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Wow & flutter: is it the tapes or the tape deck?
July 2, 2014 11:36 AM   Subscribe

I am beginning to digitize some old cassette tapes but have run into a problem: many of the cassettes have significant speed/pitch variations on playback. I can't figure out if the problem is the tapes or the tape deck (or both).

Background: I am beginning to digitize about 30 cassette tapes that contain music from bands that I was in. These tapes are from the late 1980s-mid 1990s, as is the Technics dual cassette tape deck that I am using for playback. The tapes are in good condition, having sat unplayed in a shoebox in the basement since the mid-90s, as is the tape deck, which has also sat unused in a basement since the mid-90s.

The problem: during playback, many of the tapes experience serious speed/pitch variation, and a 'crinkly' noise, primarily at the beginning of the tapes. I have tried lightly cleaning the tapes, and rewinding them all the way several times, but this doesn't seem to help.

My problem is that I can't tell whether the problem is in the old tapes or the old tape deck's old motor, either of which could be the culprit. I don't have access to any other tape decks to test the tapes (that's right: no one I know has a tape deck). These tapes have significant sentimental value, so I'm willing to buy a new tape deck if necessary, but would rather not spend the money for a one-time project if I can avoid it. What should I do?
posted by googly to Technology (11 answers total) 3 users marked this as a favorite
 
Tape can easily get stretched out, which will cause this to happen. It's predominant at the beginning and at the end, because most tape decks cause stretching during rewind or fast forward.

If the tape ever unspooled, and had to be manually rewound you may get drop-out or crackles due to actual wrinkles in the tape.

Also, tape will get brittle with age.
posted by Ruthless Bunny at 11:54 AM on July 2


How damp was the basement? That matters a lot.

If this were my project, I'd take a Q-tip and dip it in rubbing alcohol, and give a gentle rub to the heads and any other parts of the cassette deck that seem dusty. The advice on this page adds that you should "NOT TOUCH THE SURFACE OF THE HEADS WITH ANY METAL OBJECT," which seems reasonable.

Once you've cleaned with isopropyl alcohol, that's about all you can do with the cassette deck. I suspect, given the age of the cassettes (serious degradation begins around the ten-year mark) and the environment in which they were stored, that the issue is more the cassettes than the player.

(Again, if this were my project,) I'd buy a new tape deck. I would also avoid messing with the tapes for any reason whatsoever.* Cleaning the tapes will only harm them, as will rewinding--if you must rewind, gently twirl a pencil through the tape reels. It is likely that some/all of these tapes have only a few plays left in them, and you probably want that play to be preserved digitally. I'd tread lightly.

*although, if the tape does break off, it's worth a try to reconnect the ends with a gentle adhesive.
posted by magdalemon at 11:56 AM on July 2


If the pitch variation is caused by the deck, it will be different each time. If caused by the tape, it will be the same.
posted by SemiSalt at 12:19 PM on July 2


Record a short section on a new tape and play it back. If it wows, it's the deck. If not it's the tapes.
posted by Sportswriters at 12:24 PM on July 2


Depending on what you're using to digitize the material, you may be able to correct some of these artifacts with a dedicated plugin. This one, Capstan by Celemony, is outrageously pricey (but I see they have a "five day rental"), or maybe there are other lower-cost options out there?
posted by monospace at 12:24 PM on July 2


no one I know has a tape deck

Might be worth seeing if there's a library or a university A/V department near you that has equipment you could try. Alternatively, cassette decks are pretty cheap on eBay.
posted by yoink at 1:13 PM on July 2


Most tape decks relied on rubber drive belts which can get dried out or suffer rubber rot. This will cause them to lose good contact with the drive rollers. I'd see about replacing them.
posted by Gungho at 1:18 PM on July 2


Or, mixing the two previous comments, look for a used "direct drive" cassette desk on eBay or Craigslist.

My old 1980's desk was a three head direct drive, so I know there are some out there...
posted by Leenie at 1:50 PM on July 2


I went through the same process you are around 2002 and converted old tapes into digital files on my PC. Many of mine had sound issues like you are describing, even though the tape deck was only about 3 years old. I assumed the tapes had degraded over time.
posted by tacodave at 2:30 PM on July 2


Speaking as someone who has a lot of experience restoring old audio and video, it is essential that you obtain a second tape player. If you can't get one, find a friend or coworker with one or see if the library has one.

Compare the playback on each one. If the problem clears up, it's the motor/belt on your old cassette deck. If there's still trouble, try to compare the patterns in the speedup & slowdown. Is there a slowdown *exactly* at a certain instant in a song? If that's the case the tape is likely deteriorated or the original recording deck way back when had a bad motor or drive belt. If there is no correlation and it's behaving randomly between the two decks, I'd dismantle and repackage the tape in a new cassette, as I've run into a few tapes that have tight tolerance or foreign contamination and that can add resistance to the tape transport.

In any case I would also test the tape sprockets and try winding it awhile and try to feel for any resistance. If there is, repackage the tape.

Regardless, if you can't fix the issue, I would digitize the tape anyway. Cyclic distortion from drive belt problems is theoretically salvageable since the time distortion in many cases (except for random slippage) has a predictable, wavelike pattern. I don't know if there are any software programs or Audacity plugins that deal with this, but if there aren't I wouldn't be surprised if something comes along sooner or later.
posted by crapmatic at 9:08 PM on July 2


In addition, you may also want to find an old demagnetizer for the head and capstans. Don't bother with the ones that are built inside a cassette - they are simply too weak to be effective when compared to the ones designed for more precise work.

They can be expensive, but you can get them cheap on ebay, here's one for $15.

It's also important to know how to use it right and what dangers it poses - get this thing too close to tapes and other magnetic media when it's on, and it can ruin them. Take the cassette player unit to place by itself - give yourself about about a 10' perimeter from other electronic stuff and magnetic media, turn on the device when it's about an inch from the heads, and wave in in small circles around the heads and the capstans for about 5 seconds and begin moving the demagnetizer away from the heads slowly while still moving it in larger circles as you go - give it about 8 seconds to move the demagnetizer about 6 feet away from the player, then turn it off.
posted by chambers at 9:51 AM on July 4


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