Adcom GFA-565 User Manual Download Page 8

Generally speaking, when making connections to the loudspeakers from the amplifier, it is 

very important to use the correct type and size of wire in order to avoid unnecessary loss of 

amplifier  power  in  the  cable,  reduction  of  amplifier  damping  factor  (DF)  and  other 

undesirable conditions. For runs up to 12 feet, ordinary "zip" or lamp cord, made of AWG18 

stranded wire and available in a variety of insulation colors may be used. For runs up to 40 

feet, AWG16 stranded wire should be used to prevent power losses. For lengths over 40 feet 

and not exceeding 60 feet, use AWG14 stranded wire only. Runs exceeding 60 feet require 

the use of heavier conductors such as AWG12 stranded wire. If you find it difficult to obtain 

the correct-size wire for your specific connecting length, you can parallel two runs of the next 

smaller gauge of wire to keep wire resistance at a minimum. For example, if you require a 

run of 35 feet to your loudspeakers and AWG16 wire is not readily available, you can parallel 

two  35-foot  lengths  of  identical  AWG18  stranded  wire  for  use  with  each  speaker  (you'll 

require a total of four 35-foot lengths in such an instance) and solder the two conductors of 

each wire making up each double cable, at both the speaker and amplifier ends, to insure 

good electrical and mechanical connections of the conductors. 

 

Regardless  of  the  cables  you  select  to  connect  your  loudspeakers,  there  are  some  other 

requirements which 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  amplifiers,  particularly  wide-bandwidth  audio  amplifiers, 

are  susceptible  to  the  capacitance  cables  present  to  their  outputs  at  extremely  high 

frequencies. This capacitance, in conjunction with the inductance of the wire itself and the 

reactive  load  of  the  loudspeakers,  can  create  anomalies  at  ultrasonic  frequencies  which, 

although inaudible, can affect performance in the audible range. 

 

There  are  different  ways  to  connect  the  wiring  to  the  RIGHT/LEFT  STEREO  SPEAKER 

OUTPUTS. The methods used will depend on the specific type of connectors supplied with 

the loudspeakers, the speaker cables, etc. As a matter of course, we prefer to use double 

banana  plugs  because  it  is  generally  the  most  secure  method  of  connection.  Also,  the 

plated-bronze  springs  of  the  banana  plugs  effect  a  self-cleaning  action  which  insures  the 

best  contacts  between  the  binding  posts  and  the  connectors  themselves.  There  are 

"sockets" provided in the center of the binding posts' studs which permit secure seating of 

the  banana  plugs.  Make  certain,  however,  that  the  hexagonal  head  of  the  binding  post  is 

securely tightened before inserting the banana plugs firmly into the binding posts' sockets. 

 

Additionally,  when connecting the cables  to the amplifier and loudspeakers, it is important 

that  you  "tin"  the  wires  with  good  solder  (preferably  high-silver-content  solder)  in  order  to 

minimize  contact  resistance.  Tinning  prevents  the  build-up  of  surface  compounds  which 

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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