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DECIMATOR 

CONTROL NOISE REDUCTION CONTROL

 

The DECIMATOR control adjusts the THRESHOLD of the Decimator G-String II.  The 
Decimator works with both the Clean PREAMP and the DISTORT circuit and will switch 
completely out of  the signal path when both the PREAMP and DISTORT circuits are 
switched  off.    If  either  the  PREAMP  or  DISTORT  circuits  are  switched  on  the 

Decimator circuit will be automatically switched into the signal path. The DECIMATOR 
noise reduction is a down low level downward expander incorporating ISP’s patented 
TIME  VECTOR  PROCESSING.    The  Decimator  is  covered  under  multiple  patents 

including 6,944,305, 7,532,730 and 7,957,546 with other patents pending.    

 

 

 
 
A BRIEF EXPLANATION OF THE DECIMATOR NOISE REDUCTION SYSTEM 

Low  Level  Downward  Expansion

 

is  performed  by  use  of  a  high  quality  voltage 

controlled amplifier controlled by an RMS based audio level detection circuit.   A Time 
Vector Processing circuit is used which varies the release response over a 1000 to 1 

ratio  and  controls  the  release  response  of  the  Downward  Expander.      The  release 
response will be extremely fast, on the order of 2 milliseconds, if the input signal has 
a  fast  decaying  envelope  and  upwards  of  2  seconds  if  the  input  signal  has  a  slow 
decaying signal.   Downward Expansion takes place when the input signal level drops 

below  the  preset  threshold.    For  example:  if  the  threshold  is  set  for  0db  and  input 
signal  of  0db  with  produce  no  expansion.      As  the  input  signal  drops  below  0db 
downward  expansion  starts  and  increases  exponentially  the  farther  the  input  signal 

drops  below  the  threshold  point.    The  figure  below  shows  the  response  of  the 
Expander with a 0db threshold.   
 
 

 
 
 

 
 
 

 
 
 
 

 
 
  

 

 
 

 

 
 
 
 

Summary of Contents for THETA

Page 1: ......

Page 2: ...ollow all instructions Do not use this unit near water in the rain or where there is moisture If this warning is ignored a serious electrical shock or death may occur Do not attempt to service this unit No user serviceable parts inside Refer servicing to qualified ISP approved personnel Servicing is required when the unit is damaged in any way such as power adaptor is damaged liquid has been spill...

Page 3: ...ear panel has 4 inch phone jacks with one for the guitar input one for the final output signal and two remote jacks which allow the THETA preamp pedal to be switched remotely by switch closure pull to ground or with relay functions under MIDI control The PRE DIST jack allows remote control switching ON and OFF the Clean Preamp by swithing to ground the TIP connection of the inch jack The Distort s...

Page 4: ...equency semi parameteric equalizer which includes a boost cut control plus frequency sweep which will be described in more detail in the PREAMP section The output of the EQ section feeds a gain circuit allowing adjustment of the gain of the clean preamp by up to 50dB The output of the clean preamp is fed to the input of the DISTORT circuit The first section of the Distort circuit is a multi stage ...

Page 5: ...G String II noise reduction circuit As can be seen the level dectection and control circuit of the Decimator is connected directly to the input buffer allowing direct instrument tracking and also allowing the Threshold setting to be based on the noise of the instrument before any EQ gain or distortion is applied The actual noise reduction circuit is the last circuit in the signal path allowing a s...

Page 6: ...2db of boost or cut to be applied at the frequency determined by the SWEEP control SWEEP FREQUENCY CONTROL This control works in conjunction with the MID boost cut control and adjusts the center frequency of the MID boost or cut signal At the full counter clockwise setting the midrange frequency will be at 300Hz at the full clockwise setting the center frequency of the midrange will be at 6KHz NOT...

Page 7: ...YSTEM Low Level Downward Expansion is performed by use of a high quality voltage controlled amplifier controlled by an RMS based audio level detection circuit A Time Vector Processing circuit is used which varies the release response over a 1000 to 1 ratio and controls the release response of the Downward Expander The release response will be extremely fast on the order of 2 milliseconds if the in...

Page 8: ... amount of GAIN Most players will use GAIN 1 for a low level GAIN setting and GAIN 2 for high GAIN BASS This control adjusts the amount of boost or cut in the low frequency portion of the spectrum of PREAMP The available BASS boost and cut range is 15 decibels Note the Bass control is flat when the control is centered at 12 00 MIDRANGE BOOST CUT CONTROL This control works in conjunction with the S...

Page 9: ...ill not have any effect on the signal since there is no boost or cut being applied TREBLE CONTROL The TREBLE control adjusts the boost or cut that is applied in the high frequency portion of the spectrum of PREAMP The available TREBLE boost and cut range is 15 decibels SETTING THE THETA CONTROLS GETTING STARTED It s best to start with a flat response and adjust from that starting point The THETA c...

Page 10: ... and 3 00 This will provide a more classic rock tone By pulling the midrange control back between 8 00 and 12 00 you will get a more scooped midrange response Sweep the midrange frequency with the MID control in cut between 8 00 and 11 00 to find the desired mid scoop and then add BASS and TREBLE to suit PREAMP OVERDRIVING THE DISTORT FOR MASSIVE GAIN For incredible GAIN and that over the top meta...

Page 11: ...THETA SPECIFICATIONS Input Impedance Maximum Gain PREAMP DISTORT Treble Control PREAMP Treble Control DISTORT Bass Control PREAMP Bass Control DISTORT Mid Sweep Frequency PREAMP Mid Sweep Frequency DISTORT Mid Boost Cut Range PREAMP Mid Boost Cut Range DISTORT Decimator Effective Noise Reduction Dimensions Weight Power 500k ohms Greater than 150db 15db at 10Khz 15db at 10Khz 15db at 80Hz 15db at 8...

Page 12: ...y repack the unit send a copy of the original receipt a note stating the problem and send it to ISP Technologies LLC 5479 Perry Drive Unit B Waterford MI 48329 Attn Repair Dept All shipping charges must be fully prepaid ISP will not be responsible for any damages incurred in shipping of any unit Any claim will need to be settled with the shipping company The warranty will be voided if the serial n...

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