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In Reply to: RE: Why does a ten year old NOS DAC sound so good? posted by Freo-1 on May 29, 2014 at 16:48:17
No one seems certain about why NOS (digital filterless) DACs produce the sound character that they do. Typically sounding more at ease, and closer to the character of vinyl. There are several theories, but I don't believe that anyone has yet conclusively shown the reason. However, the sound isn't universally better via NOS, in my subjective opinion. NOS DACs also typically exhibit certain subjective faults which digitally filtered DACs don't. Even so, for many among us, the subjective positives of NOS overrides the subjective negatives. It seems that whether an audiophile will prefer NOS over OS or not, depends upon the kind of subjective faults that audiophile finds the more annoying. Rather than one approach always being subjectively superior to the other.
_
Ken Newton
Edits: 05/31/14Follow Ups:
"NOS DACs also typically exhibit certain subjective faults which digitally filtered DACs don't"
I am curious about what you have heard in this context. I use ladder DAC chip based DACs but both have a DF and an analog filter. I think they sound quite organic overall although I still think my analog rig is superior.
I haven't listened too much to NOS DACs but the ones I have impressed.
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
Well my experience so far with NOS DACs is only at the upper end of the price range (auditioning not purchasing that is) and they are very analog as you say but I didn't listen long enough to get the weaknesses as clearly as you have pointed out.
THat being said I have found that ladder DACs with a proper 8x oversampling digital filter and very well designed analog output stage can also sound very analog and lifelike and lacking the synthetic feel of most so-called "high end" DACs.
For reference, I am talking about the Monarchy Audio M24 DAC that uses the BurrBrown PCM63K 20bit ladder DAC with the BB DF1704, passive I/V conversion and an SRPP tube output stage. Resolved, dynamic, and organic.
I also have a Kinergetics Research KCD-55 Ultra that used 2 of the famous UltraAnalog 20bit DAC modules. Also with a Sony 8x oversampling filter and all discrete solid state output stage. Not quite as organic as the Monarchy but even better resolution and very natural tone and world class imaging and soundstaging. Very solid and tuneful bass as well.
Am finding this with my new Lite Audio system too. Most impressed with their implementation of the DAC-83.
big j.
"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."
"...THat being said I have found that ladder DACs with a proper 8x oversampling digital filter and very well designed analog output stage can also sound very analog and lifelike and lacking the synthetic feel of most so-called "high end" DACs..."Yes, and, not only via high native resolution oversampled ladder DACs, but also via low native resolution delta-sigma DACs, I've found. That's the great news, digital didn't kill the music after all. It's only been hiding it beneath many implementation details, including some which otherwise would seem quite trivial.
_
Ken Newton
Edits: 06/06/14 06/06/14 06/06/14 06/06/14
Thanks for sharing your observations. While I agree with some of your conclusions, have to demur on some others.Case in point is the sound stage. The digital playback I've heard that has both the widest and deepest sound-stage is from a Electrocompaniet ECC-1 player. It provides a significantly richer/fuller overall sound compared to NOS DACs, and the stage is both wider and deeper. However, the imaging seems more precise with the NOS DACs. There is more space around the instruments with the NOS DACs, but it (the sound) can seem a bit threadbare compared to a player like ECC-1.
If one could combine the best traits of both approaches, one could retire all vinyl playback rigs. :-)
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
Edits: 06/04/14
to explain why it sounds better. This DAC from AN however still used an Analog filter. Still it's close enough for this discussion.
It was a well done review.
Yes, the reviewer highlights some of the well known technical differences between NOS and OS. However, drawing conclusions about how those technical differences alter the subjective character of the sound amounts to mere supposition.Some believe that linear phase digital SINC filter pre-ringing is the reason for the difference in sound character between NOS and OS, while others believe that it is because OS magnifies the affect of conversion jitter, while yet others believe that it's due to the presence of ultrasonic alias images with NOS. I've even read an theory which holds that NOS provides additional, though unintended, dithering to the the D/A unit. Many theories, but no proven conclusions, to my knowledge.
