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Looping the Tape

Simon Croft gets into tape loops and comes up with some interesting conclusions.

Simon Croft explains how to make an expensive sampler with two beer bottles and some sticky back plastic...

Necessity is the mother of invention, or so they say, and my particular necessity was for a 2-second sampler. This lead to experimentation with a tape loop. One of these can be made for virtually nothing by anyone with an open reel recorder and some basic splicing gear. With practice, they can yield results that normally involve a grand's worth of hardware.

I've discovered four main uses for tape loops:

1. Creating an 'atmosphere' track, such as thunder effects for the intro of a song.

2. Making a drum loop that can form the backing for a song.

3. Assembling an entire backing track from one bar of each section of the song.

4. Spinning-in looped sections, such as a bass line, onto a song on multitrack.

As each stage is slightly harder than the last, you may care to treat each section as an exercise in itself.

Atmosphere Tracks

Let's start with a basic tape loop. If a continuous sound is used, such as rainfall or applause, the precise edit point on the tape will not be too critical. Applause can be found on almost any live album, but the sections used are normally fairly short. By looping, applause may grace your own multitrack production, without the need to constantly re-cue the record.

First, record about 30 inches of tape. At 15ips this equates to two seconds playing time. Try to choose a section with a constant dynamic level, otherwise the splice point will be heard on the loop.

Find the suitable start and end points for the loop, and mark these with a chinagraph pencil over the play head of the tape machine (see Figure 1). Use the Edit mode, if your machine has one, and spool the tape by hand. Otherwise, you can mark the tape while it is running by dabbing the chinagraph at the appropriate point. A sharp chinagraph and a very quick dab will produce a distinct mark without stretching the tape.

Now cut the start and end points, using a blade and the 60 or 45 degree slot on an editing block. Join the two ends together with about ½" of splicing tape, (making sure not to put a twist in the loop).

Any open reel recorder will play a loop because the tape is driven by the capstan and pinch roller; the reel motors are only used to maintain tape tension in the play mode. However, you'll need two extra tape guides. These will take up the slack on the loop and keep it out of the way of the machine spools. (Take the tape reels off the machine as they spin round quite fast when the machine is switched to play, with no back tension.)

There are two easy ways to improvise the tape guides. Which works best for you depends on the size of the recorder and the loops. For short loops, attach a couple of the sucker-arrows from a cowboy and indian set (or similar), to the front of the machine (see Figure 2). I found longer loops were best kept in place with a couple of 2½ litre plastic beer bottles. As these will doubtless be empty, fill them with water to make them stable!

Lay the tape machine flat on a table and position the bottles either side. You can align the tape path with the narrow neck of the bottles by raising the machine on books (see Figure 3). Now the loop may be played. If the machine will not go into play, you have either neglected to run the tape round the right-hand tension arm, or there is not enough tension on the loop. The tension arm is fitted with a switch, so the machine knows when the tape is wound off.

If the recorder has off-tape monitor, you can also use your creation as a giant Copicat echo. Feed a signal into the input, put the machine in record and monitor off-tape.

Drum Loops

A short section of percussion (perhaps stolen from a 12" mix) can be looped to make a drum machine. Otherwise, play an original drum part. Even mundane objects like plastic bins can make useful drum sounds. A modern snare sound can be created by spraying tin foil with one of those plastic garden sprays. (Put a polythene bag over the mic though.) More surreal effects could include door slams or splashing water. These can either be recorded direct onto the stereo machine or built up on multitrack and transferred.

Editing is critical, as it will affect the timing of the track. Try to position your splice points at the start of a recognisable sound, such as the bass drum. For this reason, it's advisable to record slightly more than needed, ie. three bars when only two are to be looped. This will give you the first beat of the next bar on which to edit. Once your loop is finished, record it onto multitrack as backing or just use it as an accompaniment to practice.

Assembling a Backing Track

Figure 1. Mark the tape over the play head with a Chinagraph pencil.
Figure 2. Rubber section arrows can be used as / tape guides
Figure 3. Large beer bottles can be used for bigger loops. Prop the tape machine with books to get the right height.
Figure 4. Assembling a backing track from a series of loops.
4a. Write your song out in bar blocks.
4b. Record a few bars of each section on to multitrack.
4c. Dub each section on to a stereo machine and turn them into loops.
4d. Dub the loops on to the multitrack, in the order set out on your song sheet
4e. Edit out unwanted gaps and part bars on the multitrack
Figure 5. Marking the tape so the loop has the correct start point.
(Click image for higher resolution version)

While making a drum loop, you could have included other instruments, such as a bass line. This might be satisfactory for practising, but there aren't many songs you can write around a 2-bar bass riff (sorry New Age fans). So we need a way of combining several loops, one for each section of the song. Before we talk about how it's done, let's look at this method's advantages.

Suppose you've got a song with some really tricky bass riffs. You can play each one but you can't keep it up for the whole song. (As a guitarist, I get this problem with funky bass guitar lines; the mind is willing but the fingers get cramp.) If the song could be assembled from one example of each riff, the finished result would be miraculously constant. This is possible on a sampler, but long sample times aren't cheap.

The technique below is only possible on open reel multitrack machines. If you have a cassette multitracker, try the fourth technique.

First, work out the number of bars each section contains and record one bar of each section. (It helps if there's a gap between each section.) They can be as full or as sparse as you want, but bear in mind that they're going to be bounced onto the stereo machine. It won't be possible to remove things like keyboard pads once looped.

