In a previous INSIGHT the principles of tape editing were introduced, along with a couple of suggested exercises to employ the new found skills. If the results sounded, or looked, as if they had been edited with a knife and fork, then read on as some of editing's finer points are revealed and examined.

It has been previously mentioned that a splicing block, cutter, tape and, in cases, a ruler are the only requirements for successful tape editing, but there are two other useful assets - dexterity and a suitable tape machine. Editing is possible on any tape machine; even though few amateur or semi-professional machines are ideally suited to the task their shortcomings are easily overcome. If a considerable amount of editing is anticipated it is worth either modifying an old machine for the purpose or, when buying a new one, looking for a machine incorporating the desirable features. The main plus points to look out for are the ease of access to the head, ease of threading, space on the right hand side of the tape deck, and large 10½" spools. Dealing with each point in turn:

Recorder Requirements

Ease of access to the playback head: most recorders employ pressure pads to maintain head/tape contact which usually makes access difficult. It is obviously desirable to be able to mark the edit point directly on the tape as the cutting point is aligned with the head. Because of pressure pads, direct marking in this way is not always possible, in which case, a fixed point further along the tape path is used as a reference. The splicing block also carries a reference mark which is an equal distance from the cutting point, thus when the tape mark is aligned with the reference point on the block, the cut occurs at the point which originally aligned with the head.

Ease of threading: if several tapes are used as sound sources, a speedy tape thread is essential, as it is when an edit point is returned to the head for checking - though it is best if the tape remains in the tape path.

Space on the right hand side of the deck: workspace in this position allows the permanent mounting of a splicing block. The marked tape is pulled past the headblock, the edit completed, checked, and the tape run on to the next edit without removing it from the tape path. If a machine has insufficient space on the deck plate it may be worth arranging an extension for the splicing block.

Large spools: the larger the spools, the easier it is to rock the tape back and forth past the head, though the rocking action can be achieved in other ways on some machines. In some cases, the tape may be powered past the head and drawn back by hand. To do this excess tape is drawn out on the feed spool side and held taut with the left hand, whilst the right hand is used to press the pinchwheel to the capstan. This method permits a very rapid location of an edit point but in other cases the tape may be passed around the back of the capstan thus removing the drive. Once play is selected, the tape machine's brakes are released and the tape may be rocked. This method's failing is the necessity to re-thread the tape in order to listen for the next edit point if it does not follow within a few seconds.

Editing Machine

The ideal solution is to have an editing machine. An old tape recorder could be modified by removing the head guards, pressure pads and any other non-essential (in this instance) components, which impede the editing process. Ageing domestic valve machines will probably cost nothing, whilst a suitable Brenell or Ferrograph machine in good working order could be bought for as little as £25.00.

The splicing equipment required has been mentioned in a previous issue (April 84), but it is worth repeating the main points. Use a good quality non-magnetic splicing block, use the correct adhesive tape and, if possible, a non-magnetic cutter.

Cutting Angle

The splicing block will have two cutting guides machined across it, one at right angles to the tape path, the other at 45° or 60° to it. Which to use? the answer is 45° for mono and 60° for stereo. Why this should be can best be understood by referring to the diagrams.

The time taken for a 45° stereo edit to pass the head is much longer than that for a 60° edit. So with a 45° stereo edit, the time delay between the arrival of the edit at one channel and then the other would be obvious. The 60° edit reduces this effect as does a higher tape speed. The higher tape speed not only improves quality of reproduction but also enables improved accuracy of editing to be achieved. If an edit is made in silence this of course does not apply.

In mono a 45° tape cut is normal as it provides a good mechanical joint which is less prone to peeling than a 90° cut. It also provides some degree of 'fade' up, without which any edited pure tone would 'click', though high tape speeds negate this.

If proof is required of the 'click' phenomena, listen to the Greenwich time signal tones on a good sound system. There is a distinct noise at the beginning of each tone. Anyone who has not noticed it before, will from now on! The 90° cut is usually reserved for removing clicks and other short duration noises for reasons which the third diagram makes clear.

In an ideal world all editing would just fall into place, but in a real world it occasionally falls on the floor (!) which causes a real problem because there is a fifty/fifty chance of splicing in the wrong way round. To prevent this happening is easy. When marking the tape for cutting, only mark the tape to half of its depth, this enables a quick and accurate visual identification of the upper track to be made in the event of a tape section being dropped. Finally, ensure that all the sections of splicing tape are smoothed down and free from bubbles.