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Hard Disk Recording Tricks

Craig Anderton passes on some time-saving tricks and short cuts for users of Digidesign's Sound Tools and similar hard disk recording and editing systems.

Hard disk recording is great: you can manipulate audio with the same kind of finesse as MIDI data. You can copy good notes and paste them over bad notes, adjust note attacks to fall into a particular rhythmic pocket, and even do quantisation and special effects.

If you're just getting into hard disk recording, the following tips should help you scale the learning curve a little quicker. They're oriented to the Digidesign Sound Tools system because of its pervasiveness, but are applicable to other systems too.

Before continuing, it's crucial to understand the concept of a playlist. Unlike tape, which is linear, hard disks allow random access. For example, Sound Tools can trigger audio segments of any length from hard disk, at the SMPTE times of your choice. Because of random access, you can play segments in any order; the first verse could follow the third verse if you wanted. The playlist is a set of directions for Sound Tools that describes which segments of audio to play, and their SMPTE start times. If Sound Tools is sync'ed to SMPTE along with a sequencer or tape recorder, the playlist makes it easy to fly in chunks of digital audio as needed.


I use Sound Tools not just as a high-fidelity recording medium, but because of its audio processing power (digital compression and EQ, for example). Unfortunately, it's a two-channel system (the multitrack Pro Tools costs considerably more), and I often want to digitally record and process several tracks of acoustic sounds. Bouncing Sound Tools parts over to multitrack tape is one solution.

First record a guide track on the tape, if needed. (Since I generally use at least some sequenced MIDI tracks sync'ed to tape, recording a rough mix of the sequence usually serves as the guide.) Record a part into Sound Tools while listening to the guide track, edit the part, then on playback set a SMPTE start time for the part (or assemble a longer playlist from multiple takes) and roll tape. As the Sound Tools part plays back, record it on tape. If it's not quite in sync, set a new start point and try again until everything works together.

Record the next part into Sound Tools, process it, bounce that over to tape, record the next part, and so on. Bouncing to digital tape gives the least degradation, but bouncing to analogue lets you apply tape saturation to digital recordings — often a pleasant addition. (If you have limited hard disk capacity, use DAT I/O to back up parts to DAT before erasing the hard disk to make way for new parts.)


DATs are great, but if you don't have a second DAT, how do you make a digital copy of a DAT tape? Simple: Use DAT I/O to transfer the DAT contents to Sound Tools (your DAT must have digital outs, of course). Load in a new DAT tape, then transfer the Sound Tools data over to the copy tape.

If your DAT doesn't have digital outputs, don't worry — playing the DAT into Sound Tools through the analogue inputs, then bouncing back to a second DAT tape from Sound Tools' analogue outputs is still going to sound pretty good.


When sync'ing both a sequencer and Sound Tools to SMPTE and creating playlists from chunks of audio on various parts of the hard disk, it's not easy to find a SMPTE start point that triggers the audio chunk at the exact right instant. Trial and error will do the job eventually, but here's an easier way if you're recording mono parts into Sound Tools.

Program a click track into the sequencer, and have it trigger a fast-attack sound like a clave. As you listen to the sequence and record your part into one track of Sound Tools, record the clave sound into the other track. Figure 1 shows what the tracks look like; the click is on the bottom.

Figure 1: Easy playlist sync with Sound Tools

When assembling the playlist, monitor the click coming from Sound Tools and the one triggered by the sequencer, then adjust the playlist segment start fime so that the clicks coincide. To hear large differences, it helps to pan the clicks to opposite channels; when the timing gets tighter, pan the clicks to center so that they flange if they're off. After creating a playlist, mute (or erase) the click track.

If both the sequencer and Sound Tools share the same computer, this technique can still work if you have a tape recorder striped with SMPTE.

Sync the sequencer to tape, and record the MIDI instruments and the click on separate tape tracks.

Monitor the tape; record your part into one Sound Tools track, and the taped click into the other track.

On playback, trigger Sound Tools from the tape's SMPTE, and compare the Sound Tools click track along with the taped click track.

Adjust the playlist start time so the clicks coincide. If necessary, fine-tune the delay by entering a SMPTE Offset to compensate for delays caused by the SMPTE-to-MIDI converter.

When it's time to mix, use the instrument tracks recorded on tape, and the audio from Sound Tools. Or record the Sound Tools output into one of the tape tracks, then treat the sequenced instruments as virtual tracks to be mixed along with the tape tracks.

