Let's take as a fact that the Metrum sounds good; there is ample evidence on that, and as I own one I can only confirm.
Then it might make sense to investigate why it sounds good, and what measurements are relevant.
Members like SoNic prefer to trust on traditional mearurements, and prove not to be open to any other insight; they are "sure" that -60 dB THD "can't sound good", and -2dB at 20 kHz "must be audible and detoriate the sound...". IMO these guys are pulling a dead horse, and it does not contribute at all.
It was already mentioned in a previous post that time domain factors might be more important than absolute flatness up to 20 kHz, and audibility of THD is another debatable factor.
Perception of sound and results of measurements do not correlate; this fact has been the subject of discussions on audio gear a million times, and the discussion here (with respect to dacs) is no exception.
Last edited:
As another owner of the Octave, I can only concur with pieter t's remarks.
I think we must seriously reconsider the correlation of measurements with actual perceived sound quality. First I heard the Octave, then I measured it. These measurements turned out far worse than I could ever have predicted on the basis of what the Octave sounds like.
To me there is no doubt that a scientific experiment will show that correlation may only be a fraction of what it is thought to be.
Several things that come to mind:
1) In the good old days of casette, tape hiss could only be heard during quiet passages and distortion wasn't very low either. Why obsess with them now they're much lower?
2) Flat frequency response the thing to go for? What does it matter if at 20 kHz the signal has rolled off 2 dB when you might not even hear above 16 kHz without seriously turning up the volume?
3) Flat frequency response of speakers in a real life living room? Not going to happen.
4) Even in a quiet living room ambient noise might drown that of the equipment.
With respect to filtering in digital audio: I got the PDR-555RW working and could measure some of the frequency responses. Legato Link conversion indeed doesn't suppress all of the first image! In other words: a big mainstream company already doubted the need for brick wall filtering 15 years ago.
Images from left to right:
PDR-555RW: 44.1 kHz; 20 kHz sinewave;
PDR-555RW: 44.1 kHz; 20 kHz sinewave spectrum;
PDR-555RW: 44.1 kHz; 19 kHz + 20 kHz sinewave; 1:1; audioband;
PDR-555RW: 44.1 kHz; white noise spectrum, marker at fs/2.
I think we must seriously reconsider the correlation of measurements with actual perceived sound quality. First I heard the Octave, then I measured it. These measurements turned out far worse than I could ever have predicted on the basis of what the Octave sounds like.
To me there is no doubt that a scientific experiment will show that correlation may only be a fraction of what it is thought to be.
Several things that come to mind:
1) In the good old days of casette, tape hiss could only be heard during quiet passages and distortion wasn't very low either. Why obsess with them now they're much lower?
2) Flat frequency response the thing to go for? What does it matter if at 20 kHz the signal has rolled off 2 dB when you might not even hear above 16 kHz without seriously turning up the volume?
3) Flat frequency response of speakers in a real life living room? Not going to happen.
4) Even in a quiet living room ambient noise might drown that of the equipment.
With respect to filtering in digital audio: I got the PDR-555RW working and could measure some of the frequency responses. Legato Link conversion indeed doesn't suppress all of the first image! In other words: a big mainstream company already doubted the need for brick wall filtering 15 years ago.
Images from left to right:
PDR-555RW: 44.1 kHz; 20 kHz sinewave;
PDR-555RW: 44.1 kHz; 20 kHz sinewave spectrum;
PDR-555RW: 44.1 kHz; 19 kHz + 20 kHz sinewave; 1:1; audioband;
PDR-555RW: 44.1 kHz; white noise spectrum, marker at fs/2.
Attachments
Last edited:
Thanks for the measurements, wow that sinewave, are you sure you measured it right? thats terrible.. I read that there was an imposed 4khz FM modulation, I guess thats it? I wont go on, they speak for themselves, but please, others i'm not talking to, dont take a snippet from this first post, quote it and argue; i'll simply ignore it (not at you jitter, most of this post is more general, but some directly replies to you)
I dont deny, nor did I even claim that time domain isnt important, ive spent the last 6 months working to tune the i2s and clock handling in my dac. this is just one of the parts of my post, lept on, misrepresented and reacted to, please read carefully.
I only mentioned that it was often lesser known or sometimes esoteric types of often phase related distortion that are often used as buzzwords to promote dacs that otherwise measure poorly. Phase noise/phase distortion/jitter can all be measured quite successfully too these days (not easily, but successfully), but i wont harp on.
