Q&A: Answers to Tape Questions
Simple techniques and ideas that anyone can think of can greatly increase the pleasure of working with tape. Conversely, even a small doubt or hesitation often prevents its capabilities from being fully realized.
From questions sent in by people with such concerns, we have chosen those that are familiar and useful right now. Basic questions, techniques, troubleshooting and maintenance are all practical subjects. We have also supplemented topics that could not be fully covered in the main text. Use this section together with the “Glossary of Terms” at the end of the book.
How Long Do Heads Last?
It depends on the head material and the conditions in which the deck is used, but they last surprisingly long. Ferrite and sendust heads in particular, as well as the increasingly popular amorphous heads, are highly resistant to wear, so wear can practically be disregarded. Among them, the SONY S&F (Sendust & Ferrite) head is distinguished by high wear resistance, high saturation flux density and the ability to bring out the full performance of metal tape. If your deck has heads of this type, it is enough to ask the technician to check them when you take the deck or recorder in for servicing every one or two years.
Permalloy and hard permalloy heads wear more easily by comparison, so they should be checked from time to time.
Even if a head is slightly worn, recording generally does not change seriously, but on playback the high frequencies deteriorate and the sound loses clarity, so pay particular attention during playback. Compare the sound with a prerecorded music cassette on which the high frequencies are recorded clearly; this can help you decide whether the head needs replacing.
Deck Manuals Often Say C-120 Is Not Recommended. Is It a Special Tape?
The tape is half as thick as C-60, so it is extremely thin and certainly requires careful handling. In my opinion, using it in an unstable mechanism or in poor conditions is risky.
Modern mechanisms have improved, however, and the tape itself has become stronger. If you record on a well-maintained, stable mechanism, there is little to worry about.
Because the magnetic layer is thinner too, it is safer to keep the recording level slightly lower than on C-60 and C-90, even within the same tape series. Sensitivity is also often a little lower, so high-frequency response may drop slightly when using Dolby or similar noise reduction. The main rule is not to place excessive demands on it in any respect.
Scratches Appear on the Tape Surface. Why?
It depends somewhat on whether they are scratches where the magnetic layer has peeled off or creases resembling folds. If they are actual scratches, there is a sharp projection somewhere on the head, tape guide or inside the cassette shell, so it is best to contact a service center immediately.
If they are creases, dirt on the head or guides is often responsible. Inspect the head and guides carefully and clean them gently. By looking closely at the position of the mark and inspecting the head and guides, you can usually find the cause.
When Copying Tape, Should the High-End Deck Be Used for Playback or Recording?
The basic rule is to use the better-sounding deck for playback. The reason is simple: you cannot record better sound than the playback deck supplies.
This is not about the number of heads or the price. What matters is which deck plays back steadily and sounds good, so listen carefully to both and compare them.
A three-head deck on the recording side makes it convenient to catch mistakes during recording, but ultimately use the combination that sounds better.
What Is a “Metal-Tape-Compatible” Deck?
It is a deck on which the powerful TYPE IV (METAL) tape can be used.1 Metal tape is more powerful than all previous tapes, but it also requires plenty of bias current. A deck designed for TYPE II (CrO₂) tape cannot supply enough bias current, and particularly if its erase head is not powerful enough, it cannot erase metal tape.
A metal-compatible deck has strengthened heads and a stronger bias generator and is designed to record on metal tape. Naturally, it will also demonstrate excellent performance with TYPE I (NORMAL) and TYPE II (CrO₂) tapes.
I Recorded on Metal Tape, but the Noise Did Not Decrease and the Dynamics Did Not Change. Why?
Most likely you used it in the same way as you previously used normal- or chrome-position tape. Metal tape’s distinctive feature is that it is exceptionally powerful, not that it is especially low-noise.
Therefore, if you use metal tape at the same recording level as other tapes, noise will not change and no extra power will appear. The tape does have substantial MOL headroom, so the recording should be clean and low in distortion. But if distortion was not a problem with your previous tapes, you will not hear the further reduction without sufficiently serious equipment and hearing. There are three ways to bring out metal tape’s capabilities.
❶ Take on dynamic sound. Sound with a wide dynamic range that could not be recorded on previous tapes can be recorded easily on metal tape. This is the most effective way to use it.
❷ Set the recording level higher. When recording music whose dynamic range fitted on previous tapes, metal tape still has MOL headroom. Raise the recording level by that margin and turn down the volume on playback; tape noise falls by the same difference.
