There are plenty of cassette multi-trackers on the market offering a wide range of facilities. Paul White examines the one that's right for your needs and budget.

THE INVENTION OF the Portastudio brought multitrack recording into the reach of virtually every musician - before that, recording was a rich man's game and it could get very very complicated. Now the market is full of cassette four-track systems and without a little knowledge to guide you, it's very easy to pick the wrong one. So before we look at the machines, let's take a look at you - why do you want to buy one?

There are really three types of Portastudio user: there's the musician who wants a musical notepad on which to try ideas which can then be presented to the rest of the band at rehearsals - then there's the serious hopeful who wants to make demos to attract the attention of the various record companies. And then there's the optimist who thinks he can make releasable, pro quality recordings on one. The latter character is hoping for a bit much, but with the aid of a few sequencer driven MIDI bits and pieces synced to tape, it's just about possible.

The musical notepad application is a very valid one and even people with sophisticated home studios often have a simple Portastudio kicking about so they can get their ideas down while they're still fresh. With the aid of a drum machine and a cheap synth, one person can overdub all the parts of a complete song, and though the sound quality on a cheaper machine won't be all that impressive, it will be good enough to give the rest of your band an idea of what your new song is all about.

In this notepad application, there's no real point in going over the top and buying a really fancy machine. If all you want is a general idea, then you don't need to spend unnecessary money on superlative sound quality, or superfluous facilities. But, if you want to make serious demos, then you'll need to go for the best sound quality you can afford and you'll need to be able to patch in effects to make your recording sound as professional as possible. You may even want to sync up a sequencer system so you can have MIDI instruments playing along side the real instruments and voices on tape. Because of these differing requirements, it's probably best to take a look at the popular options available and see how they affect your recordings.

SOUND QUALITY

PROFESSIONAL TAPE MACHINES sound good because they use wide tape travelling at relatively high speeds. The more tape passes over the head every second, the higher the theoretical sound quality you can achieve. With a standard cassette, not only is the tape speed very much slower than on a studio machine, but the tape width is much narrower too. And with a four-track machine, only a quarter of the tape width is available for each track. At the normal cassette speed of 1⅞ips, the sound quality is seriously compromised by hiss unless some form of noise reduction is used.

Most hi-fi recorders have a Dolby facility (usually Dolby B or C) to improve the hiss situation but many people fail to understand what the noise reduction is doing. All such tape noise reduction systems are encode/decode systems, or to put it simply, something is done to the signal during recording which must be undone during playback if the original signal is to be restored. If a tape is recorded using Dolby, then it should be played back using Dolby.

Noise is only noticeable when the music isn't loud enough to hide it - and that simple fact forms the basis for all tape noise reduction systems. What most of them do is to record the vulnerable low level sounds at a higher level than they would normally be so that they are recorded well above the level of the tape hiss. On replay, the levels are automatically restored by the decode half of the noise reduction circuitry and this not only makes the music the right level again (by turning down the bits that were recorded too loud), it also turns down the level of the tape noise accompanying it at the same time. In other words, we end up right back where we started but with less tape hiss. Dolby B and C work only on low level, high frequency sounds while the other popular system used in Portastudios, dbx, acts at all signal levels. It works by compressing the whole signal on record and by uncompressing or expanding it on replay. The reduction in noise is dramatic, but there are side effects caused by differences in the encode and decode circuits and by imperfections in the tape characteristics that can change the tone of percussive sounds and make bright sounds seem less clear. All noise reduction systems have some side effects, but when you're using cassette systems these slight tonal changes are far preferable to an annoyingly high level of background hiss. Dolby C noise reduction probably gives the best subjective result on cassette tape - dbx works very well on some models and relatively badly on others. The only way you can tell is to record a bit of drum machine and see if it comes back sounding more or less the same.

If you want to sync up a sequencer, you'll need to record a sync code from the sequencer or synchroniser to tape and these codes are often made unreliable by dbx noise reduction. For this reason, most modern multitrack machines let you turn off the noise reduction on track four to ensure reliable code operation. Dolby C machines also tend to offer this facility, though Dolby C doesn't seem to upset codes in the same way as dbx.

Because of the technicalities involved in providing multitrack facilities on a narrow format tape like cassette, the frequency performance of a standard speed system is unlikely to exceed 10 or 11 kHz. Human hearing extends right up to 20kHz or so (if you're lucky) and so a recording made on such a machine will sound slightly dull. One way around this problem is to double the tape speed to 3¾ips. Now the frequency response can extend up to 16kHz or even more and as a bonus, the tape hiss is noticeably less. The only disadvantage is that your cassette doesn't last as long. Because all four tracks are recorded in the same direction, you can't turn the tape over to play the 'other side' so a C60 only lasts 30 minutes, even at normal speed. At double speed, this is reduced to 15 minutes. Nevertheless, for serious work, a double speed machine is a great advantage.

