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Peavey DPM Spectrum Bass Module

Depth of colour

Eschewing the usual jack-of-all-trades approach to sound synthesis, Peavey's latest synth module puts the boom in your bottom and the bass in your face...

The history of synthesiser design is the history of manufacturers vying with one another to produce the instrument which offers the largest and most varied range of sounds. It's a design imperative that hasn't diminished in importance with the rise of the sample-based synth - quite the opposite, in fact. In contrast, sonic specialisation has traditionally counted for little where synths are concerned.

But let's face it, once you've got a couple of instruments which give you a bit of everything, what you really want next is an instrument which gives you a lot of something - and what better 'something' than bass sounds? The sonic vocabulary of the bassline has increased greatly over the past decade, in line with the ever-expanding vocabulary of drum and percussion sounds used in popular music. But while the latter have long been supported by dedicated instruments, in the form of the drum machine and the drum module, the bass machine/module has traditionally not been a popular option with manufacturers. Leaving aside those old analogue monosynths which have assumed the role of bass synth through popular usage rather than design, there have been surprisingly few dedicated bass instruments. Roland's TB303 Bass Line is undoubtedly the most famous; 360 Systems' MIDIbass and Pro MIDIbass are somewhat less well-known and appreciated.

So, is there a place for such an instrument today? Peavey evidently think so, for they've taken the synthesis technology underlying their DPM Series synths (DCO, DCF with resonance, DCA, Filter and Amplitude envelopes, LFO, and Pan), used it to create 200 preset bass sounds, and packaged those sounds in an inexpensive 1U 19" rackmount MIDI module. The resulting instrument - the DPM Spectrum Bass - isn't only aimed at keyboard-based MIDI musicians, however. It's also intended as a companion module for the company's Midibase MIDI bass guitar controller, as is evident from a number of its design features. Not least among these features is the module's straightforward, LCD-free front panel, which should appeal to musicians who like the quick access and ready comprehension provided by dedicated knobs. But does the module offer enough substance underneath its surface simplicity to make it worth buying?

On superficial acquaintance, the Spectrum Bass may seem not to offer much at all. Its front-panel Preset knob gives you access to just 14 Presets - not many sounds for any contemporary hi-tech instrument, dedicated or otherwise. However, turn the knob to the MIDI 1 or MIDI 2 setting and you have remote access to 200 Presets. MIDI 1 gives remote MIDI access to the first 100 of those Presets, MIDI 2 to the other 100, using patch changes only; if you can transmit MIDI Bank Select commands from your MIDI instrument or sequencer, then you can access all 200 Presets from either of these settings.

Let's run across the other front-panel features. The Power/MIDI LED indicates when power to the unit is on and, by flickering, when MIDI data is being received. The Volume knob, of course, is self-explanatory! The MIDI Channel knob lets you set the module's receive channel for Poly mode, and its base (ie. lowest) receive channel for Legato, Multi and Multi Legato modes (see the Legato Playing and Multi Mode boxes for more information on these modes).

Transposition of the master tuning is provided by, yes, the Transpose knob; you can transpose incoming notes up or down one or two octaves, or to any semitone within the first higher octave. The Spectrum Bass can also be fine-tuned within a semitone either way, in one-cent steps, using the Fine Tune up and down buttons, while the module's various MIDI receive modes can be selected using the Mode Select button and associated LEDs. Straightforward stuff, indeed.

The only front-panel function not apparent without recourse to the manual is Global Pitchbend Range; to set this, you define the range using the Transpose knob, then hold down both Fine Tune buttons while powering up the module. Yes, it's kludgy, but that's what happens when there's no LCD screen to take the parameter strain and no space on the front panel to take that extra knob which could have been dedicated to setting pitchbend range. Matters aren't improved by the absence of a power on/off switch: power connections have to be physically broken and then remade - and that means pulling out and replacing either the power lead or the supplied AC adaptor, or switching off the power at the mains. Whichever way, it's a pain. What's more, the review model didn't take kindly to connections being broken and remade in this way, exhibiting a nasty habit of remaining silent when powered up.

Although all the Spectrum Bass Preset parameters are fixed in ROM, you can make 'live' changes to selected parameters on each active MIDI channel using MIDI controllers. In addition to the familiar volume (controller #7) and pan (#10), the module implements the legato footswitch controller (#68 - see 'Legato Playing' box) and controllers for sound variation (#70), release time (#72), attack time (#73) and brightness (#74). The attack time controller is misleadingly named, as it actually turns velocity response on/off on the selected channel. Brightness, more obviously, alters the filter's cutoff point. The most unusual controller function is sound variation, which you use to layer from two to four Presets; this allows you to expand the Spectrum Bass sonic vocabulary beyond its 200 Presets, and create some massive bass sounds in the process.