❸ Record with low distortion. Without pushing anything, set the recording level to balance MOL against tape noise. The MOL headroom reduces distortion, while a slightly higher recording level reduces tape noise.
Technique is needed to bring out metal tape’s excellent recording capabilities fully.
I Want to Use Fe-Cr Tape, but My Deck Has No Fe-Cr Position. What Should I Do?
Ideally use the TYPE III (Fe-Cr) position, but on a deck without it, first try recording and playing back in TYPE I (NORMAL). The high frequencies will be slightly raised, but it is quite listenable in practice.
There is no need to worry about increased distortion. It is better to keep the recording level a little lower.
If the high frequencies are too strong, try switching to TYPE II (CrO₂) for playback only. The result is surprisingly comfortable to listen to. You can also leave it in TYPE I and adjust the tone control.
Recording and playback in different positions will not damage the deck or the tape. Feel free to experiment.
I Want to Send a Cassette to a Friend. Can I Put It in an Ordinary Envelope?
Yes. Bear in mind, though, that a standard letter is up to 1 cm thick, so even without its plastic case the cassette is a non-standard mailing. Even in a standard envelope it will be treated as non-standard, so take care. The cassette shell is 12⁺⁰·³₋₀·₁ mm thick. It misses the limit by so little!
Since the item is non-standard anyway, a thickness of up to 10 cm is permitted, so pack the cassette in light but strong material to protect it from impact. Envelopes folded from two layers of kraft paper seem convenient.
My Deck’s Tape Speed Seems Slightly Higher Than My Friend’s. Is There a Simple Way to Check?
If tape speed is 6% higher, pitch rises by a semitone, so tape speed is an important characteristic. The standard for decks calls for adjustment within ±1.5%, so there should in principle be no problem, but the setting may have drifted for some reason.
The simplest method is to use a commercially available test cassette. Play a tape on which a signal exactly 100 seconds long is recorded and time it with a stopwatch. If it finishes in 99 seconds, the speed is 1% high. The speed accuracy of prerecorded music cassettes, including test tapes, is specified within 0.5 seconds, so they are quite suitable for this test.
If you do not have such a cassette, pull exactly 4.76 m of tape from an unwanted cassette, bring a magnet to both ends to make dull clicks, wind it back into the shell and play it. When measuring the tape, take care not to damage it, for example by wearing gloves.
This method cannot be called exact either, however, since the tape may stretch. If you are concerned, ask the manufacturer’s service center to measure it.
The Left and Right Meters Show Different Levels. Is Something Broken?
In stereo recording, even if left and right sound equally loud, their levels do not necessarily match. Peak and VU meters also detect levels differently, so their deflections can differ.
However, if you feed in a mono signal and the meters deflect differently, that is naturally cause for concern. Even then, some difference between the left and right meters is to be expected, and there is also a small variation in the recording-level potentiometer. If the difference is excessive, contact a service center.
Why Can Metal Tape Be Played, but Not Recorded, on Older Decks?
Recording requires powerful heads and bias current suited to TYPE IV (METAL), but the standard playback equalization for metal tape is the same 70 μs as for TYPE II (CrO₂). It can therefore be used for playback on older decks.
“Metal tape” may sound as though it would damage the head, but its surface is polished like a mirror and its contact with the head is not substantially different from ordinary tape, so it can be used without concern. Dolby and similar systems are used in the same way as with ordinary tapes.
The Tape Squeals, and the Recorded Sound Rattles. What Should I Do?
This fault is called “tape squeal” or the “violin effect”. When dirt accumulates on the tape guide, head, pressure pad and similar parts, resistance at the contact point increases, the tape vibrates in the direction of travel and a sound appears.
Cleaning these places solves the problem. To clean the pressure pad, however, you must pull out a little tape and clean the pad behind it, so careless handling can damage the tape. Pull the tape out slightly with a toothpick and remove the dirt with its tip. Do not use cleaning fluids.
How Often Should Heads Be Cleaned and Demagnetized?
Cleaning heads. When a head becomes dirty, the top end of the sound starts to feel inadequate. In severe cases volume may fall, or sound may disappear from one channel, so the head should always be kept clean.
