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Been investigating NOS DAC’s of late, and I’ve been pleasantly surprised at their performance.
For example, recently picked up an Oritek Audio NOS DAC second hand just to see what the NOS sound had progressed over the years. The more I listened to it, the more it sounds pretty musical to me. Not having heard them for a long time, one would have thought that NOS DAC’s would have been lacking in smoothness and detail compared to the plethora of oversampling DACs available, but that may not be the case. The Oritek sounds more like a master tape than most of the DAC’s I’ve heard at its price point.
This DAC has piqued my interest with the NOS approach, so I’m going to try out a Wavelength Audio Cosine DAC with the NOS setup. The topology uses a passive I/V stage, Mangaquest transformer coupling, and a 6GM8 output valve. Should be interesting to see how it sounds.
So, who else has used NOS DAC’s, and what are the observations? Interested in folks take on them (likes, dislikes, strengths, shortfalls, etc).
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
Follow Ups:
Arrange for an Audtion of the TotalDAC D1.
It's the best DAC I've heard, by a margin, and it is NOS, among other things. Very well executed, and interesting/useful options. It's on my shopping list for the NewvYear. A good friend had it on audition, and now a customized version is on order.
Earth First- we'll screw up the other planets later....
Do you mean:NOS and brick-wall filterless?
transients seem perfect and PRAT is wonderful - but to me the highs and lows seem to be "off" tonally but mid range is just about perfect. I could never get over the tonality. I may not have found the "right" NOS DAC ... but after a few of them, I went back to my regular CD Player and recently added a DAC.
Lately it seems that 90% of what goodness you get with NOS/NoFilter can be had with the newer apodizing techniques that seem to be everywhere now - and the bass and trebles aren't as muddled. THough after doing a little experimenting - there is usually a sweet spot - and it is always better to have a phase flat reconstruction filter - even if there is a slight nearly inaudible roll off at the highest registers according to measurements (I, frankly, couldn't hear it).
I think the NOS/NoFilter was a great learning exercise - and many of the lessons are being refined and create the latest wave of DAC's and software.
They are fun - but ...
"Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad"
Edits: 09/12/12
Hi,
Filterless DAC's impose a predictable HF Rolloff.
It can be compensated with suitable analogue design techniques as you may observe here.
http://www.stereophile.com/content/abbingdon-music-research-dp-777-da-processor-measurements
And having implemented a variety of digital filters in a recent project, including dappele-dazing and minimum-philtre (and others) I find that simple "No philtre with rolloff compensations" sounds best.
I wonder why no-one else uses it? Too cheap for the licence?
Ciao T
Sometimes I'd like to be the water
sometimes shallow, sometimes wild.
Born high in the mountains,
even the seas would be mine.
(Translated from the song "Aus der ferne" by City)
The requested page could not be found.
Following, are a few comments I've previously posted regarding my own subjective assessment of NOS. I've edited some bits of those comments for improved clarity and completeness of thought. I include them here for the convenience of those in this thread who may not have realized that NOS has been a popular topic for some time. A fact that was true back in 2010, as the opening sentance of the first post below makes apparent. Enjoy!
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. Whatever it's genesis, I can tell you that it's real.
I performed a simple experiment where I wired the two stereo channels as a difference signal extractor (the old Hafler ambience extraction trick, where the speakers have their negative terminals wired together, but no longer to the amplifier). You can easily hear more out of phase inter-channel information via NOS than with the FIR filter. Whether this is a natural or a synthetic effect, I'm not certain.
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 when implemented along with some purposely warmly colored analog stage to help balance this apparent shift of energy out of the lower midrange, as well as 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.
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.
Or, possibly, the sonic congealing effect audible with the FIR filter switched in is contributing to the impression of it presenting a more tonally balanced mid-band than via NOS. There's much to investigate, it would seem.
I can't quite agree that the tonal shift which I perceive is due to the loudspeaker. I can't readily think of a reason for why there should be such be such an audible difference via a given loudspeaker. The effect is audible through DefTech mini-monitors, BC Acoustic floorstanders, and Martin-Logan electrostats I've variously had recently.
OCTOBER 4, 2010:
....The tonal shift effect I perceive may indeed be DAC dependent as you suggest. The DAC I used for evaluating NOS was an AD1865.The bass impact issue is interesting. While I perceive a lack of tightness, or an excessive looseness, particularly apparent with kettle drum, rock drum kits and bass, I do not perceive a net lack of energy. The energy seems fully present, it just seems to lack focus and a bit of organization.
