Jakob1863
Addicted to Fun and Learning
In another thread i´ve mentioned that the system dynamics figure of a 16 bit / 44.1 kHz (aka Redbook CD, i´ll use the RBCD from here) system would be around 55 - 60 dB and that surprisingly that number would be achieveable with the old vinyl system if best possible practice was followed.
For clarification i want to add that these numbers are calculated on basis of a system overall, including the reproduction system and environmental variables.
That is the reason why i would consider something like 76 dB DR for a vinyl system not as achievable, leaving laser turntables and other optical scanning devices aside.
As the usual measurement records were a limiting factor when measuring low frequency noise components, a mechanically coupling device was introduced (for example by Thorens) directly coupled to the bearing of a turntable do assess the noise ground in silence and when rotating. Usually even measured that way the best turntables were around -70 to -75 dB .
An example measurement and a picture of the coupling device:
http://www.connect.de/testbericht/rumpelspektrum-510086.html
In the graph the red curve represents the measurement record, the blue curve the coupling device result and the black one represents the noise level of the measurement setup in silence.
Additionally i reminded to the high frequency limit of RBCD which vinyl does not have and otoh pointed to the difficulties of vinyl if large out of phase content in the bass region is present.
Although under additional constraints the Nyquist limit for the RBCD is 22.05 kHz the more practical limit was/is 20 kHz.
Otoh we know that already during the development of the CD4 system (quadrophony on vinyl) the rear channels were cut using an ultrasonic carrier and were approaching ~45 - 50 kHz , afair that triggered the invention of the shibata diamond cut.
Of course there is a level limit for these high frequency as the RIAA preequalization curve can´t be extended without above 20 kHz. Again afair level of the rear channels was down at least 15 dB .
Surprisingly high frequency content (also down in level of course) was found on a direct to dics record:
http://www.gammaelectronics.xyz/audio_02-1980_TIM.html
Sheffield Lab drum and test record, cymbal crash
For clarification i want to add that these numbers are calculated on basis of a system overall, including the reproduction system and environmental variables.
That is the reason why i would consider something like 76 dB DR for a vinyl system not as achievable, leaving laser turntables and other optical scanning devices aside.
As the usual measurement records were a limiting factor when measuring low frequency noise components, a mechanically coupling device was introduced (for example by Thorens) directly coupled to the bearing of a turntable do assess the noise ground in silence and when rotating. Usually even measured that way the best turntables were around -70 to -75 dB .
An example measurement and a picture of the coupling device:
http://www.connect.de/testbericht/rumpelspektrum-510086.html
In the graph the red curve represents the measurement record, the blue curve the coupling device result and the black one represents the noise level of the measurement setup in silence.
Additionally i reminded to the high frequency limit of RBCD which vinyl does not have and otoh pointed to the difficulties of vinyl if large out of phase content in the bass region is present.
Although under additional constraints the Nyquist limit for the RBCD is 22.05 kHz the more practical limit was/is 20 kHz.
Otoh we know that already during the development of the CD4 system (quadrophony on vinyl) the rear channels were cut using an ultrasonic carrier and were approaching ~45 - 50 kHz , afair that triggered the invention of the shibata diamond cut.
Of course there is a level limit for these high frequency as the RIAA preequalization curve can´t be extended without above 20 kHz. Again afair level of the rear channels was down at least 15 dB .
Surprisingly high frequency content (also down in level of course) was found on a direct to dics record:
http://www.gammaelectronics.xyz/audio_02-1980_TIM.html
Sheffield Lab drum and test record, cymbal crash