Jitter, I had prepared a response to you that basically said that i thought on the whole we were on the same page, my main objection is using terms that promote an extreme difference where it is more subtle than that, but without proof of such differences and calling others who dont hear such big differences deaf; going by your wording in response it seems you feel mostly the same. I made no claim there were no differences either and I was NOT talking down when I mentioned liking harmonic distortions that are perhaps missing where they should be there, but that still being a form of distortion
We dont know it all, not yet, but extreme phrases like I objected to will be correlated in the bank of measurements. other longer term harmonic or experiential differences may not be so easy to detect, or define
The proof is in the pudding and I by no means belittle anyones enjoyment, but i pertained and still do, that many of these enjoyable factors can be put down forms of distortion or harmonics. man I LOVE distortion and harmonics!! I found my teens and 20's in the late 80's-late 90's and my whole world was distorted lol. So I like it, just not in my dac as I like many and varied forms of music, different priorities I guess.
yes i look back on those days fondly, but not on the hiss, it, like record pops and crackles hold a certain amount of nostalgia, but i'm glad they are gone; without the dynamic range issues of the noise reduction techniques of the day
yeah but I do, not as well as I used to but I do and i still pertain its part of the room and spacial information that is not directly heard, but has an effect
I do a lot of listening on high end headphones, one particular pair are TT-MM-WW 3 way custom fit in ears with extremely low distortion and high efficiency, the room is my ear canal and its a known quantity that the crossover is tuned for digitally using the casting taken of my ear canal and conch that they make the monitors from.
My in progress new speakers are digitally crossed with room correction/convolving and i freely admit this is a fairly extreme form of distortion (in frequency and time domains), but damn does it sound good! I feel no less of a music lover for enjoying this effect, I dont know why others can get so offended when its suggested as a factor
see above
I dont deny, nor did I even claim that time domain isnt important, ive spent the last 6 months working to tune the i2s and clock handling in my dac. this is just one of the parts of my post, lept on, misrepresented and reacted to, please read carefully.
I only mentioned that it was often lesser known or sometimes esoteric types of often phase related distortion that are often used as buzzwords to promote dacs that otherwise measure poorly. Phase noise/phase distortion/jitter can all be measured quite successfully too these days (not easily, but successfully), but i wont harp on.
Jitter, I had prepared a response to you that basically said that i thought on the whole we were on the same page, my main objection is using terms that promote an extreme difference where it is more subtle than that, but without proof of such differences and calling others who dont hear such big differences deaf; going by your wording in response it seems you feel mostly the same. I made no claim there were no differences either and I was NOT talking down when I mentioned liking harmonic distortions that are perhaps missing where they should be there, but that still being a form of distortion
We dont know it all, not yet, but extreme phrases like I objected to will be correlated in the bank of measurements. other longer term harmonic or experiential differences may not be so easy to detect, or define
The proof is in the pudding and I by no means belittle anyones enjoyment, but i pertained and still do, that many of these enjoyable factors can be put down forms of distortion or harmonics. man I LOVE distortion and harmonics!! I found my teens and 20's in the late 80's-late 90's and my whole world was distorted lol. So I like it, just not in my dac as I like many and varied forms of music, different priorities I guess.
yes i look back on those days fondly, but not on the hiss, it, like record pops and crackles hold a certain amount of nostalgia, but i'm glad they are gone; without the dynamic range issues of the noise reduction techniques of the day
yeah but I do, not as well as I used to but I do and i still pertain its part of the room and spacial information that is not directly heard, but has an effect
I do a lot of listening on high end headphones, one particular pair are TT-MM-WW 3 way custom fit in ears with extremely low distortion and high efficiency, the room is my ear canal and its a known quantity that the crossover is tuned for digitally using the casting taken of my ear canal and conch that they make the monitors from.
My in progress new speakers are digitally crossed with room correction/convolving and i freely admit this is a fairly extreme form of distortion (in frequency and time domains), but damn does it sound good! I feel no less of a music lover for enjoying this effect, I dont know why others can get so offended when its suggested as a factor
see above
Last edited:
I use headphones a lot exactly because of room response and noise. Use speakers only for surround.