It is the the placement of instrument images that I hear as being more widely separated via OS, not the ambient field accompanying those instruments. Which might explain why the soundstage sounded wider, and yet also flatter in depth.
_
Ken Newton
Edits: 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12 08/31/12
"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."
The "rolloff" in NOS products is due to modulation taking place toward the upper limit of the working audio range, which is half the sample frequency. Although the average amplitude is indeed down at 20 kHz, the peak amplitude is roughly the same. (The filtering in oversampling DACs "smooths out" the modulation, raising the average amplitude to "flat" up to 20 kHz.) This could be why people don't "hear" the rolloff in NOS DACs. Some might perceive more HF energy, in spite of the measured rolloff. Although some of the HF energy is a result of the modulation.
This modulation is benign when playing simple music, but I think this is what obscures background information and inner detail in complex music.
Uh...no. The roll-off is due to the zero-order hold operation of most DAC chips. Which is more commonly known as, sample and hold operation. It has nothing to do with whether the DAC is R2R (so,ethin which I'd unintentionally suggested due to clumsy writing), or sigma-delta. Nor is it due to modulation. It would be interesting to know where you came by this notion, Todd. Perhaps, you are thinking of sigma-delta modulation. Which is a related topic, but not the cuase of the roll-off effect. The roll-off has to do with the 'stair-step' like shape of most D/A converter outputs.The high-frequency roll-off shape and transition frequency are a function of the sample rate at which the converter is running. The higher the sample rate, the more brief is the hold period. The hold period is the flat 'step' part of the output 'stair-step' waveform. Depending on the implementation of the oversampling utilized with a given sigma-delta converter, the reason such a converter might exhibit less roll-off has to do with it having a higher effective sample rate. This is also the reason why a true NOS converter, one running at the native rate of the input samples and not utilizing any external or internal oversampling interpolation, will exhibit the most severe in-band roll-off effect.
_
Ken Newton
Edits: 09/01/12 09/01/12
"So, who else has used NOS DAC's, and what are the observations? Interested in folks take on them (likes, dislikes, strengths, shortfalls, etc)."
Strengths: Best with small scale music. The lack of digital filtering in this case produces a "palpability" unmatched by its digital-filtered brethren.......... Since there is less "digital" switching going on than with standard DACs, provided sufficient analog filtering is provided, its RFI performance should be good too.
Weaknesses: Not the best for large scale music, heavy rock, or especially orchestral........ Complex passages tend to sound "busy", where for example, it's difficult to resolve individual instruments in the symphony orchestra.
I hear the same advantages to orchestral music as with small ensembles. Not all NOS dacs sound the same.
The cosine DAC arrived yesterday. So far, very impressed! For CD playback, it is as good (and perhaps) better overall than the tube Modwright Oppo, which is high praise indeed.
The DAC does remind me a lot of a good analog source, such as a turntable or high end reel to reel (only without any noise issues to deal with). There does indeed seem to be something going on with the NOS setup. There is noticeable absence of harshness or fatigue with this DAC. One could listen for hours happily with this unit.
More to follow...
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
My Counterpoint DA-10A DAC with the Alta Vista Audio "Rapture" 24/96 upgrade sounds great to me. Best CD sound I've ever had and it's NOS.
I haven't compared any oversampling DACs to it so I can't say how it stacks up against the latest and the greatest. But I'm incredibly satisfied with my DA-10A, it ain't going anywhere!
Best regards, Ralph
I believe my current Grant Fidelity TubeDac 11 falls into the no oversampling category. Its presentation comes closer to the sound of analog than any DAC or CDP I've owned....and that includes the Aack. Great bang for the buck IMHO.
I think they use the CS4398 for conversion, so unless you take the Direct DSD path ...
Yes, all it says in the specs is that the original signal passes through with no oversampling. May not qualify as pure NOS, but the end result sounds pretty good to me.
They say no "over-sampling", but the DAC chip they use clearly does since it has internal digital filter and delta-sigma modulator stages. But as you say, all that matters is how it sounds, and the CS4398 is thought of highly by many. I was just pointing out that it doesn't belong in this thread.