If you have a hard time hearing which track is ahead or behind, the Russian Dragon (from Jeanius Electronics, MCM (Contact Details)) can show the offset visually, making it easier to 'jog' the playlist start point to the proper SMPTE time.


One of the best MIDI sequencer features is loop recording, where you can repeat part of a sequence over and over again. As you record a solo, each pass of the loop puts the solo on a different track, so you can record several solos without stopping. When you have enough solos, you can then create an ideal composite track from the best bits of the individual solos. Wouldn't it be nice if you could do that with hard disk recording?

Here's how to do it. Suppose you have a MIDI sequencer and Sound Tools, each sync'ed to SMPTE time code, and now want to record a lead guitar into Sound Tools. Although many sequencers cannot do loop recording when sync'ed to SMPTE, there is a way around that limitation if you have a DAT recorder.

Loop the part of the MIDI sequence that plays behind the solo, and start playing the sequence. As your MIDI instruments play the sequence, record several passes of the looped passage onto DAT so you have a reference to play the solo against. There are two very important cautions: 1 - Sync the MIDI sequencer to the same SMPTE signal that will synchronize Sound Tools and the sequencer during the final mix. This will prevent timing errors later on. 2 - You can no longer change the sequence tempo during the part where you're playing the solo, so make sure it's right.

Set up to monitor from DAT (not the sequencer).

Put the DAT in play mode, and as you listen to it, start recording the solo into Sound Tools. The DAT will play the looped part, allowing you to record several overdubs into Sound Tools. Remember, you're only listening to DAT, not sending any of it into Sound Tools. Sync is not a problem if you record and play back on the same machine because the DAT speed should not drift to any significant degree (however, I have heard reports that all DATs are not created equal in this respect). If you're playing along with the DAT, your part will be in sync as long as you give it the right start time.

The result will be several solos on the hard disk, one right after the other. Put the DAT tape away, and sync the sequencer and Sound Tools up to SMPTE. You now have two main options:

Choose one take as the best take, then use the Trim command to define that take as a region and erase all other takes. Create a playlist that triggers this region at the appropriate time to be in sync with the sequence.

Create a playlist that plays different segments from different solos, thus forming a composite take. After creating the composite solo, you can save the playlist as its own sound file (assuming you have enough hard disk space). Keep that file, and erase the other versions to free up memory. This technique requires a fair amount of hard disk space if you want to do lots of consecutive takes. If you don't have a big hard disk, an option is to loop the MIDI sequence and play not into Sound Tools, but into DAT. This lets you record up to two hours (that should be enough!) of solos, vocals, or whatever in your quest for The Perfect Take. Once you've attained it, use the Sound Tools DAT I/O option to digitally transfer the good bits over to Sound Tools for further processing and/or playlist creation.


As budget digital multitracks start to appear, hard disk recording looks more — not less — attractive. You can use a basic hard disk system to do editing on one or two tracks at a time, but instead of storing the results on expensive hard disks, you can store them on inexpensive digital tape and clear out the hard disk for the next tracks (after backing up, of course). And once you've mixed everything down to DAT, you can shoot the master over to hard disk and do not only your own mastering, but CD prep. Pretty cool. Perhaps best of all, hard disk recording can be a creative tool as well as utilitarian one.


I often record vocals in mono, which leaves one channel of Sound Tools free for nifty effects. For echo, copy parts of the vocal and replace silence on the other track (this works faster than pasting, and doesn't alter the sound file length). These echoes can then be reversed, EQed, set to strange polyrhythms, have levels adjusted, and so on.

Vocal doubling is easy to do, but best of all, the effect doesn't have to be consistent throughout a piece. For example, the verse could have a different flavour of doubling (due to EQ changes or different amounts of delay, for example) compared to the chorus.


Destructive edits (cutting, for example) can take a while in Sound Tools because it has to rewrite the file to 'close up' around the cut section. (I used to complain about this until I saw how long it takes a Mac to process video files!) Fortunately, operations that don't change the overall file length work much faster. To cut a piece of data and move it somewhere else:

Copy (don't cut) the piece to be moved.

Click on the destination start point and select Replace. This overwrites any data that was where the new data falls.

Return to the original chunk of audio, select it, then choose the Silence command. This erases the data without changing the sound file length.

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Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - Aug 1993

Feature by Craig Anderton

Previous article in this issue:

> Microtech Gefell UM92S

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> Sound Bites

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