Stuff you have built just because you can

Mrs TLW's project of the day: take out the Harman Kardon audio system that we haven't been using because I needed to get behind the cabinet and figure out where something came loose, and left the left channel dead, and get rid of it in favor of a new all-in-one set that will have surround sound from the movies, but doesn't have a radio reciever, and won't talk to the CD changer, cassette deck, or playstation. which is okay, because it looks like she plans to get rid of all of them, too. I guess I can add a stereo to the list of things I used to own.

(edit: and I also found out that the thing might have come loose because of her habit of poking around behind the cabinet with the vacuum.)

you haven't seen an all-in-one box set system, have you?

it consists of a cheap bluray player, and a 5.1 speaker surround speaker system, and about half as much wire as you need to position them properly. this one is a 3D model, so presumably it will give 3d video if it is plugged into a Samsung 3DTV, which we don't have and I have no plans to buy. some of them have a firewire input for the audio from a cable box, but I don't expect this one to. I am also going to threaten to staple the wires to the ceiling if I am expected to install the silly thing. the Harmon Kardon system has connections for surround sound if I really feel like putting the "rear" speakers in the back of the room - or I can get a proper surround receiver, and still use the 4-way tower speaker system to give cinema volume as well as cinema positioning. - though really the main thing we use the stereo for is to drive the center channel speaker extra loud, which lets us hear the dialogue better. - something the box set also probably doesn't do.

The home machines I am familiar with do work with all sample rates but refuse to record 44.1kHz since it might come from a CD and they always set the copy bit so when playing back, the next DAT recorder refuses to record. You can't copy a CD and even worse, you can't copy your own recordings! So you can record your own garage band but you are unable to make a copy of the master tape e.g. to send it away as a demo tape!

Recordable CDs are supplied blank and the data "burned " onto them using a laser. Mass produced commercial CDs (and DVDs) are created using a photographic process.

And you are correct, home DAT recorders could play back both sample rates but only record at 48 kHz. The commercial DAT machine I have does not set the record bit so you can make as many digital copies of any DAT tape that you wish.

The CD-R didn't kill DAT as a format for home use. DAT never caught on for home use. It was dead long before the CD-R was available. Recording studios were using CD-Rs for audio recording long before they were available on home computers. The first CD mastering machine I bought cost a fthousand dollars and had a hard drive in it. You would first transfers the material to the hard drive, and then burn the CD. When that machine came out, a blank CD – R cost almost 5 dollars each. And the machine only seemed to have a successful burn rate of 50%.

About "burning" CDs:

The first generation ROM was hand wired, later a matrix of diodes hand soldered. A present diode is a logical '1', a missing diode a logical '0'.

When silicon chips were used, the ROM was mask programmed. A logical '0' was made by painting a spot on the layout film for production.

For development purposes, making new chips over and over again to debug a program was impossible since highly expensive. Instead a special ROM design was invented and all diodes present while manufacturing the chip. The chip is full of logical '1'. To program them, you selected the memory address to program a byte and then ground the data lines which should be programmed to a zero. The particular diodes in the matrix burn out. This system was then named PROM (Programmable Read Only Memory) and the method of programming was called burning because you really had burned out diodes.

Later a complete different way of storing data in a ROM was invented using transistors instead of diodes. The trick is that you can inject a charge into the transistor by over-voltage which blocks its function. Blocked transistors give a logical '0', unaffected ones a logical '1'. By shining UV light into the chip, the charges drain out. This was called the "EPROM", E for Erasable. The process of programming was still called burning although there was no burning involved any more. Just because you had to put the chip into a programmer which looks the same as using a PROM.

Writing CD-ROM discs was then also nicknamed "burning" in tribute to the old (E)PROM ROM memories.

A commercial made CD is pressed like a record. Instead of big groves, tiny pits are pressed into the surface of the disc. Then aluminium is vapour deposited onto the surface. Then the aluminium surface is painted for protection and then a label is painted on top of the protective layer. The laser shines through the actual body of the disc and hits the aluminium layer beneath the label. When the beam hits a pit, it becomes deflected and won't return to the source.

CD-R are different. Instead of pressing the data into the surface by production, a blank spiral is pressed into the surface. This spiral is then filled with an organic paint which turns transparent when exposed to a lot of light. Like the pressed CD, a reflective layer (at first gold) is added and then the usual protective layers of paint and the label. When writing a CD-R, the data must be written bit by bit which takes time. A pressed mass produced CD is ready when it comes out the production process, a CD-R needs to be written seperately so a CD-R with data on it costs much more to make. Also CD-R is sensitive to light (e.g. direct sunlight), a pressed CD not!

DVDs are slightly different. Since they can be played from both sides, the main data layer is in the middle. Put a DVD-R into real hot water and you will get two discs since you melt the data layer in the middle. Also the manufacturers couldn't settle an argument about DVD-Rs. Half of the manufacturers favoured the CD-R process, the other half wanted really blank discs without the spiral inside. This makes it more difficult to write it and you get more errors in the process but this makes producing blank DVDs easier and the writer doesn't have to track so accurate while burning so the drive mechanics of the writer can be much cheaper. In tribute to the CD-R, the old method was named DVD-R (DVD-minus-R) and the alternative system was named DVD+R (DVD-plus-R). Since about 10 years, all players and all writers can handle both but in the beginning of DVD±R, half of the players on the market were unable to read DVD+R, the other half unable to read DVD-R. This was a great problem and to prevent that licensed third parties could make DVD±R compliant players and dominate the market, the major DVD companies soon came up with drives which could read both but burn only their own favourite version. Nowadays, any modern writer can handle both.

There are dual layer recordable DVDs (DVD-R-DL)that have been available for over 10 years now. They hold 8.5G of data and both layers are written and read from the same side.