





                                  Equalizers
                             ____________________

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Equalizers  ("EQ"  for  short)  have   been  around in the recording and motion
picture  work  for  many  years,  and  in  the last ten years or so have become
popular  items  in  many home stereo systems.   They are more often than not an
item included in most small home and semi-pro recording studios.


The term "equalizer" is just a ten-dollar name for fancy tone control.  On your
home  stereo,  the BASS and TREBLE controls are the normal tone controls;  they
break  the  audio  fequency  spectrum  up into broadly-defined "low" and "high"
parts  (or,  slices).   With  the   tone   controls,  you can vary the relative
strengths of the low and high notes you send to your speakers.


Graphic  equalizers  generally  cover  from  10  to 30 such slices of the sound
spectrum.   Home  type  EQ units generally have a seperate but identical set of
sliders for each of the two stereo channels;  hence, the presence of 20 or more
slider controls.


Equalizers  allow  you  to break the spectrum up into much more sharply-defined
"slices"  of  the spectrum.   The controls each cover a particular slice of the
spectrum, and on "Graphic equalizers," they are usually arranged as a series of
vertical  "sliders" on the front panel.   By glancing at the relative positions
of the sliders,  you can get a quick overall look at how the different parts of
the spectrum relate to each other in terms of relative strength.   The relative
positions  of the sliders draw a "graph" of the resulting spectrum (hence,  the
name "Graphic equalizer").


For  example,  you might have the sliders on your EQ set so they look something
like this (only one channel shown):


                 <----- Bass      Mid-Range      Treble ----->
 __________________________________________________________________________ 
|                                                                          |
|  + 12 dB -------------------------------------------------------------   |
|     9    -----------------------------------------------------------[ ]  |
|     6    -------------------------------------------------------------   |
|     3    ---------[ ]--[ ]-------------------------------------[ ]----   |
|     0   [ ]--[ ]------------[ ]--[ ]----------------------[ ]---------   |
|     3    -----------------------------[ ]--[ ]--[ ]--[ ]--------------   |
|     6    -------------------------------------------------------------   |
|     9    -------------------------------------------------------------   |
|  - 12 dB -------------------------------------------------------------   |
|__________________________________________________________________________|














                                  Equalizers
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The  relative  positions of the controls show at a glance that the mid-lows are
boosted  slightly  above  normal,  the   mid-range is attenuated slightly below
normal,  and  the  extreme   high  frequencies are boosted considerably.   This
example  might  be  used  during  playback of an old record or tape,  where the
"presence"  in  the  original  recording   is too strong,  and where the treble
frequencies  (such  as  snare drum brushes and cymbals) need to brought forward
from the background.


You  can,  for instance,  boost the mid-range slightly for more "presence" in a
singer's  voice,  or perhaps decrease the lower two sliders if the sound is too
"boomy."  You  can  set  both   the   right  and left channels to have the same
"curve,"  or  you can set each channel differently.   It all depends on how the
record  or  tape  you  are  playing was recorded,  and how you want it to sound
-what sounds best to you.


Equalizers  can  be  hooked into your system between the pre-amp's LINE OUT and
the power amplifier's LINE IN connections.   Or,  if you do not have a seperate
pre-amp  and  power  amp,  you can connect the EQ in the "Tape Monitor" loop on
your pre-amp or receiver.


Here are some ways you can hook your equalizer into your system:



         Pre-Amp                      EQ                     POWER AMP
    ------------------        ------------------        ------------------
   |                  |      |                  |      |                  |
   |                  |      |                  |      |                  |
   |          Line Out|----->|Line In   Line Out|----->|Line In           |
   |                  |      |                  |      |                  |
   |                  |      |                  |      |                  |
    ------------------        ------------------        ------------------

                A.  Seperate Pre-amplifier and Power Amplifier



                Amplifier (Receiver)               EQ
                 ------------------        ------------------
                |                  |      |                  |
                |      Tape Mon Out|----->|Line In           |
                |                  |      |                  |
                |      Tape Mon In |<-----|Line Out          |
                |                  |      |                  |
                 ------------------        ------------------

             B.  Combined pre-amp and power amplifier or receiver










                                  Equalizers
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In  both of the above cases,  the Tape Out and Tape In on the equalizer are for
connections to and from your open-reel or cassette tape recorder:


                        EQ                    Tape Recorder
                -------------------        -------------------
               |                   |      |                   |
               |           Tape Out|----->|Line In            |
               |                   |      |                   |
               |           Tape  In|<-----|Line Out           |
               |                   |      |                   |
                -------------------        -------------------


When  used  with recording mixers or consoles,  EQ units sometimes are inserted
into the "effects loop" circuitry.   Many of the larger consoles, however, have
connections  labeled soley for equalizers,  leaving the "effects" loop free for
other devices, such as reverb units, echo chambers, delay units, etc.


Mixers  and consoles generally have seperate controls for varying the amount of
relative  gain  or loss of the effects loop.   Each channel usually has its own
"send"  level  control,  and the console has an overall "return" level control.
Some consoles have an overall "send" level control, too.


When used with the "effects" loop circuitry, typical EQ connections for mixers/
consoles might look like this:


       Recording Mixer or Console                        EQ
     ------------------------------        ------------------------------ 
    |                              |      |                              |
    |                              |      |                              |
    |                  Effects Send|----->|Line In                       |
    |                              |      |                              |
    |                              |      |                              |
    |                Effects Return|<-----|Line Out                      |
    |                              |      |                              |
    |                              |      |                              |
     ------------------------------        ------------------------------ 



















                                  Equalizers
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Typical Equalizer controls:

   o   BYPASS/EQ  effectively inserts or removes the EQ,  without you having to
       physically  connect  or disconnect the cables.   With the control turned
       "off"  your equalizer's sliders have no effect;  ie.,  the signal passes
       through your EQ totally unaltered.   Turning the bypass on and off gives
       you  a  handy  means   of   hearing   just how effective (good or bad) a
       particular EQ setting will be.

   o   METER/OUT turns the built-in meters (or LEDs) on or off.   For instance,
       you may not wish to see them flashing in a dimly lighted room.

   o   TAPE  MON  IN/OUT  gives you an effective "Tape Monitor" circuit in case
       your pre-amp or receiver does not have one.   (It's extremely rare these
       days  to find a pre-amplifier or receiver which does not have a tape mon
       loop built in.)

   o   GAIN sets the relative overall gain or loss of the entire EQ signal, not
       just that of any particular band of frequencies.


































