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Last update: 4 December 2017

The Analogue Systems TH48 Sequencer

In the early 1990s, analogue sequencers were a bit like policemen and Number 25 buses - you could never find one when you wanted one. Then a whole bunch of them came along together. Doepfer Musikelektronik started the ball rolling in 1993 with the MAQ16/3 (although that was, strictly speaking, only analogue in style) to be followed by Analogue Systems, the company that is the brainchild of vintage synth expert and former collector, Bob Williams. Taking their lead from the TH48, numerous other analogue sequencers were released in the years that followed, so maybe it's time to look again at why this obscure piece of equipment, built using relatively primitive electronics and designed to seemingly obsolete principles, still attracts such devotion. Oh yes... and still attracts such significant wads of money.

Technically speaking

In an era when British synthesiser products exuded an air of cottage manufacturing, your first impression of a TH48 was almost certain to have been one of uncompromising quality. No doubt far more expensive to manufacture than necessary, it had custom knobs that were exact copies of original ARP2500 hardware, the switches were expensive, and the 15 chromed socket-nuts were all aligned exactly the same way. Equal care had been taken internally, proving that beauty could be more than skin deep. This was a box built to look good, and to last. It was even supplied with an Allen key for removing or replacing knob heads. A nice touch, that.

Sixteen steps was something of a norm for vintage sequencers, so Analogue Systems didn't break with tradition. However, instead of the usual single row or dual rows of voltage controls, the TH48 offered no fewer than three. Rows A and B had associated semi-tone quantisers, so these were clearly the ones designed for tradition pitch sequencing duties. In contrast, Row C had a slew control for portamento and other voltage controlled effects. Each row featured an independent Range control, offering up to +/-7.5 volts for a maximum of 15 octaves on a volt/octave synth, and all three rows shared the reset/run/trigger toggles found underneath each step.

Setting up basic sequences couldn't have been easier. First, you decided which row to use and connected the CV output and appropriate Trigger output (S-TRIG for Moogs, and the conventional TRIG for almost everything else) to your synth. Next, you decided which steps you were going to use (Run), which would send triggers (Trig) and where the sequence would loop (Reset). Then you worked your way through the sequence using the Step button and set the pitches using the small but accessible knobs. Finally, you adjusted the speed of the internal clock between one step every four seconds and 25 steps per second. It was instant Karn Evil 9 or Love to Love Ya Baby according to taste. Finally, you could leave Random 'off' for conventional sequences, or switch it on for quasi-random selection of which step played when.

But this was only the beginning. Using an ARP2600, I created some superb musical effects quite impossible without the TH48. For example, I connected 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 acid bleeps and bloops. Next, I fed two different but harmonically related sequences to the CV inputs of oscillators 1 and 2 and directed them through the filter to add a pulsating musical backing. Then I patched oscillator 3 directly to the ARP's on-board mixer, and played melodies from the keyboard. Hold on... a 4-part polyphonic ARP2600? Damn right!

The fun didn't stop there. The TH48 was designed by a vintage synth enthusiast for the benefit of like-minded vintage synth enthusiasts, and it had many exotic features. These were accessed using the remaining knobs and I/O sockets. Clearly a close relative of the voltage control modules of the late '60s and early '70s, the TH48 would sit happily alongside Roland System 700s, ARP2500s and 2600s, and Moog Modular Systems, and experimentation yielded startling results.

In retrospect, it's tempting to compare the TH48 to the Doepfer MAQ. After all, both products were designed to produce repetitive sequences and effects that could easily be modified in real-time but, while a MIDI sequencer can look like its analogue counterpart and can 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 to the TH48 or its vintage brethren.


Some users complained about the small knobs and compact styling of the TH48, but Analogue Systems had obviously made a conscious decision to keep the TH48 as small as possible and, while 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. Nonetheless, the TH48 could have been improved, and three modifications would have made it very difficult to criticise. The first would have been the ability to step through rows at different speeds, making it possible to create poly-sequences by modulating one row using another. The second would have been a method to create simultaneous sequences of differing lengths, and the third would have been the capacity to chain rows together for sequences of up to 48 steps. Mind you, no other product offered all these facilities. Indeed, no other combined all the existing capabilities of the TH48, which is why they are so highly sought-after today.

Copyright ©2007, Gordon Reid.

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