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32.216.149.93
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Edits: 11/18/23Follow Ups:
Here is a good vid that compares a NOS DAC to the Quetest (ok, its an fpga dac):
https://www.youtube.com/watch?v=XmPRQzsM0Cw&t=59s
Cut to razor sounding violins
I have a Schiit Modi Multibit 2 for my headphone setup. This DAC is switchable between NOS and the regular mode. I happen to prefer the regular mode as I find the NOS highs a bit grittier. But it is not too hard to find listeners who prefer the NOS mode. There is a pretty extensive thread on this unit over on Head-Fi.
or are you asking about how NOS compares to sigma-delta?
From a technical standpoint the difference is that NOS has no filtering whereas oversampling DACs include a filter. I've never heard a NOS DAC but many like them. They are certainly not more technically accurate than an oversampling type - there is no filter to remove the aliases and they have a small high frequency roll-off (that is usually compensated by a small boost in the oversampling filter design). NOS DACs have to be a 'flash-type' converter than converts the whole 16 bit, or 24 bit word in one go, whereas oversampling types usually work at lower amplitude resolution (less bits) but make it up by converting them more often and averaging (i.e. low pass filtering) to regain the full resolution.
Is there something inherently better about NOS - I can't see that unless it is related to better phase response because no filter (though the signal will still get low pass filtered somewhere further down the chain by amplifiers and speakers)? Or, it is because the aliases aren't removed and the flash-type DACs are less linear an add a bit more distortion and people like those additions?
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Edits: 11/16/23 11/18/23 11/18/23
There is no pre-ringing if the signal sent to the DAC is band limited, which it should/must be. And there is much irony criticizing digital's impulse response and then praising vinyl - try cutting and playing back an impulse response on that medium!
There have been incredible improvements in modern DACs so I would consider widening your search beyond old filterless NOS DACs. Just my 2-cents worth.The DAC maker featured in that 20 year old article is out of business as best I can tell.
Edits: 11/17/23
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Edits: 11/18/23
...in the body of my two posts directed at you? I thought it was civil conversation but sorry if you felt it was unpleasant.
Edits: 11/17/23
Current DACs offering NOS mode are generally R2R or Multi-Bit DACs. The stated goal of these designs is a more analog or smoother sound.I believe all Delta Sigma based DACs apply over sampling to all incoming signals.
R2R/Multi-bit DACs don't try to become "more Delta Sigma" their entire approach is to sound LESS Delta Sigma-like. Not as harsh, bright fatiguing.
The truth is, the bad rap about harshness with Delta Sigma designs probably lays more with a designer's poor implementation of the input and analog output stages of the DAC and less about the kind of chip used for the digital to audio conversion.
Edits: 11/16/23
"ALL DACs including NOS DACs digitally oversample - the term NOS for a DAC is a non sequitur or a delusion. In the case of NOS it is technically a first order hold oversampling filter. And this digital filter is the worst possible digital interpolation filter to use; it's got horrendous measured and transient timing recovery performance."
Quote from Rob Watts, digital guru behind Chord Electronics:
https://www.head-fi.org/threads/chord-electronics-dave.766517/page-1660
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Edits: 11/16/23 11/18/23
The article you linked to is nearly 20 years old. Lots have improved since then. Is AudioZone the DAC maker still in business?"By removing the digital filter altogether; the impulse response is essentially perfect, without pre or post ringing."
Solving one problem perfectly and not addressing the many others is the easy way out and not a TOTAL solution.
"But from what I have read, NOS DAC's are supposed to time better."
Again, only one parameter is addressed.
From the ~20 year old article you linked to:
"Perhaps these unsuppressed images [in filter-less DACs] were partially or wholly responsible for the warm, slightly opaque yet relaxed, easy-going nature of these DACs?"
Sounds about right based on my experience with a couple NOS DACs. But here's my take on it. "These unsuppressed images were partially responsible for the warm, veiled, and dynamically challenged, almost lifeless nature of these DACs" ...... UNLESS one is playing 'simple music' like a female vocalist and piano. Play anything more complex and it all starts to fall apart sounding congested and compressed.
Edits: 11/17/23
The sample and hold is a filter of sorts but the conversions happen at the input sample rate so I think it fair to use the term NOS.
"The truth is, the bad rap about harshness with Delta Sigma designs probably lays more with a designer's poor implementation of the input and analog output stages of the DAC and less about the kind of chip used for the digital to audio conversion."I would have to agree with that.
And I would have to say that not all R2R / NOS DACs sound better. In my limited experience with two R2R DACs both were smooth and excellent with 'simple music' like a female vocalist and piano but they became 'congested' and lacked dynamics with more 'complex music'.
Edits: 11/16/23
Is this the legendary Abe Collins, after all these years? Good to see you are still caviling about something. Neal
Audiomaven
Yes it is I and Yes there's lots of petty differences of opinion in this audiophile hobby. Always has been.... which is probably true of any hobby.
To me, NOS means New Old Stock, usually used in reference to tubes which were manufactured a few decades ago but which have never been put into service.
Lack of skill dictates economy of style. - Joey Ramone
Many (most?) current DACs oversample (upsample) automatically. You feed it a 16/44.1 from a CD or CD quality streaming service and the DAC converts it, internally and automatically, to something higher, such as 16/88.2. Some DAC upsample all the way to DSD.Even less expensive DACs using cheap DAC chips do this.
Very few current DACs do not over sample the data stream.
Edits: 11/16/23
Yes all of them do (either up- or over-sample) unless of course explicitly sold as NOS.
Inherent to DA conversion is the alias, a mirroring of the audio signal starting at 1/2 fs (fs=sample rate). If you do nothing, this starts at 22 k with a peak (the mirror of the bass) at 40 kHz. To avoid this you need a pretty sharp brick-wall filter starting around 21 kHz or simple accept it and that is exactly what filter less NOS DAC's do.
A simple trick is oversampling. This was introduced somewhere late 80's with the second generation of CD payers. Oversample 4 or later 8 times. As it is digital, all remains the same. So you get this alias but as 8x44.1= 352.8 now half fs will be at 176.4
This is probably out of the range your gear can reproduce and if it can, one might decide to implement a far less intrusive first order filter starting way out of the audible range.
Even today you can buy NOS DAC's based on the original 80's Philips TDA1540 DAC
The Well Tempered Computer
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