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Toronto AES BulletinMarch 97
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Our March meeting illuminated the latest emerging standard for digital audio recording: 24 bits, sampled at 96KHz, also known as 24/96. Toronto Section chair Peter Cook introduced 36 members and guests to Steven Lee, president of Canorus Inc, a recording studio supply company. Steven knows there is an active, eager market for 24/96 in Japan, Europe and N.A., where response to his demonstrations has been very positive. The 24/96 format is used in recording, mastering, production and distribution.
Steven's preferred ADC/DAC and sample rate/format converters are from dCS (Data Conversion Systems Ltd.), in the UK To state it simply, this equipment is impressive: all popular I/O interface standards are supported (11 to 96 kHz), heavy-duty clock jitter filtering is standard, 5-bit oversampling is applied, the linear circuitry is the main noise contributor in the DAC at -145 dB (for a -120 dB test tone), and -100 dB spuriae max. for high-level 1 kHz input. Several dither schemes can be selected.
Since 96 kHz is a new sampling rate, interfacing has yet to be officially standardized, but two systems are emerging: L channel data on one AES/EBU input and R channel data on the other, or both channels clocked at twice the usual data rate on one cable.
Steven suggested several reasons for working at 24/96: increased resolution for post-production (e.g. EQ), improved frequency response and therefor fewer time-domain anomalies, archiving at the highest possible resolution for future release formats. While the increased expense may seem like a tough sell in a market that has readily accepted 16/44.1, Steven reports ready acceptance of 24/96 after just one demo at several major recording studios and mastering facilities. He points out that a top-notch reproduction system must be used to reveal the improvement in audio quality. Loudspeakers are still the weakest link.
Steven is of the opinion that the filters in the converters are very important, (assuming good, linear, low-noise behavior elsewhere) and that real-time, (analog) rather than switched filtering is a key to audible improvement, along with low group delay distortion. This is practiced in the dCS equipment. Improved filter design apparently is audible as greater clarity, though it is not visible in a spectrum analyzer display of S/N or linearity.
Next we broke up into groups of 9 people to listen to a demo of the dCS equipment. Playback took place in the CBC Records editing suite using a Nagra-D recorder with stereo music source material, the dCS 952 DAC, a Bryston 4B amp and B&W 801 speakers. Some deficiencies in the playback system were noted: insufficient power amplification, very long amp to loudspeaker cable runs, and aging loudspeaker technology.
Several selections of music were reproduced in 20/44.1 (converter brand X), 20/44.1 (dCS) and 24/96 formats. As is often the case some people were enthusiastic about the audible improvement in 24/96 format, while others were less convinced. Steven explained that on high resolution playback systems the response from listeners has always been instant and unanimous: there is a large improvement. Much informal discussion took place following the listening sessions.
You can find out more about Canorus and dCS at the Canorus web site <http://www.canorus.com/>.
Thank you Steven Lee for a fascinating evening of new technology. Thanks to Peter Cook for organizing this meeting. 24bit/96K...A New Standard For Professional Audio
Our March meeting illuminated the latest emerging standard for digital audio recording: 24 bits, sampled at 96KHz, also known as 24/96. Toronto Section chair Peter Cook introduced 36 members and guests to Steven Lee, president of Canorus Inc, a recording studio supply company. Steven knows there is an active, eager market for 24/96 in Japan, Europe and N.A., where response to his demonstrations has been very positive. The 24/96 format is used in recording, mastering, production and distribution.
Steven's preferred ADC/DAC and sample rate/format converters are from dCS (Data Conversion Systems Ltd.), in the UK To state it simply, this equipment is impressive: all popular I/O interface standards are supported (11 to 96 kHz), heavy-duty clock jitter filtering is standard, 5-bit oversampling is applied, the linear circuitry is the main noise contributor in the DAC at -145 dB (for a -120 dB test tone), and -100 dB spuriae max. for high-level 1 kHz input. Several dither schemes can be selected.
Since 96 kHz is a new sampling rate, interfacing has yet to be officially standardized, but two systems are emerging: L channel data on one AES/EBU input and R channel data on the other, or both channels clocked at twice the usual data rate on one cable.
Steven suggested several reasons for working at 24/96: increased resolution for post-production (e.g. EQ), improved frequency response and therefor fewer time-domain anomalies, archiving at the highest possible resolution for future release formats. While the increased expense may seem like a tough sell in a market that has readily accepted 16/44.1, Steven reports ready acceptance of 24/96 after just one demo at several major recording studios and mastering facilities. He points out that a top-notch reproduction system must be used to reveal the improvement in audio quality. Loudspeakers are still the weakest link.
Steven is of the opinion that the filters in the converters are very important, (assuming good, linear, low-noise behavior elsewhere) and that real-time, (analog) rather than switched filtering is a key to audible improvement, along with low group delay distortion. This is practiced in the dCS equipment. Improved filter design apparently is audible as greater clarity, though it is not visible in a spectrum analyzer display of S/N or linearity.
Next we broke up into groups of 9 people to listen to a demo of the dCS equipment. Playback took place in the CBC Records editing suite using a Nagra-D recorder with stereo music source material, the dCS 952 DAC, a Bryston 4B amp and B&W 801 speakers. Some deficiencies in the playback system were noted: insufficient power amplification, very long amp to loudspeaker cable runs, and aging loudspeaker technology.
Several selections of music were reproduced in 20/44.1 (converter brand X), 20/44.1 (dCS) and 24/96 formats. As is often the case some people were enthusiastic about the audible improvement in 24/96 format, while others were less convinced. Steven explained that on high resolution playback systems the response from listeners has always been instant and unanimous: there is a large improvement. Much informal discussion took place following the listening sessions.
You can find out more about Canorus and dCS at the Canorus web site http://www.canorus.com/.
Thank you Steven Lee for a fascinating evening of new technology. Thanks to Peter Cook for organizing this meeting.
Reviewed by John Fourdraine.
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1997 at 21:39
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