DAT Do's and Don't's

The following was posted by Art Munson, who has the following initial comments:

I scanned the following article, TOP 20 DAT RECORDING DO'S and DON'TS, out of the latest TASCAM users guide. No author was listed so I don't know who to give credit to. For those of you new to the DAT world it contains some valuable information. Those of us not so new can probably learn something or at least be reminded of some things about this format. I was particuarly interested in the tip #1 as it's something I have been harping on for the last 6 months or so, also tip #4 on their comments on cleaning the heads. I found tips #13 and #18 interesting also.

The DAT (Digital Audio Tape) recorder is a project studio owner's dream come true. Not only does it deliver CD - quality (or better) sound in a recordable, compact, taped-based format its near-universal adoption as a mastering and audio backup standard makes it easy to exchange tapes with other studios and musicians.

However, digital tape is not the same breed as analog tape. DAT has a few surprises up its sleeve, and to get the most out of this medium you need to observe some important do's and don'ts.

Following are 20 tips that can help give you a better sound as well as more reliable operation. Remember, although DATs sound miraculous, they are still taped based. Most of the cautions that apply to analog apply just as much, if not more so, to DAT.

1. Do fast forward new DAT tapes (or analog tapes, for that matter) all the way to the end, then rewind to the beginning before using. This "unpacks" the tape and disperses any lubricant more evenly over the tape surface.

2. Listen to a tape after recording to verify that there are no glitches. However, note that some top-of-the-line DAT decks, such as TASCAM's DA-60, let you monitor off the tape as you're recording. These machines are more costly because they use 4 heads, but being able to verify that signals are being properly recorded on tape can be invaluable, especially for live recordings.

3. Don't overuse "cue" and "review" modes. These modes are similar to rewind and fast forward, but maintain contact between the tape and head so you can hear what's on the tape as it whizzes by. You usually enter these modes by pressing rewind or fast forward while the tape is playing instead of pressing stop first. Cue and review speeds are slower than rewind and fast forward but faster than normal playback; although the monitored sound won't be high fidelity, it will be good enough to let you know where you are on the tape. The down side of these modes is that the continued tape contact causes head and tape wear, so unless you absolutely need to monitor the sound as it goes by, press stop before selecting rewind or fast forward to disengage the tape from the heads.

4. Do clean the DAT heads periodically (the manual should mention how regularly this needs to be done), or if there seems to be an increase in errors. DATs can be cleaned with commonly available dry-cleaning cassettes; never use wetting agents of any kind, or do analog tape recorder cleaning techniques. If you experience any problem with a rotating head-based machine, first run a cleaning cassette and see if the problem fixes itself. This will provide a solution in most cases; if not, take the DAT deck to your local authorized service center for professional cleaning and inspection.

5. Don't write on DAT labels with pencil or ball point pens. You don't want graphite or ink particles flaking off of the DAT machine transport; use a felt-tip marker that doesn't leave any solid residue. Do back up your tapes. It's as important to make DAT copies as it is to make safety copies of analog tapes. It's best to do digital transfers, but if it isn't possible, analog copies still sound fine. If at all possible, keep an additional set of tapes offsite in case of fire, flood, earthquake, volcanoes, or UFO visitations.

6. There is a major caution concerning digital copies: "consumer" grade DAT recorders often include SCMS (Serial Copy Management System), which is designed to thwart unauthorized digital dubbing and piracy by inserting "flags" in the digital data stream. You can generally make one copy of a tape, but you can't make a digital copy of that copy. (SCMS does not affect the analog inputs and outputs.) Why is this a problem? Suppose you mix down several tunes to a DAT, then "assemble" these tunes in the proper order by copying them to a second DAT. If you try to make a backup copy of the master, SCMS will prevent this. Pro decks either dispense with SCMS entirely, or provide some means to defeat it. Which brings us to...