The CS4398 is a complete stereo 24 bit/192 kHz digitalto-
analog system. This D/A system includes digital deemphasis,
half dB step size volume control, ATAPI
channel mixing, selectable fast and slow digital interpolation
filters followed by an oversampled multi-bit deltasigma
modulator that includes mismatch shaping technology
that eliminates distortion due to capacitor
mismatch. Following this stage is a multi-element
switched capacitor stage and low pass filter with differential
analog outputs.
Thanks for all the technical info on the TubeDac 11. I now realize it isn't a pure NOS DAC, but I posted with good intent and not to confuse anyone. Saying a post "does not belong here" is the moderator's call, not yours.......unless of course, you are the moderator. Even though the BiFrost( mentioned below) and the TubeDac 11 do not fall in the "proper" category, possibly some useful technical information has surfaced because of these posts that "do not belong here". No harm, no foul IMHO.
I agree with you that any discussion can be helpful and interesting, and I like reading what you think about your Grant Fidelity DAC. I'm not interested in a moderating job, and obviously wouldn't be very good at it :)
Edits: 08/29/12
No problem. I think we're all here to help each other out for the most part..... and of course, pick up a little knowledge along the way.
The AMR gives several oversampling & upsampling choices; best results to my ears (and manufacturer recommendation) is no over/upsampling. Seems to give a more holistic sound, without the aural equivalent of too much edge enhancement (as one gets when using too much "contrast" in digital photo manipulation, or in video).
"Your liver suffers dearly now for youthful magic moments...so rock on completely with some brand new components"
Pity that it doesn't handle 24/96 files.
This was an AB test against the Ack! DAC both connected to a Krell transport.
.
Dynobots Audio
Music is the Bridge between Heaven and Earth - 音楽は天国と地球のかけ橋
.
Using it with the Dumpty PS like the one in your photo.
Was non-over-sampling, last time I looked, and a very smooth, musical piece.
One of us is confused. I too have finally heard music from digital by listening to a non-oversampling DAC (Bifrost). As I understand, prior to Schiit (and probably some others that I am not aware of), some hand-made non-oversampling DACs were made from New Old Stock DAC chips (unused chips made a long time ago.
So, maybe there is some confusion between non-oversampling vs NOS?
The Schiit Bifrost uses an oversampling digital filter. It is advertised as non-upsampling, meaning no sample rate conversion.
Some NOS DACs do use new old-stock parts, but the NOS designation in this case, and in this context, has historically meant non-oversampling.
"The Schiit Bifrost uses an oversampling digital filter. It is advertised as non-upsampling, meaning no sample rate conversion.
The distinction of "oversampling" vs. "upsampling" is confusing. It is marketing speak that should never have been created. Both are sample rate conversions, with the difference being whether the ratio between the frequencies is an integer or a fraction. Whether one method sounds better than another will depend on details of execution, but the algorithms for doing non-integer are more complex, and hence it is more likely that a poor upsampling design will get a detail incorrect.
A pure NOS DAC has the virtue of being the simplest possible design. Unfortunately, it does not follow Einstein's dictum of making things as simple as possible. A NOS DAC is too simple, i.e. incapable of even reproducing a sine wave correctly at high frequencies, thanks to high frequency images which can beat with the signal signal and produce audible distortion. In addition, there will be roll off of the upper octave due to aperture effect. (The width of the aperture determines the specific filtering provided by the circuit, i.e. the tradeoff between these evils.) However implemented, a pure NOS DAC does not, and can not, provide an output that matches the input signal sent to the ADC that created the recording. The best that can be said about it is that other DACs may be worse, or that its distortion complements other defects in a playback chain.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"A NOS DAC is too simple, i.e. incapable of even reproducing a sine wave correctly at high frequencies, thanks to high frequency images which can beat with the signal signal and produce audible distortion. In addition, there will be roll off of the upper octave due to aperture effect."Mr Lauck, how did you form the opinion above?
The Metrum NOS(Non OverSampling) DAC has gotten rave reviews from no less than half a dozen credible reviewers. See link from 6Moons, which shows a graphic of perfect 1Khz square wave.
Edits: 09/08/12
"which shows a graphic of perfect 1Khz square wave"That is a party trick, often used for selling NOS digital audio.
Ask yourself: where does that 'perfect' square wave originate from?
It has also nothing to do with what Tony mentioned.
Thorin sits down and starts singing about gold.
Edits: 09/09/12
"Party trick"?
Yet another substantiated claim? There seem to be ton here on Digital and PC Audio. But please explain..