Of course, layered presets means reduced note polyphony - though if you're playing a single monophonic bassline you shouldn't run into problems. The Spectrum is eight-voice polyphonic, so if you really must have more voices you'll have to chain two modules together using MIDI overflow mode on the first module; this 'overflows' incoming notes to the second module when all the first's voices are in use.

It is possible to get at all of the Spectrum Bass's Preset parameters - but only if you're prepared to enter the world of MIDI SysEx edit commands. For intrepid explorers, a full list of parameters along with the necessary SysEx programming information can be found towards the back of the slender manual. If you're comfortable tapping SysEx data strings into the MIDI Mixer page of a software sequencer, a little work will greatly expand the sonic capabilities of the Spectrum Bass. In fact, it makes a lot of sense to store parameter edits in a sequencer, because any edited values are confined to the edit buffer on the module itself (remember, its Presets are stored in ROM). It does seem a shame, not to mention a touch ironic, though, that most users will effectively be prevented from exploring the full sonic capabilities of what is meant to be an easy-to-use instrument. Then again, with 200 Presets onboard there are plenty enough sounds to keep most people happy - or are there?

Now we come to the crucial questions: does the Spectrum Bass sound any good, and does it provide a varied-enough palette of bass sounds to justify its dedicated status? Anyone who has used one of Peavey's DPM Series synths will know that the Peavey sound has a powerful, warm, full bass end; not surprisingly, this has been carried over to the Spectrum Bass. All in all, the module is well able to hold its end up (or should that be down?) where it matters most. What's more, the variety of bass sounds which it provides represent the best attempt that I've come across to reflect, on a single instrument, the broad spectrum of bass sounds in use today. Having said that, I have come across better examples of certain individual sounds, such as acoustic, fretless and slapped bass sounds, than those provided by the Spectrum Bass.

All in all, though, the sonic strength and quality of the module, the number and variety of bass sounds it provides, and its modest asking price add up to an instrument which is well worth buying if you're into bassline creativity and the 'science' of bass sound.

Price: £279 including VAT

More from: Peavey Electronics (UK) Ltd, (Contact Details)

Multi mode

You can get the Spectrum Bass to respond multitimbrally across four consecutive MIDI channels by selecting either Multi or Multi Legato mode from its front panel; the lowest channel is set using the MIDI Channel knob. If you only want to use two or three bass sounds at once, you can disable the Spectrum Bass's response on the remaining channel(s) by transmitting patch number 128 to it on those channels. This lets you use the remaining channels for parts played on other MIDI instruments. However, as soon as you send the bass module a patch number in the range 1-100 on one of its multitimbral channels, its response on that channel is re-enabled. In practice, this makes it difficult if not impossible to use these channels for other MIDI instruments when the Spectrum Bass is in Multi mode. So what can you do if you want to use two bass sounds at once but spare MIDI channels are in short supply? Well, you can select MIDI channel 15 as the lowest channel; this way, only channels 15 and 16 will be used up by the Spectrum Bass. However, if you're used to putting your bass parts on the lowest channel(s), you might find this an annoyance.

The Spec

Presets: 200
Wave ROM: 1 Mb
Polyphony: eight voices
Layering: up to four Presets
Multitimbrality: four parts
MIDI Receive Modes: Omni, Poly, Multi, Legato, Poly Legato, Multi Legato
Front Panel: Power/MIDI LED, Volume knob, Preset knob. MIDI Channel knob. Transpose knob. Fine Tune up and down buttons, Mode select button and LEDs
Rear Panel: power input socket, MIDI In, Out and Thru sockets, Stereo/left audio output jack, Mono/right audio output jack
Casing: 1U 19"

Legato playing

Normally when you play notes consecutively on the keyboard, each one is triggered anew, beginning from its attack stage. However, in legato mode there's a smooth transition between consecutive notes, so long as each new note is played before the previous one is released; in effect, one amplitude-envelope sustain stage extends across any series of legato notes. Legato mode is the nearest that a keyboard instrument can get to mimicking hammer-ons and pull-offs on a stringed instrument - making its inclusion on the Spectrum Bass wholly appropriate. If you select Legato mode on the module, the same Preset is assigned to four consecutive MIDI channels, and is played legato on each channel. Multi Legato mode, on the other hand, lets you assign a different Preset to each of the four channels.

But why four channels? Well, that's one channel for each of the four strings on a Peavey Midibase MIDI bass guitar. Legato playing is also a valid performance style for synth bass, of course, and so the Spectrum Bass also has a Poly Legato mode; ie. it responds on a single MIDI channel in legato mode. The bass module can also respond to the MIDI Legato Footswitch controller (#68) on each channel, allowing you to switch quickly in and out of legato mode. Alternatively, while in legato mode you can simply vary your playing technique, overlapping consecutive notes when you want to play them legato and 'separating' them when you want to trigger them individually.

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


Music Technology - Mar 1993

Gear in this article:

Sound Module > Peavey > DPM Spectrum Bass

Review by Simon Trask

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