To say that "cassete tape never bothered us" is just laughable to me. I was fanatic about the sound even then, my LP's where perfectly clean while listening, I was using reel-to-reel recorders to transfer LP and avoid wear, looking for the best magnetic tapes that I could get, I did my own preamp stages for RIAA and modded the ones in the reel-to-reel, bought better cartidges and heads, ballanced the arm... When katter I got a cassete player, it had dbx and I used minimum CrO2 tapes with dynamic bias.
I could hear the hiss and distortions then and I hated them. My analog devices where all better than -60dB, I don't see why I would take less today.
I guess I have to agree that some don't care about the real details in music and like better to hear the artificial colorations and products of the unfiltered NOS.
Time to leave this thread.
To say that "cassete tape never bothered us" is just laughable to me. I was fanatic about the sound even then, my LP's where perfectly clean while listening, I was using reel-to-reel recorders to transfer LP and avoid wear, looking for the best magnetic tapes that I could get, I did my own preamp stages for RIAA and modded the ones in the reel-to-reel, bought better cartidges and heads, ballanced the arm... When katter I got a cassete player, it had dbx and I used minimum CrO2 tapes with dynamic bias.
I could hear the hiss and distortions then and I hated them. My analog devices where all better than -60dB, I don't see why I would take less today.
I guess I have to agree that some don't care about the real details in music and like better to hear the artificial colorations and products of the unfiltered NOS.
Time to leave this thread.
Last edited:
Hi,
I really think you must stop to listen to music then.
Because -60dB OR WORSE H2 is very common for many "high fidelity" speakers at 1 Watt input and HD rises with level, H3 to a cubic function. Hence if -60dB cannot realistically sound good - then good sound is essentially impossible, using current speakers.
One of my personal favourite speakers (Tannoy corner horns loaded with alnico magnet 15" Monitor Red's) are actually very low HD speakers, but even they exceed 0.3% HD at 101dB/1m, though it is mostly H2...
Ciao T
I really think you must stop to listen to music then.
Because -60dB OR WORSE H2 is very common for many "high fidelity" speakers at 1 Watt input and HD rises with level, H3 to a cubic function. Hence if -60dB cannot realistically sound good - then good sound is essentially impossible, using current speakers.
One of my personal favourite speakers (Tannoy corner horns loaded with alnico magnet 15" Monitor Red's) are actually very low HD speakers, but even they exceed 0.3% HD at 101dB/1m, though it is mostly H2...
Ciao T
Hi,
Did that include your speakers at 102dB/1m or rated input power (whichever comes first)?
BTW, the same applies to headphones, though some of the best are moderately low distortion, but < -60dB HD at 102dB 20Hz-20Khz still seems a tall order..
Ciao T
Did that include your speakers at 102dB/1m or rated input power (whichever comes first)?
BTW, the same applies to headphones, though some of the best are moderately low distortion, but < -60dB HD at 102dB 20Hz-20Khz still seems a tall order..
Ciao T
The way I measured wasn't really scientific, i.e. no precise calibration of any sort. So don't look at the dB values in the plots. I did measure all three devices the same way so that comparisons between these three can be made.
I'm pretty sure that I measured the sinewaves correctly, there isn't that much to go wrong. For reference to a traditional approach I included the Micromega DAC1, and the sinewaves look fine on that one all the way up to 20 kHz.
The Legato Link conversion in the PDR-555RW and the Octave show other frequency components. Obviously the '555-RW doesn't measure that extreme down the frequency range as the Octave; the distortion as a result of gentle filtering runs out below 10 kHz, in the Octave it is probably present in all frequencies.
I would argue that the Octave belongs to that group. But what are these esoteric types of phase related distortion?
Yes, I know, one of the standard measurements of PCBs for the broadcasting industry is the eye pattern and even a little bit of jitter clearly shows.
I think we are, indeed. When I was younger I read a lot of HiFi magazines but eventually stopped reading them. Not only were most of them biased towards products of important advertisers, reviews were written as if there was a world of difference between device A and device B. When I was making enough money to buy good quality equipment, I found that those differences we exaggerated.
I'm not saying that differences cannot be perceived as big by some, but I'm not among them. Is it my hearing? Who knows? Maybe I'm not so easily fooled by what some salesperson tells me. I'm very aware of the power of suggestion, so that in most cases it doesn't work with me anymore.
For auditioning of the Octave I had brought with me my own CD player. During warming it up I talked to the vendor for a while. Without having seriously listened to my CD-player he already knew to tell me that it couldn't hold a candle to the Octave. Yeah, right... I'll decide for myself. And of course, the differences weren't nearly as big as they were made out to be.
