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UNIVERSAL AUDIO Model 175 B LIMITING AMPLIFIER 

 

OPERATING INSTRUCTIONS 

UNIVERSAL AUDIO INC. 

Model 175 B 

LIMITING AMPLIFIER 

 

The  Universal  Model  175  B  is an  extremely  versatile  professional  quality  peak 
limiting  amplifier  designed  for  use  in  the  recording,  broadcasting  and  motion 
picture  industries  as  well  as  other  high  quality  audio  systems.  The  175  B  is  a 
true limiting amplifier capable of high gain,  low distortion, linear amplification 
at  levels  below  the  threshold  of  limiting  and  with  excellent  limiting 
characteristics and negligible increase in distortion at levels above. 

The  model  175  B  is  designed  to  be  mounted  in  a  standard  19”  rack.  The  unit 
requires  only  3½”  of  rack  space,  and  the  front  panel  is  hinged  to  provide 
accessibility to the inner components. The highest quality military type printed 
circuitry  is  combined  with  1%  precision  resistors  and  over  rated  components 
throughout  to  insure  maximum  performance  and  reliability.  Plug-in  type  “FP” 
electrolytic capacitors are used for ease of replacement. 

The 175 B has a self contained power supply, a VU meter that is switchable to 
indicate  input  or  output  level  as  well  as  gain  reduction  in  dB,  and  input  and 
output attenuators graduated in 2 dB steps, with vernier adjustments in excess 
of 2dB for each step. 

The limiter is provided with input and output jacks on the front panel as well as 
a terminal strip on the rear of the unit for interconnecting the amplifier with a 
system.  The  terminal  strip  also  provides  for  connecting  a  remote  VU  meter  if 
desired. 

Separate adjustments of the attack and release times are provided on the front 
panel as well as a limit defeat switch mounted on the rear of the attack control to 
allow for the wide variety of program material that the 175 B will be expected to 
handle.  Checking  the  unit  for  balance,  or  rebalancing  may  be  accomplished 
without the need for test equipment, because an internal signal for balancing is 
provided  on  the  position  of  the  test  switch.  Screw-driver  adjustment  holes  are 
provided  on  the  front  panel  so that  the  VU  meter  may be  easily  observed  with 
the panel closed during balancing. 

Содержание 175 B

Страница 1: ... FP electrolytic capacitors are used for ease of replacement The 175 B has a self contained power supply a VU meter that is switchable to indicate input or output level as well as gain reduction in dB and input and output attenuators graduated in 2 dB steps with vernier adjustments in excess of 2dB for each step The limiter is provided with input and output jacks on the front panel as well as a te...

Страница 2: ...gram allows the remote VU meter to perform gain reduction while the internal meter is still usable to indicate input and output level ATTENUATORS The input and output attenuators are both adjustable from 0 to 40 dB For this reason the 175 B may be utilised at any point in the system where input signal level is between 24 dBm and 13 dBm The attenuators are adjusted for proper operating levels as fo...

Страница 3: ...erial being used The following general suggestions are given for use of ATTACK and RELEASE adjustments a For vocal or narration program material with minimum low frequency information best results are usually obtained by adjusting for very fast attack and release times b The release time should be lengthened as the low frequency content of the program material increase c The attack time should be ...

Страница 4: ... observed on the meter g Adjust first the PLATE BALANCE and then the CATHODE BALANCE controls for minimum meter deflection h Rotate the output attenuator fully clockwise zero attenuation i Adjust first the PLATE BALANCE and then the CATHODE BALANCE controls for minimum meter deflection Note meter indication j Adjust the PLATE BALANCE control slightly clockwise until a change in meter indication is...

Страница 5: ...e absolute minimum meter deflection should be in the order of 20 dB If the two sections of the 6BC8 are not reasonably symmetrical optimum balancing cannot be obtained NOTE The fastest attack or release time is attained by turning the control full clockwise ...

Страница 6: ...er in high gain position 37 dB MINIMUM INPUT LEVEL TO ACCOMPLISH LIMITING Jumper in low gain position 24 dBm Jumper in high gain position 24 dBm MAXIMUM OUTPUT AT THERSHOLD OF LIMITING 13 dBm INPUT AND OUTPUT IMPEDANCE 600 ohms unbalanced SIGNAL TO NOISE RATIO 80 dB COMPRESSION RATIO above threshold of limiting 12 to 1 ATTACK TIME Adjustable from 100 to 1000 microseconds REALEASE TIME Adjustable f...

Страница 7: ...UNIVERSAL AUDIO Model 175 B LIMITING AMPLIFIER 7 ...

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