4
(or before the active speakers), with the amplifier volume
set to maximum. If the SP2120 were to be connected earlier
in the chain, prior to the pre-amp/mixer for example, then
it would be possible to add gain, sending noise levels higher
than required.
The SP2120 can be used in a configuration where a stereo
output is distributed around several speakers. Fig.3 shows
a setup where the signal is distributed into six pairs using
a Drawmer DA6, whilst still providing speaker protection
for all twelve speakers. Again, note the position of the
SP2120’s along the audio chain - they should all be
connected directly before the amplifier that is supplying
the speakers (or active speakers), with the amplifier volume
set to maximum.
INSTALLATION
AUDIO CONNECTIONS
The inputs and outputs are electronically balanced XLRs where pin 1 is screen, pin 2 hot, pin 3 cold and the XLR shell
• Interference:
If the unit is to be used where it maybe
exposed to high levels of disturbance such
as found close to a TV or radio transmitter,
we advise that the unit is operated in a
balanced configuration. The screens of the
signal cables should be connected to the
chassis connection on the XLR connector
as opposed to connecting to pin1. The
SP2120 conforms to the EMC standards.
• Ground Loops:
If ground loop problems are encountered,
never disconnect the mains earth, but
instead, try disconnecting the signal
screen on one end of each of the cables
connecting the outputs of the SP2120 to
the patchbay. If such measures are
necessary, balanced operation is
recommended.
fig.1
XLR WIRING
The SP2120 Speaker Protector is designed for standard
19" rack mounting and occupies 1U of rack space. Where
possible, avoid mounting the unit directly above power
amplifiers or power supplies that radiate significant amounts
of heat.
If the unit is to be used in a mobile situation, it is strongly
recommended that the rear of the unit is supported in the
carrying rack to avoid bending the front panel rack mounting
‘ears’. Use fibre or plastic washers to prevent the front panel
becoming marked by the mounting bolts. Always connect
the mains earth to the unit.
Fig. 2 shows the ideal connection setup, providing the
greatest protection for your system. Note the position of
the SP2120 along the audio chain - it should be connected
directly before the amplifier that is supplying the speakers,
Drawmer have gone to great lengths to make the Speaker
Protector tamper-proof by incorporating the locking
mechanism on the front. However, if the rear of the unit,
along with the power amplifier, were reconnected then the
protection system would effectively be bypassed. For this
reason Drawmer have designed the Speaker Protector
Tamper-proof Bracket - trapping the XLR’s in place and
making it extremely difficult to disconnect them without
removing the bracket. This bracket could be specified in
order to conform to Local Authority noise abatement
regulations.
Installation of the Tamper-proof bracket could not be
simpler: After setting up the SP2120 Speaker Protector
as described in the manual, with the XLR’s in place,
simply slide the Tamper-proof Bracket over the rear of the
unit, making sure that the protruding cables locate through
is connected to chassis. The operating
level is nom4dBu. Balanced use is
recommended.
the gaps on the bracket. Next, screw in to place at the
four locating points (arrowed below) using the M3 screws
provided. Further protection can be gained by fitting M3
TORX tamperproof screws, to a maximum length of 6mm,
though a specialist screwdriver will also be required.
In addition, for extra protection, both the SP2120 and the
power amp should be locked in a rack, where access to
the rear is very difficult.
You should note that the Tamper-proof bracket is only
available for SP2120’s who’s serial number is 0845 or higher
(September 2006). On older versions the bracket could
be retro- fitted, though this would invalidate any warranty
that Drawmer has provided for the SP2120. Alternatively,
Drawmer could bring your SP2120 up to current Drawmer
specification - please contact your local distributor or email:
[email protected] for further details.
TAMPER-PROOF BRACKET