I think we should already know quite a bit, there must have gone a lot of research into the properties of the human auditory system during the development of lossy compression.
Long ago I read an article on human hearing and the brain. Turns out that some people can go deaf for certain unpleasant sounds without any physical damage to the auditory system. The sound is completely blocked by the brain. If such an extreme is possible, no doubt the brain has all sorts of subtle influences on how and what we hear.
It's what makes one instrument sound totally different from another despite playing the exact same note.
Perhaps the idea of Legato Link, allowing some of the image that is playing in the same rythm as the audio band is in that respect not even so bad. Enter NOS and take it to the extreme.
For me it's merely a Sennheiser HD600 on a diy class A headphone amp.
Exactly... nobody listen for long term at the nominal levels. Or whan it does it doesn't care about distortions.
At medium sound levels the distortions of good, open-back, headphones are smaller than the usual graphs for 90-100dB. And all those are harmonic distortions, not random aliases.
A few comparative measurements:
At medium sound levels the distortions of good, open-back, headphones are smaller than the usual graphs for 90-100dB. And all those are harmonic distortions, not random aliases.
A few comparative measurements:
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
Hi,
I don't listen to headphones.
The 102dB come from the peak demands of music signals and would correspond to around 85dB average SPL and equally to "0dBFS" peaks in the signal. The crest factor in this case is 17dB, which is often exceeded by truly un-manipulated recordings.
Of course much modern "popular" music is compressed to a point where the dynamic range is barely 6dB, but I personally rarely listen to that sort of stuff seriously.
At any extent, if you worry about "x" distortion at digital full scale, look at the distortion of your transducers at the corresponding SPL...
And if they do not offer less than "x" distortion then any thesis that "x amount of distortion makes high quality impossible"is instantly falsified.
Ciao T
I don't listen to headphones.
The 102dB come from the peak demands of music signals and would correspond to around 85dB average SPL and equally to "0dBFS" peaks in the signal. The crest factor in this case is 17dB, which is often exceeded by truly un-manipulated recordings.
Of course much modern "popular" music is compressed to a point where the dynamic range is barely 6dB, but I personally rarely listen to that sort of stuff seriously.
At any extent, if you worry about "x" distortion at digital full scale, look at the distortion of your transducers at the corresponding SPL...
And if they do not offer less than "x" distortion then any thesis that "x amount of distortion makes high quality impossible"is instantly falsified.
Ciao T
Hi,
Nor does music contain sinewaves with 0dBFS. So your point is?
We do not know how the Metrum DAC performs at -12dBFS (equal to 90dB SPL if 0dBFS peaks are at 102dB), unless someone carries out the measurements.
Do not try to change the topic, we where discussing the Metrum's measured HD, nothing else. If you want to make a separate case that the ultrasonic images constitute distortion (they don't, in the traditional sense) or that they are random (which they are not of course - that being a crucial point BTW) you are welcome to do so separatly.
These measurements correspond to a single frequency and AFAICT to 90dB SPL. In other words, these are at around -12dBFS if we want normalise them.
Here alternative data on headphone distortion BTW...
Headphone non-linear distortion measurements
What I can see is between -75dB/0.02% H3 (the headroom measurement at I believe 500Hz) and -40dB/1% H3 (the Headfi thread) at 90dB. No measurements for higher SPL's are readily available, but we can predict H3 levels will be much higher and easily exceed your stated -60dB/0.1% that you claim make high sound quality impossible.
Ciao T
Nor does music contain sinewaves with 0dBFS. So your point is?
We do not know how the Metrum DAC performs at -12dBFS (equal to 90dB SPL if 0dBFS peaks are at 102dB), unless someone carries out the measurements.
Do not try to change the topic, we where discussing the Metrum's measured HD, nothing else. If you want to make a separate case that the ultrasonic images constitute distortion (they don't, in the traditional sense) or that they are random (which they are not of course - that being a crucial point BTW) you are welcome to do so separatly.
These measurements correspond to a single frequency and AFAICT to 90dB SPL. In other words, these are at around -12dBFS if we want normalise them.
Here alternative data on headphone distortion BTW...
