Analogue Systems Sequencer
SOUND ON SOUND REVIEWS
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An edited version of this text also appears in
SOUND ON SOUND magazine Vol.14 No.3. December 1999

Review by Chris Carter 


Analogue Systems RS200 Sequencer
Analogue Systems RS260 Quantiser
Analogue Systems RS150 Sequential Switcher

(see also:
Analogue Systems RS Integrator review)
(see also:
Analogue Systems RS System8000 review)


THE NEW BOY
In my earlier review of the Analogue Systems RS Integrator modular synth (SOS June 1998) I mentioned that further modules and systems were in development and 6 months down the line up pops a new sequencer, a handfull of new modules and a repackaged (and upmarket) version of the RS Integrator.

 
AS EASY AS ABC
First up is the RS200 Analogue Step Sequencer. This is a non-MIDI 3 channel, 8 step sequencer, 72 HP units wide and designed to slot into the current standard Analogue Systems 19" case, while still leaving room for a couple of additional modules (more on this later). The RS200 design is based on the earlier Analogue Systems TH48 Sequencer, a 3 channel, 16 step self contained, free standing unit (SOS April 1995).

As I mentioned the RS200 is a three channel sequencer (channels A,B and C), with individual controls for each of the 8 steps and a stepped range knob for adjusting the overall output voltage of each channel (0v to +10v). Channel C also has a Slew control for smoothing the output voltage or introducing a portamento effect if used with a VCO. In addition to a step indicator LED each channel also has two toggle switches. One is a three-way Skip/Off/Reset switch which skips selected events or resets the pattern back to step 1 at a specified step, or in the off position lets the sequence play uninterupted.


ONE STEP AT A TIME
The other switch (Trig1/Off/Trig2) is a three-way trigger gate pulse output selector. But first the implementation of the trigger outputs need a little explanation. Rather than the usual method of using a trigger output for each channel there are instead two switchable trigger outputs (either trigger 1 or 2) for each step and a third gate pulse that's activated at each step regardless of the trigger output switches. There is also a separate End Pulse output that triggers on the last step of a sequence. Not having three individual and simultaneous channel triggers could be thought of as restrictive but switchable triggers do allow for some interesting rhythmic variations, a case of swings and roundabouts I suppose. The internal clock (LFO) has a range of 0.01Hz (about one step every 7 seconds) to 30Hz (8 steps every half a second or so) and can be voltage controlled. An external clock, LFO, VCO or 10v trigger source can also be used to drive the sequencer.

 
SKIP A DEE DOO DAH
An unusual feature I haven't seen before on an analogue sequencer is the Skip-In socket. This is descriibed by Analogue Systems as an 'experimental socket', to be used in conjunction with the Skip/Off/Reset switches and, as I discovered, you can get some interesting if sometimes unpredictable results. For example: sending the output of the sequencer's internal clock to a frequency divider and putting all the switches to Skip then feeding the divided signal into the Skip In socket causes a sequence play, then pause at a step, play again then pause at the next step and so on and so on. Or feeding a noise source into the Skip-In will introduce a random element into the playback speed and I found that using a random sample and hold voltage can even cause the sequence to step backwards. For such a seemingly innocuous socket this is a very useful and unique feature and I'm sure many users will find all kind of creative uses and abuses for it. Lastly a Step button allows you to shift the sequence along one step at a time while the Start/Stop button and Start/Stop input socket allow you to trigger playback from the front panel or an external source.


STANDING ALONE
The RS200 sequencer is also available as a stand-alone package in an RS10 3U case and with two additional modules, the RS150 Sequential Switch and the RS260 Voltage Quantiser. The RS150 is a basic 4 into 1 pulse (or clock) driven sequential switcher. Each of the inputs can accept audio or control voltage signals which can be selected sequentially using a control signal fed into the Clock Input socket, or by flicking the Stop/Step toggle switch. Another toggle switch sets the number of active inputs (2, 3 or 4) which then appear at the switcher output socket one after another.
 

FREE RUN
The RS260 module is a single channel quantiser with a range of approximately 5 octaves. It responds to changes at either of the two V-In sockets and at each detected voltage change transmits a new quantised voltage (0v-5v) and a separate gate pulse (+10v). The controls are kept to a minimum with just an output Offset knob for tuning and a Free Run/Ext Gate toggle switch. With the switch set to Gate-In the quantiser only shifts to a new output voltage if a separate gate/trigger is detected. If it's set to Free Run mode the quantiser only shifts to a new quantised output if it detects a change in voltage at either of the CV inputs. Having two mixable CV inputs gives rise to some unusual glissando effects if, for instance, two waveforms (at different speeds) such as a triangle or sawtooth waves are used. A third CV input is also available, the Trans In socket. Connecting a CV keyboard output to this socket lets you to additionally transpose the quantised output over a five octave scale, a useful feature if the module is being used to quantise the output of the analogue sequencer. The Quantiser is an indispensable module, with or without the sequencer but for which it's obviously ideally suited, as its main use is faster and more accurate setting up of the unquantised sequencer outputs.

The RS150 Sequential switcher is also a versatile module in its own right (almost a mini sequencer) but when used with the RS200 it definitely makes the sum greater than the parts. One feature lacking in the RS200 is the ability to run the channels in series to get 16 or 24 step sequences. However, by sending each of the three sequencer channels into three of the RS150 switcher inputs you can use the sequencer End pulse output to step the switcher clock through the sequencer channels, hey presto! 8, 16 or 24 step sequences at the flick of a switch.

SMART CHOICE
It's a shame that unlike its earlier TH48 incarnation the RS200 is only an 8 step sequencer and the CV outputs are unquantised, also I missed not having a variable gate time control, although you could use the RS50 Trigger Shaper module for that purpose.

But as with most analogue sequencers using the RS200 is a doddle and very easy to get to grips with and although adding the additional modules makes programming a little more complex you do have a seriously versatile unit. The price of the basic RS200 module is very good value and the build quality is particularly high. Even though the standalone package with sequencer, quantiser, switcher, case and all costs substantially more I still think it's still a fairly reasonable price for such pro piece of analogue kit. If you are a user of Analogue Systems modular synths (or Doepfer modules) and you don't yet have an analogue sequencer the RS200 is going to be a very smart choice.

 

ANALOGUE SYSTEMS RS200 SEQUENCER

SUMMARY
A versatile, well equipped, non-MID analogue sequencer and even more so with the additional modules and as a stand-alone unit. It may lack some features of its earlier incarnation (the TH48) but then again it includes a few unique features of its own. A quality sequencer at a acceptable price.

 

PROS:
Versatile and relatively easy to use.
Some unique features
Excellent build quality.
Available as a stand-alone unit or module by module.
Reasonably priced.

CONS:
Only 8 steps per channel
Channels can only be chained in series using the RS150 module.
No control of gate output width.
Unusual Trigger output configuration.

 
PRICES:
RS200 Analogue Step Sequencer £325 Incl. VAT
RS260 Quantiser £95 Incl. VAT
RS150 Sequential Switcher £55 Incl. VAT
Complete self contained sequencer package: £649 Incl. VAT


Copyright © 1999 Chris Carter / SOS Publications.