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Analogue Systems TH48

Sequencer By Gordon Reid
Published April 1995

We've had the analogue synth revival; now it's the turn of the analogue sequencer! Gordon Reid checks out Analogue Systems' brand‑new 16‑step analogue sequencer, and explains just why you might want such an apparently obsolete device.

Analogue sequencers, it seems, are a bit like policemen and Number 25 buses — you can never find one when you want one, and then a whole bunch of them come along together. So, is 1995 going to be the year of the vintage sequencer? Doepfer Musikelektronik started the ball rolling in 1993 with the MAQ16/3 (although that is, strictly speaking, a MIDI sequencer, and only analogue in style) and Analogue Systems, brainchild of vintage synth expert Bob Williams, are now following in their footsteps. With more British 16‑step sequencers already in development, maybe it's time to look again at why these obscure pieces of equipment, built from relatively primitive electronics to obsolete principles, can still attract such devotion — and such significant wads of money. After all, look what you can get for £700... a round‑trip ticket to Colombia, an Atari, colour monitor, hard drive and squillion event 100‑channel MIDI sequencer... or, a 3‑channel 16‑event analogue sequencer in a 2U box. But which is the right one for you?

Quality Street

In a world where British synthesizer products have traditionally exuded the unmistakable air of "cottage industry" manufacturing, the first impression you get when taking the TH48 from its box is one of uncompromising quality. No doubt far more expensive to manufacture than necessary, it looks good, it feels good, and... well, we'll see. The custom‑built knobs are exact copies of original ARP2500 hardware, the switches are expensive 'rocker' types, and the 15 chromed socket‑nuts are all aligned exactly the same way. Equal care has been taken internally, proving that beauty can be more than skin deep. This is a box built to look good, and to last.

The TH48 is supplied with a mains lead, three 3.5mm patch leads, and an Allen key for removing or replacing knob heads. A nice touch, that. Unfortunately, the review unit had no manual, but not to worry — operation is easy and intuitive, so let's get sequencing...

In Use

Sixteen steps has become something of a norm for analogue sequencers, and Analogue Systems have not seen fit to beak with tradition. However, instead of the usual single or dual row of voltage controls, the TH48 offers three. Since Rows A and B have associated semitone Quantisers, these are clearly the ones designed for traditional pitch sequencing duties. On the other hand, Row C has a zero to two‑second 'Slew' control for portamento and other voltage‑controlled effects. Each Row features an independent 'range' control, offering ±7.5 volts for a maximum of 15 octaves on a volt/octave synth, while all three Rows share the reset/run/trigger toggles found underneath each step.

Setting up basic sequences couldn't be easier: first, decide which row to use, and connect the 'CV Out' and appropriate 'Trigger Out' ('S‑Trig' for Moogs, and the conventional 'Trig' for almost everything else) to your synth. Don't forget to use the quantiser or there'll be tears! Next, decide which steps you are going to use ('run'), which will send triggers ('trig') and where the sequence will loop ('reset'). Then work your way through the sequence, using the Step button, and set the pitches using the small but accessible knobs. Finally, adjust the Speed of the internal clock between one step every four seconds and 25 steps per second. It's instant 'Karn Evil 9' or 'Love to Love Ya Baby', according to taste. Finally, leave 'Random' Off for conventional sequences, or switch it On for quasi‑random selection of which step plays when.

But this is only where the fun begins. Using an ARP2600 as a test bed, it was possible to create some superb musical effects quite impossible without the TH48. For example, connect Row C's CV Out to the ARP's filter pitch control, and direct white noise into the audio input to re‑create some seriously acidic bleeps and bloops. Next, feed two different, but harmonically related, sequences to the CV inputs of oscillators 1 and 2, and direct them through the filter to add a pulsating musical backing. You're now ready to patch oscillator 3 directly to the ARP's on‑board mixer, and play melodies from the keyboard. Hold on... a 4‑part polyphonic ARP2600? Damn right. Now we're cookin'.

The Fun Goes On...

The TH48 was designed by a vintage synth enthusiast for the benefit of like‑minded vintage synth enthusiasts, and I've yet to explore fully some of its more exotic features. These are accessed using the remaining knobs and I/O sockets: Trans In, Quantiser A In, Quantiser B In, Clock Int/Ext, Ext Clock In, Shape, Shape Out, Shape CV In, Int Clock Out, and Int Clock CV In (see box 'Exotic Features' for more details). Clearly a close relative of the voltage control modules of the late '60s and early '70s, the TH48 will sit happily alongside Roland System 700s, ARP2500s and 2600s, and Moog Modular Systems. Consequently, an open mind and some free experimentation can yield startling results. There's no room within this review to do more than scratch the surface, but see the separate 'VCF' box for some idea of what the TH48 makes possible.

