"Jay - atldigi" wrote in message
In article , "Arny Krueger"
wrote:
"Jay - atldigi" wrote in message
In article ,
(White Swan) wrote:
Let's take a 1 bit
system. Now we have only two volume values: full volume, and full
silence. using the 6dB per bit formula, we have values of 0dB and
6 dB.
Something to ponder: Why does DSD (SACD) work?
Because it's a different data stream and it's not PCM.
But how do they make 1 bit work if it can only be off or full 6dB?
The point is that digital doesn't actually work that way.
As you no doubt know, there are many forms of digital coding that aren't
anything like PCM. A common non-PCM digital coding method is PDM or Pulse
Duration Modulation, which is frequently used by switchmode power amps. The
classic non-PCM coding scheme that most closely resembles DSD is PDM, or
Pulse Density Modulation.
A DSD data stream is composed of pulses that are basically integrated to
produce an analog signal. Pulses have a value of either +1 or -1. Alternate
pulses with opposite polarities sum out to zero. If the pulses are
predominately +1, then the integrated signal goes positive. The more
predominately the pulses are +1, the faster the integrated signal goes
positive. If the pulses are predominately -1 then the integrated signal goes
minus, and so on.