Thoughts on the future of HiFi

[Sir Terrence the Terrible]

Mr. Terrible said that NOS DACs have to use brickwall filters and that they ring. You stated that the decision comes down to choosing perfect frequency response or perfect phase response, the former of which requires the use of brickwall filters, which causes ringing. The implication with both of these posts in mind is that NOS DACs use brickwall filters, which ring, and this achieves perfect freq. response. The alternative, implying this is the route chosen by OS DACs, is perfect phase response, and a rolling off of high frequencies.

Maybe I'm just misreading this, and of course I shouldn't take what two entirely different people say and frame it as if it's coming from one source. But it reads like NOS DACs must use brickwall filters - however, some clearly do not. I'm definitely interested in the MHDT Havana DAC, which from my readings does not oversample nor use brickwall filters. I don't know how it handles phase response (to be honest I'm not even sure what phase response is). The reviews of MHDT DACs however, of which there are many, are positively glowing. How bad can this ringing be?

Ringing can sound quite bad, as it can give the sound a hardness, harsh digital haze that is very noticeable and not very musical. The Havana incorporates tubes in the signal path, and that can mitigate these characteristics quite a bit. However when compared to well designed up sampling or oversampling(algorithm) DAC, they can sound less detailed and airy, and a bit smoothed over. On the plus side, they can sound very natural(still less detailed) and easy to listen to much like analog. Tubes are used to buffer the signal which mitigates the need for a filter(supposedly). This however leaves the digital noise intact, and you are forced to use the natural aging of the hairs in the ears to filter that out(roll off the sound). For those like me who's hearing has not degraded that much(I can still hear a tone at 18khz) that noise results in less air, and a rather dark sound. Another characteristic of NOS DAC's is they can make a poorly recorded mix sound more musical, which leads me to believe it is not very accurate. A poor recording should sound poor period. That's accuracy.

Another issue is that they don't sound good tucked into to everyone's equipment. In other words, no universal compatibility. This is much like tube amps. If your system shades on the brighter side of things, NOS DAC's may be a good match for your system. If your system chain is flatter or even slightly laid back, there is no way it will sound good. They would probably sound pretty good on a computer based system which is why Poppa likes it so much. From what I heard, the sound of NOS DAC's deteriorate as the components within the system age. It is very parts intensive design.

I am going to add that I prefer high resolution audio over any CD based band-aid. Oversampling, upsamping, no filter tube signal paths, brick wall filters are all bandages that are not needed if the sample rate is above 48khz.

[Sir Terrence the Terrible]

That's what I am asking too. Thanks for the run down guys, but since I know there's no audible "ringing", does this mean the ringing is actually diminishing what I am able to hear?

Since there is a tube in the signal path after conversion, it is used as a filter along with the listeners hearing capability. The use of the tube does reduce resolution just a bit though, and I suspect the cause of this is no word re-clocking within the system.

BTW, my DAC in the H/T is a 4 x TDA 1543 using a DIR 9001. I just love it to bits and have done tons of comparisons with it. Gives the music such a natural sound, it's mind boggling.

Natural sound is a quality of NOS DAC, but it comes at the expense of subtle details within the mix. Not a big deal if you don't have the master tapes to compare the sound to.

[RGA]

YBArcam

I have had a number of CD players through here and at my favorite dealer - Soundhounds in Victoria. The player I am currently reviewing is The CD 2.1x MKII and the interesting thing is that it takes on more Solid State attributes being discussed in this thread than tube attributes. It doesn't paper over the cracks and homogenize recordings the way my Cambridge Audio CD 6 player does or the way the Bryston BCD-1 does where it "helps out" lesser recordings.

The 2.1X is doing an extraordinary thing in that seems not to be presenting as much of an inherent signature signature sound of its own on the recordings. By not having a pile of band aid technologies it is allowing everything on the disc to come through unlike other players that noise shape and filter out music they are arguably taking music program with them. Remarkable.

There is nothing "valve-like" about the sound of this player and you will be sorely disappointed if you want something that sounds mushy or warm. The 1.1 I compared against a Sim Audio and Bryston BCD-1 - all three use the same Philips L1210 transport mechanism and it's interesting that the AN 1.1 sounded the most open, and the most "airy" of the bunch.

The other two in direct comparison sounded darker and less transparent again making me want to turn the volume up to hear what is on the disc. Though the strange thing is they had more of a black back drop in a way that the AN did not. I will have to audition more here to figure out what is going on there. Still it should have been the other way round since the AN is using a tube in there someplace - like a higher noise floor though no noise whatsoever can be heard. WTF? was my reaction.

