The evolution of the digital audio workstation (DAW) has revolutionized the way most of us compose and record music. As computers - and the software they run - become more powerful, the need for hardware sound generators and processors has diminished to the point where many composers and producers today work within totally self-contained digital environments, with a level of flexibility, fidelity and, of course, portability that would have been inconceivable in the past.

And yet hardware still has a place in many home and professional studios. Whether it's familiarity, that hands-on feel or certain unique characteristics of the sound. while many specific types of hardware have fallen out of favor with (samplers, for example), there are some that have maintained or gone on to develop a certain "classic" status, and that many of us choose to integrate into our setups, often at the expense of space and practicality.

There comes a point for many computer musicians when they ask themselves whether a piece of audio hardware - often an analog or virtual analog synthesizer, or a piece of high·end outboard, such as an EQ or compressor - might add something to their software-based setup. The choice of whether or not to go down this route is rarely a straightforward one. though. While a nice new analog synth might offer a fantastic sound, as well as providing an alternative way to interact with your music - and possibly taking some of the heat off your computer's processor - working with a piece of external hardware often requires a careful rethink of your usual recording methods and workflow.

In this feature we'll be looking at the various reasons why you might consider integrating certain choice pieces of hardware into your computer-based setup, showing you how to connect everything together. and discussing how the addition of such gear might affect the way in which you work.

The most obvious considerations when weighing up whether or not to integrate hardware into your setup will be price. practicality and the possibility that it may need fixing or replacing at some point.

The price issue can be offset by the fact that a lot of hardware retains its second-hand value quite well. If you buy carefully, you might even make money on some of it when it comes to selling it later.

The practicality of hardware comes down mainly to its size and weight. While a 1U compressor won't be a difficult thing to accommodate, a large workstation or vintage analog synth will require serious space and could even be an issue when it comes to moving into a new house.

Reliability is another thing to consider. While there are synthesizers and EQs from the 70s that still work perfectly, some instruments and effects tend to suffer from common ailments and may be difficult to obtain parts for. This might be a reason why you'd choose a modern Moog Voyager over a 1970s Minimoog, for example.

Luckily, there's a lot of useful information readily available on the internet, as well as many specialist firms who repair and source parts for rarer instruments. However, it's always best to be careful with your equipment- use surge-protected power supplies, dust covers where appropriate, and don't leave things switched on day and night.

Also, if you intend to use your hardware for live gigs, or in a busy studio environment where it's likely to receive heavy, daily usage, getting your gear serviced regularly is generally a good idea.

While analog modelling enables us to create hugely convincing emulations of analog outboard processors and synths. there's a certain musicality in sounds generated by analog circuitry that can be difficult to achieve any other way. We generally attribute these qualities to the non-linear characteristics that analog circuitry imparts on audio signals.

While many (us included) are skeptical over just how much these differences matter, or if they're even noticeable in a full mix, some consider them central to their sound or production style.

Somewhat more divisive is whether VA (virtual analog) hardware synths really offer any audible advantages over their software equivalents. Traditionally, with VAs having their own dedicated DSP architecture, synthesizer models could be run with less corner cutting. They'd generally be sample-processed, rather than block-processed. meaning that they recalculated many of the synthesizer's parameters and its audio output sample by sample, rather than in blocks. This ensured higher control rates, resulting in smoother movements as sounds phased and fluctuated. They could also often run more accurate filter algorithms. as DSP chips are very efficient at that type of processing.

Today, with home computers being as powerful as they are, these differences are negligible. In fact, some soft synths now offer control rates at double sample rate, so any perceived audio characteristics from hardware VAs are likely to be down to the digital-to-analog converters they use and the characteristics programmed into the software they run. There are very few things that can't be done natively (without the involvement of dedicated hardware DSP) to a very high standard these days. Go with the flow Your decision to use a piece of hardware will often come down to how it affects your workflow. For some. having a hands-on synthesizer to program sounds. write melodies and improvise on is a source of inspiration and a way to break up the writing process. For others, having to switch between a computer and a hardware synth is just a huge inconvenience.

Outboard effects processors should always be carefully weighed up in terms of workflow. While a high-quality compressor may provide a slightly superior sound, the trouble of recording things through it in an otherwise native setup may leave it gathering dust once the novelty has worn off.