For the record, I am actually a fan of Upsampling DACs. So I am not a NOS defender, I just prefer statements be made with facts to back them up.
There is no such thing as a square wave signal that can be represented in PCM. Given that such a signal can not exist in a PCM file, it is nonsense to talk about "reproducing" it correctly.
These forums are not the place to explain the theory behind digital signal processing, especially considering that several years of college mathematics are required before even being able to begin to study this field. Many people here have little more than a high school education when it comes to mathematics, that's even assuming that they haven't forgotten their high school algebra and trig.
The facts exist, and they are on solid ground, much like like it is a fact that 2 + 2 = 4.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
I don't understand why you can't offer a simplified explanation for us non PHD's.
I assume you are implying that NOS DACs are a marketing fad like clear or red vinyl, SHM CD/SACD, or Green Pens?
I mentioned I am a fan of Upsampling DACs, especially integer based. I was just curious as to why you condemned NOS out of the box. There seems to be a fan base. But then again, there is a fan base for $50 Lps which has me puzzled too.
This has been discussed ad nauseum in various AA forums. You can do a search. Werner, I, and others have attempted to explain this several times and based on my experience it is a fruitless quest.In the real world perfect square waves are physically impossible, as they would require infinite acceleration among moving objects or infinite current flow charging a capacitor, i.e. infinite peak power. However, one can procure a reasonable analog approximation to such a square wave generator. If one then feeds this into an analog to digital converter that does not have any anti-aliasing filtering and plays back the resulting waveform through a NOS DAC one will get back the original waveform, but only if the original square wave is exactly synchronized to the clock, e.g. 1102.5 Hz would be an example, since it is 1/40 of the sampling rate. This is the "party trick". Now continuing to use this signal generator and unfiltered ADC, turn the frequency knob on the dial slowly. If you listen to the analog output of the signal generator you will hear a square wave that slowly changes in pitch. However, if you listen to the output of the NOS DAC you will hear ever changing artifacts or "birdies". These are caused by the lack of filtering in the analog to digital converter. Technically, what happens is that the higher harmonics of the square wave exceed 22050, the Nyquist limit, and alias back into lower frequencies. The result are spurious tones at frequencies that are unrelated to the frequency of the input signal. They can even be heard at frequencies lower than the fundamental frequency of the square wave.
To avoid this problem, all decent analog to digital converters that operate at the 44100 Hz sampling rate have a steep anti-alias filter. This filter strips the harmonics above 22050 from the input waveform that is fed to the actual analog to digital converter. In other words, the actual analog to digital converter no longer sees a square wave. The resulting audio file, when one looks at the actual samples, is not a square wave, and the NOS DAC will not reproduce it as such. So there is a tradeoff. The square wave at certain frequencies are less accurately reproduced (their edge is missing) while the square wave at other frequencies are more accurately reproduced (the birdies are gone which are highly annoying and noticeable, whereas there is only a slight loss of the original edge).
So much for square waves. The NOS DAC can't properly reproduce them except in artificially contrived cases because these square waves can not be recorded properly in the first place.
Now, take sine waves. A sine wave at any frequency up to about 20 kHz can be properly recorded and reproduced by a decent ADC - DAC loop. One can easily confirm this by listening tests, including sweep tests similar to what did before with the square wave generator. One can also look at the output on a scope and see a nice stable sine wave, with smooth waveform and an even envelope. However, this is not what one will see if a sine wave in the upper octave is played back by a NOS DAC. One will see a modulated waveform with a time varying envelope. That's because the playback process has not eliminated the image tones. For example, a sine wave at 19000 kHz is 3050 Hz below the Nyquist frequency, and the NOS DAC will create an image 3050 Hz above, at 25100 Hz. The combination of the two tones has an envelope modulated at 6100 Hz. If there is any distortion in the playback electronics, speaker, or one's ear the result will be an audible "beat" tone at 6100 Hz, a frequency that has nothing to do with the original input frequency. If one varies the input frequency in a sweep fashion, this beat frequency will go down as the signal frequency goes up, another audible "birdie" this time due to a poor quality DAC.
All these distortions are real and can easily be generated and measured. They can also be heard, as they are not harmonically related to the input signals. If one has a computer audio system and an audio editor it is not difficult to perform simple experiments that visually plot these effects as well as listen to the resulting distortions.