Bass was handled a bit differently as well. I had the Pulp Fiction soundtrack and a Santana Disc the stood out because the bass of the Sim Audio and Bryston seemed deeper on one track and vocals seemed a semi-octave lower while the AN the same track the vocals seems airier and in some respects vocally strained. Yet on another disc the Sim/bryston players played the same kind of bass lines as previous and with most all the music I brought in this general genre while the AN then came in with deeper bass than those two on a different track. The previous two players clearly presented the signature stamped on sound the units are pushing on every disc while the AN was bouncing from disc to disc. Where there was real bass - you get it and when it's not there you get a lighter presentation while the other two players presented very similar sounding results from disc to disc to disc while the AN was putting out considerably different results from disc to disc to disc. Illustrating more of the differences between the recordings.

My Cambridge Audio CD 6 in comparison sounds veiled and brooding in comparison with a lack of openness and even a stunted treble. Quite intriguing results since the tube should actually sound veiled and warm and dark yet it is this bizzaro world of reversal. We'll see when I get more time with it and run wildly different music just what is happening. Perhaps there is something to the chipset as this guy seems to suggest http://www.lampizator.eu/lampizator/...note_dac4.html or the oddball topology diagram shown here http://www.audionotekits.com/agrovedac.html

[YBArcam]

Thanks for the responses RGA and Terrence. I enjoyed reading through this thread even though it has gone massively off topic from what the OP planned. There is lots of good debate here. I guess there is no consensus though, other than perhaps it depends. It depends on the ears of the listener and the associated gear, when determining which amp or CD player fits best into a given system. I look forward to listening to Audio Note sources (CD players and turntables ~ their way of doing things seems different enough to warrant a serious look), valve amps, SS amps, and NOS and OS DACs. Up till now I've limited myself to SS and oversampling and filtering players, which isn't unusual for a newbie. But for my next system change in probably a few years it'll be time to branch out a little, at least in terms of my search.

[RGA]

There are too many viewpoints and technical arguments and hoopla in both camps. I gave up years ago going down the paths (sorta went down it here too) but I am simply not interested in technical arguments that don't remotely support what it is that I hear.

I have never heard hybrid amps that I liked and yet recently had some hybrid monoblocks in and they very much impressed. At CES I heard speakers that I normally have not at all liked and some of them wound up being some of the best I heard there.

I used to be a numbers guys interested in big power, slew rates, IM and TIM and THD and amps and ability to double into 1ohm and all that wondrous stuff. It is with almost great frustration that I could actually like SET, tube non oversampling CD players, and vinyl. All of which is technically absurd. And when a company adds them all together the result should be a system so far out of whack as to be utterly ridiculous. And, not to get too far off here, I hate to say it but it almost sounds like a religious conversion. As an Atheist of the Richard Dawkins camp I don't like the idea of supporting what looks to be a religious cult of gear. It bugs my science/philosophical sensibilities.

Take headphones. You can have the best sounding headphone in the world but if it is uncomfortable it's useless. You can have the most technically accurate stereo in the world but if it sounds better in the OFF position then being technically accurate isn't much consolation.

Besides, the future of hi-fi is unwritten. In 25 years it is very possible that people will still be cutting vinyl and selling tubes while 10 year olds will be looking puzzled when you talk about CD. Hell, a school I was at the other day subbing had a Laser Disc player. No discs and I had to explain to the kids what a Laser Disc was. I have about 50 of them someplace but no player. They're a hoot - a strange little oddity now.

[Ajani]

Despite the tech debates in this thread (I've certainly enjoyed tossing around a few theories), I don't think there is any one answer in HiFi yet. If there was then everyone would use it. All technologies have benefits and disadvantages. So it really comes down to personal preferences. Also, many of us in HiFi get obsessed with one tech or the other and prejudice ourselves too easily. This is why you see persons having to confess that X brand or Y tech surprised them by sounding good... For example; Just because someone has never heard a horn speaker they like, doesn't mean that all horns sound bad, and one day that person may well find a horn that does it for him... I've seen persons bad mouth a particular tech/brand for years and then turn around and buy them (perhaps their tastes changed or perhaps they were too prejudiced to give the item a fair chance before, either way it shows how silly it is to get obsessed with any one belief system)...