Using good tape on a well-maintained deck is one thing; using it in poor conditions, as with a car stereo or radio-cassette recorder, is another. Naturally, the amount of head contamination differs. As a rough guide, cleaning about once a week is sufficient. Always use a dedicated cleaning fluid or pure alcohol. Medical alcohol is diluted with distilled water and must not be used. Put a little head-cleaning fluid on the tip of a cotton swab - just enough to moisten it - and wipe the head lightly up and down, across the direction of tape travel. If you press, the head alignment may shift and high-frequency response may deteriorate.
Clean the capstan, pinch roller and tape guide along with the head. Always use a dedicated pinch-roller fluid for the roller. This protects the rubber against aging. After cleaning, wait about a minute for the fluid to dry before inserting a cassette.
Demagnetizing the head. If a head becomes magnetized, playback not only has more noise and less high-frequency content; clicks and similar impulses can also record noise onto the tape.
If crackling begins to be recorded, you can confidently say that the head has become magnetized. Modern heads are relatively resistant to magnetization, but if you relax your guard a head may become magnetized without your noticing, so remain vigilant.
Rather than doing it every fixed number of weeks, demagnetize before playing an important tape.
I Heard That a Dolby-Recorded Tape Is Better Copied “Directly”. Is That True?
Yes. If a Dolby-recorded tape is copied as it is, then Dolby NR is switched on for playback, you can enjoy low-noise sound. If the copy is made carefully, the result will be the same as before copying.
An exact one-to-one copy is desirable, but requires quite serious equipment and test tapes for matching levels. If the level shifts during copying, Dolby NR will assume the tape was originally recorded at that level and process it accordingly, changing the tone.
For ordinary music enthusiasts, it is safer to play with Dolby switched on and copy to a deck whose Dolby switch is also on. In this case, even if levels differ, the tone does not change.
Does the Tape Itself Need Maintenance?
Taking a tape out after recording or playback and leaving it lying “bare” is a problem, of course, but as long as it is kept in its plastic case, no special maintenance is needed. Dirt can accumulate on the pad after prolonged use in a car stereo or on decks that have not been cleaned. See the answer about “tape squeal” on page 86 for this maintenance.
Wind important tapes, and those you know will not be used for a long time, to the end before putting them in their plastic cases for storage.
How Many Times Can Tape Be Used? Does Its Life Depend on Handling?
Tape has two kinds of service life: it may be stretched on one side and become “like wakame seaweed” or twist, becoming unusable through mechanical deformation, or it may change magnetically. In most cases, mechanical deformation is the issue.
It is no exaggeration to say that its main causes are inadequate cassette deck maintenance and accidents caused by handling errors. When tape is mechanically deformed, many dropouts and variations in pitch occur, making good-sounding recording impossible. Unlike stationary decks, simple note-taking cassette recorders and car stereos in particular tend to receive only minimal maintenance while being used in poor conditions, so they should require even more attention than decks.
The main handling precautions are to remove tape slack before loading a cassette, always store it in its plastic case, avoid rough treatment and avoid high-speed winding where possible.
Longer recording times deserve more attention: C-90 compared with C-60, or C-120 compared with C-90. The longer the recording time, the thinner the tape. On a well-maintained deck, tape can be used for recording for quite a long time.
The Tape Has Jammed Inside the Deck. What Should I Do?
First stop the deck, turn off the power and carefully inspect the situation. If the tape is wound around the capstan, leave it as it is and contact a service center to have it dealt with.
If the tape is valuable, be sure to say so clearly. It may even be better to include a note. A tape that has suffered such an accident is often considered unusable, and sometimes it is simply cut and removed. If you say it is valuable, the service charge may be slightly higher, but they will do their best to save it.
If the tape is wound only around the pinch roller, you can try dealing with it yourself. Prepare a bamboo ear-cleaning stick and gently turn the pinch roller. The tape will slacken slightly; wind that section back into the cassette shell. Continue and you should be able to free the tape.
If the tape enters the mechanism in folds, try gently pulling it out. Surprisingly, it comes out relatively easily. The last part may catch somewhere deep inside, so be especially careful. Even so, it generally comes out somehow. Tape deformed by folds becomes considerably more acceptable to listen to after several plays.
Примечания
-
The original text on page 82 gives type VI, a typo by the book’s authors. The IEC standard correctly identifies TYPE I as NORMAL (Fe₂O₃), TYPE II as CrO₂, TYPE III as Fe-Cr and TYPE IV as METAL. The translation corrects it to type IV. Sources: IEC 60094-1 (1981), Wikipedia (Russian), “Compact Cassette”. ↩