New Type of DAC

Something is spooky about D-1 published specs on DR and SNR of 168dB, which are significantly higher than any DAC in the market.  According to manufacture, D-1 has 10 volts line output, so it provides 22dBu max. signal level.  Here are its published specs:

• THD+N at 1kHz (22kHz BW):
  • 0.0002% at +22dBu
• THD+N at 20kHz (80kHz BW):
  • 0.0005% at +22dBu
• Dynamic Range:
  • 168dB (28-bits)
• Signal-to-Noise Ratio:
  • 168dB (28-bits)

At the full scale (22dBu), its THD+N is measured at 0.0002% (let’s take the best of the two).  Expressing that ratio to dB = 20 log(0.000002) = -114 dB.  Assuming its distortion is much much less than the signal (it got to be for a claimed audiophile grade DAC), the SNR = -THD+N = 114dB.  Assuming its noise/distortion measurements are correct, how can its DR and SNR be so high as 168dB which leads to 28 effective number of bits?

How can it be possible?  Can someone shed a light?

Interesting numbers, but how can a DAC add dynamic range to what's on a recording?  One also has the issue of our listening rooms.  Short of being in an anechoic chamber, the lowest background noise in most homes is around 30 dB and often higher.  Assuming one is listening at 100 dB (which is bad for one's hearing for extended periods), that's 70 dB of dynamic range. Add another 10 dB for peaks at the top end (and 110 dB is really unsafe) and we're talking 80 dB.  Sounds below the 30 dB bottom end are lost in room noise.   So, we're back to the issue of what's the point?  

Now I finally understand how the DR = 168 dB comes from.  One of the D-1 specs also says

• Self-Noise 20Hz-22kHz bandwidth:
  • -146dBu unweighted (calculated)

The self-noise is "calculated" under no load (signal) at idle when integrated over the entire frequency bandwidth (noise level is freq. dependent).  Conversion back to the ’ratio’ = 10^(-146/20) = 50 nV (nano-volts=10^-9V).  So, by definition, DR = 20 log(Vfs / Vn) = 20 log[10 / (50x10^-9)] = 166 dB. (slightly deviate from 168 dB due to the calculated self-noise inaccuracy)  Note that Vfs is the full-scale (max.) voltage from its line out and Vn is the self-noise voltage.

I don’t know how other high-end DACs are compared with D-1 in terms of self-noise measure (again, at idle) simply because other DACs do not publish it.  BUT, based on the DR / SNR converted from THD+N measure, D-1 (-114 dB) is actually no better than the top measured DAC such as Benchmark DAC 3 (128dB), Topping D90 III Discrete (131dB) or dCS Bartok (135dB).  *** Note I do not imply how D-1 sounds compared to these top measured devices.

    Just my 2cents as the D-1 is way over my "budget"....but from the discussion I smell BS marketing, lost in measurements. 

  But Misti's question of how can a DAC expand dynamic range above recorded levels reminded me of actually hearing an improvement the other day.  Listening with three different stand alone headphone stacks to a standard rebook cd of     Dire Straits it was obvious that the top tier stack (OPPO 83, I2s, Pontus II 12th, Holo Bliss KTE, Susvara OGs) on some of the very low volume vocal intervals were more detailed and "hearable" while at the same time sudden drum hit or guitar note were still very fast and textured and suddenly loud, compared to the 2 lower performing systems.

   That is what dynamic range we're discussing here is, right?  That is, the lowest level sounds at the same time VS the loudest sounds.  The faster a DAC can react, the better usually. Beside speed the other how is probably in the DSP processing mentioned in the D-1, raise the low volume, increase the high volume, maintain average volume.

  As far as increasing it above the recorded levels that's almost a remaster on the fly and very probably subject to "taste".

I compare DACs to my turntable to see how good they are. They never come close. I would like to compare the new DCS $250,000 DAC to my turntable. Michael Fraemer was jazzed because he said it came close to analogue. So, I've invested in a good turntable and a not-very-expensive streamer from Moon. All I ask is that it doesn't ruin the music, and it doesn't. It's very musical. I've never noticed that it doesn't sound good when the volume is low.