FACILITIES

HAVING SEEN WHAT affects the raw sound quality of a multitrack recorder, what facilities are necessary to make a good recording? At the bottom end of the scale, you'll get a standard speed machine that allows you to record on only two tracks at a time. This is fine if you intend to build up your recording in layers, a track at a time, but it won't allow you to use all four tracks at once to record a live session. The chances are that this level of machine will only allow you to use EQ in a very limited way: you probably have a pair of treble and bass controls that can be used to affect the sound as you record it and again to alter the tonality of the overall stereo mix when you come to combine your four tracks into stereo. You are unlikely to get the facility to add effects as you mix at this level so all your effects will have to be recorded to tape as you put the tracks down. This isn't a problem, but it does mean that you're committed to the type and amount of effect from the word go - you can't change your mind during the mix. Perhaps the most popular machine falling into this category is the Fostex X15.

The next step up the ladder is a similar machine which incorporates EQ in each of its four mixer channels and also has 'effects send' facilities allowing you to add at least one effect as you mix. Tascam's Porta 05 falls into this bracket and has a surprising number of features given its budget price.

For the serious demo user, a double speed machine might be the next logical step incorporating all the other features so far mentioned. Simultaneous four-channel record is normally available on machines of this calibre and all four mixer channels can be used during recording to mix several instruments onto one tape track. Again, this might be useful if you're a sequencer user. However, sequencers always need more mixer channels than self contained Portastudios provide, so you may benefit from one of the more sophisticated machines with six mixer channels or, alternatively, buy a separate mixer which will enable you to combine the output from your Portastudio with all your synths and drum machines when you come to mix. Figure 1 shows how this might be wired up along with a budget reverb unit.

ADDITIONAL FACILITIES

STUDIO MIXING CONSOLES usually have what are known as insert points, a pair of sockets on each channel that allow effects or processors to be patched in during a mix. These differ from the effects send connections, in that insert points can only be used to connect an effect to one channel at a time. This is useful if you need to compress the vocals a little as you mix or if you want to add echo only to the lead guitar. Any type of effect can be used via an insert point but only reverbs, delays, echoes, pitch shifters and chorus/flangers can be used in the effects send circuit. If you're in any doubt, the devices with a mix control on the front panel can be used in the effects send circuit - if they don't have one, then they can probably be used only on the inserts. If you need more details on this, see our article on mixing consoles in May '89.

Other useful features include direct outputs which can be used to feed the outputs from the four tape tracks to an external mixer where there may be more facilities for adding effects or equalisation.

FINER POINTS

THAT JUST ABOUT wraps up the important differences between models but there are a few other things to keep in mind. One is the choice of mains or battery operation. Many models don't offer battery operation so you have to decide if you're likely to be doing any mobile recording where power may be unavailable. If not, then don't worry about battery use because cassette machines eat up batteries at a rate of knots anyway.

When it comes to metering, you get some models that use moving coil VU meters and others that use LED ladder affairs which usually monitor signal peaks. VU meters tend to average out the signal levels in much the same way as the human ear does, so they give you a good idea of the loudness of a sound - but it's all too easy to sneak a loud, short sound such as a drum beat past them without them registering its full level. This means that you could be running the recorder into distortion while the meters are happily telling you all is well. In practice you soon get used to this and back off the record level a bit when working with drums or other percussive sounds.

The peak reading LED meter, on the other hand, really does show up short peaks like drums and so you can more easily set up the correct recording level. However, it is best to let your ears be the final arbiters because you need to get all the level onto tape you can in order to keep the dreaded hiss to a minimum. If the meters are peaking well into the red but the sound is still OK, then by all means record it like that. The best bet is, whatever type of metering you have, do a few experiments with different sounds and see how loud you can record them before you can hear the distortion - the results might surprise you!

Do keep in mind that whatever system you choose, the end result can never be better than the cassette machine onto which you mix your stereo master. You need a proper hi-fi model with recording level controls and proper metering - music centres with automatic level controls are really no good at all. A suitable model can be picked up for around £100 so if you don't have something suitable, fit one into your budget somehow.

On a final note, serious home recording is arguably the most expensive indoor hobby you can indulge in, apart from collecting gold bars or rare stamps. The Portastudio could be just the thin end of the wedge and before long, you'll be reading Home and Studio Recording and drooling over equipment costing thousands. I started off some 15 years ago when I passed a second hand shop that had a second hand four-track open reel machine in the window. I bought it of course, and now, 15 years on, I have a home studio that has cost around twice what I originally paid for my house... Be warned!