifier  is 

ON

,  or  using  what  has  been 

commonly termed the "thumb test" - that is, touching the center pin of the RCA jack on one 

end of the audio interconnecting cable while the other end is plugged into the amplifier and 

the amplifier is 

ON

 

NOTE

 

In the event that the DC RAIL FUSES need to be replaced, only one of the fuse types listed 

in the table below should be used. Please note that the fuses listed in the table, and their 

time-current blowing points, have been carefully selected and thoroughly tested to del

iver 

optimal  performance  while  still  accomplishing  their  protective  functions.  Replace  these 

fuses,  individually,  only  with  the  specific  types  listed. 

DO  NOT  USE  ANY  SUBSTITUTE 

FUSES WITH  DIFFERENT  RATINGS,  TIME-CURRENT  CURVES  OR VALUES. 

Failure 

to  observe  this  precaution  may  cause  serious  damage  to  the  amplifier  circuits, 

MAY 

CREATE A FIRE HAZARD, AND MAY VOID YOUR WARRANTY. 

For your convenience, 

a replacement set of two of the correct DC RAIL FUSES is supplied with each amplifier to 

facilitate restoration of the amplifier to operation in the event of a blown fuse. 

 

 

The GFA-565 has a massive power supply which remains charged for up to 

FIVE MINUTES 

after  the  amplifier  is 

turned 

off  and  the  POWER  LED  ceases  to  glow.  It  also  remains 

energized when the POWER. LED glows even if the THERMAL PROTECTION LED is 

ON

Therefore,  you  should  exercise  great  caution  when  connecting  arid/or  disconnecting 

loudspeakers  to  or  from  the  RIGHT/LEFT  STEREO  SPEAKER  OUTPUTS.  Should  you 

inadvertently  short  out  the  RED  ("+")  and  BLACK  ("-")  STEREO  SPEAKER  OUTPUTS, 

enough power may remain  in the power supply to cause sufficient current  to blow the DC 

RAIL FUSES on the affected channel. When connecting or disconnecting loudspeakers to or 

from  the  RIGHT/LEFT  STEREO  SPEAKER  OUTPUTS,  always  be  certain  to  wait  at  least 

FIVE MINUTES 

after turning the amplifier 

OFF 

before undertaking any such procedure. 

Summary of Contents for GFA-565

Page 1: ...HIGH CURRENT POWER AMPLIFIER GFA 565 The contents of this manual are subject to change Please check our website www adcom com or www adcom usa com for the most current version Copyright 2011 Adcom LLC...

Page 2: ...can drive a very broad range of loudspeakers including those with very low impedances at sustained high power levels even when the impedances are highly reactive Great care was taken to insure that di...

Page 3: ...her efficiency was insured by using a toroidal design Additionally thermal and dynamic tracking of the bias for the triple Darlington driver and output stages is provided to insure that the amplifier...

Page 4: ...outer carton If any number is altered or missing you should notify us immediately in order to insure that you have received a genuine ADCOM product which has not been opened mishandled or tampered wi...

Page 5: ...t only will the heat generated by the amplifier affect the performance of equipment stacked on top of the GFA 565 but the free flow of air through the ventilating slots provided in the chassis of the...

Page 6: ...lication Your ADCOM dealer can help select the best cable for your needs RIGHT LEFT INPUT Unbalanced The audio inputs to the GFA 565 are through two high quality gold plated brass RCA jacks using Tefl...

Page 7: ...OUTPUT should be connected to the right channel loudspeaker as you face the pair of loudspeakers and the LEFT STEREO OUTPUT to the left channel loudspeaker Be certain when the GFA 565 is used in Its...

Page 8: ...hich you should observe in order to insure maximum performance from your amplifier It is most important that you make certain the wiring you have selected has as Iowa capacitance as possible All ampli...

Page 9: ...wer levels with no difficulty It should be noted here that many loudspeaker systems which are rated nominally at 4 ohms drop in impedance in some parts of their frequency range to as low as 2 ohms and...

Page 10: ...inal of the loudspeaker to the negative terminal of the loudspeaker and vice versa Repeat the listening test with the mono signal to make sure you are correct in your initial evaluation If you can now...

Page 11: ...of the DC RAIL FUSES e Please refer to the section RIGHT LEFT STEREO SPEAKER OUTPUT for further clarification A little known fact is that when any amplifier is operated in the bridged mode the load i...

Page 12: ...d their time current blowing points have been carefully selected and thoroughly tested to deliver optimal performance while still accomplishing their protective functions Replace these fuses individua...

Page 13: ...ts Its plug should be inserted in a standard 120V 60Hz outlet with a minimum capacity of 15amperes and should have a dedicated branch circuit It is not recommended that you connect the GFA 565 into a...

Page 14: ...g on the amplifier POWER LED does not glow a failed electronic component or other internal malfunction must be suspected Make no further attempts at fuse replacement or operation of the amplifier Refe...

Page 15: ...LED indicates that there is AC voltage being fed to the amplifier but it does not signify that all the amplifier s circuits are in operation If for example you have blown one or more of the DC RAIL FU...

Page 16: ...l to reduce the listening level demands or you may blow the DC RAIL FUSES cause the THERMAL PROTECTION to be activated or in extreme cases damage your loudspeakers THERMAL PROTECTION LED The GFA 565 i...

Page 17: ...ility The chassis top cover and rear panel are of heavy gauge steel both painted and baked If the front panel top or sides should become dusty or fingerprinted they can be cleaned with a soft Iintless...

Page 18: ...of purchase and the ADCOM authorized dealer from whom it was purchased In the event the unit must be returned for service you will be instructed as to the proper procedure when you call or write UNDER...

Page 19: ...05 THD 700 watts continuous average power into 8 ohms at any frequency between 20Hz and 20kHz at less than 0 1 THD bridged IM Distortion SMPTE 1 watt to 250 watts into 8 ohms 0 009 1 watt to 350 watts...

Page 20: ...10Hz to 20kHz 0 0 25dB Power Bandwidth 3dB 5 Hz to 100kHz Dynamic Headroom into 4 Ohms 2 5dB Signal to Noise Ratio A Weighted 250 watts into 8 ohms 110dB Gain 27 0dB Input Impedance 100 000 ohms Inpu...

Page 21: ...om logo are registered trademarks of Adcom LLC No part of this manual may be reproduced or electronically transmitted without the express written consent of Adcom LLC Adcom LLC shale not be liable for...

Page 22: ......

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