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Drum Machine Supplement


As the successor to the very successful Linn LM-1 Drum Computer, the new Linn digital drum machine has a lot to live up to, in addition to the manufacturers' claims that it's smaller, cheaper and more efficient than its predecessor. However, since the volume of orders for the new machine has been so great that the LM-1 can no longer be produced, the LinnDrum remains the top of the market in self-contained drum machines and it's only fair to regard it as such.

As most people will be aware, the Linn uses EPROM's to store sampled acoustic sounds from genuine drum kits, and triggers these sounds from a sophisticated chainable memory matched with a miniature stereo mixer and a comprehensive set of inputs, outputs and trigger options. The LinnDrum comes in a 22" x 12" x 4½" case with wooden end cheeks, a black metal panel slightly angled, and white lettering, and weighs 22lbs.

The control layout has been changed considerably as compared to the LM-1, allowing space for stereo panning sliders as opposed to the left/right switches of the older model, and for a more comprehensive programming display. There are three types of control, sliders with small plastic caps reminiscent of ARP synthesisers for mixing and panning; rotaries with knurled-edged knobs for Tuning, Volume and Tempo; and large square tablet pushbuttons with a slight indentation for Play/Stop, individual voices and all the control functions.

Using the Linn

The simplest way to use the machine is by simply pressing the individual pushbuttons. Some instruments have more than one button, referring to the same sounds being played at different volumes and so enabling dynamics to be programmed. Snare has three; Bass, High Hat, Cabasa, Tambourine and Ride Cymbal each have two. High Hat also has two options, open or closed. Some of the buttons programme two sounds according to a selector on the bottom row; this doesn't mean that Clap and Ride Cymbal, or Conga and LowTom, can't occur simultaneously in a programme, but simply that they have to be programmed in separately.

While playing by hand or during automatic playback some of the drums can be tuned; in each case this involves clocking through the EPROM at a faster or slower speed, resulting in a shorter or longer sound in addition to a shift in pitch. The snare drum in particular sounds very strange at its lowest tuning due to this 'time expansion' effect. There's also a control to adjust the decay of the closed High Hat.

The basic sounds and dynamics can be arranged in up to 49 separate rhythm patterns, numbered 1.1 to 7.7. The first 35 patterns contain preset rhythms loaded at the factory which can, of course, be erased. These can be called up easily by pressing two of the seven 'Select Rhythm Pattern' buttons to produce the correct two digits on the LED display, and pressing Play/Stop. If another pattern number is typed in, the new pattern begins playing at the end of the bar in the previous pattern.

Programming new patterns takes a little skill, but this is quickly acquired. Pushing Record and Play starts a metronome click (which has a volume control on the mixing section), every eighth click being slightly louder and representing the downbeat of a two-measure, 4/4 time repeating loop. If required, the time signature or length can be changed before programming by using the length function and cutting the loop to a new length, counting the number of clicks desired. In fact this can also be done to existing programmes, for instance turning a two measure 4/4 loop into one measure of 7/8 by keeping only the first seven one-eighth notes and permanently chopping off the rest. Once the metronome is running the instruments are tapped in individually or together until the complete pattern is built up, the loop continuing in the record mode until this is done. If a mistake is made an individual sound can be removed and reprogrammed using the Erase button.

Tempo can be displayed in Beats Per Minute simply by pushing the BPM button whether playing or stopped. It's also possible to gain a readout of the amount of memory still available (remembering that this depends on the complexity of the patterns programmed rather than just the number of them used) by pressing Record alone. This gives a percentage readout from 0 to 99%.

EPROM voice board.

Cassette Interface

If the memories are full, it's possible to dump their contents onto cassette tape simply by connecting a tape recorder to the rear panel In/Out sockets via a Speaker or Headphone output (line level being insufficient) and Aux In socket, starting the tape and pushing Store. It's possible to load the entire contents of the Memory, or only certain chains of patterns or 'Songs'. It's also possible to copy from one LinnDrum to another, to completely erase the memory contents, or to copy a pattern from one memory location within the machine to another in order to rearrange Rhythms according to performance order, perhaps.

A 'Song' is defined as a list of rhythm patterns to be played in sequence. These could represent an introduction, verse, chorus, fill, solo and coda. Various songs come pre-set at the factory, and can be called up simply by switching from Pattern to Song and pressing Play.

To construct a song, the upper row of control buttons are switched to their alternative functions and the required patterns are entered in order. Up to 99 patterns can be entered; after the last one, the Song is terminated by pushing End. Interestingly enough this doesn't actually stop the Linn's clock, but returns the machine to the start of the Song. In practice it will be found necessary to enter a few empty bars therefore, to allow time to stop the machine before it begins to play the whole song again.