Incidentally, because of limitations of the 44100 Hz sampling, there is no way that a square wave above 7350 Hz can be distinguished from a sine wave at the same frequency. A correctly working analog to digital converter will record both waveforms with the exact same sequence of samples. This means that it is not possible to build any DAC that reproduces both of these signals correctly, unless one pulls the party trick of selecting an input signal that matches what a particular DAC happens to do. When an audio salesman uses these tricks to peddle their products, this moves from the realm of a "party trick" into the realm of a "scam".
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Edits: 09/09/12
I was able to digest most of your explanation, thanks for taking the time. Of course, some of it was a bit fuzzy. None the less, informative.
This leads us to the question why there is such a fan base around NOS DAC units. Hipster fad? Pleasing, if not accurate sound?
As I mentioned, I find the vinyl revival quaint at best, and maybe this category of digital source component falls into the same category.
The history of NOS convertors can be traced at least back to the 1996 article by Kusunoki, which may take it a little beyond fad ...
Sakura NOS
And Burmester, in the early 90s. Their first standalone DAC used
an instrumentation DAC chip, and could optionally be operated with
its digital filter disabled. The magazines swooned over the 'perfect' impulse response.
The Kusunoki article is typical in that it tried to explain a subjective disliking of orthodox digital audio by an analogy based on a very incomplete or even erroneous comprehension of what is going on (both in digital filtering and in the actual string-of-loudspeakers model).
The resulting images appeal to those with lacking mathematical background (i.e. 99.99% of all audiophiles, including reviewers, experts, and even designers) and combined with the subjective preference for unorthodox digital (NOS) constitute proof that oversampled/filtered digital is obviously wrong.
Thorin sits down and starts singing about gold.
I honestly don't know if it is a fad or not.
Mr. Lauck claims that the NOS implementation is mostly a fraud with respect to the technology, or lack there of, involved.
My point was that NOS designs have been around almost as long as separate DACs have been around in the consumer world, so over 15 years down the road they probably wouldn't be considered a "hipster fad" by most people.
I agree with you. But obviously some have chose to label NOS DACs as inferior on paper.
I took issue with what you said.
But now I see that you do tend to bounce around quite a bit :)
Not too much bouncing...!
Just to clarify my position:
NOS DACs seem to have a following, but some here have labeled them technically inferior, which implies they are popular for some other reason.
Which raises that old, yet interesting audiophile philosophical question. Would you rather listen to sound that was pleasing but not accurate, or accurate but not pleasing?
_
Ken Newton
Edits: 09/09/12
Regardless of what it is, I recommend the schiit bifrost. It sounds good and synergizes well with my system. On that account I endorse it heartily.
Freedom is the right to discipline yourself.
The Schitt Bifrost Dac does not belong in this thread about NOS DACs.
The Bifrost is a standard Delta Sigma DAC and as such it oversamples. What the Bifrost does not do is upsample before oversampling.
I have heard NOS DACs and I find them generally to be excellent sounding components. So I guess if you get terrible measurements but excellent sound then you are measuring the wrong things?
BTW, I own a Bifrost. It is a terrific sounding DAC for the money. Running my laptop with JRiver 17 through Toslink SPDIF into the Bifrost was a simple and inexpensive way to get pretty good digital sound from my system.
My buddy gave me a couple of spare 6GM8 tubes. They are labeled GE, but they state "Made in Holland". They look mid 60's to me. They look the same as 6DJ8/6922 type.
I replaced the tube in the DAC (Amperex 73 A frame). The 60's tube improved the DAC even further (and it already was sounding great).
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
Well, after spending some time with the Wavelength Cosine DAC, I can say with absolute certainty that it is without question one of the finest sounding DAC’s I ever heard. On CD playback, (IMHO) it actually outperforms the Modwright Oppo BDP 95 with the tube upgrade. It also sounds better than the Eastern Electric Mini Max plus.
The Cosine sounds very natural, and possesses sonic qualities one would normally associate with a first generation master tape (or listening in the studio itself). I’ll be keeping this for quite some time.
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
I think the use of the word "scam" in this particular case is over extending, to say the least.
But yes, it is the age old question.
The big advantage with the NOS DAC is that you can use it with software (over/up) sampling which can significantly reduce the aliasing and high frequency drop, BUT bypasses the compromised filter implementations built into the DAC chips.