CV Versus MIDI

It's tempting to compare the TH48 to the Doepfer MAQ 16/3 (reviewed Sound on Sound, July '93). After all, both products are designed to produce repetitive sequences and effects that can easily be modified in real‑time. But, whilst a MIDI sequencer like the Doepfer can look like its analogue counterpart and offer many additional facilities, it lacks one important facility inherent to voltage control: you can't add multiple MIDI controllers and audio signals together to create new effects. Consequently, you can't realistically compare a MIDI sequencer (the Doepfer) to a computer‑based MIDI software sequencer, or to the TH48 and its vintage brethren. If you need an analogue sequencer, you need an analogue sequencer. Period.

Omissions And Improvements

I can see some users complaining about the small knobs and compact styling of the TH48. After all, faders give far better visual feedback than knobs ever can. But I'm not one of the whingers. Analogue Systems have obviously made a conscious decision to keep the TH48 as small as possible and, whilst 2U is a very tight space into which to cram so many controls and interfaces, I never once found myself nudging the wrong knob or knocking an interface lead. Maybe I've just got lovely petite fingers...?

Despite all of the above, the TH48 could be improved, although three modifications would make it very difficult to criticise. The first would be the ability to step through Rows at different speeds, making it possible to create more musical poly‑sequences by modulating one Row from another. The second would be a method of creating simultaneous sequences of differing lengths, and the third would be the capacity to chain Rows together for sequences of up to 48 steps. Mind you, no other product, current or vintage, offers all these facilities. Indeed, none combines all the existing abilities of the TH48. Still, one can dream.

Conclusions

There will be many players in this MIDI‑dominated world who can't imagine why anybody should want to spend £700 on an analogue sequencer. But you can't dismiss the genre. Second‑hand units from ARP and Korg, far more limited than the TH48, sell for hundreds of pounds. Indeed, you'll be lucky to get change from a grand if you want a genuine Moog sequencer. Consequently, if you're after a true analogue sequencer, the TH48 deserves to be the first, and until more competition appears, may be the last unit to check out. Alternatively, Bogota can be nice at this time of year. The choice, as they say, is yours...

Exotic Features

  • Trans In: apply keyboard CV to this socket, and play the keyboard to modulate the sequence in real time.
  • Quantiser A In/Quantiser B In: these allow any voltage from a synthesizer to play musical scale‑type patterns that will always have chromatic tuning.
  • Shape: this circuit shortens or lengthens clock pulses to give enhanced triggering effects to envelope shapers.

VCF — Voltage Controlled Fun

  • Set up a sequence and apply an LFO to the Int Clock CV In. This, of course, modulates the speed at which the sequence runs.
  • Apply keyboard CV to the Trans (transpose) In socket, and play the keyboard to modulate the sequence in real time.
  • Apply heavily filtered noise or Sample & Hold to any input for random pitch or temporal modulation.
  • Modify the shape of the gate pulse (Shape) to alter the amplitude and/or filter envelopes on the synth. This results in more human sounds and sequences. Apply noise to the Shape CV In for random envelope modulation.
  • Drive the Ext Clock In at audio frequencies, and use the 16 steps to define a complex waveform. Direct this back to the synth as an independent oscillator. The shape is multi‑stage and heavily quantised, so it's sort‑of digital. And it sounds it.
  • Use the Quantiser Ins and Outs to quantise changes in control voltages, such as the synthesizer's initial filter frequency. Synchronise and process an analogue drum machine through the ARP in this way for pure techno.
  • Shortages of patch‑leads and inputs notwithstanding, try all or as many as possible of the above simultaneously.

Pros

  • Excellent construction and attention to detail.
  • Lots of Ins and Outs for flexible signal routing.
  • Clear, simple and quick to use.
  • 15‑volt range.

Cons

  • Mains On/Off switch inaccessible on the back panel.
  • No way to step through Rows at different speeds.
  • No way to chain Rows together.

Summary

A well‑built, simple‑to‑use, yet flexible analogue sequencer with little (if any) current competition. The Germans will love it.