Using VST Instruments

Frequently Asked Questions

Published in SOS December 2000
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VST Instruments can create a huge variety of sounds from the comfort of your MIDI + Audio sequencer, but can also be a source of confusion for many computer users. Martin Walker answers the most common questions, and provides advice about automation, timing, and sound quality.

A couple of years ago musicians would have laughed if you had told them that classic synths would be successfully re-created in software form and sold at a fraction of the original price. They would have been even less likely to believe that you might have half a dozen or more of them neatly integrated into your favourite MIDI + Audio sequencer to be summoned at will. Yet VST Instruments do exactly this -- and with the likes of the Minimoog, TB303, TR808, Prophet Five, PPG Wave and Mellotron already available, it's hardly surprising that they're proving extremely popular.

However, you rarely get something for nothing, and the situation's no different here. Each sound you create in software consumes some precious processing power and, despite manufacturers' claims that their products can produce 64 or more simultaneous notes, this is only possible if your computer has mountains of spare CPU power -- not perhaps all that likely when you're already running a clutch of audio tracks and a fistful of effects plug-ins.

Running all the VST instruments you want, without your computer grinding to a halt, can be a tricky process and at SOS we receive many queries from readers who are having trouble using these versatile soft synths with their systems. So I've selected the most common of these questions to answer here, in order to make the whole process of installing and using VST Instruments less daunting.

Q What is a VST Instrument, and how do they work?

The VST (Virtual Studio Technology) system was developed by Steinberg to enable a complete studio to be created in software. Even in its earliest incarnation, it allowed third-party developers to produce real-time effect modules that could 'plug in' to the host application. However, when Steinberg introduced the second version of the VST plug-in standard it also became possible to send MIDI data to and from such effects. This enabled developers to add more features, such as MIDI control of effect parameters and locking of effect settings to tempo. The inevitable result of this advance in the protocol was that this MIDI information was also used to run synth engines, rather than just effects processors. It is these synths, masquerading as effects plug-ins in order to fit directly into the sequencing environment, that are called VST Instruments.

Q What do I need to be able to use VST Instruments?

The most important thing is a suitable VST 2.0-compatible host application. The main ones are Steinberg's Cubase VST from version 3.7 onwards for PC owners, and from version 4.1 on the Mac, along with the entry-level Cubasis VST, and the latest versions of Emagic's Logic Audio range, including their entry-level MicroLogic AV 4.5. A few other applications (mostly shareware and freeware) also support VST Instruments, such as the freeware VSTi Host for Mac that turns them into stand-alone synths, and Orion and n-Track Studio, both shareware virtual studios with comprehensive MIDI and Audio support.

You will also need a fairly powerful CPU, since the sounds are created in real time using some of the processing power of your computer -- each extra note you play needs more calculations, and thus consumes additional CPU cycles. As a rough guide, you should add together the minimum specifications quoted by both your MIDI + Audio sequencer and the VST Instrument, since you will obviously be running them both simultaneously.

Q How do I install a VST Instrument?

Thankfully these are among the easiest programs to install, since they don't need to be able to run by themselves. All you need to do is to drag the DLL file into your plug-ins folder, and then the next time you launch your sequencer the new instrument should appear in your list of available VST Instruments. Steinberg Cubase VST users can place this folder outside the main VST application to keep all their plug-in effects and VST Instruments safe from accidental deletion during program updates, but Emagic Logic Audio users must place this folder inside their main sequencing program folder.

Q How do I select and connect a VST Instrument?

This depends on the individual host application. In the case of Cubase VST, you first need to launch the appropriate panel by selecting the VST Instruments option in the Audio menu (Cubase 3.7) or Panels menu (Cubase 5.0). Now you can choose your synth using the drop-down selection box in this panel, and its audio outputs will then appear in the VST Channel Mixer. Since the VSTi output signal is an audio waveform, it can be treated with EQ and effects in exactly the same way as would a normal audio track.

