Shift and Conquer; Compress and Sustain; Simple Midi Switch

SHIFT AND CONQUER

In this era of digital synths, elec-tronic tuners and drift-free digital tape machines, tuning problems have ceased to be a major issue -- until it comes to vocals. Though multitrack allows us to drop in new sections, there are occasions where the singer can't hit the note or where the performance on tape has the perfect feel, but where one note in the line may be a touch sharp or flat. It's at times like this that it can be worthwhile to try to salvage what exists rather than risk doing a retake and losing the feel.

One way of correcting the problem is to use a pitch shifter. While the pitch shifters included in typical budget multi-effects units sound disastrously unnatural when set up to shift the pitch by several semitones, most produce perfectly acceptable results when used to create shifts in the order of a few tens of cents. You can, occasionally, get away with setting up the shifter to compensate for the duff note and then using the bypass button to bring it in at the beginning of the note that needs fixing. However, that invites clicks or other glitches; a better way is to copy the entire phrase to a spare tape track, then feed this through the shifter, routing the shifted output so that it can be punched back onto the original vocal track. The skill comes in punching in and out at the right time so that the shifted note replaces the original duff one. In doing this, you need to be aware that many analogue machines leave a slight gap after the punch-out point, so timing is critical. Life is much easier if you have a tape machine that features an auto punch in/punch out facility with a rehearse mode, because then you can check and approve the manoeuvre before committing yourself. In this respect, digital multitracks such as ADAT have a distinct advantage, in that the punch-in and punch-out points never drift and there's no gap when you punch out. Even so, with a little care, you can do the same trick on a Portastudio and salvage what otherwise might be an unusable take. If you don't have a rehearse mode, make doubly sure that the level of the punch in matches that of the original track. If the unthinkable happens and you do mess it up, you do at least have the copied phrase intact so all isn't lost.

An alternative approach is to use a pitch shifter that can respond to real-time MIDI control. Simply pass the whole audio track through the shifter, set for zero shift, and then use a sequencer bend or mod wheel to control the pitch change. By recording the bend data into a sequencer, you can fine edit it until the offending word or phrase is perfectly in tune. If the pitch shifter compromises the sound quality in an unacceptable way, a combination of both methods should allow you to punch in just the word or phrase where the correction has been applied. Paul White

The diagram in Figure 1 shows a very basic, two-in, one-out MIDI switch box based around a two-pole, two-way toggle switch. However, multiple inputs can be accommodated just as easily by using a rotary, two-pole wafer switch. Wafer switches are available with various numbers of positions; I use a four-position switch in my own studio to give me four possible MIDI Ins. Such switches are readily available from the Maplin catalogue or from your local Tandy shop. Paul White