Once you've grabbed that Moog Voyager or Prophet 08 off eBay at a bargain price, your first question may well be, "How do I connect it to my Mac or PC?"

To sequence and record a hardware synth with a computer, you need two things: the synth has to be told what notes to play by the computer, and the computer needs to be able to record the audio coming out of the synthesizer.

Most commonly, a computer tells a hardware synth what notes to play via a MIDI output port. This is a five·pin DIN socket featured on many audio interfaces. If yours doesn't have one. you'll need to buy an external MIDI interface, connected to your Mac or PC via USB. There'll be at least one MIDI In socket - into which you can plug a synthesizer or MIDI keyboard in order to input note or control data-and at least one MIDI Out socket, which enables the computer to tell the synthesizer what to do.

Once you've configured the MIDI interface in your DAW software. you should have the option to send MIDI tracks from it to your external MIDI hardware. A single MIDI input or output can send and receive note data over 16 MIDI channels.

Which MIDI channel your hardware synth responds to is usually configured on the synth itself. A multitimbral synth will respond to several MIDI channels simultaneously. If you want to use multiple MIDI synths, you can daisy·chain them together via their MIDI ports. The MIDI signal is sent into the MIDI In of the first synth, then out of the MIDI Thru and into the MIDI In of the second synth. and so on. Or you can use a MIDI Thru box, which gives you a number of MIDI Out ports, all carrying the same signal. Alternatively, your MIDI interface may have more than one MIDI Out port, which will increase the number of MIDI channels you have available.

If the hardware synth you're connecting sends and receives MIDI controller data (CC), you may want to record knob/fader/wheel changes along with your note data. To do this, you'll need to connect the MIDI Out of the synth to the MIDI In of your soundcard.

The next step is getting the audio from your external synthesizer back Into your computer and into your DAW software, where it can be mixed and processed. To do this, simply connect the audio outputs on your synth to the Inputs on your audio Interface.

For every external synth or synthesizer track you use in a recording, you'll typically need two channels in your DAW - a MIDI channel. which tells the synth what notes to play, and an audio channel, on which the audio generated by the synth Is fed back via your audio interface into your DAW environment.

The first problem you might notice is that this loop creates a delay between a note being triggered and the sound it generates making its way through the audio interface, with whatever latency its buffer incurs, into the DAW. This can be kept to a minimum by setting your interface's sample buffer as low as possible, but it can also be fine-tuned manually using your DAW's track delay/offset setting.

This parameter is usually set independently for each track In your project. Using it, you can shift the MIDI output of your synth track back in time by a few milliseconds, so that the audio returning from the synthesizer lands in your DAW at the exact time it's supposed to.

Working out how many milliseconds you should be compensating is done by ear. A good technique is to record a percussive sound from your external synth onto an audio track, edit the part so that it plays back tightly, and trigger it. looped. from your DAW on every downbeat Then. create a MIDI track to sequence the same sound from the synthesizer and feed it back into your DAW. Hard-pan one track left and the other right. The brain is good at identifying tiny delays In the stereo field, so when the tracks sound centered, they're in sync.

If you plan to record your external synths as audio clips fairly quickly (as opposed to keeping them "live" until final mixdown), this won't be such an issue, because audio can be easily edited and synced very precisely to the beat.

Another hardware integration issue might rear its head if your DAW doesn't offer real-time (on-line) rendering. If offline rendering is your only option, your final mix won't include the signals coming in from any external MIDI hardware. The most obvious way around this is to manually record your complete mix back onto a stereo audio track in real time, but that may not be hugely convenient.

A better solution is to record any external synth tracks and/or outboard processing into your DAW as audio, where it can then be manipulated and included in your offline render along with all your other audio and plug-ins. You might choose to do this right at the end of the recording process, so as to be able to edit your synth patch on a whim. or you may elect to record your synth lines as audio as soon as they're written. thereby freeing up the instrument to provide further parts if required.

Another consideration is the length of the recordings you plan to make. If a synth line simply repeats a short section throughout a track, you can take a short recording from it and loop it or copy and paste it where needed.

