sx-1 introduction

sx-1 introduction
FSM 600
The FSM-600 is a compact fixed format stereo production mixer. The design allows
the unit to accept two microphone inputs and ten stereo music inputs.
The FSM-600 is essentially a six channel mixer with each channel switchable to
two inputs. Channels 1 and 2 are switchable between low impedance microphone
and stereo line inputs. Channels 3 to 6 are switchable between A and B stereo line
inputs. The A input may be internally selected to RIAA or normal line. These
channels are fully assignable to the cross fader. Three band equalisation is fitted to
all inputs along with gain and auxiliary send controls. Illuminated push buttons and
a 60 mm fader complete the channel controls. Internal settings provide for the unit
to be set to individual needs. The output section provides plenty of facilities to cope
with the most demanding applications.
Unlike the majority of fixed format mixers on the market all connectors are fitted to
the back face which allows unrestricted access when the mixer is fitted through a
work top or in a rack.
Although the FSM-600 is a fixed format design the use of individual circuit cards per
channel improve reliability and aid servicing should the need arise. Construction
and audio quality are to Formula Sound’s usual highest standards.
The mixer features a fully regulated internal power supply that is designed to
operate on 220-240Vac or 110-120Vac. The selection is by an internal switch
mounted on the power supply circuit board and is accessed by removing the front
Mains fuse sizes are 315mA anti surge for 220-240V operation and 800mA anti
surge for 110-120V operation. It is important for safety reasons that the correct
fuse sizes are always used.
N.B. Internal settings should only be undertaken by skilled
Always remove the power cord before removing any covers.
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Input selector switch selects input used. A = input A
B = input B. Input B is always a stereo line input (internal
jumpers selects input A to be either RIAA magnetic cartridge or a
standard line input. (phono connectors)).
L.e.d.s and label area clearly show which input is in use.
Gain control sets the input gain level. Check by selecting PFL
and adjusting so that V.U. meter just peaks into the red.
3 band equalisation provides +/- 10dB control, internal jumpers
allow selection of +/- 5dB or no E.Q.
Auxiliary send allows a separate mix of channels summed to the
auxiliary output (stereo bus). Internal jumpers allow the auxiliary
pot to function pre or post channel fader.
XF A and XF B (Illuminated push buttons) assign the channel to
the cross fader if neither button is pressed the channel is fed via
the stereo buss to the output and the cross fader will have no
effect on this channel if both buttons are pressed the channel will
be assigned to A only
PFL (pre-fade listen) routes the channel signal to the monitoring
system (V.U. meter and phones). If more than 1 PFL is selected
the sum is routed to the monitoring system. If no PFL is selected
the monitoring system reads main output.
60mm channel fader.
For normal operation the fader would normally be used at
maximum and the gain control adjusted for normal volume. If the
fader is set below No. 7 during normal operation turn down the
gain control and turn up the fader. This gives the best
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Output Section
Power switch switches the
mains feed to the mixer power
supply. N.B. to avoid switch on
thrumps audio systems need
powering up in sequence. A
good rule to remember is power amps on last and off first.
The BNC connector will provide
12V at a maximum 500mA for
working illumination. A
suitable light on a flexible stem
is available, ask our sales office
for details.
Twin l.e.d. bargraph V.U.
meters show the main output
signal or PFL signals. The
changeover is by selecting PFL
on any channel. Any number of
PFL sources may be selected
and the sum of these will be
monitored. This provides a very
versatile monitoring facility.
Depressing the SPLIT button
allows both main output and
PFL signals to be monitored
simultaneously. This function is
often preferred when mixing
tracks in synchronisation. The
two signals are summed to mono
and presented to the monitor
section with the main output fed
to left and PFL fed to right
sections. The phones output
always follows the metering so
what you see is what you hear.
As an extra aid an adjacent l.e.d. illuminates to indicate when any PFL source is selected.
A microphone limiter circuit is fitted to the FSM-600 to keep dynamics under control. If
any microphone is routed via this limiter a yellow l.e.d. positioned below the V.U. meter
will show when the limiter threshold is exceeded. The factory setting for the limiter
threshold allows an output level of +2dBm. An internal trimmer provides different settings
of the threshold if required.
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AUX - controls the summed output level of the individual channel auxiliary send controls.
Stereo or mono outputs are available via the 0.25” jacks on the rear panel.
BOOTH - controls the booth output level. This output may be used to provide a local
monitor output. To eliminate any possibility of feedback no microphones are fed to this
output. Stereo or mono outputs are available via the 0.25” jacks on the rear panel.
PHONES - the master volume control for the headphone monitoring system. Two stereo
jacks are provided, one on the front panel and one on the rear. STEREO jacks must be used
- a mono two circuit jack will present a short to one half of the phones amplifier and
although current limiting protection is included, prolonged use should be avoided. The
phones amplifier is very powerful and capable of delivering over 1 Watt per channel into
the optimum load of 30 ohms.
MASTER - controls the level of the main output and features balanced outputs on XLR
connectors as well as a separate mono output on a 0.25” jack.
CROSSFADE - A 45mm fader is featured that can be used to smoothly fade between the
XF-A buss and XF-B buss. To improve cross fader life and also ensure good attenuation at
the ends of travel, studio quality VCA circuits have been used. The use of VCA ‘s over
conventional faders give superior crossfade performance.
PUNCH - A momentary action push button is fitted, which when pressed, switches both
XF-A and X-FB signals on. Wherever the crossfader is set pressing the punch button will
always add the opposite side. The Punch circuit action is click free, and provides the
creative operator with a useful facility.