Various Editing options are of course available; Step Up and Step Down buttons allow a Song to be scanned and individual patterns moved or removed, and in the pattern mode individual instruments can be erased and repositioned. Up to 49 songs can be held in the memory, each consisting of up to 99 steps or patterns. A Song can be played starting at any step by repositioning the starting point.

Extra Features

The LinnDrum has several other features intended to make it 'user friendly' to musicians. It can be programmed either to correct errors in timing during programming, by assigning a sound to the nearest metronome beat; or to artificially induce errors in playback, giving a 'human feel' with a variable amount of offset from the correct beat. This can vary from 'straight' to 'shuffle' or 'swingtime' in 6 increments, A to F.

In addition it has a trigger output to drive sequencers or arpeggiators at 5 volt level, programmable to operate on ⅛ notes, ⅛ note triplets, 1/16 note triplets, 1/32 notes, 1/32 note triplets, or on every repetition of the cowbell. The BPM/Trigger display can indicate which setting has been chosen.

Internal construction.

Five trigger inputs are assignable to any of the LinnDrum's sounds, but normally refer to Bass, Snare, High Hat, Low Tom and Crash Cymbal. Each input has a sensitivity control and so can operate off a wide range of audio or click inputs, including click tracks which make it possible to replace poorly recorded sounds of conventional drum kits with Linn sounds. One possible application is to install crystal or piezo pickups in a set of practice pads and to 'play' the Linn manually by way of a change.

Two control voltage inputs at 0-5 Volts DC level allow variation of the Snare and Tom pitches, for instance by a control voltage pedal or a synchronised or random sequencer pattern. A rear panel socket allows connection of a Start/Stop footswitch, and every instrument has its own audio output for individual equalisation or effects.

Rear panel connections.

Internally the Linndrum is a superb example of electronic engineering. All of the components, apart from the transformer, 5V regulator and battery back-up are mounted on three PCB's. The main board mounted in the base (see photograph) holds all of the power supply components, voicing circuitry, DAC's and output mixing circuitry. The Z80 CPU, Firmware EPROM's and CMOS program memory are mounted on the front panel PCB along with the pushbutton keys, LED displays, trigger, sync, and cassette interface circuitry. The third board holds the mix and pan sliders as well as the timing and volume controls.

Connections between the boards are made in usual computer fashion using DIL headed ribbon cables, apart from the power supplies.

Despite the data compression techniques used the huge amount of memory required to produce the voicing can be seen from the close-up of the voice board; in fact 124K of EPROM is used.

The Bass drum, Snare, Sidestick, Cabasa, Tambourine, Cowbell and Claps are each contained in one 4k x 8 memory; TomTom and Conga use two 4k x 8; Hi-Hat requires four 4k x 8; while the Ride and Crash cymbals each need eight 4k x 8 chips! The IC's surrounding the EPROM's are mainly counters, used to clock through the memory data for each voice. The clock rate can be varied for the Snare, Tom-Tom, Conga and Hi-Hat according to the controls on the front panel.

Note that there is only one Tom-Tom voice which can be programmed to run through at different speeds to simulate 3 Toms therefore they cannot be played simultaneously. The same is true for the 2 Congas.

The Linn's EPROM's can be exchanged for any of those on a sample recording available from Linn. The dealer installs a low insertion force socket which allows the user to change chips simply and easily himself; alternatively, Linn can prepare a set of chips from a tape provided by the user, so theoretically the LinnDrum could be used to produce any percussion sound, or for that matter any short sound effect to order.

Clearly the LinnDrum is in a class of its own in terms of sound quality and user options. Already well-established is studios and groups throughout the world, it's now become clearly identifiable on several successful recordings, and musicians are starting to investigate the ways in which its various options can be used to maintain the same sort of flexibility that has always been associated with conventional percussion. For those who can afford it, the LinnDrum remains for the moment unequalled.

The LinnDrum is available from the UK distributors. These are: Scenic Sounds, (Contact Details), and Syco Systems, (Contact Details). Recommended price is around £2,650 including VAT, dependent upon the dollar exchange rate.

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Book Reviews

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Godwin Drummaker 32P

Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - Feb 1983

Drum Machine Supplement

Gear in this article:

Drum Machine > Linn > LinnDrum

Gear Tags:

Digital Drums


Previous article in this issue:

> Book Reviews

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> Godwin Drummaker 32P

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