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Direct-To-Stereo Recording

Tips & Tricks By Paul White
Published June 1999

Direct-To-Stereo Recording

You don't necessarily need a multitrack recorder or audio sequencer to make a master‑quality recording. Paul White explains how good results can be produced using stereo recording techniques married with MIDI sequencing.

These days, albums can and often do take months to record — and as the makers of computer‑based recording systems add more and more features to the list they offer us, it becomes ever harder to actually get anything finished! Back in the '50s and '60s, by contrast, it was quite common to record and mix an album in just a few days. This wasn't because the engineers were more efficient than they are today: it was simply because they only had the tools to record the performance pretty much as it was. All the hard work lay in getting the bands rehearsed properly, and of course skilled session musicians were used for many backing tracks.

Today, anyone working on a budget can combine the traditional mic techniques used by those veteran engineers with the wonders of MIDI, to produce an instant master tape without the use of complicated multitrack software or hardware.

The MIDI Session Band

Figure 1: Typical setup for a live MIDI + Audio stereo recording.Figure 1: Typical setup for a live MIDI + Audio stereo recording.

If you're one of the many musicians out there using an Atari ST computer, or some other MIDI‑only sequencing system, it's a fairly straightforward matter to create your backing track using the MIDI sequencer, then add any live instrument or vocal parts at the same time as you record this to stereo. All you need is a small mixer with enough channels to handle your MIDI instruments plus the live vocal and instrumental parts — though for truly professional results you'll also need a compressor (to keep vocal levels even) and a reverb unit. Figure 1 shows a typical setup. Because you can work in this way using relatively basic equipment, you can hone your recording techniques while you're saving up enough money to go multitrack. Providing you're reasonably well rehearsed, you'll also be surprised at how good the results can be, and how quickly you can achieve them.

Mic Techniques

Figure 2: (Left) Coincident mic setup. Figure 3: (Right) Spaced mic setup.Figure 2: (Left) Coincident mic setup. Figure 3: (Right) Spaced mic setup.

The first thing I'm going to do is revisit some basic mic techniques which you'll need if you want to try combining direct‑to‑stereo recording with MIDI. These techniques have been covered in depth in SOS many times over the years (see 'Further Reading' box), but I'll run over the essentials here.

Depending on which instruments or voices you want to record live, and on how many mics and mixer channels you have available, you can choose to use either close miking or stereo miking techniques. The simplest way to make a stereo recording is to use two microphones and a pair of mic preamps to record a complete live performance directly onto a DAT machine or other high‑quality recorder. Though simple, this remains the most accurate way to record a live performance. Many of the better classical recordings are made using a single stereo pair of microphones, because the sound picked up is a good approximation of what a listener in the same position would hear.

This method isn't without its problems — the performers have to be able to play the song all the way through without making mistakes, and the balance between the instruments can't be changed retrospectively. Having said that, many pop records now considered classics were made with the backing band and singer performing at the same time, and what was lost in technical perfection was often more than compensated for in musical feel

Stereo Miking In Brief

Using a single stereo pair of mics is probably most effective when recording acoustic music, such as piano, acoustic guitar, choirs, small classical ensembles and folk bands. The most common stereo miking arrangement is the coincident pair, where two cardioid‑pattern microphones (see the 'Why Cardioid?' box) are mounted at around 90 degrees to each other, as shown in Figure 2 (see page 74). The output from the left‑hand mic is recorded onto the left‑hand track of a stereo recorder, and the right‑hand microphone onto the right‑hand track. Because the mics are placed very close to each other, there's no significant phase difference between the signals arriving at the two mics, so mono compatibility is good.

The so‑called spaced pair creates a more pronounced stereo image, because it does result in phase differences between the two signals. This can compromise mono compatibility — but hey, real life isn't mono‑compatible either, so why worry! The mics may be either cardioids or omnis, but in either case, good‑quality capacitor models are recommended. Figure 3 (see page 74) shows a typical mic arrangement. The actual distance between the mics and the sound source will depend on the contribution of room acoustics, but as a rule start with the mic distance being similar to the width of the sound source. The spacing between the mics should be around two‑thirds of the width of the sound source.

Honing The Sound

It's crucial, when recording direct to stereo master tape, to make sure all the voices and instruments sound right before you hit the Record button. You also need to keep an eye on those recording levels. You can't fix things in the mix, because this recording is your mix!

Classical acoustic instruments sound best when playing in an acoustically sympathetic room with all tuning and maintenance problems taken care of before the session starts, while pop sessions can usually be conducted quite successfully in a domestic room. When you're recording the acoustic guitar, it may be advantageous to place a sheet of hardboard or linoleum beneath the player to reflect back some of the sound that would normally be absorbed by the carpet.

