Rane SM 82 User manual

Manual-1
OPERATORS MANUAL SM 82
STEREO MIXER
QUICK START
No one likes to read manuals. Everyone likes to just start pushing buttons and turning knobs until the desired results
magically emerge. That’s usually OK, and with only a very few exceptions, damage is unlikely to result from such proce-
dures with the SM 82.
This product is quite obvious: Input LEVEL controls make Inputs louder or not, the stereo SENDs make things happen
at the LOOP SEND outputs, and so on. No real magic there. You should be aware, however, that if you want to connect a
mono source to the SM 82, use only the LEFT Input of a channel so that the mono source will drive both the Left and the
Right channels.
Set the levels of the mixer so that the red lights stay off. If they come on, you are overdoing it and distortion will result.
Never connect anything except an RS 1 or other approved Rane AC power supply to the thing that looks like a
telephone jack on the rear of the SM 82. This is an AC input and requires some special attention if you do not have an
operational power supply EXACTLY like the one that was originally packed with your unit. See the full explanation of the
power supply requirements elsewhere in this manual.
SM 82 CONNECTION
When connecting the SM 82 to other components in your
system for the first time, leave the power supply for last. This
will give you a chance to make mistakes and correct them
before any damage is done to your fragile speakers, ears,
headphones, et al.
INPUTS
The SM 82’s Inputs are unbalanced. This means that
standard ¼" connectors on the ends of any good quality cable
will work well between your signal sources, signal processing
and amplification. Most of the above mentioned sources give
you the choice of stereo or mono output. The mixer gives you
the same choice. You will note that nomenclature has been
placed beneath the input jacks indicating which is RIGHT
and which is LEFT (MONO). If a source is plugged only into
the Left jack and not into the Right, both Right and Left
channels will be fed with the Left Input. This allows the use
of either stereo or mono sources.
OUTPUTS
The SM 82 offers balanced main outputs only. This means
that you may use them as either balanced or unbalanced, the
choice being made by the way the connectors are wired. It’s a
good idea to always use a TRS or stereo connector in the
outputs no matter which mode you are using. If a “mono”
connector is used, inserting it into the output will short the
ring (–) to ground and could conceivably cause a small
amount of distortion to be placed on the tip (+). While this is
not destructive, it may be significant enough to be audible.
Balanced operation therefore requires that both tip (+) and
ring (–) be wired to the following device. Unbalanced
requires only tip and sleeve connected. The unused ring
should be left open.
EFFECTS DEVICES
External devices which might be used with the SM 82
could be either mono in and out, while some may be mono in
and stereo out, while still others may be stereo on both ends.
The SM 82 easily accommodates all of these varieties. If your
effect is mono on both ends, connect its input to the SM 82
LEFT LOOP SEND and the effect’s output to the SM 82
LEFT LOOP RETURN. This configuration will sum Right
and Left Loop Outputs to the mono effect input and will sum
the mono effect output to the Left and Right Input buses. A
mono-in stereo-out device would connect to the loop outputs
in the same way; however the stereo outputs connect to the
respective LEFT and RIGHT LOOP RETURNS.
EXPANDING
Connecting two or more SM 82s together to achieve more
than eight stereo Inputs requires that a stereo cable (tip, ring,
sleeve) be connected between the MAIN EXPAND OUT of
the first mixer and the MAIN EXPAND IN of the second. All
32 inputs will then appear at the main OUTPUT of mixer
number two. Only the first sixteen Inputs will be available at
the main Outputs of mixer number one. Should you wish to
have all Loop buses tied, connect the LOOP SENDS of mixer
one to the LOOP EXPAND IN of mixer two. All sixteen stereo
sends will then become active at the LOOP SENDS of the
second mixer.
WEAR PARTS: This product contains no wear parts.

Manual-2
FRONT PANEL DESCRIPTION
햲POWER switch: Depress the upper portion of this switch to turn the unit on (with power supply plugged in); depress the
lower portion to turn the unit off. Depressing the center portion of the switch causes acute indecision stress to the switch’s
personality profile, which in turn depresses it. To alleviate this condition, the switch must be “turned on”, so to speak.
햳Input SEND Level control: determines the amount of Post-Fade stereo input is fed to the auxiliary buses. Each Input’s
stereo SEND is summed on this bus and is available at the respective LEFT and RIGHT LOOP SENDS on the rear of the
mixer.
