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In Reply to: Re: You probably missed it...(link) posted by Christine Tham on June 18, 2004 at 03:20:38:
***No I wasn't. You were the one who said it was "impossible" to reach 20kHz at full dynamic range. but clearly the technology to do so was there in the 70s.***No you didn't get my point or are twisting my words.
I said it is impossible to reach 20kHz at the full dynamic range *you* claimed. (80..90dB)Fancy audiophile pressings are limited by the cutting heads limitations just as much as normal pressings.
If hf content is pushed to hard then the cutting head gets into trouble.***So then it's not impossible to have extended frequency response and dynamic range, then, as you originally claim?
***Yep, flat response up to 50kHz? Simply not possible.
The encoded quad info in the disc beyond 20Khz had a lower level.
Follow Ups:
*** I said it is impossible to reach 20kHz at the full dynamic range *you* claimed. (80..90dB) ***And i supplied a counter example to your "impossibility"
you may not realise this, but not all cutting heads are equal. there are different types, and they have different limitations. also, 20kHz at full dynamic range is easy to obtain if you slow down to half speed mastering. widening the spacing between grooves will also help.
just because you have visited one pressing plant and attended one seminar means you know everything there is to know.
by the way, DVD-A has limitations that require filtering as well. 96/24 5.1 channels require MLP encoding to fit into maximum bitrate of 9.6 Mb/s. however, MLP assumes it is able to achieve a certain level of compression.
Some program material cannot be compressed easily and generate "illegal" files. For example, by definition white noise cannot be compressed, so 96/24 5.1 of white noise will generate an illegal MLP file. The solution is - guess what: filtering the high frequencies.
SACD avoids this issue by specifying a higher maximum transfer rate for the player: 16 Mb/s. so if the material cannot be compressed by DST, it is still legal and able to be transferred to SACD without filtering. you do reduce the maximum playing time though.
***by the way, DVD-A has limitations that require filtering as well. 96/24 5.1 channels require MLP encoding to fit into maximum bitrate of 9.6 Mb/s. however, MLP assumes it is able to achieve a certain level of compression.***'require filtering'? Apart from very rare occurring events in normal music content other filtering requirements than that to fulfill the nyguest criteria are not neccesary.
***Some program material cannot be compressed easily and generate "illegal" files. For example, by definition white noise cannot be compressed, so 96/24 5.1 of white noise will generate an illegal MLP file. The solution is - guess what: filtering the high frequencies.***
White noise at full level is very usefull in a music format.
Filtering at 30kHz instead of 40kHz probably solves the issue.
No big deal.***SACD avoids this issue by specifying a higher maximum transfer rate for the player: 16 Mb/s. so if the material cannot be compressed by DST, it is still legal and able to be transferred to SACD without filtering. you do reduce the maximum playing time though.
Obviously dst is less efficient in reducing the bitrate so a higher bitrate from the player is needed.
The maximum playing time is less than that of a dvda with mlp.
DVDA with mlp is a more flexible format. If the bitrate is too high than mild filtering can be used to remedy the problem.
Filtering hf is only needed during the difficult passage.Maximum playing time isn't compromised by a fancy ability to handle vary rare occurring musical signals or non musical signals like wideband noise at high levels.
Frank
you were very quick to criticize limitations in vinyl technology that require certain signals to be filtered or compressed in rare circumstances (and even then the problem can be solved by using half speed mastering or widening the groove spacing).but a very similar limitation is in DVD-A where certain signals require filtering before they can be mastered onto DVD-A.
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