DevillEars
Dedicated ignorer of fashion
I think it is important to differentiate between analogue and digital replay when defining any "transport".
The elements of an "analogue transport" would include:
1) Some accurate media drive mechanism (eg: turntable/tonearm/tape drive)
2) Some signal transcription mechanism (eg cartridge, tape head)
3) Some signal level booster where needed (eg step-up device)
4) Output is an analogue signal
These basic elements are all that are required for any analogue source medium.
If we look at a "digital transport", this changes in some areas:
1) Some accurate media drive mechanism (eg: motor/spindle/clamp or HDD)
2) Some signal read mechanism (eg: laser pickup or read mech in HDD)
3) Some timing/buffer elements (eg master clock/output buffer)
4) Output is a digital signal
Before the output signal from a digital transport can be amplified in most audio topologies, the signal needs to be converted from digital to analogue and this is where the key difference exists between analogue and digital transports.
For analogue transports, there is also the need for an interface between the base transport and a line-level pre-amp - a phono stage, which boosts the low output from the cartridge to a level that the pre-amp/power amp/integrated can manage.
In digital transports, a DAC can be viewed as analogous (sorry - couldn't resist) to the phono stage, except it must also convert the digital signal to an analogue signal. (Yes, this is an over-simplification!)
In both of these, it is important to maintain the original pitch, phase, timing, tonal balance, etc. while carefully avoiding any spurious artefacts that would negatively impact the analogue sound to amplified and drive the speakers.
Over the years of analogue replay, since the release of the microgroove stereo LP standard with its RIAA equalisation, the manufacturers of turntables, cartridges and phono-stages have focused on maintaining the "good" and eliminating the "bad" in this chain.
Digital replay has had less time for development and was, initially, plagued by some incorrect assumptions as to what was "good" and what was "bad". The early assumption that "bits is bits" and nothing else mattered was soon disproved when it was discovered that timing errors (aka jitter) could also have a negative effect on SQ. During these "development years" various approaches were adopted in attempts to improve the SQ of digital replay.
This "development phase" is on-going and - in recent years - has been more focused on DAC development rather than transport development (apart from their ability to support emerging digital formats).
Do we - at this point - know all there is to know about digital replay?
I doubt it...
Dave
The elements of an "analogue transport" would include:
1) Some accurate media drive mechanism (eg: turntable/tonearm/tape drive)
2) Some signal transcription mechanism (eg cartridge, tape head)
3) Some signal level booster where needed (eg step-up device)
4) Output is an analogue signal
These basic elements are all that are required for any analogue source medium.
If we look at a "digital transport", this changes in some areas:
1) Some accurate media drive mechanism (eg: motor/spindle/clamp or HDD)
2) Some signal read mechanism (eg: laser pickup or read mech in HDD)
3) Some timing/buffer elements (eg master clock/output buffer)
4) Output is a digital signal
Before the output signal from a digital transport can be amplified in most audio topologies, the signal needs to be converted from digital to analogue and this is where the key difference exists between analogue and digital transports.
For analogue transports, there is also the need for an interface between the base transport and a line-level pre-amp - a phono stage, which boosts the low output from the cartridge to a level that the pre-amp/power amp/integrated can manage.
In digital transports, a DAC can be viewed as analogous (sorry - couldn't resist) to the phono stage, except it must also convert the digital signal to an analogue signal. (Yes, this is an over-simplification!)
In both of these, it is important to maintain the original pitch, phase, timing, tonal balance, etc. while carefully avoiding any spurious artefacts that would negatively impact the analogue sound to amplified and drive the speakers.
Over the years of analogue replay, since the release of the microgroove stereo LP standard with its RIAA equalisation, the manufacturers of turntables, cartridges and phono-stages have focused on maintaining the "good" and eliminating the "bad" in this chain.
Digital replay has had less time for development and was, initially, plagued by some incorrect assumptions as to what was "good" and what was "bad". The early assumption that "bits is bits" and nothing else mattered was soon disproved when it was discovered that timing errors (aka jitter) could also have a negative effect on SQ. During these "development years" various approaches were adopted in attempts to improve the SQ of digital replay.
This "development phase" is on-going and - in recent years - has been more focused on DAC development rather than transport development (apart from their ability to support emerging digital formats).
Do we - at this point - know all there is to know about digital replay?
I doubt it...
Dave
