Every writer performs optimum power calibration (OPC) on the mounted disc at
the user selected speed before writing. OPC tweaks laser power for best
results using the current writer and disc. Some writers have running OPC
that makes further adjustments during the recording process to compensate
for non-uniform media or laser drift as it heats up.
Media Sciences, Inc.
> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of Don Cox
> Sent: Monday, January 07, 2008 8:10 AM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] CD-R error rates
> On 07/01/08, Richard L. Hess wrote:
> > While one CD does not make solid test, this indicates that the higher
> > speed produces more errors.
> Burning a CD is a photographic process. There will be an optimum
> exposure for each batch of CDs.
> The stated maximum speed is the least exposure that could possibly give
> acceptable results, like the stated speed rating of a traditional
> black-and-white negative film in a camera.
> A couple of stops more exposure, corresponding to one quarter the
> maximum speed, is more likely to give good results. There will be a
> range of speeds over which error rates are low. The intensity of the
> laser affects this, and is I believe adjusted by the burner to some
> extent after doing a short test burn at the start.
> I would expect error rates to rise with very low speeds such as 1x on
> current CD-Rs, as these have been optimised for higher speeds. They
> would be over-exposed at 1X, unless the laser intensity is reduced
> enough to compensate.
> > So, looking at it this way, what is an acceptable C1 rate for audio?
> > I was pleased not to get any C2 errors which Plextor showed in their
> > documentation as being acceptable at a low rate.
> > What are others getting?
> > I had a client ask me how I was burning CDs earlier this year. They
> > have some flavour of Clover analyzer and my CDs were showing lower
> > error rates than their in-house CDs--that was a pleasant surprise!
> > They are burning HHB blanks in HHB audio burners at 1X. Up until
> > tonight, I had burned at 16x ever since I got the Plexwriter CD/DVD
> > burners several years ago.
> Don Cox
> [log in to unmask]