Modern tape recorders, both cassette and open‑reel, are capable of giving years of service — but they can also deteriorate very quickly if not properly cared for. Paul White explains the essentials of cleaning and demagnetising.
Tape machine cleaning is something we all know we should do, but how many of us do it on a regular basis and — more importantly — who really believes that it makes that much difference? From experience, I can confirm that it really can make an enormous difference, especially if the machine in question hasn't been cleaned for some time; even after a few hours of use, the performance of a tape machine will deteriorate unless the heads are cleaned.
The cause of the problem is a build‑up of brown oxide from the surface of tapes previously played on the machine.The presence of this oxide prevents good tape‑to‑head contact, the result being a loss of brightness and, occasionally, drop‑outs where the recorded level dips noticeably.
Rather than waste money on a tape cleaning kit, it is far more cost‑effective to buy a bottle of isopropyl alcohol from your local chemist and apply it with ordinary cotton buds — though you can also get very useful, long‑handled cotton buds for around £2‑3 per 100 from Tandy and Studiospares, which can make cleaning a little easier. The procedure is as follows:
- In the case of a cassette deck, open the cassette door and, if possible, remove it for better access. Most open reel decks provide good access to the heads, though some have a lift‑up cover to make this even easier.
- Soak a fresh cotton bud in the alcohol and wipe away all traces of dirt from the tape heads and the metal tape guides. You may need to rub quite hard if the machine hasn't been cleaned for some time, but this won't do any damage. You will see the old tape oxide coming off as a brown discoloration on the cotton bud; if necessary, use a fresh cotton bud to ensure that all the oxide has been removed.
- Don't use the isopropyl alcohol to clean the rubber pinch roller — this is best cleaned using a cotton bud dipped in a solution of washing‑up liquid in water.
- Dry all the cleaned parts with a fresh cotton bud and then leave the machine to dry out for a further two minutes before putting in a new tape.
- Repeat the cleaning process at least every week and, ideally, before each important recording.
Demagnetising
After a long period of use, the metal parts of a tape deck can become magnetically charged. If the level of charge is too high, new recordings will be compromised and existing tapes may actually become permanently degraded if they are played back on a charged machine. Because the build‑up of magnetism is slow, it isn't easy to tell when the machine needs demagnetising, so the best approach is to treat it as a routine job and do it every month.
Cassette decks are best dealt with using automatic demagnetisers — small electronic devices built into cassette shells. These are available from most hi‑fi stores and are quite automatic to use, the whole process taking only a few minutes.
Open reel decks need to be treated with a hand‑held demagnetiser, and it's best to buy a decent one, which might cost you around £20 — the very small ones lack the power to do a good job. It is important that the manufacturer's instructions are followed carefully, as inappropriate use of a demagnetiser can actually increase the magnetic charge rather than reduce it.
The usual technique is to switch the demagnetiser on a few feet from the tape machine and then bring it slowly towards the heads. The device is passed slowly over the heads and tape guides, usually as close as possible without touching, and then moved slowly away from the tape machine again before being switched off. Under no circumstances switch the demagnetiser on or off when it is close to the tape heads, as this can create a high level of magnetic charge on the heads which no amount of demagnetising will remove.
Whether your machine is cassette or open reel, it is vitally important that it is switched off before attempting to demagnetise it, otherwise there's a chance of damaging the circuitry — and your monitor speakers. As far as the tape machine is concerned, the magnetic field from a demagnetiser is just a 50Hz signal at about +1000 VU recording level!