Producer Joel Zimmerman, AKA Deadmau5, uses plenty of hardware synth lines in his tracks, usually with a high degree of dynamics manipulation. tweaking the filter or envelope settings on his synth parts, live, to create epic builds and drops. As such, we would imagine he records his synth parts as audio, one by one. for the full duration of each track, in order to gain complete hands-on control of how each part evolves throughout the mix.

There may be situations, however. in which offline rendering of your finished track might not be the best solution. For example, if you've bought an outboard compressor, enhancer or EQ to run your mixes through, you'd need to send the audio from your Mac or PC into said outboard, then feed it back into your computer to record your final, processed mix onto a spare stereo audio track. This track will need to be muted or sent straight to your main stereo outputs- avoiding the master buss -to avoid creating a feedback loop.

Outboard effects can also be set up to work on send/return loops. For example, a hardware reverb unit could be connected to the stereo inputs and outputs of your audio interface. and the signal from an auxiliary channel in your DAW fed to it. The returning signal from the reverb is then fed back into a spare audio channel in your DAW. with monitoring activated.

If you start building up a collection of multiple hardware synthesizers and outboard processors, you may end up needing quite a few audio inputs and outputs. An interface with eight analog inputs and eight analog outputs is a good choice for the primarily software-based studio, where you need the flexibility to work with a few pieces of hardware from time to time. However, if it suits your workflow. you could also stick with an audio interface with less ins and outs. recording your hardware instruments and outboard gear, one by one, as you go.

Tube/valve gear is typically the most sought after when working in an otherwise entirely software environment, primarily for the natural harmonic distortion - sometimes referred to as 'warmth' or "character" - that it can bring to a recording.

Common valve processors include EQs, compressors and preamps, which give you a simple channel through which you can run audio in order to achieve variable degrees of subtle soft clipping or distortion.

Valve gear ranges from the relatively affordable, such as the TL Audio Fatman - which gives you a preamp and compressor designed for warming up digital recordings - up to the very expensive, such as the Fairchild 670 compressor, which might set you back more than $20,000.

Empirical Labs' Distressor uses a combination of analog circuitry and digital processing to emulate a range of classic compressor and limiter behaviors, and has become very popular with recording engineers. While a unit like this would be overkill for most home studios- especially as you need to buy a pair to run them in stereo- being able to dial up the sound of a Urei 1176 limiter whenever you need it might be invaluable to a rock producer.

The effect of recording to analog tape is also sometimes desirable for adding warmth and a sense of physicality to an audio signal. While there are high· priced processors dedicated entirely to emulating this effect, you could always p ick up a second-hand reel-to-reel tape recorder instead. Two-track Revox and Tandberg tape recorders can often be found going cheaply on sites such as eBay, or in second-hand shops.

A basic audio interface will typically offer a pair of stereo analog inputs and outputs. Along with a MIDI Interface, this Is enough to work with a single hardware synth. or two hardware synths each providing monophonic signals-one fed into the left input and the other fed into the right.

When working with multiple external synthesizers, or multitimbral synths that provide multiple analog outputs for separate mixing, your requirement for audio inputs goes up. A soundcard with eight analog inputs will enable you to connect four stereo synth channels to your computer, or eight mono channels, or a combination of the two. Another option when using multiple synths or synth outputs is to buy a small mixer, mix the lot all down to a stereo pair and route that back into a stereo input pair on your audio interface.

When working with an outboard effects processor, in addition to your main stereo monitoring outputs, you'll need extra outputs to route signals out of your computer and into your effects processor. This means you'll need an interface with at least four outputs. And, of course, you'll also need at least one pair of inputs to get the outboard signal back into your computer.

Aside from the number of inputs and outputs an audio Interface provides, the quality of its digital-to-analog and analog-to-digital converters will be an important consideration. Good-quality converters typically have a steady digital clock and a natural-sounding roll-off in the high frequencies. This enables them to accurately capture the detail and character that you'll want to preserve from your hardware, as well as sending a high-quality signal to your monitors and whatever outboard processing you may want to use.

Some outboard effects and audio interfaces offer digital inputs and outputs. This avoids having to convert the signal from digital to analog and back as it leaves and re-enters the computer, which can potentially degrade the audio quality. Bear in mind, however. that in some cases. the sound of a hardware unit's converters is actually considered part of its character.