Unfortunately there are a lot of 16 bit NOS DACs out there which don't take as much advantage of the software upsampling as a higher bit NOS DAC does. NOS DACs which can do 20 bits or more have a big advantage here (the Metrum Octave, some of the Audio GD models etc.)
John S.
I agree that a "NOS DAC" when used with a computer can work quite well, but then I think one has to consider that the resulting DAC is not really NOS. It differs from a traditional oversampling DAC only in which box the filter is located. See the link below for an example of this approach.
If the DAC chip can't have its filter bypassed its filter can be made to do little to the sound quality if it is fed with an oversampled signal. (This assumes as you pointed out that there is enough bit depth.) All of the filter aberrations occur at least an octave higher up the Fscale, as I do it typically two octaves. In addition, any ringing won't be excited at all, if the software filtering is done well, as there will be no energy in the transition band of the chip filter to excite any ringing. This has been the approach that I used with the juli@ DAC and it seems to work with my SABRE chip based Mytek. (Here, upsampling to DSD128 seems to work slightly better than upsampling to 176/32.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Ok. My attempt to clarify:
We have Non-UpSampling (I'll call NUS), Non-Over Sampling and New Old Stock DAC chips (and some combinations of those).
NOS tubes are old but many NOS DACs are new.
Upsampling, all seem to agree, is bad. Some take the purity of the original signal further and do not oversample. And, apparently some do both using old chips?
I don't care too much how things are done, I just know when I hear something that I like. I just wanted to clarify terminology, but it seems that there is much confusion on the 'net about this.
I've always had a slightly different definition:
Oversampling came to be used in relation to the digital filter used in a DAC chip. Upsampling was an increase in sample rate to the data sent to the DAC chip (which was then oversampled by the filter in the DAC chip)
In some instances the upsampling was done in hardware (usually with an ASRC chip) and some times it was done in software. The software upsampling could either be done realtime by a program as it played a file, or the file could be upsampled to a new larger file.
John S.
The Wavelength is a very good sounding DAC. I will be reviewing the AcousticPlan DigiMaster NOS DAC at AudioStream. The review should hit in about 6 weeks. I will also be reviewing other NOS DACs.
Edits: 08/27/12
Thanks to all for the inputs. I’ll look forward to your review of the DAC. I’ll post observations once the unit arrives and get some time with it.
"What this country needs is a good 5 watt amplifier!" (Paul Klipsch)
Do you want digital to sound like vinyl?
Keith.
I'm a reviewer. I don't know how these DACs will sound until I hear them. If you want my opinion, please read the review.
Edits: 08/27/12
I am using an MHDT Havana NOS DAC. I think it sounds very good and really see no reason to replace it in the near future. It does sound very analog like, but doesn't seem to be lacking in resolution or detail.
Oz
Don't worry about avoiding temptation. As you grow older, it will avoid you.
- Winston Churchill
Funny you should mention NOS DACs. I took delivery of one on Friday: a Metrum Acoustics Mini NOS DAC Octave. It appears to have much more in common with "good" sounding analog than just about any piece of digital equipment I've heard .To say that I'm pleased with what I'm hearing from this DAC so far is putting it very mildly !
Right now I'm listening the Lyrita version of Malcolm Arnold's English dances, etc uncompressed flac ripped to HD & played through my Auraliti PK100 into the Octave. It sounds more like what I remember the LP version sounding like on my VPI table . While the CD it originated from sounds pretty good it you probably wouldn't mistake it as the LP you were listening to . I'm telling you this is very, very close.
The thing I'm most excited about is that I can detect an actual "attack" of when a musical note starts & as a result of this the instruments have a sense of solidity that , until hearing this DAC, I wasn't sure I would hear through digital. Granted, I have'nt heard much of the "higher spread" digital gear , but I think a few designers may end up going back to the drawing board just to be competitive after they listen to this DAC.
I would agree that 6moons got what they had to say about the Octave right !
Edits: 08/26/12
The best NOS DAC's use a true buffer and clock alignment to make jitter insignificant to the ear. This technology has been used brilliantly in the AMR products with thier OptiClockLock and similarly with the other even more expensive european TDA1541 DAC.
The good news is a there is a new grass-roots project in the works for those of us who can't afford such products over at DIYA. Would allow the use of not only TDA1541 but other good chips like PCM1704 and PCM63 for NOS. Even allows oversampling from a computer if you are interested in that. I think it is worth checking out
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