As I said at the beginning of this thread: we will still be debating tech in the future. And until we finally figure out how to measure everything that affects why we hear what we hear, then I can't see any one tech reigning supreme. Sadly, I find that too many brands are either obsessed with traditional (insufficient) measurements, while others seem to just dismiss measurements entirely. So in extreme (yet not so uncommon) scenarios you'll have brands producing 'technically perfect' but awful sounding gear, while at the other you'll have a designer in a remote cave in Japan tuning an exotic amp by ear, that sounds magnificent but has a 50% chance of exploding and killing you, when you press the power button...

[RGA]

I think most manufacturers pay close attention to measurements. It's being a slave to them when they are so lacking on so many levels that you rightly note. Audio Note pays close attention to measurements which is why they get closer tolerances than anyone else on a number of fronts. The TT3 is an in house design and it's technically superb. I'd make the case that to design a cd player without filters and oversampling you better know what the hell you're doing from a technical standpoint to not have a hint of blur, ringing or any other anomolies. The fact that others say it can't be done is usually indicative of their abilities and not necessarily the competition.

I don't entirely agree with your point that everyone else would copy. There are clear marketing reasons not to copy because everyone will think your not innovative. And there is also a "cost" involved where it may be considerably higher in cost to make a given design over another and if like most companies you are creating product for a price point it may not be possible to copy, meet the price point. And if you copy and you get caught you may get a lawsuit filed against you. It is far easier to design something that looks sexy and you can advertise rather than try and copy someone else and reduce profit.

[Sir Terrence the Terrible]

I agree with Ajani, and it has been my assertion all long; it all boils down to our personal preferences, of which no better or best tag can be effectively applied. It all becomes too subjective for hard fast generalizations which are applied different designs. Once again, there is more than one way to skin a cat.

Everyone has different taste when it comes to audio(and are far less critical when it comes to video), and that is why there are so many different ways of reproducing it. Every design has a market out there, or it goes away for lack of sales. Everyone has the right to re-examine what is good sounding for themselves as their taste in audio change. This is based on the reality that the ear's sensitivities change over time. What we could hear at 20, we cannot hear at 50 and above. Sometimes the deterioration happens early in ones life, and sometimes much later. One of the things I have learned over the years is that ones taste in audio formats and technology are not necessarily driven by sound alone. Sometimes it is familiarity, sometimes visceral, others it is what makes them relaxed and comfortable. It is a known fact that analog sound relaxes the brain, and its euphoric qualities stimulates our emotions which changes the way we listen to it. Digital stimulates the brain, makes us alert and not relaxed, which makes it harder to obtain a emotional attachment to it. Even this theory while recognized, is not universal to all listeners. It does go a long way to explaining at least some differences as to why some people gravitate towards one technology or another.

I think the idea of some tube component and amp designs being insinuated as forward thinking is not founded in fact. The analog world is so old that it has had many chances for different playback designs to be explored and refined over the years. Technology has been introduced, used, and fallen by the wayside for other perceivably better technology. Later down the road, they are re-introduced when the quality of parts(and understanding) come along. Applying analog technology to digital recordings makes the digital recordings sound more analog. Those who love analog have adapted their old technology to make a new technology sound more like the old technology. Analog is what they are used to, and what they like no matter what trade offs there are to obtaining it. If you think there are no trade offs, listen to a digital master reproduced by high quality tube based source in front of a SET or other tube based amp. The playback system changes the sonic character of the master noticeably. The same with analog audio trans coded to digital - it is going to sound different. Better? not to everyone. Different? anyone can hear it.

If you like if you like the various tube based amplifiers and source components, nothing wrong with that. It however is not a better choice than digital audio and SS based amps. Good design is good design, good implementation is good implementation, and good system synergy is good system synergy.

My only issue with analog sound now is its lack of multichannel ability. Otherwise as I have said before, there is nothing like a recording on 3" magnetic tape encoded with Dolby SR, except high resolution digital.

[Sir Terrence the Terrible]

I'd make the case that to design a cd player without filters and oversampling you better know what the hell you're doing from a technical standpoint to not have a hint of blur, ringing or any other anomolies. The fact that others say it can't be done is usually indicative of their abilities and not necessarily the competition.

The reality is while you have eliminated the digital filters, but you have implemented an analog one via the tube being used as a buffer. You are also leaning heavily on the hearing capabilities of the listener by allowing anti aliasing to take place, and using the tube to smoothen, disguise and shape its negative effects. You are "analoging" the digital sound and there is nothing new about that. If there is no brick wall filter, there is no ringing or blur, that is well known. The end effect is a unique sonic character, which allows you a marketing tool you can use to compete on the market. It is called product differentiation. Innovation and differentiation is driven by the competition, this is also well known.