햴Input BALANCE control: In its center detent, Left and Right signals to each channel are allowed to pass at their original
relative levels, therefore preserving the stereo image developed by the program or instrument connected to the Inputs.
When the control is moved vertically toward the “L” position, the Right channel level is decreased while the Left channel
level is maintained. The opposite occurs if the control is moved from the detent toward the “R”. When a mono input is used
(no plug in the RIGHT Input jack), the BAL control becomes a PAN control, panning the mono signal from the Left to
Right channels.
햵Input LEVEL control: is a rotary stereo attenuator that adjusts the amount of both Left and Right signals applied to the
Input. Its output is routed to the main summing amplifier for mixing with all other Inputs. The unity gain position of this
control is located at “7.5".
햶Input OVERLOAD indicator: This red LED illuminates whenever the Input’s output exceeds a level 4 dB below clipping.
햷RETURN BALANCE control: is a vertical slider that controls the effect or source connected to the LOOP RETURN in the
same way the Input BALANCE controls work (see 햴above).
햸RETURN LEVEL control: is a rotary stereo attenuator that controls the amount of Return which is to be added to the
Main Output. The unity gain position of this control is located at “7.5"
햹RETURN OVERLOAD indicator: This red LED illuminates whenever the return levels exceed a level of 4 dB below
clipping.
햺OUTPUT BALANCE control: is a vertical slider that operates in the same fashion as the BALANCE control described in
item 햴above. It however, determines the relative levels of the LEFT and RIGHT main OUTPUTS only.
햻OUTPUT LEVEL control: is a rotary stereo attenuator that controls the final signal Level at the main OUTPUT jacks. The
unity gain position of this control is located at “7.5".
햽OUTPUT OVERLOAD indicator: This red LED illuminates any time the output level exceeds 4 dB below clipping.

Manual-3
REAR PANEL DESCRIPTION
햲MAIN OUTPUT jacks: These balanced Tip-Ring-Sleeve jacks are used to connect the main Outputs of the SM 82 to a
power amplifier or to additional signal processing. As is the standard with all Rane balanced outputs using ¼" TRS jacks,
the Tip is (+), the Ring is (–) and the Sleeve is ground.
햳MAIN EXPAND OUTPUT jack: This ¼" TRS stereo (Tip = left, Ring = right) Output jack connects one SM 82 to another
for the purpose of expanding the number of Inputs available in the system. Only a stereo plug and cord should be used. To
do otherwise will cause loss of Right channel signal and possibly distortion to the Left channel. This Output also serves as a
fixed pre-fader level useful as tape outputs or other applications.
햴LOOP RETURN jacks: These ¼" aux returns may connect the output of a reverb or other effect unit to the Loop bus of the
SM 82. If no effect is used, they can be used as a ninth stereo Input to the mixer in addition to those described in 햶. As with
the other stereo Inputs, mono signal may be connected to the LEFT input to obtain two channel mono operation.
햵LOOP SEND jacks: This pair of ¼" jacks may drive an effect or similar device which is to be returned to item 햴above. If a
mono device is used, both the Left and Right Send channels of the SM 82 are summed together and presented at the LEFT
Output if nothing is inserted in the RIGHT Output.
햶CHANNEL INPUT jacks: Yet another pair of ¼" jacks, these unbalanced Inputs are used to connect any line-level signal
source to the SM 82. As indicated, only the LEFT is to be used if the Input is mono and should therefore appear in both Left
and Right channels, depending on the position of the front panel BALANCE control which is now effectively a PAN.
햷MAIN EXPAND INPUT jack: A ¼" TRS stereo Input jack may link two or more SM 82s together. The Left input is on the
Tip, Right on the Ring and the Sleeve is ground. This may also be used to sum any fixed-level stereo signal into the Main
Outputs, producing a tenth stereo Input when added with 햴and 햷. As in 햳above, use only a stereo TRS cable.
햸LOOP EXPAND INPUT jack: Another ¼" TRS stereo Input, expands the stereo LOOP buses of two SM 82s similar to the
MAIN EXPAND OUTPUT in 햳. A stereo TRS (Tip-Ring-Sleeve) cable must be used for this application. Connect the LEFT
and RIGHT LOOP SENDS (햵)of the first unit to the LOOP EXPAND IN of the second unit. (Tip = left; Ring = right.)
