REAR PANEL DESCRIPTION
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1. LEFT AND RIGHT MASTER INPUTS. These are automatic balanced or unbalanced Tip-Ring-Sleeve (TRS) 1/4" in
puts. These inputs feed all six MONO OU'fs when all MONO INs are not used. Connecting to individual MONO INs discon
nects that channel from these inputs (refer to the Block Diagram found on the SM 26 Data Sheet). For unbalanced
operation use a standard mono 1/4" plug; for balanced operation use a stereo 1/4" plug wired as follows:
TIP is si
gn
al hot (connect to Pin 2 on a 3-pin connector).
RING is si
gn
al ground (pin 3 in a 3-pin connector).
SLEEVE is case or chassis ground ( case on a 3 -pin connector) .
.
2. LEFT AND RIGHT EXPAND OUTPUTS. These 1/4" TRS jacks are connected in parallel with
.
the Master LEFT &
RIGHT INPUT jacks, allowing two or more SM 26s to be daisychained for multiple splitting. Simply connect these EXPAND
OU'fPUTS to the LEFT & RIGHT
-
INPU'fs of anotlier SM 26; there is no limit to the number of expansions possible with the
SM26.
NOTE: These Expand Outputs are NOT buffere
.
d from the Master Inputs. Therefore it is not possible to mix both
balanced and unbalanced lines in the same channel between several units: once the ring and sleeve are shorted anywhere in
the chain (by using a mono plug) the entire line becomes unbalanced.
3. MONO INPUTS. These are TRS 1/4" jacks which accept either balanced or unbalanced mono si
gn
als. These are switch
ing jacks which automatically b
yp
ass the Master LEFT & RIGHT INPUTs whenever a plug is inserted (see the Block
Diagram).
·
4. MONO OUTPUTS. These 1/4" TRS jacks deliver either a conventional unbalanced output (use mono cords), or a float
ing unbalanced output (use stereo cords). The floating unbalanced output is preferred for all balanced inputs.
5.
LEFT & RIGHT MIX OUTPUTS. These floating, or grounded, unbalanced TRS 1/4" outputs are controlled by the
MASTER OU'fPUT LEVEL control. They are fed either by the Master LEFT & RIGHT INPUTS (respectively) or by any of
the six MONO INPUTS, or a combination of both (Rane Note 108 helps).
6. GROUND LIFT SWITCH. This switch provides the ability to separate chassis ground and si
gn
al ground. Normally, this
switch should be in the LIFr position. In some circumstances it may be necessary to move it to the
-
6pposite position to
eliminate stubborn hum and buzz problems. We realize a scientific explanation of this switch would be helpful, unfortunately
science doesn't seem to have much to do with it.
If you are tempted to try moving this switch with your power amplifiers turned on or turned up, DON'T BE. ALWAYS
TURN YOUR AMPLIFIER LEVELS DOWN BEFORE CHANGING YOUR GROUNDS AROUND and then bring
them up slowly.
7. REMOTE POWER SUPPLY INPUT. The SM 26 is supplied from the factory with a Model RS 1 Remote Power Supply
suitable for connection to this input jack. The power requirements of the SM 26 call for a 18-24 volt AC center-tapped trans
former only.
THIS IS NOT A DC INPUT. IT IS NOT A TELEPHONE JACK
NEVER USE A POWER SUPPLY WITH YOUR SM 26 OTHER THAN THE ONE SUPPLIED OR A RANE AP
PROVED REPLACEMENT.
8. CHASSIS GROUND POINT. A 6-32 threaded bole used for chassis grounding purposes. See CHASSIS GROUNDING
note on the last page for details.