I think what Ajani means is a lack of product differentiation, not exactly copying.

[theaudiohobby]

It is a known fact that analog sound relaxes the brain, and its euphoric qualities stimulates our emotions which changes the way we listen to it. Digital stimulates the brain, makes us alert and not relaxed, which makes it harder to obtain a emotional attachment to it. Even this theory while recognized

Sorry for being pedantic, the output of a DAC is an analogue signal and strictly speaking no one ever really listens to digital but to a analogue output recovered from a digital encoding scheme. And if the sampling frequency and word length are high enough, it's becomes impossible to differentiate between a signal that passed through an ADC-DAC stage and one that hasn't. Therefore I doubt that this theory has any credence at all.

[Sir Terrence the Terrible]

Sorry for being pedantic, the output of a DAC is an analogue signal and strictly speaking no one ever really listens to digital but to a analogue output recovered from a digital encoding scheme. And if the sampling frequency and word length are high enough, it's becomes impossible to differentiate between a signal that passed through an ADC-DAC stage and one that hasn't. Therefore I doubt that this theory has any credence at all.

First, you are out of the context of this discussion. We are not talking about high resolution audio(I have already made my case on that). We are talking about CD audio.

Secondly, you are being very pedantic. What I describe is not a theory at all, it is a proven fact. AES several years ago had one white paper submission (and exhibit) that looked at the brain activity of quite a few listeners while listening analog recordings on a analog based system, and a digital recording on a digitally based system. The brain activity was totally different with the listeners of the analog recording having brain activity that showed relaxation and emotional response. Brain activity slowed, and the area of the brain that was stimulated is where the emotional response activity happens. The listeners relaxed while listening.

The digital recording produced increased brain activity, but not on the side of the brain where emotional responses come from. That area was no longer stimulated, and the increased brain activity showed there was no relaxation. So whether you think the theory has credibility or not is irrelevant to the facts.

Lastly, just because a digitally encoded signal passes through a DAC, and becomes analog, does not mean it erases it's digital heritage. The only time that signal was analog, was when it was in the air. After it hits the microphone and is transcoded to digital, all of its analog character has been transformed into 0 and 1's. This changes its waveform, and that waveform does not change back to a analog looking waveform just because it passes through a DAC.

[theaudiohobby]

What I describe is not a theory at all, it is a proven fact. AES several years ago had one white paper submission (and exhibit) that looked at the brain activity of quite a few listeners while listening analog recordings on a analog based system, and a digital recording on a digitally based system. The brain activity was totally different with the listeners of the analog recording having brain activity that showed relaxation and emotional response. Brain activity slowed, and the area of the brain that was stimulated is where the emotional response activity happens. The listeners relaxed while listening.

What paper would this be? A single paper submission does not in itself constitute established theory. The paper was probably forgotten because it's conclusions could not be replicated as well as it flying in the face of other established theory.

Lastly, just because a digitally encoded signal passes through a DAC, and becomes analog, does not mean it erases it's digital heritage. The only time that signal was analog, was when it was in the air. After it hits the microphone and is transcoded to digital, all of its analog character has been transformed into 0 and 1's. This changes its waveform, and that waveform does not change back to a analog looking waveform just because it passes through a DAC.

This whole thought is simply wrong, what is digital heritage? If the bit depth and sampling rate is insufficient, what digital heritage would accompany the recovered analog signal. what digital heritage accompanies a recovered CD signal aside from the fact it does not capture any data above 22Khz?

"This changes its waveform, and that waveform does not change back to a analog looking waveform just because it passes through a DAC"

The converse is true, it changes back to an analog waveform in it's entirety, that's a fundamental principle in digital theory.

[Sir Terrence the Terrible]

What paper would this be? A single paper submission does not in itself constitute established theory. The paper was probably forgotten because it's conclusions could not be replicated as well as it flying in the face of other established theory.

If you read what I said clearly, there was a exhibit that went along with the paper. You were allowed into to dedicated listen rooms(just as I described), and the test was administered just as the white paper test was. The conclusions done in the booth were exactly the same as the white paper described, and you could see the measurements taken of the brain activity right after the test was done. It correlated exactly to the measurements outlined in the white paper. It was peer reviewed, which establishes its legitimacy. There has been nothing to dispute this since it was submitted. So it was probably forgotten is nothing more than your theory. It hasn't been challenged is more accurate.