ZONE - controls a further output similar to the master output but without the balanced
output driver. Stereo or mono outputs are available via the 0.25” jacks on the rear panel.
AUTO VOICE OVER - circuitry is included that is selected via an illuminated push button .
The action of this circuit is to attenuate the music when a microphone signal is present. The
attenuation level of the music is variable, turning the pot clockwise turns up the music. The
sensitivity pot adjusts the point where the AVO circuit is triggered. Adjust the sensitivity
control so that the circuit triggers on normal speech but not on background pick up.
RECORD OUTPUTS - Two sets of stereo record outputs are available via phono
connectors. One is a complete programme mix, the other is music sources only (similar to
the booth output). All record outputs are unaffected by the master controls.
SUB BASS OUTPUT - a mono output via 0.25” jack is provided for driving a sub bass
loudspeaker system to enhance low frequency performance. The filter allows frequencies
below 70Hz to pass through. An internal jumper allows higher bass output if required.
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SOUND TO LIGHT (TRIG) - a fully floating transformer isolated trigger output is
available on a 0.25” jack to provide safe connection to lighting equipment.
REMOTE MUSIC MUTE - To cater for the increasing requirement to mute music signals
in entertainment venues when the fire alarm is activated the FSM-600 has provision to
remotely mute all music sources by linking two pins on the connector provided. The fire
alarm panel needs to provide a fully floating pair of contacts which close when the alarm is
activated. An l.e.d. positioned below the V.U. meter clearly shows if the music mute is
Service and Configuration
Several internal options are available on the FSM-600. These should only be undertaken by
qualified personnel.
Always remove the power cord before removing covers.
To gain access to the internal parts of the FSM-600 remove 4 screws from each of the two
side covers which surround the FSM-600. This will give access to the majority of the
internal jumpers and adjustments. The only exception to this is the jumpers which set the
channel E.Q. range and AUXILIARY pre or post. To gain access to these jumpers the back
panel also has to be removed. ( See removing back panel).
Channel options (remove top cover).
Channel 1 & 2 - 1 jumper fitted towards the top of the channel pcb provides microphone
phantom power selection. Pcb notation shows positions.
Channels 3-6 - 2 jumpers fitted towards top of pcb provide selection for input A to be a flat
line input or an RIAA magnetic cartridge input. Pcb notation shows the position for the
jumpers. Also each of these channels has an internal gain trim pot located above the input
setting jumpers. This pot allows the maximum gain to be reduced. Adjust as necessary.
E.Q. Range Select - This function is set by the position of 4 jumpers - notation on the pcb
show the positions. Take care to locate the jumpers in the correct positions.
AUXILIARY SEND - two jumpers set the selection of pre or post fader - notation on the
pcb show the positions. Take care to locate the jumpers in the correct positions.
MAINS VOLTAGE SELECTION - The FSM-600 can be switched to operate on
220-240Vac or 110-120Vac. The selection is by a slide switch mounted on the power
supply pcb, at the mains transformer end. Notation on the pcb and switch clearly show the
switch position. If you need to change the mains operating voltage you will also need to
change the main fuse. The fuse is located in a slide out drawer which is part of the mains
connector. The connector is mounted on the mixer rear panel.
Fuse sizes 220-240v operation = 315mA anti surge 5 X 20mm fuse
110-120V operation = 800mA anti surge 5 X 20mm fuse
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Removing The Back Panel
To remove the back panel first remove the side covers. Now remove the centre screw on
each block of phono connectors. Remove the jack socket retaining nuts. Remove the four
corner panel retaining screws and the panel will now lift away but will be captive by the
connections to the power supply and mains connector You may at this point be able to
make the adjustments you require. If not the power supply may be removed from the back
panel by removing 3 more screws. Ensure that the power supply is supported and no strain
is put on the connectors or wiring.
Refit in the reverse order taking care to line up all the connectors in the holes and making
sure that no strain is put on the connectors. Ensure that all screws are fitted and tightened.
Removing the top cover also exposes the right end output pcb. Two adjustments are located
on this board - the microphone limiter threshold preset and the sub bass output level. The
latter is controlled by 1 jumper located above the sub bass jack socket. Adjacent notation
shows the positions.
Fader Replacement
Should fader replacement become necessary any of the faders can be replaced by removing
the bottom side cover. Remove the 2 screws securing the fader. If the connector is
obstructed by the power supply remove the 3 screws securing the power supply. Carefully
disconnect the fader connector and replace with the new fader assembly. Assemble in
reverse order.
Mixer Dimensions
483mm (19”)
312mm (12.25” 7 RU)
110mm (4.33”)
Installation cut out for mounting the FSM-600 through a work surface.
440mm wide X 305mm height
Formula Sound Ltd
Unit 23; Stadium Business Centre
North End Road
HA9 0AT Tel +44 (0)208 900 0947 Fax +44 (0)208 903 8657
Email: [email protected]
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TELEPHONE +44 (0)208-900-0947 FAX +44 (0)208-903-8657 email [email protected]
We declare that the products listed conform to the following directives and standards
89/336/EEC amended by 92/31/EEC and 93/68/EEC
BS EN 50082-1 BS EN 50081-1
FSM 600
The CE mark was first applied in 1995
B. J. Penaligon General Manager
The attention of the specifier, purchaser, installer, or user is drawn to the fact that
good wiring practice must be observed when connecting the above equipment. Good
quality connectors and screened cables must be used for all audio connections. Twin
screened cables should be used for all balanced lines.
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