Sony MDS-JA50ES MiniDisc Deck
Spyflash from the Tokyo Audio Fair '96
Sony's MD pages covering the 1996 Audio Fair give information about this unit.
MDS-JA50ES
- On sale from 12/1, MSRP: JPY 180,000 (yow!).
- Equipped with a high accuracy A/D converter and sampling rate converter, realizing high quality sound.
- Adjustable recording level control for both digital and analog input.
- Newly developed tray loading mechanism adopted.
- Rigid vibration resistant FB(?) chassis.
Translation and summary of a Technical Report on the JA50ES
- Sony's new high end MDS-JA50ES deck employs the ATRAC 4.5 DSP chip (CXD2537R). This chip has 20 bit digital audio I/O. Calculations are done in 24 bit ``data'' X 24 bit coefficient word lengths. The block floating calculations allow recording and playback with basically 20 bit (120dB) dynamic range.
- New ``adaptive high frequency control technology'' has been developed, and high frequency reproduction and sound naturalness have been improved. (There's a long explanation of how an algorithm has been developed to adaptively control high frequencies, based upon human hearing and the input signal, in order to best make use of the available bits. The basic message is that the human hearing system is very sensitive to quantization noise in simple signals, so in these cases high frequencies are rolled off (or fewer bits are allocated to them?) to provide more bits for the simple signals. When there are complex signals, we are less sensitive to quantization noise so that high frequencies are once again allocated bits. In short, it appears they've been further improving the bit allocation algorithm).
- The JA50ES's newly developed 20 bit sampling rate converter chip (CXD8591) has a digital gain function included. The center click position on the record level control knob is 0dB, full right is +12dB, full left is -(infinity)dB. You can also select the gain curve function (linear, log and sin), note that gain increases upwards from 0dB are fixed at linear scale.
- Non-Clip circuit. When recording analog, signal clipping can cause distortion. The CXD8591 sampling rate converter can be set to automatically adjust the digital volume level on signals over 0dB to avoid clipping behavior. This is called ``over-level gain down'' (the report says the volume knob is not moved).
- Variable coefficient digital filter. Like the new ES series CD players, the JA50ES can be set during playback to have various digital filter coefficients. There appears to be 4 settings: standard, spline, plane, analog.
- Various track mark functions, level based, as well as 1 minute and 5 minute intervals.
- Resume function (!), just like the portables, starts play where it left off, even after power off.
- Peak hold function, functions during recording or playback.
- Digital out word length selector, 16 or 20 bit digital output can be selected. When connected to another 20 bit machine or D/A converter the unit can do 20 bit dubbing.
- Fade in/Fade out. Digital input recording level and playback D/A converter output can be faded in or out. Fade time and curve can be selected, just as with the digital recording level curve (sin, linear log).
- FB chassis and the BASC (Brass, Aluminum, Steel Construction) Panel.
Tray loading mechanism