This whole thought is simply wrong, what is digital heritage? If the bit depth and sampling rate is insufficient, what digital heritage would accompany the recovered analog signal.

Let's start with the waveform. Once a analog signal is encoded to 16bit resolution, it appears as a stair stepped waveform, unlike a recorded analog which is more rounded. A DAC see's that waveform, and attempts to transcode that waveform exactly as it is represented - a series of snapshots that represent a stair stepped pattern. Remember, there are two chief distinctions between an analog and a digital signal. The first is that the analog signal is continuous in time, meaning that it varies smoothly over time no matter how short a time period you consider(the rounded waveform), whereas the digital signal, in contrast, is discrete in time, meaning it has distinct parts that follow one after another with definite, unambiguous division points (called signal transitions) between them.(the square tooth waveform). A DAC will represent the same square tooth pattern it had during encoding. That is the beauty of digital audio, its input looks just like the output on a high quality DAC. However what is good in theory is not always good in the field. Jitter is a problem with digital that is not a problem with analog. Aliasing is a problem with digital that is not a problem with analog. Quantization errors (noise) occurs with digital audio, that does not occur with analog, and overload characteristics of digital are profoundly different than that of analog. The addition of dither will also make a digital waveform profoundly different than a analog waveform. In saying this, even after conversion, a digitally encoded signal's waveform will look different from a analog recorded waveform. In the field using real world ADC and DAC, all things are not perfect until the bit and sample rate are increased dramatically from 16bit 44.1khz.

what digital heritage accompanies a recovered CD signal aside from the fact it does not capture any data above 22Khz?

A different waveform pattern just to start.

"This changes its waveform, and that waveform does not change back to a analog looking waveform just because it passes through a DAC"

The converse is true, it changes back to an analog waveform in it's entirety, that's a fundamental principle in digital theory.

That is a theory argument, not a real world one. If all things were perfect, you would be right. But in the real world all things are not perfect, and that is a fact. No signal chain is perfect whether it is digital or analog.

[theaudiohobby]

If you read what I said clearly, there was a exhibit that went along with the paper. You were allowed into to dedicated listen rooms(just as I described), and the test was administered just as the white paper test was. The conclusions done in the booth were exactly the same as the white paper described, and you could see the measurements taken of the brain activity right after the test was done. It correlated exactly to the measurements outlined in the white paper. It was peer reviewed, which establishes its legitimacy. There has been nothing to dispute this since it was submitted. So it was probably forgotten is nothing more than your theory. It hasn't been challenged is more accurate.

Without the paper, all this is simply handwaving, Accepted theory that establishes a connection between digital encoding and agitation in test subjects would not be hidden away in a single AES paper.

Let's start with the waveform. Once a analog signal is encoded to 16bit resolution, it appears as a stair stepped waveform, unlike a recorded analog which is more rounded

You got this wrong from get-go, a DAC does not see a waveform in the sense you use the term, it recovers a digital datastream of some sort PCM, DSM or whatever from the carrier signal at it's input. The reconstruction filter reconstructs the orignal analog waveform from the datastream recovered at DAC input.

Remember, there are two chief distinctions between an analog and a digital signal. The first is that the analog signal is continuous in time, meaning that it varies smoothly over time no matter how short a time period you consider(the rounded waveform), whereas the digital signal, in contrast, is discrete in time, meaning it has distinct parts that follow one after another with definite, unambiguous division points (called signal transitions) between them.(the square tooth waveform).

As stated previously, a DAC recovers a datastream at it's input, You've conflated the quantization process and the reconstruction process. A DAC uses a filter to reconstruct an analog signal from a quantized datastream. The recovered analog signal is continuous in time by definition whereas the digital datastream received at it's input is quantized.

Jitter is a problem with digital that is not a problem with analog. Aliasing is a problem with digital that is not a problem with analog. Quantization errors (noise) occurs with digital audio, that does not occur with analog, and overload characteristics of digital are profoundly different than that of analog

You've thrown a scatter load of unrelated stuff out there. Aliasing is non-issue, a well designed will reject out-of-band images with no problem, Quantisation noise occurs at the noise floor, dither lowers it even further. Analog has similar issues with noise, tape noise and groove noise are two well known examples.