_
Ken Newton
Edits: 06/03/14
I suppose that's true of most things in audio. Trying to prove that A is better than B is a difficult task when you can put 20 engineers in a room and say here is $20,000 build me what you think is the best sounding loudspeaker and you get 20 completely different products. ESL, Active, Ribbon, line array, open baffle, T-Line etc etc etc.
At some point virtually all of them (that bother to listen not just read graphs) will "make a call" on how the thing sounds and if the superior sound comes from something detrimental to the measured result then a decision is made. At Audio Note the decision is made on the sound. Many companies may make the decision based on a future soundstage or Stereophile review measurements and or which one makes them the most profit margin. Knowing that good measurements is the only way to get a class A designation = more sales they may opt for the better graph over what they actually hear.
I suppose we're left with blind level matched preference based tests. Stick 30 classically trained musicians in a room and see how many choose the NOS versus the "jitter to zero at all costs" units. But even this doesn;t prove much - if it is 16/14 or even 29/1 there is still the chance you'd agree with the 1.
Having recorded professional musicians for over 20 years they are notorious to have very different ideas as to what is good sound. After all they are used to the sound behind there instrument or from within the orchestra. As an audio engineer I usually took a musicians comments about sound with a grain of salt unless he was paying the bill. Heifits once told an engineer I don't care what I sound like but I better be louder than the orchestra.
Alan
My late musician wife refused to help me audition amplifiers some years ago when I had several on loan for in-house evaluation. She said that she could sometimes hear differences, but didn't care. She told me that she was listening to what the musicians were thinking while playing, not the sound that came out of my speakers. (I know she did listen attentively; she once memorized an entire Schubert sonata by listening to an LP that I played twice.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
As other musicians may also attest, I recognise this description so well - listening to what musicians were 'thinking'. Very, very few systems seem capable of suggesting this, no matter how esoteric they sound.
The last system that gave me a sense of this was a complete 47 Labs system. Another, was a non-descript Marantz SACD surround-sound system set up by Ken Ishiwata himself at a UK hi-fi show with some very modest speakers. Still another was one set up by Kevin Scott (such that everyone was compelled to stand and clap at the end of a CD performance). And these still stand out.
My present systems often fool me into thinking the instruments are there. But rarely the musicians themselves, and their intent.
big j.
"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."
"It seems that whether an audiophile will prefer NOS over OS or not, depends upon the kind of subjective faults that audiophile finds the more annoying. Rather than one approach always being subjectively superior to the other."
Hmmm, I think you've just summed up audiophilia in a nutshell. Perfection isn't possible in a spatially undersampled system even if perfect capture and reproduction existed. However I do think there are some things that are universally trying such as crossover distortion and dragging voice-coils. There are levels of "unnaturalness" and as you say, our tolerance varies.
I'm coming to believe that Stereo itself was a mistake. Mono is a clean capture of that which it does then I'd say binaural, surround, stereo. Given the current popularity of "personal audio" I'd opt for binaural especially since I think it works fine in a stereo set-up.
Ultimately it is indeed in the ear of the listener but the GIGO principle is an unavoidable no matter how much loot is poured into the reproducer.
Regards, Rick
You may be onto something. We all have subjective preferences with regard to sound. For example, I find well made tube amps to sound closer to my expectations for sound reproduction than solid state. They have a mid-range presence that no solid state amp can quite achieve. Not everyone would agree, hence the preferences.
Within solid state, I find most class D amps are sorely lacking in midrange presence compared to well made class a a/b amps. The one exception I've heard is the Yamaha MX-D1, which sounds great, especially for class D. It is a special, one of a kind high end unit, which in part explains its outstanding performance.
Getting back to the DAC's the NOS DAC's I've heard just seem to sound more natural than the OS DAC's (in general). The waveforms when looking at the signals from the O-Scope conform that they are different.
The Cosine DAC has a single S/PIDF input (no USB).
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
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