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. 

tvrgeek

@tvrgeek Lets impart some knowledge on the PA-10.

I’d guessed given the overall sound of the PA-10 that it was in some way Class D in its architecture, but Gold Note makes no mention of this in their technical specifications. Personally, I’m a massive advocate of Class D technology when it is done well and so I asked Gold Note directly “What Class of amplifier is the PA-10?”. Here is the response I got – “ The PA-10 features quite an interesting design. It is not a Class D amplifier but it leverages a new technology that uses MOSFETs for the output stage, in common with the Class D, featuring an output oscillator (GaN Mosfets with Gallium Nitride), a proprietary design that actually doubles the power of the amplifier when reducing the impedance – exactly as a pure Class A but with extremely high efficiency to deliver great amounts of energy.” So there you have it. 

Sad Gold Note only gave marketing BS as a description.  I would love to see an IEEE or AES paper on whatever they are doing to see if it really is innovative. The  bummer is it is within my price, but only direct sales and no audition/return policy I could find. Their published specs are not defined so even though they are not impressive, not knowing the parameters makes them meaningless.  At what power/frequency is .01% distortion?  Is it .0001% half a Watt lower?   Could be a great amp, could be not so.  Totally useless specs. 

"Well executed" does seem to be the issue. I guess my best bet is a Buckeye/Purify based amp. Either that or go the safe rout with a Schiit Vidar.  I have recently heard a Hypex based amp and it is far better than the older ICE amps or the new CH-FI $80 wonders, but not there yet. 

The mentioned Peachtree "digital input amplifier " I started the thread on, maybe some clarification.  Their point is they did not have a DAC on the front end.   Their block diagram, not mine. 

If the specific implementation of using a triangle and an analog signal to generate the PWM control only being class D, then that implementation needs a DAC somewhere along the line before the conversion.  Two DACs if you count the output filter.  That is not what they were saying as they  do the entire processing from PCM to the PWM control in the digital domain.  I would still call it a class D, just a different way to get there. That is what their literature says. 

 

This is easily summed up -- take sales and marketing literature with more than a grain of salt.

Example -- cigarette companies once used medical doctors in their ads to promote the health benefits of their brand. Advertising execs will spare nothing, perhaps short of lawsuits and jail, in trying to get you to think their product is advanced and unique.

Only way to find out would be to listen to one. Or are you spec sheet jockey?

Totally useless spec like you post I guess. Love these keyboard engineers. Head on back to ASR.

Sad Gold Note only gave marketing BS as a description.  I would love to see an IEEE or AES paper on whatever they are doing to see if it really is innovative. The  bummer is it is within my price, but only direct sales and no audition/return policy I could find. Their published specs are not defined so even though they are not impressive, not knowing the parameters makes them meaningless.  At what power/frequency is .01% distortion?  Is it .0001% half a Watt lower?   Could be a great amp, could be not so.  Totally useless specs. 

 

 

 

Guess Google is new to you:

https://goldnoteusa.com/dealer-locator/

 

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