This new regular feature offers a feast of easily-digested recording tips and techniques designed to help you get the best results in your studio.

DIY Phase Reversal

How can I use your stereo enhancement tricks if my console isn't fitted with phase invert switches?

Following our article on stereo width expansion tricks in January this year, we've had several enquiries from readers who use mixers that aren't equipped with phase invert buttons. One way of getting a phase inverted input is to use the mic input: for normal phase, join the screen of your signal lead to pins 1 and 3 in the XLR plug and the centre conductor to pin 2. For phase inversion, join the screen to pins 1 and 2 and feed the centre core to pin 3.

An alternative is to build the simple circuit shown in Figure 1, which is based around a unity gain amplifier with phase reversal. The components are inexpensive and are readily available from outlets such as Tandy or from the Maplin catalogue. Because the circuit is so simple, no layout has been provided, but the easiest option is to build it on a piece of Veroboard. The completed circuit may be used in line with any line-level signal or connected via the channel insert point. Take care to mount the electrolytic capacitors the right way round and check the finished circuit for faults or shorts before you connect the batteries.

Graphic Equaliser

Where does the graphic equaliser get its name and do I need one?

The graphic equaliser can be recognised by the large number of faders on the front panel, the principle being that each fader controls the EQ cut and boost in one section of the audio band. The different bands are arranged to overlap so that when all the faders are set in a straight line, the overall frequency response is flat with no frequency being cut or boosted more than any other. The usual arrangement is to have a detented centre point on each fader which signifies no cut or boost; when the faders are moved up from this point, the signal is boosted in that particular section of the audio range, and when the fader is pulled down below the centre, the same range of frequencies is cut. The term 'Graphic Equaliser' comes about because if you look at the fader cap positions when the equaliser is set up, they give a graphic representation of the overall frequency response of the equaliser.

Graphic EQs are used quite extensively in live sound, where their ability to act on relatively narrow sections of the audio band makes them useful for tailoring a sound system to sound acceptable in a less than perfect venue. They are also used in stage foldback systems to allow any feedback-prone frequency ranges to be cut (see the Live Sound article in the March '93 issue of RM for more advice on how to do this).

In the studio, a graphic equaliser provides an easy way to modify the tone of an instrument or recorded sound without the complexity of something like a parametric equaliser. They are often used on bass guitars, where they can be used to create a whole range of different sounds, while some engineers use them to process a whole mix. In general, the more bands a graphic equaliser has, the more fine the degree of control it offers. The most bands you'd expect on a standard equaliser is 31, which means the whole audio spectrum is covered in one-third octave bands. This provides a very high degree of selectivity, with each individual band covering just four musical semitones.

At one time there was a trend for people to use graphic equalisers in an attempt to compensate for bad control room acoustics. It is now widely recognised that this type of problem cannot be solved correctly using equalisers, though it is acceptable to use equalisers to a limited degree to fine tune a monitoring system.

The Big Mix

Most of the sounds I use come directly from sequenced synths, and though my mixes sound OK, they don't have that 'certain something' you hear on records. What do I need to do?

Many of the professionals use the same synths as we use for home recording, but there are a few tricks you can use to create a bigger sound. One area in which professionals have an advantage is that they often have access to rather more esoteric equalisers than the rest of use, but by processing a mix through one of the psychoacoustic enhancers currently available, similar results can be achieved. Most enhancers only treat the top end of the audio spectrum but units such as the excellent SPL Vitalizer or the somewhat less costly Aphex Type C2 also provide control over the bass end, which can really help in this situation.

The effect of the high frequency enhancement is to improve the perceived separation between individual sounds — fine details are enhanced and the whole mix takes on extra clarity. By countering this effect with a little bass enhancement, a mix can be made both powerful and clear.