Jitter is an issue, but it's minor compared to the gross distortions that occur in the analog. And it related cousins in the analog world are wow and flutter and then there is stuff like rumble.

That is a theory argument, not a real world one. If all things were perfect, you would be right. But in the real world all things are not perfect, and that is a fact. No signal chain is perfect whether it is digital or analog.

Ha! Perfection is a non-issue, a DAC always outputs analog waveform, if it doesn't it's broken. Analog waveforms ( at least, audio ones) are continuous in time by definition.

[Sir Terrence the Terrible]

Without the paper, all this is simply handwaving, Accepted theory that establishes a connection between digital encoding and agitation in test subjects would not be hidden away in a single AES paper.

I never said there was only one paper on the subject, I said I read it a couple of years ago, and I saw the test being performed at AES. I am only aware of one study, but I am pretty sure more has been done on the subject, just not for the same reasons.

You got this wrong from get-go, a DAC does not see a waveform in the sense you use the term, it recovers a digital datastream of some sort PCM, DSM or whatever from the carrier signal at it's input. The reconstruction filter reconstructs the orignal analog waveform from the datastream recovered at DAC input.

The DAC turns the binary data in a analog signal, and the reconstruction filter is used to construct a smooth analog signal from the output of a DAC. The question is does the waveform after reconstruction look exactly like the waveform from an all analog signal that never get's digitally processed. The answer to that is no.

As stated previously, a DAC recovers a datastream at it's input, You've conflated the quantization process and the reconstruction process. A DAC uses a filter to reconstruct an analog signal from a quantized datastream. The recovered analog signal is continuous in time by definition whereas the digital datastream received at it's input is quantized.

Agreed.

You've thrown a scatter load of unrelated stuff out there. Aliasing is non-issue, a well designed will reject out-of-band images with no problem, Quantisation noise occurs at the noise floor, dither lowers it even further. Analog has similar issues with noise, tape noise and groove noise are two well known examples.

Actually the issues are not so similar. Quantization noise is more audibly disturbing than the noise-floor in analog system. Dither helps can make that noise less audible, but dither can add grain to the sound as well.

Aliasing is indeed an issue, and if it wasn't an issue, the techniques such as oversampling and upsampling would not be necessary. Reconstruction filters that do not effect the frequency response in the higher frequencies have not been made. You have two choices, begin rolling off the signal before Nyquist frequency is reached, or create a brick wall filter which stands a good chance of ringing. Neither is a perfect solution, which is where oversampling comes into play.

Jitter is an issue, but it's minor compared to the gross distortions that occur in the analog. And it related cousins in the analog world are wow and flutter and then there is stuff like rumble.

Jitter can be just as big a problem as wow and flutter. It depends on how much is in the signal.

Ha! Perfection is a non-issue, a DAC always outputs analog waveform, if it doesn't it's broken. Analog waveforms ( at least, audio ones) are continuous in time by definition.

We can argue digital audio 101 till the cows come home but there is this one basic point. My point is simply this, I can record a live concert using split feeds from my board to two separate paths. One can be sent via a clean all analog path to an analog recorder, the other to a digital recorder or hard drive at 16bits. In a perfect world they should sound exactly alike during playback, but in reality they don't. In the end they both end up as analog, but the sonic character is clearly different. Neither is better(except to the listener), but they sure sound different coming from the same mikes and mixing board. Increasing the bit and sample rate decreases the difference between the digital sound and analog sound.

[pixelthis]

Hey I have an idea, why don't you tell them you don't know what you are talking about?!? Try a history book, oh right...you've opted to write your own.

Oh, I sharpened my teeth on various tube designs, you'd be surprized at just how much I know about them.
And my version of history is correct.
Tubes get hot( heat is the primary enemy of electronic circuits), they cause a ton of distortion (that "tube" sound) and have to have a seperate heating circuit for the emiters,
which are basically the same as the filament in a light bulb.
Hi fi types like tubes because of the "tube" sound( harmonic distortion) , the fact that
they are "exclusive"( the great unwashed can't afford them) and the basic herd
mentality that exists in all humans.
THE TUBERS in HI FI tend to be non electronic types.
PEEPS who know even a smigen about electronics shy away from tubes,
because using tube circuits is like commuting to work every day on a horse.

[theaudiohobby]

I never said there was only one paper on the subject, I said I read it a couple of years ago, and I saw the test being performed at AES. I am only aware of one study, but I am pretty sure more has been done on the subject, just not for the same reasons.

