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William

Burn Speed And Sound Quality

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I have heard people say that CDs and DVD-As sound better if you use slower burn speeds to create them. Is that true? The idea makes no sense to me, since it would seem that digital information is digital information regardless of the speed at which it is burned.

Does anyone know for sure?

William Osborne

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It's a question of trial and error. The burning is actually ANALOG! The burn depends upon how hot your laser is and how long the disc stay under it. Like toast, if it stays too long uner the grill it gets overdone. This is a bit of a problem in that, given the error correction that tries to conceal poorly burnt CDs, it is hard to tell whether the burning was optimum.

CDRs that are rated for 50X burning are rather sensitive and dont always like to be burned at 1X.

So, suck it and see!

david

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hi,

the saying that you should use for long life data storage using the lowest possible speed for burning is right because of some physical effects. (and therefore burning is an ANALOG process)

at the start of burning most burner make a small testrun for calibrating the laser-output regarding the inserted media and burn speed. (if this test fails, you won't be able to burn at all.)

so if the media will be burned with high speed, the laser uses more power to create the bubble inside the polycarbonate-disc because of lesser time the laser-beam can heat the plastic at the focus point.

second point is, that we have to take in consideration the inertia of the whole system (laser switch on/off; rotation of disc; heat consumtion of plastic). at higher speed it is more difficult to place a well defined point at a well defined place than at lower speed. so it might happen that two bubbles will join together during burning. error correction will conceal that but if you loose too much of these informations the whole data is lost.

and the last point is a possible buffer underrun, if you do a lot things at the same time you burn with high speed. the burning process will stop for seconds and this also can cause artifacts in your cd-r.

so after all it is, in my opinion, always the best thing is to choose the lowest possible speed for burning. then the whole system has enough time to do a very good "carving".

but note, all these hints are done from the point of view making a long life data storage cd.

if you are in a hurry and don't care for data safety, don't hesitate to burn faster.

cheers, andy

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Hi William,

investing in a HF analyser for optical media will tell you how good the signal is that is coming from your CDs. That's the relevant quality parameter. Costs a couple of 10.000s, as usual for professional only machines.

There are some software tools like PlexTools that give you a rough approximation that may be as well relevant as long as you read with a device that is ok.

The signal quality analysis issue is one of the key issues that render recordable optical media useless for archiving, as more and more people are about to finding out.

Cheers,

Sebastian

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Thanks to all for the information. What medium would you recommend for long term storage of stereo and 5.1 recordings. I have an ADAT and could export to that via a light pipe.

William Osborne

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Don't ask... :D

The most reliant standalone medium is maybe data tape.

Digital Audio Tape is certainly the worst crap for archiving possible.

It is however most important that you store copies on different media and do backups. If you have little data (>1TB), managed storage by a service provider as Moving Media might be a good option. If you have more stuff, one day you might find you operating an HSM...

Cheers,

Sebastian

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I have heard people say that CDs and DVD-As sound better if you use slower burn speeds to create them. Is that true? The idea makes no sense to me, since it would seem that digital information is digital information regardless of the speed at which it is burned.

Does anyone know for sure?

William Osborne

Hi,

modern CD-recordables are designed for high speed burning, so in most cases you get even worse results if you burn with speeds lower than 10x or 8x, because the dye of the discs is too thin and 'melts away' when the laser stays too long on it.

But as Sebastian Gabler said there are some simple software tools and some of them are even free like this one. With these you should just try out which media and which speed works best with your burner. Cds with an error rate lower than 50 per second are ok; the red book prescribes a maximum of 220 errors per second. And of course these tools cannot replace professional measuring tools.

And never use audio-cdrs in a computer-burner, these ones are designed for 1x-speed-recording in stand alone-hifi-recorders.

If you want to use cds for long-term-storage I have heard that you should use the golden ones, because the gold cannot oxidise like silver. (Actually there shouldn't get any oxygen through the protection layer anyway, but who knows :D )

Regards,

Ben

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Hi,

the problem with reflection layer oxidation is not the only issue when going for long term retrievablility of recordable optical media.

The more generic issue is the general decay of the HF signal. The verdict is more or less that the signal level on golden media is inferior from the first second due of inferior reflection properties of gold (it's apparently coloured). That leaves you with a smaller headroom for all the deteriorations that happen to the dye. Just assume that you have less than 10 years for CD-Rs before you have to migrate to a new copy. Then you are more or less safe.

Cheers,

Sebastian

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