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UNIVERSAL AUDIO Model 175 B LIMITING AMPLIFIER 

 

g.

 

Decrease attenuation with the output attenuator until the desired output 
level is observed on the meter. 
 

h.

 

Return  the  meter  switch  to  GR  position  to  verify  amount  of  limiting 
during operation. 

Note: The output level may be increased 6 dB by replacing the output attenuator 
with Langevin model AT 601 attenuator. 

ATTACK AND RELEASE TIME 

The  ATTACK  and  RELEASE  potentiometers  should  be  adjusted  for  optimum 
results  in  accordance  with  the  type  of  program  material  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  lengthened  when  the  program  material 
contains tremolo or vibrato which the limiter might possibly follow. 

The  limit  defeat  switch  is  located  on  the  attack  potentiometer.  By  turning  the 
attack control full counter clockwise, the limiting action may be defeated and the 
unit perform as a normal line amplifier. 

 

 

 

 

 

 

 

 

 

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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