Digital recording, mixing Need professional help.

To continue with Phil's discussion... a DAT is a 16 bit word just the same as CD redbook. However, DAT has the ability to record sample frequencies of 32 kHZ, 44.1 kHZ (CD standard), and 48 kHZ ( original consumer DAT standard). A DAT can make a direct digital duplication of a CD. However, a DAT recorded with a different sampling frequency from 44.1 doesn't work with CD. A DAT at 48 kHZ has a higher maximum frequency response of 24 kHZ as compared with CD's maximum of 22.05 kHz.

If a DAT is recorded at 48 kHZ and it is to be pressed onto a CD-R, it will require a sample rate convertor. Quality external sample rate convertors are expensive and typically diminish sound quality. Sample rate conversion can also be accomplished using a computer editor but there are still sound quality issues. Most people recording on DAT use them at 44.1 kHZ sampling frequency.

The process which Phil mentioned where a 24 bit word is crammed into a 16 bit word is called dithering. It is basically a fancy way of rounding down. Sometimes instead of dithering, the word is simply truncated from the higher bit rate to 16 bits but this is a practice that should be avoided. As far as dithering higher bit rates to a 16 bit CD standard, there are numerous mechanisms available such as Apogee's UV22, Pacific Microsonics HDCD, Meridian, etc...

There are also newer multi-track and high-bit technologies available to record with. These are things such as units by Tascam or Nagra. These typically record multi-track 16 bit /44.1 kHZ signals but some can record at 24 bit with a 96 kHz sampling frequency (such as the Nagra). These can be dithered down to a 16 bit CD.

Now for the history of digital recording for vinyl, there are two predominant recorders out there. The first was a proprietary mechanism used by the Decca record company. The other was the Soundstream and was the most common. Neither of these formats is a supported standard today. They were used as the master source and the lacquer to cut the LP was made from the digital source converted to analog rather than an analog tape master. A high quality analog recorder of the day (such as an Ampex ATR) is superior to either the Decca or Soundstream and goes head to head with the finest digital recorders made today.

Once upon a time, our friends at the RIAA threatened to sue anyone who introduced a medium which could faithfully copy a CD... so, when DAT was being introduced it was greatly delayed because of fear of retaliation from the music industry. It was introduced with what is known as SCMS (Serial Copy Management System) as a compromise with the RIAA where only a single digital copy would be allowed on a consumer DAT. Professional machines were not restricted by the agreement with the RIAA. The first company to introduce a consumer DAT was Nakamichi with the 1000 but its cost was sky high (around $10K) and avoided problems with the RIAA. Eventually, the delay of DAT had killed its application as a consumer medium and became supported only in recording studios. CD-R followed close enough that it became the digital medium of choice for copying and we all know what has happened to the RIAA fears of piracy in the meantime.

For recording sessions, when doing a live 2 channel recording the CD-R is a very poor medium to use (dropouts, errors writing the CD-R, etc...). Therefore, DAT is very popular for this and has kept its foothold in studios and location recording. It is much cheaper to use than analog, much more robust than CD-R, and very convenient.

A top analog machine is still superior to 16 bit digital (even with high quality 24 bit A/Ds). The big reason analog has been overshadowed by DAT is mostly a financial issue. A high quality analog mastering machine will cost between $5-15K depending on how nuts you go. Couple that to the fact that a 2Hr DAT tape is only a few bucks and 25 minutes of 1/4" 10" reel of Quantegy 499 is $20, you can see how people have moved away from analog. Its also kinda hard to pick up a 200 lb Ampex and throw it in the car.

As far as DAT v CD as a transport, it is all relative. It is subject to the same jitter issues as a CD transport. The medium doesn't inherrintly reduce the jitter and in reality, the most popular early DAT was the Panasonic SV-3700 which has some horrible jitter specifications and was used to record a rather large amount of music.

People have also questioned the long term shelf life of a DAT so I would be hesitant to use it as a long term storage format. Analog tape is still the best for this and is what the Smithsonian and various others recommend for long term shelf life.

When doing live recording, hard drivers or DAT is still the medium of choice. The CD-R is too prone to dropouts and is not reliable for live recording.

And Clueless- Already done them all minues the jitter tests... Results: winner - 2 track analog. As far as digital goes though, you can get a darn fine recording with an Apogee 24 bit A/D dithered to 16 bits with the built in UV-22. The key to 16 bit recording is using a high quality 24 bit A/D so you can keep the bit rate high. A straight 16 bit recording never makes good use of the 16bits and you usually get a resolution no better than 14 bits (especially with classical).