7. Do defeat SCMS on the DA-30. There's no reason for professionals to have to put up with SCMS, since pros often need to make copies of their own music. The basic procedure is to unplug the DA-30, remove the top cover, and locate the digital printed circuit board (looking from the front of the unit, this is the large green board to the right of the transport). Locate a short jumper wire labeled W-402, then use a small diagonal cutters to clip this wire (or, desolder the wire and install a switch if you want to be able to choose between enabling and disabling SCMS). Put the cover back on and you're done. For more details on how to do this simple modification, see Issue #8 (Spring/Summer 1992) of the TASCAM Users Group guide.

8. Don't overlook the fact that DATs are compatible with many hard disk recording systems. If you don't have two DATs to make backups, you can copy the data from the DAT to the hard disk recorder, then load in a second DAT tape and bounce the hard disk data to it.

9. Do use the write protect tab to differentiate between a "current" and "old" backup. Many pros keep two backups. Only one is updated at a time; that way if a problem happens during the backup process, the older backup is still available. On the next backup, the older backup is updated. protect the current backup and unprotect the older backup so that the next time you back up, there won't be any mistaking which tape should be backed up to.

10. Do keep DAT tapes in proper environmental conditions: dust-free, low humidity, and cool. Since DATs aren't very big, you may be able to store back-up copies in a climate-controlled office environment, which gives the additional advantage of off-site redundancy. Humidity and heat are particularly bad; moisture can rust or corrode metal tapes.

11. Do record at 44.1 khz if you expect your material to end up on CD. Although DAT's 48 khz sampling frequency theoretically gives better high frequency response than 44.1 khz, the real world difference is negligible. Material recorded at 48 will have to undergo a sample rate conversion to 44.1 khz prior to appearing on CD, which costs between $5O and $100 and can degrade the sound to a minor degree.

12. Don't be too afraid to go over 0 VU. No, that's not a typo! Granted, 99.9 percent of the time you'll want to avoid overload like the plague. But on tunes where extremely short percussive transients are the reason for the overload, they can be slightly clipped. This allows for a higher average signal level without compression, assuming of course that the duration of any distorted signals are so short that you don't hear any adverse effects to the overall sound. (Tapes recorded on the DA-3O can actually sound good with a little clipping, since the DA-30's clipping characteristics are somewhat more like the "soft" clipping associated with analog gear.

13. Do date your DAT tapes. After a tape has been around more than five years or so, it's prudent to make a digital copy of it to a new tape, and keep the older tape as a backup.

14. Don't leave tapes in a DAT machine after the power is turned off. Should there be any type of problem (e.g., blown fuse) when you turn the machine on again, it may be difficult to get the tape out.

15. Do keep abreast of software changes in your machine. DATs, like most devices these days, are software-driven and occasionally their software is updated or improved. Check with the company periodically to see if any updates have been made available that are pertinent to the gear you own.

16. Don't go over and over the same piece of tape when doing final mixes. The more you use a piece of tape, the more it deteriorates and the greater the likelihood of errors. Do consecutive mixes, and note which one is the final mix. You can then do a digital transfer to another DAT deck to build up a tape with nothing but final mixes (but remember the earlier caution about SCMS-equipped gear.)

17. On a related topic, don't leave the DAT in pause mode; pause is intended for a very specific function. When stopped, DAT tape is disengaged from the transport, and is not in contact with the heads. When you enter play or record modes, it takes a few seconds to engage the tape and have it contact the head. However, in pause mode the tape remains engaged and the head remains in contact; if you then initiate play or record, the tape kicks into action much faster. Since pause mode causes head and tape wear, use this only when you need to go from a paused to playing or recording status in the minimum possible time.

18. Do leave at least a minute of blank, but recorded, tape at the beginning of a tape before laying down any of your tunes (two minutes is probably safer). Also make sure you don't record all the way to the end. With virtually all tapes, the ends are the most prone to having quality problems.

19. Don't let DAT tapes get near magnetic fields. As with analog tapes, this can erase signals on the tape.

20. Do give each tape a unique ID. DAT tapes have a way of proliferating, and it's important to be able to locate what you want quickly. Similarly, do keep a notebook of what's on each tape. Dats can hold two or even three hours of material, and that's a lot of tunes - you don't want to record over something accidentally!