Which DACs bypass digital filtering?

[opus101]

54 minutes ago, Jud said:

I suppose it depends on how much distortion you like.

 

Its not that, at least from my perspective as a designer of NOS DACs. Rather its more to do with the dynamic performance of DAC chips. Put it another way, it depends on what proportion of the time you want your DAC's output to be at the wrong value. NOS minimizes this fraction.

[opus101]

That spectrum looks to me to be an incontinent NOS. By using the TLA 'NOS' I was only referring to the lack of oversampling, not to the lack of filter.

[opus101]

11 minutes ago, Miska said:

There's just no advantage in trying to avoid digital filters, you can do all you can do with analog filters and more, without the extra problems.

 

My own aim in designing NOS isn't trying to avoid digital filters. Perhaps other designs have that aim, I wouldn't know. Do you think they have that as an aim?

[opus101]

7 hours ago, Miska said:

Oversampling == digital filters. Or maybe you want to open up a bit more what is your aim specifically.

 

No secret about that - its to get the best SQ at the lowest BOM cost. Adding a digital filter adds to the BOM. Admittedly its not a huge cost up in absolute terms to introduce a $2 ARM SoC but in the context of lowest cost, that is significant.

[opus101]

2 minutes ago, Miska said:

If you do that in playback software, it doesn't add any cost!  If you are already using computer for playback, you can as well utilize it's CPU power, instead of keeping it running do-nothing-idle-loop.

 

Yes, I see. However there's no computer being used for playback, its a portable application.

[opus101]

I consider that more in the realm of transportable than portable

[opus101]

55 minutes ago, buonassi said:

So through an OS DAC, you're hearing a wave form that's been transcribed two times (once via ADC decimation and another through DAC reconstruction).  My theory is that by omitting the latter, you get one step closer to the original wave form.  Yes, at the expense of IMD nasties, etc. 

 

If you use a fairly steep analog reconstruction filter - to attenuate those IMD nasties - NOS gets even better IME.

[opus101]

46 minutes ago, Em2016 said:

"With analogue electronics, very tiny amounts of RF noise will cause intermodulation distortion with the audio signal, and the intermodulation products is noise floor modulation. The effect is that the noise floor changes with signal level, and the effect is very audible - you perceive it as a brightness to the sound quality. Less noise floor modulation, smoother sound quality.

 

While I'm in agreement with Rob Watts on the importance of minimizing noise modulation I suspect the subjective effects are rather context-dependent. In my experience the presence of noise modulation hasn't been limited to just perceived brightness, it extends to other factors such as loss of ambience information, greying out of tonal colours, flattening of the soundstage and loss of overall dynamics.

[opus101]

Quite likely they know nothing of FFT gain so they just read that figure off their FFT. It would equate to the noise in a rather narrow bandwidth, perhaps <1Hz. But without knowing parameters of the FFT (number of bins, windowing) its relatively a meaningless number.

[opus101]

14 hours ago, The Computer Audiophile said:

What makes you believe half aren't true NOS? Serious question. 

 

I suspect 'NOS' no longer has its original meaning of No OverSampling. Any DAC using an S-D modulator cannot be NOS. As far as I'm aware all AKM, Wolfson, Cirrus and ESS DACs are S-D architecture and therefore cannot be NOS in its true sense. (I'm speaking only in the context of PCM here)

[opus101]

18 minutes ago, barrows said:

This is incorrect.  Just because a DAC chip has a SD modulator on board, does not it mean the signal passes through that SD modulator in every configuration: AKM, with their "direct DSD" mode are an example of this (this can be easily understood by looking at AKM data sheets).  

 

Yes, that's why I added the qualification in brackets at the end. I wasn't talking about DSD input modes.

[opus101]

PCM1795 relies on oversampling and noise shaping for its operation. Therefore it can't be 'NOS' in the original meaning of the word. However there is a DIY implementation of PCM179X chips which does use 'NOS' in the product description, I take it by 'NOS' they just mean they found a way to bypass the first upsampling filter on the chip. I very much doubt that Asus has taken that route in their Essence DAC.