Another popular studio trick to add energy to a mix is to feed it through a stereo compressor. Different compressors have different tonal characters and certain engineers have their own favourites, but any good unit can be used. Soft-knee models produce the most natural effect on mixes and these should be set so as to achieve between 4 and 12 dB of compression on signal peaks. Dual channel compressors should always be set to Stereo link mode when processing stereo mixes.

Finally, if you have a mixer with sweep mid EQ controls, you can use these to tune into individual sounds in a mix, giving you the opportunity to pull the sound out of the mix for more impact. Even though instruments produce a whole spectrum of frequencies, by tuning through the range with your equaliser set to maximum boost, you'll come across a spot where most of the sound seems to be 'happening'. You can then back off the EQ boost until you have achieved the right effect or, if the sound is too dominant in the mix, apply a little cut at this frequency instead. By focusing in on each sound in this way, the EQ controls on the different mixer channels can be used to separate the individual sounds to a surprising extent, and though this isn't as accurate or honest as leaving the EQ flat, it is used more than you might imagine when mixing pop records. And the bottom line is — if it works, do it!

Faking The High Notes

Ever had the problem of the vocalist who can't hit that final high note?

One solution is to record all the parts of the song that the singer can manage, then use the varispeed to slow the tape down so that the elusive notes come down into the singer's range. Drop in the required note/s, switch the varispeed back to normal, and congratulate the singer on his/her wonderful performance. Remember, however, that this trick may produce a chipmunk-like effect if the note being sung carries words or if the degree of pitch shift is great — so use carefully. If you find that your singer still can't hit all the high notes in the song, tactfully suggest that the key is changed.

Cheap De-esser

I occasionally suffer from sibilance when recording vocals. How can I cure this without resorting to an expensive de-esser?

It is well known that a good capacitor or back electret microphone will produce a brighter, more airy vocal sound than a dynamic microphone, but they may also emphasise any sibilance present in the singer's performance. Sibilance is caused by air passing over the lips and between gaps in the teeth; this results in a high-pitched whistling on S and T sounds. To make things worse, this sound tends to encourage high frequency overload on tape, producing a noticeable, unpleasant form of distortion which makes the vocal appear even more sibilant. Cassette tapes are particularly susceptible to this problem.

The traditional solution to sibilance is a frequency-conscious compressor or dedicated de-esser, but here's a rather cheaper tip that might just do the trick. Simply take a pencil and position it vertically, right in front of the microphone grille and in line with the centre of the mic. With large-diameter microphones, the pencil can be held in place by means of a couple of elastic bands. By shadowing part of the diaphragm and disrupting any sibilant blasts of air, the effect of sibilance is reduced. Just how effective this technique is depends on the severity of the sibilance and the type of microphone used, but considering how simple it is, it's worth trying before you reach for the de-esser.

If you experience sibilance only when copying to cassette, try a few different brands of tape, because some are dramatically more prone to high frequency break-up than others. The tape that costs the most isn't necessarily the best in this respect.

Balancing Act

I often find that what I'm mixing seems fine while I'm actually doing the mix, but when I play it back later, I find that something is either too loud or too quiet. What am I doing wrong?

Recording and mixing can be quite stressful, and it is certainly fatiguing as far as the human hearing system is concerned. The result is that you can't trust your ears and any mix you do is likely to sound different in the cold light of day. If you can, mix your material on a different day to the recording, so that you can approach it with fresh ears. It also helps to play a few commercial records over your monitor system so you can get a better sense of perspective before you start.

One tip I stumbled across which has never let me down is to listen from the next room (with the adjoining door open) as the mix is playing through. For some reason, which may have to do with the fact that you're hearing reflected rather than direct sound, anything that is even slightly out of balance becomes obvious straight away. And yet you can be sitting right in front of the speakers and not notice it. Since discovering this, it has come to light that many professional engineers and producers do exactly the same, so there must be something in it! So, next time you think you've set up a perfect mix, stand outside the studio door and see if the balance still sounds right. Working in this way also seems to help ensure the mix sounds right on other speakers and not just the ones it was engineered on.