As soon as you activate your synth by clicking on its rack power button, a similarly named MIDI output entry will also appear in the list of MIDI track output options in the Arrange page. Create a new MIDI track, choose this new MIDI output for it, and you can then play the VST Instrument in real time from a suitable external MIDI keyboard and record the results.

Q Can a VST Instrument produce more than one sound at a time?

Most VST Instruments are multitimbral, so you could create entire songs using them, although you would probably need a very powerful computer processor to do so. Some, like Steinberg's Model E respond to multiple MIDI channels simultaneously, so you only need to launch one instrument and then allocate different sounds to each channel. Often this type also provide four or more outputs, so you can get a basic stereo mix on the main pair, and then send sounds that need individual EQ or effect treatment to one of the others.

Other VST Instruments, such as Native Instruments' Pro 5, are mono-timbral, but you can still run multiple sounds by launching a separate instance for each additional MIDI channel you want to run. Although this approach may take slightly more processing power overall, it does have the advantage of giving every sound its own stereo mixer channel for EQ and effects.

Q What types of sounds can VST Instruments produce?

Most VST Instruments specialise in one type of sound, the most popular being analogue synth simulations, but you can already buy simulations of Hammond tonewheel organs, Mellotrons, and Wavetable synths -- no doubt many more will follow. It's perfectly possible to design them using physical modelling as well -- Steinberg's VB1 is a virtual bass guitar whose sound can be altered by moving pickup, plectrum, and mute positions.

While you can certainly create many drum and percussion sounds using analogue synths, you'll probably find it easier to use a dedicated Instrument for this function, such as the LM9 bundled with Cubase version 5, or the more advanced LM4. These let you load various sets of sampled drum sounds for more realism, and respond to velocity for greater expression. Also bundled with Cubase is Universal Sound Module -- a General MIDI VST Instrument with a complete range of sounds for general purpose use.

Q Are there any VST Instruments which allow sampling?

There have been no major commercial releases of VST-compatible samplers yet, although NI's Reaktor can be used as a sampler and can also run as a VST Instrument. However, a few shareware and even freeware ones are available. For instance, S&C Develop (www.multimania.com/scdevelop/syntha.htm) have their SC Virtual Sampler, already at version 2.1. Remember that you'll need plenty of system RAM to run your applications, and that you'll have to leave enough spare for sample storage -- 128Mb is an absolute minimum, while 256Mb is more suitable for serious sampling work.

Q Do VST Instruments have any advantages compared to stand-alone hardware synths?

For most musicians, the biggest advantage is that they are considerably cheaper than their hardware equivalents, although for talented developers they do offer the opportunity to create synth designs unfettered by practical considerations such as cost. An excellent example of this is Native Instruments' Reaktor -- a completely open-ended synth construction kit for Mac and PC that can either mimic existing hardware designs or create completely new ones at the whim of the user. Although the design process needs the stand-alone version, you can launch a VST-compatible playback-only version for using your designs within Cubase.

At a more general level this freedom allows developers to create user interfaces with a separate control for every parameter (no more multi-function buttons!), graphic display windows, and any groovy colour scheme imaginable. What's more, once you've edited something to perfection, you know that the sound will still be there the next day, because the patch will be saved with your song data.

Q Are there any other ways of integrating soft synths into my sequencer, other than using the VST 2 standard and, if so, how do they measure up?

The Rewire protocol, developed by Propellerheads in conjunction with Steinberg, is one alternative. This allows stand-alone soft synths to integrate neatly with host applications like Cubase VST. Various soft synths are now Rewire-compatible, including Propellerheads' own Rebirth RB338 drum and bass synth, Bitheadz Retro AS1 synth and Unity DS1 sampler.

Although the synth still runs as a separate application alongside its host, its outputs are piped across directly to their own VST mixer channels for further EQ and effects, just like VST Instruments. You can also start and stop Rewire-linked applications in sample-accurate sync. What's more, a Rewired synth isn't limited to a single-window interface. This integration makes conflicts far less likely than when you're using several unlinked applications side by side. However, you have to launch a Rewired synth application before your sequencer, which isn't as convenient as launching VST Instruments on a whim at any time. You can find more details in Rewired For Sound, SOS November '99.

