johngw said:
To nit-pick a little more (and this could become arcane), bit depth, or wordlength, only affects dynamic range (SNR), and sample rate only affects frequency response, so I think NS theory does hold good, in terms of recreating the original waveform at the converter. It's just that 'Red Book' is a little noisier than 24bit.
Distortion, expressed mathematically, and also in practice, is merely increased noise.
JC
This is how they build posts. Post something controversial. Be controversial. Wind people up. Be more controversial. Troll a bit.
Ad infinitum.
Sad.
Ad infinitum.
Sad.
jcbrum said:
Class D amps measure horrible, it's like swallowing camels (Class D) while hunting for flies (Redbook CD).
Yet, reviews state that Class D can be real HiFi. Redbook CD is all that is needed.
altruistic.lemon said:
Then can I kindly suggest that you both butt out......... :doh:
I have made quite a few posts on here and some of my assertations have been challenged in such a way as to change my perception of the way digital audio works in practice.
By moving my understanding forward it helps me to choose and get the best out of my, and other peoples, systems.
Personally I consider that worthwhile.
Measurements in hi-fi can be a funny old thing. For example here's the results from putting 10 khz square waves through 2 different £multi-thousand amps. One of them has less than 0.06% THD+N, whilst the other has less than 5% THD+N.
Can you guess which amplifier produced which oscilloscope output?
And how these measurements relate to how they actually sound?
Can you guess which amplifier produced which oscilloscope output?
And how these measurements relate to how they actually sound?
lindsayt said:Measurements in hi-fi can be a funny old thing. For example here's the results from putting 10 khz square waves through 2 different £multi-thousand amps. One of them has less than 0.06% THD+N, whilst the other has less than 5% THD+N.
Can you guess which amplifier produced which oscilloscope output?
And how these measurements relate to how they actually sound?
In some cases they are not related.
In other cases they are. I see no reason to be dogmatic about it.
I find anything that helps my understanding of how things work to be a good thing.
I also know that in audio, measurement does not tell the whole story. For example, in my main system I use an EL34 based valve amplifier. I know that, for the money, I could choose a different, solid state amplifier, with measured distortion one or even two orders of magnitude lower, but I choose not to. In this case the measurements are put to one side.
On the other side of the coin, I know, from measurements, that some dacs have considerable high frequency output outside the audible range and can upset some amplifiers in ways that are not immediately obvious. In this case the measurements are very helpful.
LenBarleno said:
When I find a television programme I don't like, I turn to a different station, when I read a newspaper I find objectionable, I move to a different story.
Can I suggest that if you find the thread so offensive, that you stop reading, and then posting on it?
lindsayt said:
The top one looks like a low power valve amp to me.
The bottom one is almost certainly a class D amp.
They probably both sound ok-ish, but the valve amp will only sound good on efficient higher impedance speakers, whilst the Class D amp will probably be very powerful and sound ok-ish on any speakers, it has a lot of noise on the signal which is probably at too high a frequency to be humanly audible.
Neither of them will be worth the asking price, I suspect.
JC
davedotco said:
No. I am entitled to post what I like as much as any on here. It's all quite sad though really, doesn't everyone think?
*Retires, for now, to 320 kbps MP3 audio ripped onto PC with a modest 16-bit DAC.
professorhat
Well-known member
You're also entitled to write into Points of View to complain about something that you watched and thought was offensive, when you could of just turned over and left the people who enjoyed watching it to do so. It's not something I would do though as I personally think this sort of behaviour is quite sad.
Each to their own.
Each to their own.
LenBarleno said:
Weren't you demanding that the thread be locked a few pages ago? So you are entitled to post as much as you like, but the rest of us aren't?
shadders
Well-known member
lindsayt said:Measurements in hi-fi can be a funny old thing. For example here's the results from putting 10 khz square waves through 2 different £multi-thousand amps. One of them has less than 0.06% THD+N, whilst the other has less than 5% THD+N.
Can you guess which amplifier produced which oscilloscope output?
And how these measurements relate to how they actually sound?
Hi,
Can you provide the frequency spectrum of both plots - it is not possible to determine if the second trace has even or odd order THD - maybe a sine wave would be better to determine exactly the order of the distortion.
Regards,
Shadders.
lindsayt said:Measurements in hi-fi can be a funny old thing. For example here's the results from putting 10 khz square waves through 2 different £multi-thousand amps. One of them has less than 0.06% THD+N, whilst the other has less than 5% THD+N.
Can you guess which amplifier produced which oscilloscope output?
And how these measurements relate to how they actually sound?
OK, while completely off topic, we have moved from Nyquist-Shannon to the world of Fourier transforms. Mr Fourier showed that a square wave is comprised of an infinite series of odd harmonic sine waves. To fully represent a square wave, an amplifier needs to have infinite bandwidth. No amplifier does, and hence the wonky shape of the top trace. Thats just fine, 'cos your ear doesn't have infinite bandwidth either.
The second trace shows the danger of too much bandwith. I can't be bothered to count the cycles, but lets say the lower amplitude trace is 100KHz. Either the amp is self oscillating (not than uncommon), or it is picking up something nasty from a switching power supply or other noisy source. If the amp had a frequency response that rolled off nicely above 20KHz then this wouldn't have happened. So when the amp says 'flat to 100KHz' that is a bad thing, not good. The oscillation itself wouldn't be audible, but it may create other problems that are.