Electric basses can be DI'd (Direct Injected) via a suitable DI box or bass recording preamp, though if there are no vocals or quiet acoustic instruments being recorded at the same time, you could mic the amplifier. The same is true of electric guitars, but now that there's a choice of really excellent‑sounding DI preamps it's often far more convenient to DI. If you're recording vocals or non DI'd instruments, all monitoring will need to be via headphones, but if you're simply adding DI guitar and bass parts to a MIDI backing track, you may get a better impression of the mix by listening over monitors. If you must record miked guitar amps and vocals at the same time, try to set the amps and their mics up in another room so that you don't get excessive spill from the amps into the vocal mics.

Balancing Act

When you're recording several acoustic musicians playing together using a single stereo pair of mics, the only way to modify the sound balance is to change the position of the musicians relative to the microphones. However, vocal recording is generally done using separate close mics for each performer (don't forget to use a pop shield), so you can adjust the balance on the mixer. Whether you're miking, DI'ing or using MIDI sound sources, remember to keep any bass or drum sounds near the centre of the mix.

When a singer/acoustic guitarist is being recorded using a single microphone, the balance between the voice and the guitar can be varied over a limited range by changing the height of the microphone so that it favours either the voice or the instrument, whichever is the quieter. Just avoid aiming the mic directly at the guitar's sound hole, as this can produce a boomy tone. After each mic‑position change, make a test recording to check the balance, then re‑adjust as necessary. To save time, wear headphones while adjusting the mics so you can monitor the results directly — closed phones work best for this.

You'll probably find that you have to do a few dummy runs to get the balance right, and you also need to ensure that you have just the right amount of reverb and/or effects on the various instruments and voices. Compressing the vocals as you record will help keep the level from wandering too much, but don't over‑compress, as you won't be able to remedy this after the recording is done.

Cheap & Cheerful

While this method of recording will obviously be of most interest to those who haven't yet built up a multitrack setup, it also has appeal for anyone who wants to produce spontaneous‑sounding tracks combining the best of both worlds — the sophisticated arrangement potential offered by MIDI sequencing and the unmistakable feel of live musicians — in the mininum of time. Any mistakes, of course, will mean starting the song all over again, but the simple, clean signal path you'll be using might actually result in better recording quality than you'd achieve by multitracking!

Why Cardioid?

Different types of microphone pick up sound in different ways. The most basic pickup pattern is omnidirectional, so called because it picks up sound equally from all angles — a property which may not be ideal for live stereo recording, where several instruments are playing close to each other. An omnidirectional mic may pick up sounds not intended for it in this situation. Cardioid (unidirectional) mics pick up sound more efficiently from one angle, making them more able to reject sounds that are 'off‑axis' — that is, away from the mic's most sensitive spot — and better for miking in small studios. Incidentally, cardioids acquired their name because the graph showing their sensitivity at different angles appears heart‑shaped.

Room Acoustics: Problems & Plus Points

In a live‑sounding room you'll need to get the performers closer to the mics to reduce the amount of reverberation, but if the ambience is working in your favour you can pull the mics back a bit and let the room have its say. Using the room acoustics to warm up an instrument works well with classical instruments, but for pop work a reasonably dead environment is easier to manage, as it leaves you with more scope for adding electronic effects. If, after finishing the recording, you come to the conclusion that everything sounds too dry, you can always consider the possibility of running the whole recording through a suitable reverb to supply the missing ambience.

When you're optimising the microphone positions for acoustic instruments, listen to the musicians rehearsing and move around the room to see if you can identify 'sweet' spots that sound better than elsewhere. Setting up mics in one of these sweet spots can produce noticeably improved results over just going by the book. This is especially true if you're using a stereo pair to capture an ensemble rather than miking each instrument separately.

If your song features electric guitars or basses being played along to a MIDI sequence coming from a computer sequencer, it may help to turn the computer monitor off, then use keyboard commands to start and stop the sequence. This way, you'll avoid unnecessary interference from the monitor.

Further Reading

As mentioned in the main text, miking techniques have been covered in more depth by SOS on various occasions. The February 1997 issue carried an article by Hugh Robjohns on stereo miking ('Stereo Lab'), and in the March 1996 issue the same subject was covered by Paul White's 'Live & Direct: First Steps In Direct‑To‑Stereo Recording'. There's detailed information on the miking of acoustic instruments in the September 1995 issue of SOS ('Miking The Take').

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