Headphone non-linear distortion measurements
What I can see is between -75dB/0.02% H3 (the headroom measurement at I believe 500Hz) and -40dB/1% H3 (the Headfi thread) at 90dB. No measurements for higher SPL's are readily available, but we can predict H3 levels will be much higher and easily exceed your stated -60dB/0.1% that you claim make high sound quality impossible.
Ciao T
I cant find the measurements of the jh13 right now, the FR plot would no doubt sets some jaws wagging as they are heavily Eq'd with the XO to produce something that is flat at the eardrum. there are some somewhere though, perhaps at Tyll's forum.
how about feeding that dac a sinewave or music with -60db distortion then..... what do the measurements look like now
how about feeding that dac a sinewave or music with -60db distortion then..... what do the measurements look like now
Exactly. If the headphones add distortion (mostly 2nd and 3rd), why don't feed them as clean as possible? Input all that garbage and sure they will make even more distortion and IM from that and on a wider range. We will have IM products made in headphones that where never there in a filtered situation.
And I don't know about the rest of you, but I have a volume pot between DAC and headphones. So while the DAC ouptut is always at odB FS, my headphones are probably at -20dB FS (can't measure now). So all those graphs of headphones distortion should be taken at that level too - I bet will be lower than at the full scale.
Last edited:
agreed, I actually meant to say feed those headphones with -60db distortion, but same difference... it compounds. not all the distortion products will be correlated, but i'm sure it will be an additive process that will sporn new spikes.
my customs would blow my eardrums at that level; I know many argue it has to be sized for the dynamic peaks at a live event, but who listens to music at that level? if you sat in the front row at events all the time youde get hearing damage pretty quick too
anyway I think we better leave these guys to it Sonic, i've made my point and as long as we're talking NOS rather than this dac, others not really interested in the dac will come in to argue as well and i'm not interested in further conflict, i'm still interested in hearing the dac, just to see what the fuss is about, but if I owned one i'd be upsampling externally
my customs would blow my eardrums at that level; I know many argue it has to be sized for the dynamic peaks at a live event, but who listens to music at that level? if you sat in the front row at events all the time youde get hearing damage pretty quick too
anyway I think we better leave these guys to it Sonic, i've made my point and as long as we're talking NOS rather than this dac, others not really interested in the dac will come in to argue as well and i'm not interested in further conflict, i'm still interested in hearing the dac, just to see what the fuss is about, but if I owned one i'd be upsampling externally
Last edited:
IMHO, hearing it for yourself and making up your own mind is the only way to go. Chances are you'll love it, but I'm also willing to accept that maybe this DAC isn't for everyone. Hope you can audition one, around where you live...
yeah it'll never work with my system (I need i2s input and my system is multichannel for digital XO duties) but i'm still interested to hear it. i'll send you a PM tomorrow as our conversation was a bit unfinished, i'm part way through a reply, but i'd rather not post in the thread and start things off all over again
I've been looking at the shape of the 5 kHz sinewave at 44.1 kHz fs of the Octave again, and I realized I'm not looking at IM here. These are the steps from DA-conversion without low pass filter (reconstruction filter).
The scale is 50 us/div, so full scale is 500 us. At 44.1 kHz (or ksps) that would mean 22.05 samples. Counting the number of visible steps indeed reveals 22 distinguishable jumps. That square wave like distortion would account for a lot of the harmonics.
Am I right in thinking that most of the measured distortion isn't IM related at all, but are the harmonics of this square wave like distortion of the sine?
The scale is 50 us/div, so full scale is 500 us. At 44.1 kHz (or ksps) that would mean 22.05 samples. Counting the number of visible steps indeed reveals 22 distinguishable jumps. That square wave like distortion would account for a lot of the harmonics.
Am I right in thinking that most of the measured distortion isn't IM related at all, but are the harmonics of this square wave like distortion of the sine?
Attachments
Last edited:
Well... yes it is a lot of harmonics due to the square shapes. It will not be IM since in that case you play just one frequency.
But as you notice, without interpolation and oversampling, the original "16 bit" are worthless at high frequency (closer of 1/2 SR). At 1/4SR you have actually only 8 levels there because of large sampling time - that is only a 3 bit resolution.
PS: This observation was the basis of sigma-delta theory anyway...
But as you notice, without interpolation and oversampling, the original "16 bit" are worthless at high frequency (closer of 1/2 SR). At 1/4SR you have actually only 8 levels there because of large sampling time - that is only a 3 bit resolution.
PS: This observation was the basis of sigma-delta theory anyway...
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.