DMAS Design [SPDIF-Optical]

Ferather · May 1, 2024

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An upgrade for optical pulses, and PowerDAC's, both apply to the DMAS sound system.

Note: The total THD, THD+N for the main DMAS audio output should be extremely low (SoC mostly).
Conversion to power (main THD point) is done by each speaker (PowerDAC).

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Ferather · May 3, 2024

Here is a SFX digital filter (I got the idea from ferrite beads), it attenuates frequencies beyond the set value, which is set to 22kHz. Human hearing range is 20Hz-20kHz so 22kHz is above.
Digital sample rate divided by two, equals the maximum frequency it can represent (without aliasing), 44.1 = 22.5kHz, 48 = 24kHz audio frequency.

In an ADC situation (analogue to digital), if a DMAS was to support analogue, an analogue filter would do a similar job.
Oversampling allows the higher frequencies to be captured, then removed (down sampled).

Technically speaking, in 32 bit float terms, the attenuation should amount to 'silent aliasing' if any occurred.

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Ferather · Wednesday at 6:55 PM

Interesting SPDIF item: https://www.matrix-digi.com/product/20/X-SPDIF_2 | Not a DMAS but similar in the basic sense.

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My RTN method uses nil start-stop (off state) and packets, it does have a clock, however its a bit clock.

Ferather · Thursday at 7:07 PM

Here is something else similar to my DMAS design, except the DMAS speakers have their own individual P-DAC, it does focus on lossless audio and bitperfect audio data.
Personally I feel the unit is potentially over priced, considering it doesn't seem to do multichannel. It can be updated via firmware updates.

It uses TOSLink and advertises < 0.001% THD (lower than, distortion), 2 Ohms balanced (see the specs sheet).

https://ecdesigns.nl/product/powerdac-sx/

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Not as flexible as the DMAS, as the programmable SFX, MFX and EFX processing points can be used in various ways, including SFX lookahead and MFX or EFX application.
AVR these days also use 32 bit (not float unfortunately) digital processing, but then a 24 bit DAC, in better cases a 32 bit DAC, but still an amp.

The DMAS (Digitally Managed Audio System) is fully digital right up to, into, the speaker, which is essentially a digital speaker.

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DMAS note, since there is no DAC or analogue amp, the number of channels is limited by input, processing, power supply + physical combo modules (per speaker).