Q Can VST Instruments cause any damage to my computer?

If you download them from the Internet then it's vaguely possible that you might infect your computer with some sort of virus, but in general there isn't really much scope for VST Instruments to create problems within your system. However, if you try to play too many simultaneous voices with any Instrument you will run out of processing power, and this may cause your computer audio to stutter or to stop altogether -- in extreme cases it could lead to a system crash. Many let you cap the maximum number of voices, and you should set this figure to a value appropriate to the power of your system.

Don't assume, just because your song doesn't use huge chords, that your polyphony will automatically be very low -- some sounds have long decays and can still be using a voice even when almost inaudible. The best way to optimise CPU usage is to reduce the maximum number of voices until you start to hear missing notes in your song, and then edge it back up a little.

Q How do I switch off the time delay when playing my VST Instrument in real time?

Sadly, this is not an option -- if you hear an obvious gap between pressing a note on an external MIDI keyboard and hearing any sound on a VST Instrument then you are suffering from the latency of your soundcard drivers (see the feature on latency in SOS April '99 for more details). For the delay to be small enough to be unnoticeable you'll need a latency of 20mS or less, and for this you really need to be running ASIO or EASI drivers. If your soundcard doesn't provide these as an option then PC owners may still get very acceptable performance using DirectX drivers, although you can't normally record audio when using these.

Thankfully, latency only affects you when recording, so one option for those suffering from a slow real-time response is to play in your MIDI tracks using a hardware synth, so that you can perform properly, and then to direct the output of the track to your VST Instrument once you have finished recording. It may not be ideal, but it works.

Q Is the timing of VST Instruments as accurate as that of hardware MIDI synths?

When you're playing them in real time the timing accuracy is largely determined by your soundcard drivers, and as long as you have low-latency ones your timing should be as tight as that on most hardware MIDI synths. However, timing can also suffer from jitter (see last month's PC Musician feature for more details), and this is dependent on the host application. The result can be a variation in beat placement of as much as twice the normal latency value -- although MIDI + Audio sequencer developers do now seem to be aware of the problem and are committed to solving it in future updates.

However, once recorded into your sequencer, MIDI events are passed to VST Instruments with sample-accurate time-stamps, so there can be no loss of timing resolution between the host and instrument. This means that anyone who subsequently quantises their MIDI tracks or enters them in step time should have sample-accurate timing. This is far better than hardware MIDI synths, that have a gap of about one millisecond between 'simultaneous' notes, because of the restricted transmission rate of the MIDI standard.

Q Can I use MIDI to alter VST Instrument parameters in real time?

This depends on the individual instrument, but nearly all will respond in some way to pitchbend, modulation and aftertouch. Most will also let you control at least some of their front-panel parameters externally, for the purposes of automation. Normally you'll find a list in the Instrument's manual of the MIDI Controller numbers allocated to each parameter, so all you have to do is generate the appropriate MIDI information to move each control on the screen -- recording these controllers allows you to automate things like filter sweeps. Conversely, moving the software controls will normally generate similar MIDI information, so that you can create automation data using only a mouse.

Unfortunately, Logic Audio already uses Controller numbers 64 through to 120 for its plug-in automation, so if the VST Instrument also uses any of these then things may work slightly differently -- often MIDI control will still be available, but using altered controller numbers. You can find translation tables for some VST Instruments on Dave B's Logic Audio web site -- surf over to www.ozemail.com.au/~oscwilde/index.html to check out this useful site.

Q Are the VST Instruments which are based on classic synths really as good as the originals?

Well, they don't go out of tune as easily, but most developers have managed to capture the quirks of filter response, envelope shape, and oscillator waveforms that made the originals what they were. Of course, nearly all analogue synths went through a period during their lifespan where refinements and component changes were made, so they don't have one truly definitive sound. However, the bottom line is that each tribute VST Instrument can make unique sounds that true enthusiasts will recognise and enjoy as a modern variation on the original.

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