Once every section is recorded to your satisfaction, make the loops up. Transfer the material on multitrack to the stereo machine and start editing. When transferring, make sure the levels remain the same. Otherwise there will be tell-tale differences between one section and another.

Each loop must be perfectly edited so that it keeps time. If you screw one up, don't bother re-splicing, transfer from multitrack and start again. Hang each loop up individually. Those plastic clothes hangers with the notches for shoulder straps are ideal. Stick a label on each hanger to identify the loop.

Now to reassemble this master-piece on the multitrack. (Keep the original sections just in case.) Place the first loop on the stereo machine with the splice over the play head. Record your first loop onto the multitrack, counting the bars as you go. Record one more beat than needed at the end; this will act as your guide when editing. Repeating this process with all the other sections will give a multitrack tape with all sections in sequence. In between will be half-bars and gaps you don't need. Guess how we're going to get rid of those.

To edit the multitrack tape, you will need an editing block and splicing tape of the appropriate width. Tascam 34 and Fostex A8 owners have got it easy but machines like an E16 need a ½ inch block.

Editing will be easier than it sounds for three reasons; the material is in the correct order, so you can edit as you go, if you have recorded your loops properly there will be one extra beat to remove at the end of each section and a readily indentifiable start to the next section, and having filled two tracks at the most, you'll be dubbing other parts over the joins.

Figure 4 describes the whole process diagramatically. The example used is two verses of 12-bar blues.

Spinning in Looped Sections

There are instances where it's not possible to edit the multitrack. However, cassette multitrack units do not lend themselves to editing. It may be that you also want to improve a track on a song that is otherwise finished. In such a case, it is possible to spin-in a looped section.

Normal spin-ins are used when, for instance, the vocal is noticeably better on one chorus. This vocal part is recorded onto the stereo machine and then transferred onto every chorus of the song. How, though, are the two machines kept in sync?

The tape on the stereo machine is marked at the record head. When the part on multitrack is transferred, the stereo machine is started exactly one bar early. This gives the stereo machine time to reach full speed. The stereo tape is then rewound and the tape mark placed over the play head. On the first spin-in, the stereo machine is again started exactly one bar early. As the stereo machine will take exactly the same time as before to reach full speed, there is a very good chance that the two machines will be in sync and will certainly stay this way for the length of chorus.

Spinning-in from a tape loop is an ideal way of correcting a badly played instrumental part because many successive bars can be corrected in one go. This is how it's done.

Listen to the song, paying particular attention to the track requiring correction. Make a note of the places in which the part is played correctly, even if it's only one riff. Next, set up the stereo machine so that you can transfer each section needed. As with a normal spin-in, mark the stereo tape over the record head and start the stereo machine one bar ahead of the section you want.

Rewind the stereo machine and locate the actual start of the riff. Mark it with the chinagraph. Locate the end of the riff and mark the beginning of the next bar. You should now have a tape with three marks: the 'start point for play', the 'start of the loop' and the 'end of the loop'. But if you cut the loop to size aren't you going to lose the 'start point for play'? Yes, so this is what you do.

Cut the tape at the 'start point for play' (first mark) and the 'end of loop' (last mark). Lay the tape out on a non magnetic rule, such as a wooden yardstick. Measure the distance between the 'start point for play' and the 'start of loop' mark and write it down. Go to the end of the loop, measure the distance and mark it with a chinagraph. You can now cut the 'start of loop' point, knowing that the correct play point will be marked on the loop. Confused? See Figure 5.

Put your loop on the stereo machine and check that it plays in time. If all is well, stop the machine and set the start mark over the play head. Set the multitrack in motion and start the stereo machine exactly one bar ahead of the spin-in point. At the correct moment, put the relevant track into record for as many bars as you wish to transfer.

There are a few points to bear in mind. Firstly, the looping technique will only work for successive, incidental bars. When the riff or key changes, another loop will be needed to repair that section. If you know you're going to need several loops, transfer all the parts to the stereo machine and then make up the loops. That way the level will remain more even from section to section.

The loop drifts out of time over several bars. This will certainly happen if the loop is not exactly the right length. Depending on how bad the problem is, either make up a fresh loop or drop in the successive section a few bars at a time.

For non-destructive experimentation, it is obviously best to put your repaired part onto a spare track. Otherwise you will have to drop in on the original track. If you're going to do this, I suggest you practice the technique on a tape that is not important!

Being Creative

Don't worry if the results are less than 100% first time, just keep practising. Care in the preparation stage (marking and editing the tape) is the most important point. Once you can apply your newfound technique with confidence, here are a couple of creative ideas.

How about creating an 'a cappella' intro to the song by looping a vocal line from the chorus? Or spin-in a backwards loop of the hi-hat for a touch of psychedelia? Or create an extended mix by dubbing a loop of the bass and drums onto a fresh multitrack tape and experiment with looping other parts of the mix on top. Then edit this into the rest of the song on mixdown.

These ideas aren't crazy, just a little loopy!

Previous Article in this issue

Simmons SPM8:2

Next article in this issue

A Bit on the Side

Home & Studio Recording - Copyright: Music Maker Publications (UK), Future Publishing.


Home & Studio Recording - May 1987

Donated by: Rob Hodder

Feature by Simon Croft

Previous article in this issue:

> Simmons SPM8:2

Next article in this issue:

> A Bit on the Side

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