In otherwords, you have precisely zero evidence to support of what is supposedly a well-accepted theory, or proven fact as you put it. Digital encoding schemes are at the heart of telecommunications the world over, if digital induced agitation were an issue, it would be widely known and published.

The DAC turns the binary data in a analog signal, and the reconstruction filter is used to construct a smooth analog signal from the output of a DAC. The question is does the waveform after reconstruction look exactly like the waveform from an all analog signal that never get's digitally processed. The answer to that is no.

My original proposition was the output of a DAC is an analog signal, a continuous waveform by definition. Your claim that the analog signal at the DAC output is not exactly identical to the original analog signal is a strawman.

Actually the issues are not so similar. Quantization noise is more audibly disturbing than the noise-floor in analog system. Dither helps can make that noise less audible, but dither can add grain to the sound as well.

At -96dB in an undithered 16-bit system across the entire passband and greater than -100dB in a dithered one, I think not. tape noise in analog tape was so bad, it required equalisation (i.e. Dolby) to mitigate it's effects.

Aliasing is indeed an issue, and if it wasn't an issue, the techniques such as oversampling and upsampling would not be necessary. Reconstruction filters that do not effect the frequency response in the higher frequencies have not been made. You have two choices, begin rolling off the signal before Nyquist frequency is reached, or create a brick wall filter which stands a good chance of ringing. Neither is a perfect solution, which is where oversampling comes into play.

not sure what your point is here, anti-aliasing is an integral part of DAC design, and like any other engineering endeavour there are trade-offs.

We can argue digital audio 101 till the cows come home but there is this one basic point. My point is simply this, I can record a live concert using split feeds from my board to two separate paths. One can be sent via a clean all analog path to an analog recorder, the other to a digital recorder or hard drive at 16bits. In a perfect world they should sound exactly alike during playback, but in reality they don't. In the end they both end up as analog, but the sonic character is clearly different.

There are any number of reasons why the scenario you describe above can happen, however none of these reasons invalidate the basic fact that the output of a DAC is an analog signal that closely resembles the encoded analog signal within the limits of practical digital design and theory. Secondly, an analog audio signal irrespective of it's source, be it a DAC or a pure analog component is always a continuous signal.

[E-Stat]

Hi fi types like tubes because of the "tube" sound( harmonic distortion)

It is because of the superior spectral distribution. At what level can you detect distortion? If you were intellectually honest, you would take the distortion test link I posted a while back and find yourself eating your words over the threshold of distortion audibility.

the fact that they are "exclusive"( the great unwashed can't afford them)

Only those who are unaware of the many options available to them.

rw

[theaudiohobby]

It is because of the superior spectral distribution.

rw

'superior spectral distribution', now that's a note taken right out of the cable peddler's marketing notebook. good job

[E-Stat]

'superior spectral distribution', now that's a note taken right out of the cable peddler's marketing notebook. good job

It's certainly fine by me that you don't understand the auditory system sensitivity difference between even and odd order harmonics. Fortunately, most designers do these days and SS has made some significant strides in recent years with simpler, more linear circuits requiring far less feedback which has always added to the problem.

"Audiophiles have been accused of using 2nd or 3rd harmonic distortion as tone controls to deliberately alter the sound. I suppose that there are people who like it that way, but I don't think this is generally the case. For reasons which will become clearer when we talk about inter-modulation distortion, high levels of any harmonic become problematic with musical material having multiple instruments, and the argument that 2nd or 3rd adds “musicality” doesn't quite hold up."

Distortion and feedback

rw

[Ajani]

Distortion and feedback

rw

Thanks for sharing. I've certainly enjoyed reading the links you've provided in this thread.

That article from Pass + the reviews of the XA30.5 on Stereophile; notably the one where Eric Lichte compares the sound of Kanye West's love lockdown replayed with the 30 watt pass amp versus with Musical Fidelity 750 watt monos, clearly reinforces my view that just about all designs have some merit. Now I'm convinced that all I need is a 200 - 300 watt pure Class A amp, so I think a pair of Pass Labs XA200.5 monos would do the trick:

http://www.passlabs.com/xa_5_series.htm

Now if anyone would like to make a donation towards the $31K for the Pass Amps, feel free to pm me...

