Ref: UM21
SQN-4S series 1V Miniature 4:2 Sound Mixer
Complete with Portabrace shoulder bag that will take a recorder and radio microphones, 12 pin Tajimi cable and Tajimi tail with 2 x XLR/M and 3.5 jack return
Includes:
The original broadcast quality stereo portable mixer for TV, film and radio locations
The SQN-4S has been the unraveled Industry standard portable audio mixer since it was the first to arrive on the scene back in 1984.
The new SERIES IV is the culmination of an extensive development program to ensure that the SQN-4S remains at the forefront of location sound technology. Extending the control panel to include all the required functions on one face of the mixer has made it even easier to use than before.
Newly designed tranformerless input amplifiers, larger output transformers for low distortion bass, virtually unbreakable analogue level meters, pre-fade listening, slating microphone, logic processing of many switching functions leading to a minimal length audio path, optional feed for four output channels and improved filtering and screening have all contributed to making it a welcome successor to its illustrious forbears.
The essential information for connecting to and operating the mixer is permanently printed on the baseplate.
Features and Specification - SQN-4S Series IV
Mixer Inputs
Four transformerless balanced inputs using XLR-3 type female
connectors. Channels one and two also share an XLR-5 type
connector.
Each channel is switchable for:
Powering:
Attenuation:
0dB, -12dB or -24dB
Bass Cut:
Flat, -4dB or -10dB at 100Hz
Line Attenuation:
Adds 50dB attenuation before the mic preamp.
Sensitivity
-78dBu for nominal line level (PPM4, 0VU) with the channel
gain at maximum and the master gain at 0dB
Max Level, Mic Inputs
-20dBu (+4dBu with 24dB attenuation)
Noise Figure
-130dBu (A weighted) from a 200 Ohm source.
Frequency Response
20Hz to 20kHz +0, -1dB, referred to 1kHz.
Crosstalk
Isolation, channel to unrelated channel: 75dB at 1kHz, 60dB at
15kHz.
Channel Configuration
[GANG]
[MAT]
The mixer is intended to work in several modes. The mode
controls affect channel pairs CH1 & 2 and CH3 & 4.
Within the pairs, channels 1 & 3 are called "first
channels" and 2 & 4 "second channels".
Twin MONO [O] in which the channels are unganged and each input channel can be routed or panpotted to either or both of the output channels.
Stereo [S] ganging in which the first channel fader controls the gain of both channels and the first channel panpot acts as a stereo balance control
Mid-Side [MS] ganging in which the first channel fader controls the gain of both channels and the second channel fader acts as an image width control.
Mid-Side Matrix [MAT] matrixing in which each channel pair has a mid-side matrix which will convert an MS input into AB stereo or vice-versa.
Panning Mode [PAN]. The CH3, CH4 pair has a selectable panning mode in which the output is treated as MS encoded stereo and the channel signal is panned to move across the equivalent AB stereo image.
Phase Switch
The second channel of each pair can have its phase inverted by
means of a front panel switch. This has the incidental effect
of interchanging left and right in an MS encoded signal.
Monitor Return Input
Unbalanced inputs with a range of sensitivity from -20dBu to
+20dBu for loudness parity with the internal monitoring. The
sensitivity is adjusted by a screwdriver preset on the base.
Mixing Bus Inputs
Two inputs directly into the summing amplifiers with their
gain adjustable inside the mixer. Maximum sensitivity is 0dBu
for +8dBu at the balanced outputs with the master gain set at
0.
Balanced Outputs
Two line driver amplifiers provide the output channels and
each output is available on both an individual XLR and a
combined 12-way connector.
Output Attenuators
The level at either set of connectors can be attenuated by
50dB to provide a nominally microphone level feed.
Line Drivers
Floating sources (transformer coupled) with a clipping level
of +20dBm into 600 Ohms. Distortion at the nominal peak level
of +8dBm is less than 0.01% with a 600 Ohm load 20Hz to 20kHz.
The output resistance is switchable from 60 Ohms to 180 Ohms.
At 180 Ohms, with the limiter switched on, the mixer can be
worked into an arbitrarily low impedance load with acceptable
distortion. The balanced Mic-Level send is derived from a
separate winding on the output transformer and has an
essentially resistive source impedance of 200 Ohms.
Unbalanced Outputs
A subsidiary connector carries separately buffered outputs at
10dB below the level of the main line drivers.
Post-Fader Outputs,
CH3 & CH4
Buffered outputs at 10dB below the level of the main line
drivers. Channels three and four may also be switched out of
the mixing bus so that they can be recorded separately.
