Unique Technology - the past and the future
Over 10 years ago early DACs were all 16 bit ladder DACs, with a precision laser- trimmed resistor creating the appropriate analog level for each of the bits. The DACs worked well and sounded good. They were quite expensive as very accurate resistors were required. Then along came the “single bit” DACs. Rather than using a resistor to create an analog level, pulse width modulation was used. Basically each bit was created by turning a switch on and off for the appropriate length of time. The resulting square wave pattern was filtered to create a smooth output. The expensive resistors were gone, and so was the good performance. Next came the Delta Sigma DAC. It used the same pulse width modulation but rather than creating a single large pulse for each data point, the data point was created with many small pulses. This allows the pulses to be smoothed with a less radical filter, and improves the sound. As you can see, upsampling the input signal to a higher frequency reduces the filtering requirements and thus improves the sound. This is the current
Right Channel
MSB DAC Module
23 bit positive sign DAC
23 bit negative sign DAC
MSB DAC Module (Inverted signal) | Coaxial Out |
23 bit positive sign DAC
23 bit negative sign DAC
Balanced Out
BLOCK DIAGRAM
The Platinum draws from the older, superior ladder technology, but with incredible improvements. The Platinum contains four 24 bit MSB DAC modules (seen below). The Platinum is fully balanced so there is a matched pair of 24 bit DAC modules for the inverted and non- inverted signals on each of the right and left channels. Finally, each DAC module contains one R2R ladder DAC with a 23 bit negative sign and one R2R ladder DAC with a 23 bit positive sign. Together this makes a true 24 bit DAC. This design allows the quieter moments in your music to be true to the music, without the linearity errors near zero that plague normal ladder and
muck up your high end or smear your bass attack. And for those who require a balanced analog output, the separate positive and negative DACs directly drive the balanced outputs, with no analog output stage at all!
Another major difference in the Platinum is the type of output. Essentially all ladder DACs produce a current output. This is converted to a voltage output with a current to voltage converter. This problematic circuit colors the sound and introduces
Front Panel Features
The DAC II has 4 control buttons on the front panel, a knob and a display. The buttons toggle on and off. When on, the LED next to the button is lit.
Upsampling and filtering
The MSB Platinum grants the user the ability to upsample from ANY lower audio standard to four times the rate, but limited to 24bit/192kHz (so CD is upsampled to 176.4k and everything else is 192k). This is a selectable feature and may be turned off. To play a 24/ 192 disc the Platinum only needs to be plugged into a
source directly to the DACs.
The selectable digital filter response permits the user to choose the filter design they prefer. It allows for the selection of a standard
4X
UPSAMPLING
ON
SIGN WAVE (0DB, 19.95 KHZ TEST TONE
SCOPE SETTINGS 2 V/DIV, 10USEC/DIV)
3