Either way, it is impossible by eyeballing the graphs to make any statement about THD or how they sound.
busb
Well-known member
andyjm said:
Some here just don't seem to understand the simple concept of ignoring threads they don't like - they effectively troll them I instead. The only reason I can think of is that they are so arrogant that they expect every thread to be either interesting (to them) or understandable - when not, they kick up.
There's no crossover distortion, so both amps are probably not Class B in any degree. Class C is not used in HiFi designs, so that leaves Classs A or Class D.
In the first graph, that upper left hand corner of the trace is very characteristic of 1950's valve designs, and the lower graph shows comparetively little distortion of the upper left hand corner, indicating a solid state design.
Therefore, I'm guessing at a low power valve class A design for the first graph, and a solid state Class D design, with a lot of hash, for the second graph.
We should get back on topic.
JC
In the first graph, that upper left hand corner of the trace is very characteristic of 1950's valve designs, and the lower graph shows comparetively little distortion of the upper left hand corner, indicating a solid state design.
Therefore, I'm guessing at a low power valve class A design for the first graph, and a solid state Class D design, with a lot of hash, for the second graph.
We should get back on topic.
JC
busb
Well-known member
The Nyquist Shannon theorem does hold but describes the minimum requirement, not the maximum! Red book spec doesn't brick-wall at 20k but allows for real-world filter design. The question to my mind is whether or not enough safety margin has been allowed for low phase distortion.
What many don't seem to understand is that our ears are bandwidth limited (& that our physical perception of sound is equally bandwidth limited) so allowing out-of-band signals into the music is either completely pointless or even detrimental in producing artefacts that cause distortion therefore having the opposite effect. These artefacts may sound "nice" to some but if our collective goal is to get to "The closest approach to the original sound" then ALL added artefacts are just artefacts not present in the original.
Not only are our ears bandwidth limited so are most microphones, amplifiers, all ADCs, mixing desks, all DACs & digital processing is similarly BW limited! They have to be. The trick with digital audio is to balance out phase delay across the audio BW without introducing unneeded out-of-band mush. I don't pretend to know everything there is to know about digital audio but many seem willing to parade a laughable lack of knowledge when arguing against the laws of physics. The point that engineers & technologists get things spectacularly wrong is well made & once cherished theories get ditched but by who - audiophiles? No, by engineers! Usually by engineers with open minds who say unlikely rather than impossible when addressing the perceived need to up the sample rate of audio. The fact that mixing is done at 24/96 makes perfect sense for 16/44.1 output.
What's far more important to music lovers is less to do with sampling rate & a lot more to do with quality recordings to start with!
What many don't seem to understand is that our ears are bandwidth limited (& that our physical perception of sound is equally bandwidth limited) so allowing out-of-band signals into the music is either completely pointless or even detrimental in producing artefacts that cause distortion therefore having the opposite effect. These artefacts may sound "nice" to some but if our collective goal is to get to "The closest approach to the original sound" then ALL added artefacts are just artefacts not present in the original.
Not only are our ears bandwidth limited so are most microphones, amplifiers, all ADCs, mixing desks, all DACs & digital processing is similarly BW limited! They have to be. The trick with digital audio is to balance out phase delay across the audio BW without introducing unneeded out-of-band mush. I don't pretend to know everything there is to know about digital audio but many seem willing to parade a laughable lack of knowledge when arguing against the laws of physics. The point that engineers & technologists get things spectacularly wrong is well made & once cherished theories get ditched but by who - audiophiles? No, by engineers! Usually by engineers with open minds who say unlikely rather than impossible when addressing the perceived need to up the sample rate of audio. The fact that mixing is done at 24/96 makes perfect sense for 16/44.1 output.
What's far more important to music lovers is less to do with sampling rate & a lot more to do with quality recordings to start with!
LenBarleno said:
No.
You are the real saddo for trying to put people down for posting in a thread that they find interesting. Epic Fail on your part.
BigH
Well-known member
lindsayt said:Measurements in hi-fi can be a funny old thing. For example here's the results from putting 10 khz square waves through 2 different £multi-thousand amps. One of them has less than 0.06% THD+N, whilst the other has less than 5% THD+N.
Can you guess which amplifier produced which oscilloscope output?
And how these measurements relate to how they actually sound?
I would be interested to know what the amps are, 5% does seems very high?
busb
Well-known member
LenBarleno said:
13 posts. I'd personally be a bit more circumspect when going on the attact. As Dave points out: epic fail on your part. As for trolling - the pot calling the kettle black!
djh1697
Well-known member
"So please, without insults or petty put-downs, can someone give me any concrete,scientific information on why they think HD (for playback) is any better?"
No insults, I went to Cymbiosis earlier this afternoon, and my ears told me that HD sounded better, even on a blind listening test.
"Remastered" was generally not as good as the original. The computer term GIGO "Garbage In Garbage Out" springs to mind. A rip taken from an original CD could sound better than a HD download if the download wasn't done from an original master tape.
As Linn say "Just Listen" :cheers:
No insults, I went to Cymbiosis earlier this afternoon, and my ears told me that HD sounded better, even on a blind listening test.
"Remastered" was generally not as good as the original. The computer term GIGO "Garbage In Garbage Out" springs to mind. A rip taken from an original CD could sound better than a HD download if the download wasn't done from an original master tape.
As Linn say "Just Listen" :cheers:
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