Meters
Twin peak reading, logarithmic level meters with Peak
Programme Meter (PPM) dynamics. Scaling may be BBC PPM, Nordic
Norm, or SMPTE.
VU meters can also be provided. The meters are normally calibrated with the mixer driving a bridging load of 10k Ohms. Meter illumination is by permanently lit glow tubes which consume no electrical power.
Line Output Level
The nominal line level is normally set at 0dBu for PPM metered
mixers and +4dBu for VU metered mixers. Peak level, which is
used as a reference for the limiters, is considered to be 8dB
above this setting. Other calibration levels are readily
available to order.
Output Limiters
Switchable [O]ff [M]ono [S]tereo (ganged). Approximately 40:1
compression over a 17dB range. Attack time constant 0.5ms,
release time 100ms. The limiter threshold is set 1dB below the
nominal peak level. An LED indicator for each output channel
shows when the limiter is attenuating the signal.
Line-up Tone
A tone at 1.05kHz which is injected into both channels upon
operating a front panel switch. Two modes are available,
[M]ono in which the tone is injected at a fixed level into
both outputs and [S]tereo in which the left hand channel tone
is interrupted for 250ms every 3s. The tone displaces the
normal channel signal.
Monitoring
Headphone amplifiers with adjustable gain capable of driving
most headphone types to a suitable level. The use of
headphones with a resistance of between 200 Ohms and 600 Ohms
per side will make best use of battery power. The gain control
is on the connector side panel. Please note that with some
sets of headphones it will be possible to produce sound levels
capable of damaging the hearing if the phones gain is set too
high. Pre-Fade listening to each of the input channels is
possible as is MS matrixing of the two output channels so that
an MS recording may be monitored in the equivalent AB stereo.
Monitoring Mode Selector
The monitoring mode rotary selector switch on the front panel
[PHONES] has the following functions.
Slating Microphone
A microphone mounted behind the front panel at the right hand
end of the mixer is brought into operation by pressing a
button on the side panel. The output of the microphone is
levelled by a 2:1 compressor and overrides the main audio,
appearing on the mixer outputs and in the monitoring system.
While the microphone is active, the monitoring mode
automatically reverts to the internal or [MXR] setting.
Batteries
Eight AA size cells housed in a quick-change compartment. The
acceptable range of voltages is 6 to 24 Vdc allowing the use
of most cell technologies. Battery life with alkaline cells
will be 10 hours when using unpowered microphones.
Battery Test
The right channel meter is fitted with a suppressed-zero
scale, brought into operation by a front panel push button,
which indicates the battery voltage directly.
External
Power
A supply in the range 6 to 24 Vdc may be used. The maximum
consumption will be 2.5W and quiescent consumption, without
microphones, 1.6W. The input terminals float with respect to
ground. Either (or neither) side may be grounded at will,
thereby allowing the use of floating supplies or grounded
supplies of either polarity. There will be no possibility of
hum-loops being formed.
Power Distribution
The mixer carries two four-way connectors, one of which [DC]
gives access to the internal batteries for charging and also
serves to connect to an external power source. The second
connector [PT] is an output which provides a switched, short
circuit proof connection to the power supplied to [DC]. This
allows the mixer to be used as the focal point for a system of
interconnected devices, all controlled from the mixer’s power
switch.
Temperature Range
The mixer is designed to work over the temperature range of
-20 to +60 °C.
Dimensions
The dimensions of the mixer case are: Height 47mm, Width
297mm, Depth 161mm
Weight
The weight of the mixer without batteries is 2.2kg
Construction
The outer case of the mixer is made of aluminium. The end
blocks holding the connectors and the panpots are milled from
solid aluminium bar. Inside the mixer is an inner compartment
of steel, tin-plated after forming, which contains all of the
circuitry that might be sensitive to radio frequency
interference. The top and bottom of this compartment are
sealed by copper screens and rf gasket material and all inputs
to and outputs from this compartment are filtered. The
circuitry is constructed on multi-layer printed circuit boards
with internal ground and power planes which ensure the
integrity of the internal grounding system.
All control knobs are special to SQN and are turned and milled from solid aluminium bar. The internal battery compartment is milled and bored from a solid block of polyacetal engineering plastics material and the moving parts are aluminium and stainless steel.
All labels and legends on the mixer are permanent. On the end blocks they are engraved; on the front panel they are printed into the hard-anodised surface; on the baseplate they are reverse printed on a polycarbonate label.
The mechanical construction is a development of a system which has proven in the past to be resistant to mechanical damage.
The SQN-4S series IV mixer offers the professional recordist:
Reasonable offers welcomed. Collection in person from London advised.
To buy this item please contact Charles Weiseld on: 07946 522845 or email: charlieweiseld@gmail.com