Digital recording, mixing Need professional help.

I just want to know what kind of information is stored on digital audio tapes and how it's different from red-book CD?

Will it be the same if the DAT is transfered to analogue vinyl or CD? If not what is the difference.

And finally How the digital vinyls are recorded?
By "digital audio tapes" are you strictly referring to the DAT format, or do you mean digital recording in general?

All digital formats use 1's and 0's, but the red-book CD technology is basically something that was developed in the early 80's (late 70's?). Things have changed a lot since then, but unfortunately, the general market is still extremely committed to that old format. I don't know how to describe the differences in an effective way, but try to think of the musical event as a book. The book is written using a 26 letter alphabet. 24 bit/192khz digital recording is limited to 24 letters, so it captures 90-some percent of the book. The final printing (Red-book CD technology) is limited to 16 letters, so you're taking a book written with a 26 letter alphabet, re-writing it with 24 letters, and then trying to publish it on a printing press that is limited to a 16 letter alphabet. That's a very general (and maybe lame) analogy, but I think it does the trick. Good analog equipment is able to capture all 26 letters used in the original book (though it does fatten a few of them up). :-)

I don't know the technical specifications of the DAT format. I think they were 20 or 24 bit and capable of various sampling rates (depending on the unit), so that would mean that they are capable of better resolution than red-book CDs. As far as professional recording eqipment goes...there are tape-based (and hard-disk based) systems that range from 16/44.1 to 24/192. Any newer digital recorder should be able to capture more information than a red-book CD is capable of holding. Current digital technology is finally getting to the point where it can capture the same amount of information as analog tape (many 24/192 units, and especially things recorded using Sony's SACD process and the DVD-A process). A good analog process is technically capable of holding more information than red-book CDs...vinyl included (assuming all the equipment in the recording / mastering / playback chain is up to the task). A well done digital recording could sound better on vinyl than red-book CD because the vinyl could, theoretically, capture more of the information from the master tape. Red-book mastering technology has come a long way...CDs do sound better than ever's just that the format is ultimately hampered by the old 16/44.1 technology.

The "digital vinyl" is recorded exactly the same way that any vinyl is recorded, but it's source is a digital one (playing through analog outputs) instead of an analog tape...that's the only difference.

I hope I managed to answer a question or two in my rambling. Are you trying to figure out which is better?? I'd say that depends on who is doing the recording and mastering. A recording made on a professional 16/44.1 system by talented people (with great mics, preamps, and circuitry) could sound better than a recording made on a cheap 24/192 all depends. A well done digital recording could sound amazing on a well made LP. It could also sound amazing on a well made CD too, but the LP should *technically* be a more representative copy of the music. On the other hand, a poor digital recording will probably sound like crap on both formats.

There was a trend that started in the late 80s and it continues today...especially on LP reissues. The labels have been cutting their LPs from the digital master tapes that were made for the CD release. That's okay (and unavoidable) if it was originally a digital recording, but it's a little lame when they do it to analog-recorded material. Why convert the signal from analog to digital, and then back to analog? I know it's a financial decision on the labels' part, but it doesn't make sense to me. I don't think there's any way that a digital re-master could sound as good as all-analog LP mastering...not if it's done right.

Okay...I'm done.
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.
Excellent and accurate responses!

Thanks to both of you for staying on topic and giving an unbiased and through answer.
I realy enjoyed reading these responces and I figured another sub-question in my own thread:

Why DATs arn't used in consumer media meaning why for instance there are no car DAT players or portable ones. Why there is no brand records sold on DATs such as on CDs or portable audio cassettes?
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.
And to add to the above...I think it also became a victim of the constant format wars that plague the audio industry. At the time the DAT was being introduced (by Sony?? I'm not sure), Phillips was pushing their own digital cassette format. Besides that, Sony seemed to be pushing their own mini-disc format for many of the same consumer uses as the DAT. Who may have successfully replaced the cassette if all of the companies (record labels included) embraced it, but the recordable CD was inevitable and it's certainly more convenient for home users.

Thanks to Slartibartfast for the DAT bit rate info. I knew that Tascam (or Alesis?) came out with a 24/96 DAT a few years ago, but I wasn't sure what format the older DATs used.

And to the end it seems like the DAT has become one of the official replacements for the reel to reel recorder (though many people still prefer the analog feel and tape compression of a reel to reel recorder). Pros and enthusiasts use them to record live music...musicians used them for mix downs, and most studios, mastering houses, and CD duplicators accept them as a standard format. Many people have been slowly replacing them with CD burners and hard-drives for mix-downs, but they're still very useful for live recording.
Kudos..Would you guys do a series on digital recording and playback.... Sampling, jitter, aliasing, dynamic range, ect...the whole 44.1k yards. Just kidding... great posts folks.

I remain,
Nicely done! DAT101 course is almost complete. As to reproduce performance can DAT be better than CD-player or transport-DAC combo if used in the consumer media?
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).
I've certainly no doubt about analogue machines vs any digital for music recording.
80% of my listening collection is analogue as well.
I'm pretty sure that there is a number of artists being recorded analogue first but within the time it will not probably grow...