Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it.

---

[ Follow Ups ] [ Post Followup ] Thread: [ Display  All  Email ] [ Digital Drive ]

---

[ Alert Moderator ]

---

RE: Care to expand on this quote

Posted by knewton (A) on June 3, 2014 at 14:19:02

In Reply to: Care to expand on this quote posted by morricab on June 3, 2014 at 08:39:38:

Following, are excerpts of some of my previous comments regarding my own subjective observations of NOS.

OCTOBER 2, 2010:
While NOS (more descriptively called, digital filter-less) DACs has long been a popular topic of discussion here, it appears that many may not have seen those past discussions. Below, are some of my own past comments. There are many posted comments from many others which can be found by doing a search on the terms, DAC and NOS. Here then are my extended observations of NOS via an AD1865 based DAC of my own design which allowed me to switch a typical half-band digital FIR filter in and out of circuit on-the-fly via a toggle switch.

What NOS gets right:

1) NOS delivers CD digital which is non-fatiguing or relaxing, indeed, much in the way that vinyl is. I can listen to NOS for many hours without tiring while standard digital usually has me feeling anxious and switching the music off before even a single CD has been fully played.

2) The soundstage is very open, separating what is often a rather congealed sounding mass of music from standard digital in to a much more natural and three-dimensional sounding presentation. There is a naturalness absent with the FIR filter in, well, except for what sounds like a tonal energy shift to the upper midrange (see further comment on this below).

3) I also found cymbals and bells to have a very natural tone and long decay. The FIR filter seemed to add what sounds like synthetic splashes of white noise to such higher register instruments, making them sound more homogeneous.

4) The sense of dynamic freedom by NOS is not to be overlooked. It's not so much that NOS sounds louder, or like it has greater dynamic range. It's that there is much less of that distracting, 'on alert to quickly turn down the volume' feeling which so often accompanies the build up to crescendos while listening to common, sharply digital filtered, CD playback.

What NOS gets wrong:

1) There is the well known high-frequency roll-off of about 3dB at 20KHz due to the zeroth-order hold operation of R2R ladder DACs. I don't believe that sigma-delta DACs have this problem due to their high inherent oversampling operation, pushing any such roll-off way up in frequency.

2) NOS seems to shift musical energy from the upper bass-lower midrange region to the upper midrange region, altering the tonality of most instruments and vocalists. This highlighting of the the upper midrange is initially pleasing by presenting more musical detail, but ultimately, becomes increasingly noticeable until is reaches distraction. This effect also seems to soften or loosen the impact of bass register instruments, almost as if they were no longer dampened properly.

3) Actually, I'm uncertain whether the following final observation constitutes a flaw or a benefit. Along with the aforementioned shift of energy to the upper midrange I hear a large increase in the ambient field via NOS. While this greatly illuminates the upper midrange, and may even be what's responsible for creating the impression of there being more upper midrange energy in the first place, I'm not convinced it should be there. It's almost as if out of phase (inter-channel difference information) is being artificially added rather than being naturally revealed.

3) While the soundstage sounds deeper and more three-dimensional via NOS, it also sounds less wide. That may seem contradictory, but that is what I hear. The left to right spread of instrument placements was much wider with the FIR filter switched in, but was also much flatter in front to back depth and separation.

My Conclusion:

NOS DACs can provide outstanding overall musicality, aside from an apparent shift of energy out of the lower midrange, and a vaguely unfocused quality.. An anti-SINC equalizer to counter the zeroth-order hold based in-band treble roll-off when if utilizing an R2R ladder type DAC chip also benefits tonality.

OCTOBER 4, 2010:
....Regarding the tonal energy shift which I described. It may just be that there is not an actual energy deficit in the lower midrange, maybe I'm just perceiving an excess in the upper midrange. Such perceived tonal energy aberrations can be difficult to isolate - do I hear a deficiency in the lower midrange creating the impression of an excess in the upper midrange, or do I hear an excess in the upper midrange creating the impression of a deficit in the lower, or some combination of the two? Or, perhaps, as I indicated as another possibility, I'm perceiving the expansion of the ambient field via NOS as disproportionately illuminating the upper midrange, thereby giving the impression of greater energy there and a relative deficiency in the lower midrange.

_
Ken Newton

Edits: 06/03/14

This post is made possible by the generous support of people like you and our sponsors:

Signature Sound

[ Signature Sound Lounge ]

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---