햹Remote POWER supply input: Use only an RS 1 or other remote AC power supply approved by Rane. The SM 82 is
supplied from the factory with a remote power supply suitable for connection to this input jack. The power requirements of
the SM 82 call for an 18-24 volt AC center-tapped transformer only. It is not a telephone jack.
햺Chassis ground point: A #6-32 screw is provided for chassis grounding purposes. See the note below for details.
CHASSIS GROUNDING
If after hooking up your system it exhibits excessive hum or buzzing, there is an incompatibility in the grounding
configuration between units somewhere. Your mission is to discover how your particular system wants to be grounded.
Here are some things to try:
1. Try combinations of lifting grounds on units that are supplied with ground lift switches or links.
2. If your equipment is in a rack, verify that all chassis are tied to a good earth ground, either through the line cord
grounding pin or the rack screws to another grounded chassis.
3. Units with outboard power supplies, such as the SM 82, do not ground the chassis through the line cord. Make sure
that these units are grounded either to -another chassis which is earth grounded, or directly to the grounding screw on an
AC outlet cover by means of a wire connected to a screw on the chassis with a star washer to guarantee proper contact.
Please refer to RaneNote 110, “Sound System Interconnection” (supplied in this manual and available separately) for
further information on system grounding.

Manual-4
OPERATING INSTRUCTIONS
CIRCUIT DESCRIPTION
Learning to operate the SM 82 might be a bit easier if you
glance at the Block Diagram which is included as a part of
the SM 82 data sheet (enclosed). All eight stereo Inputs
operate in exactly the same way. Signal applied to the Inputs
is acted on by a radio interference filter (we have assumed
that local broadcasts should not be a part of your music) and
is then routed to a stereo LEVEL control. If you are using a
mono source, it should be connected only to the LEFT Input
to place this mono signal on both the Left and Right sides of
the input circuitry. The output of the Level control sections is
applied to a unity gain buffer to prevent the LEVEL control
from adversely interacting with downstream circuitry. The
input overload sensor monitors the output of the buffer to
alert the user via LED to any possible overload conditions.
Left and Right audio is then subjected to the channel
BALance control to allow the user to place the stereo image
of the source as desired to the Left and Right Outputs. If a
mono input is present, the BALance control becomes a PAN
control. After the BALance control has done its job, a stereo
SEND LEVEL control adjusts the amount of each Input’s
level which is to be routed to the Loop Output bus.
All eight stereo Inputs are simultaneously adjusted for
stereo placement by the OUTPUT BALance control. The
resultant signal is added together and fed to a gain stage
whose level is set by the OUTPUT LEVEL control. The main
Outputs are fully actively balanced via the line drivers
appearing just prior to the OUTPUT jacks.
EFFECTS LOOP
The LOOP SENDS receive their audio from the Send bus
which is the sum of all Input program as determined by the
Input SEND controls. This Output may be used to drive
reverberation devices, flangers, phasers, etc. The output of the
effect device placed in this loop is returned to the SM 82
through the LOOP RETURNS. The level of the returned effect
is determined by the RETURN LEVEL control on the front
panel. The return section also provides a BALance control for
image placement.
BALANCE CONTROLS
These do not increase the level of either Left or Right
signal. As the controls are moved toward one channel, the
level of the other channel is reduced only.
HIGH NOISE IMMUNITY
One of the most unusual features of the SM 82 is its
inherent immunity from noise. All eight of the stereo inputs
may be turned all the way up without increasing the internal
noise of the mixer. This is critical due to the wide variation in
output levels found in musical instruments and tape devices.
A fairly low-level synthesizer may be combined in the same
system with a high level unit without any undesirable side-
effects. The SM 82 eliminates the concerns normally associ-
ated with mixing so-called -l0 dBV units with +4 dBu types.
POWER SUPPLY
As noted elsewhere in this manual, never use a power
supply with your SM 82 other than the one supplied with the
unit or a replacement approved from Rane Corporation. The
SM 82s power supply is an AC supply, which is a 18-24 volt
center tapped transformer capable of supplying at least the
demanded 650 milliamps. Using any other type of supply
may damage the mixer and will void the warranty (which at
two years parts and labor is worth safeguarding, don’t you
think?).
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