Mola Mola Tambaqui DAC and Streamer Review

[gjm]

A sufficiently high frequency DSD could emulate a PWM
It's all about engineering compromise

True. It could. DSD128 or higher..

 

[boXem]

A sufficiently high frequency DSD could emulate a PWM
It's all about engineering compromise

The concept of PWM is a bit hard to grasp since instead of being coded "vertically" like PCM/DSD, the information becomes coded "horizontally".

Say the hardware is able to handle pulses at 100 MHz, one can oversample to 100 MHz, convert to DSD with a delta sigma modulator and send the pulses to a 1 bit DAC.

With the same hardware, including the one bit DAC, you can choose to convert to PWM. Say the chosen PWM carrier frequency is 3.125 MHz, this means that the pulse length can be chosen between 32 values (32 * 3.125 = 100). Since 2^5 = 32, the information carried by each pulse is coded on 5 bits.
For each doubling of the carrier frequency, you loose one bit to code the information, until only one bit remains and you have DSD.

The engineering compromise is to choose a carrier frequency
- low enough to have the space you need to encode what you want to encode
- high enough to be efficiently attenuated by a not too complicated low pass filter in the analog domain