[Geoffcin]

Oh, I sharpened my teeth on various tube designs, you'd be surprized at just how much I know about them.
And my version of history is correct.
Tubes get hot( heat is the primary enemy of electronic circuits), they cause a ton of distortion (that "tube" sound) and have to have a seperate heating circuit for the emiters,
which are basically the same as the filament in a light bulb.
Hi fi types like tubes because of the "tube" sound( harmonic distortion) , the fact that
they are "exclusive"( the great unwashed can't afford them) and the basic herd
mentality that exists in all humans.
THE TUBERS in HI FI tend to be non electronic types.
PEEPS who know even a smigen about electronics shy away from tubes,
because using tube circuits is like commuting to work every day on a horse.

I disgree with you on several points;

One, that tube amps are somehow very distorted. Most well made tube amps have very good THD measurments within their specified power ratings. Certainly the specs on mine are well under 1% until it reaches rated power (.05% for the first several watts) . Even after that the distortion rises gradually into clipping. Most good SS amps have vanishing levels of distortion until clipping and then produce a sharp "clipped" waveform. If you've got an amp that is properly powered for the speakers it's hooked to then by the time you reach clipping with either a tubed _OR_ SS amp your pushing your speakers well into distortion. Even good speakers distort on the order of 5-10% or more when played above ~95dB or so. So, it's a good bet is that if your hearing distortion, look to your speakers.

Two, that tubed amps are somehow unatainable for the "average Joe". With the Chinese onslaught of GOOD tubed amps, you can get into the game for well under 1k. I would call that pretty cheap when we're talking "HI-FI". Even if you wanted to go with classic gear then a decent older US tubed amp like a Dynaco can be had for under a grand. Sure it's a little more expensive than a panny reciever,

I will give you that there's a unique "tubed" sound to tubed amps, but i would say that it is mostly from the higher output impedence at the taps. Higher output impedence affects the frequency response of the speakers and tends to roll off the highs although it does NOT filter them. Good output transformers often have response well into the 100's of thousands of Hz which gives a very extended high frequency, if slightly rolled off because of impedence issues.

[theaudiohobby]

It's certainly fine by me that you don't understand the auditory system sensitivity difference between even and odd order harmonics.
rw

What's the relevance of the excerpt to your contention that tubes have "superior spectral distribution"? Over here, we say you are 'blagging'.

[E-Stat]

Now I'm convinced that all I need is a 200 - 300 watt pure Class A amp, so I think a pair of Pass Labs XA200.5 monos would do the trick:

With my power hungry speakers, I would likely opt for the X600.5. It uses the same singled ended A front end, massive chassis, power supply and output stage of the XA200.5, but runs AB at the top end of its power range.

rw

[Sir Terrence the Terrible]

In otherwords, you have precisely zero evidence to support of what is supposedly a well-accepted theory, or proven fact as you put it. Digital encoding schemes are at the heart of telecommunications the world over, if digital induced agitation were an issue, it would be widely known and published.

We are not talking about speech here, we are talking music only. If you choose not to beleive what I have stated, that's your business. I am not here to convince anyone of anything, I gave up that battle years ago, and it will not start again with you.

Who said anything about agitation? I said less relaxed. There is a difference.

Are you asking me to produce the paper? Hey, I know it exists, but I didn't purchase it, and I have no interest in doing so just to appease you. So if you think the evidence is not there, bask in your own ignorance, I don't care. Even if I did purchase it, I could not post it as it would be against AES rules.

My original proposition was the output of a DAC is an analog signal, a continuous waveform by definition. Your claim that the analog signal at the DAC output is not exactly identical to the original analog signal is a strawman.

Once again, that is your opinion, and you are welcomed to keep it. My claim is the fact they are not identical goes along way in explaining why each sounds different even when using the same microphones mixer, amps and speakers(and with zero processing).

At -96dB in an undithered 16-bit system across the entire passband and greater than -100dB in a dithered one, I think not. tape noise in analog tape was so bad, it required equalisation (i.e. Dolby) to mitigate it's effects.

Hey, both examples require bandaids, which is why I prefer high resolution over all of them.

not sure what your point is here, anti-aliasing is an integral part of DAC design, and like any other engineering endeavour there are trade-offs.

Exactly my point.

There are any number of reasons why the scenario you describe above can happen, however none of these reasons invalidate the basic fact that the output of a DAC is an analog signal that closely resembles the encoded analog signal within the limits of practical digital design and theory. Secondly, an analog audio signal irrespective of it's source, be it a DAC or a pure analog component is always a continuous signal.

I never said that what leaves the DAC is not a analog signal, my point is that its waveform is different from an all analog signal, and that can account to why our ears respond differently to each's output.