Not these designs. They take a bitstream , do DSP, do the digital conversion to PWM and feed the output. So the actual integrator and filter is the output. There is no DAC on their input.
Digital input amp
I see a few coming on market. Previous threads were quite old.
They take a USB or other input. No DAC on the front end. Just the DSP engine to do volume, eq, etc, then whatever conversion to PCM to feed the class D output. So the only "DAC" is the output stage. This makes sense as it further reduces the functions in the chain. I have not seen objective testing or any reliable subjective testing. The ones I have seen are Infineon processer based. No idea if the output filtering or feedback implementation is up to the Purify quality. I guess the next innovation is the GaNFET output. One has a DAC to feed a sub out. Easy as any old $5 DAC will wo there.
I was browsing and came across the Sajab A30a. ( quite inexpensive) Peachtree has the old Gan-1 but coax PCM only. That would be fine if it managed buffering and clocks internally. Unfortunately my all-in-one only has USB out.
I suspect there is a lot to be learned here but it makes sense to me for the future.
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@tvrgeek What you are describing above means that the DAC is at the input of the class D amp portion of the product. Put another way, the PWM portion of the circuit is at the input of a class D amp, not its output. Digital at its fastest might be 192KHz sampling frequency. Class D amps often switch at 500KHz or higher. You can design a DAC that can produce a PWM output, but it really does have to be at the input of the class D amp in order to work. I know a lot of companies say they have a 'digital amp' but if they also say its class D then the DAC is always at the input to the class D circuitry. |
This technology HAS NO DAC. Please go look at the products. Look at the Peachtree GAN1 as well as the Sabaj. I think NAD has one with built in streamer. PCM in. Convert to PWM. Switch outputs. Integrate. NO DAC. I don;t know what other companies are advertising. The copy writers may not have a clue either. |
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