Gain Knobs; Rca Inputs [Channel 2 Only] - Mackie SRM550 Owner's Manual

SRM Loudspeaker: Rear Panel Features continued...
To connect balanced lines to these inputs, use a
1/4" Tip-Ring-Sleeve (TRS) plug. "TRS" stands for
Tip-Ring-Sleeve, the three connection points
available on a stereo 1/4" or balanced phone jack
or plug. TRS jacks and plugs are used for balanced
signals and stereo headphones and are wired as follows
according to standards specified by the AES (Audio
Engineering Society):
Balanced 1/4" TRS Connector
Sleeve – Shield (ground)
Tip – Positive (+ or hot)
Ring – Negative (– or cold)
Balanced 1/4" TRS Connector
To connect unbalanced lines to these inputs, use a
1/4" mono (TS) phone plug, wired as follows according
to standards specified by the AES (Audio Engineering
Society):
Unbalanced 1/4" TS Connector
Sleeve – Shield (ground)
Tip – Positive (+ or hot)
Unbalanced 1/4" TS Connector
For more information on these connectors, see
Appendix B on page 20.

4. Gain Knobs

The gain knobs adjust the input sensitivity of the
mic and mic/line/RCA inputs. This allows signals from
the outside world to be adjusted to run through each
channel at optimal internal operating levels.
There is – dB of gain with the knob fully down
(off), ramping up to 50 dB of gain fully up (max).
The accompanying LED will illuminate green when
the channel's input signal is present, indicating signal.
It will remain lit so long as there is signal above
–20 dBu present in that channel.
10
SRM550 • SRM650 • SRM750 Powered Loudspeakers
RING SLEEVE SLEEVE RING TIP
TIP
RING
TIP
SLEEVE
SLEEVE SLEEVE TIP
TIP
TIP
SLEEVE
8 9
SIG/OL SIG/OL
4
3
The accompanying LED will illuminate red when the
amplifier in the SRM loudspeaker is near the clipping
point. It is okay if this LED blinks occasionally, because
this means that the transient peaks are just reaching
the maximum output of the amplifiers and you are
getting the most out of your loudspeaker.
If connecting mixer outputs to loudspeaker
inputs, set the gain knob to 10:00 ["Line"]
for optimal sound and performance.

5. RCA Inputs [Channel 2 Only]

The stereo unbalanced RCA inputs allow you to
play a CD player, iPod , or other line-level source.
®
The RCA jacks accept an unbalanced signal using
standard hi-fi [RCA] hookup cables.
NEVER connect the output of an amplifier
directly to the input of the loudspeaker.
This could damage the input circuitry
of the active loudspeaker.
They are wired as follows, according to standards
specified by the AES (Audio Engineering Society):
Unbalanced RCA Connector
Sleeve – Shield (ground)
Tip – Positive (+ or hot)
Unbalanced RCA Connector
For more information on these connectors, see
Appendix B on page 20.
10
7
5 6
SLEEVE TIP SLEEVE TIP