There is no ISO document I'm aware of that defines Hi-Fi.
There is a British standard from the 80s? that defined certain aspects of sound reproduction with the intent of standardizing the marketplace.
There is a British standard from the 80s? that defined certain aspects of sound reproduction with the intent of standardizing the marketplace.
Indeed. I was just in my local supermarket and they sell hi-fi! Or micro systems to you and me. 😀
I think DF96's position is more a wish than a fact, which I can understand and sympathise with, but is hardly an undisputed truth. As we have seen.
If you go back to this post: http://www.diyaudio.com/forums/lounge/204456-you-really-interested-hi-fi-86.html#post4951076
The guy who claims to have coined the phrase way back in the 1920's, says what he meant it to refer to. See the highlighted text.
It appears that what he says is more consistent with the view that air should be pressurized adjacent to the playback transducers according to the data on the CD, as compared to a definition based on, playback indistinguishable from real for most people.
The guy who claims to have coined the phrase way back in the 1920's, says what he meant it to refer to. See the highlighted text.
It appears that what he says is more consistent with the view that air should be pressurized adjacent to the playback transducers according to the data on the CD, as compared to a definition based on, playback indistinguishable from real for most people.
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Well yes, but how do you decide what "the musical signal" is? And round we go again.
Anyway, just because he coined it doesn't mean it has to have the same meaning today.
Stop trying to spoil the fun!
Anyway, just because he coined it doesn't mean it has to have the same meaning today.
Stop trying to spoil the fun!
The thing is, the data on CD (even after going through the reconstruction filter and being turned into an analog electronic signal) can never be exactly reproduced as actual sound waves at your eardrums, for a number of reasons.
The first, and completely fundamental (i.e. it's a law of nature) one, is that when a sound wave travels through air from the speaker to your ears, every centimetre of travel is accompanied by a change (increase) in total phase, at the rate of 360 degrees for every wavelength traveled.
As an example, suppose you have magic perfect speakers that exactly reproduce the electrical signal fed to them. And suppose your ears are 3 metres from these perfect loudspeakers.
A 34Hz sound wave from the speakers is phase shifted by 108 degrees by the time it travels 3 metres and gets to your ear. A 3.4 kHz sound wave would be phase shifted by 10800 degrees, because its wavelength is a hundred times smaller. So the two different frequencies arrive at your ear with a completely different phase relationship than was recorded on the CD.
Real music, of course, has a lot more than two frequencies at a time. By the time it gets to your ear from the speakers, every frequency present is phase-shifted by a different amount, and some of the phase shifts are measured in thousands and even tens of thousands of degrees. This utterly and totally scrambles up waveforms. Ergo, (to an oscilloscope, etc) the acoustic signal at your ears is inevitably, and unavoidably, utterly different from the signal encoded on the CD.
Remember, we haven't even considered all the other issues: room reflections, speaker imperfections, et cetera. In real life all of these add a huge number of additional signals to the original sound from the speakers. The waveform at your ears is even more unrecognizable as the signal that left the CD player.
The magic, of course, is that your brain and ears don't find the signal at your ears utterly different from what's on the CD, even though it actually looks utterly different in the time domain. We hear and recognize the same sounds, more or less, that were recorded on the CD.
Tens of thousands of degrees of phase shift, it turns out, are irrelevant to the way our brains process and interpret sound. A guitar chord still sounds like a guitar chord whether it's three feet away, or six. An angry lion still sounds like an angry lion when it's half a kilometre away, and a very good thing too, for the survival of our ancestors.
But this brings us right back to our starting point: our ears do not need (and never get) the exact same signal to hear essentially the same sound.
Therefore, suggesting that Hi-Fi means reproducing exactly the same waveform at your ears is a meaningless standard. It might represent some sort of impossible mathematical perfection, like a geometrically perfect point with zero area, but it is utterly useless (and utterly impossible) in reality.
The original standard ("it sounds like the real thing") made a lot of sense. With one clean logical stroke, it eliminated everything that your ear/brain perceptual system doesn't actually care about, and included everything that it does care about.
I would suggest that this original standard (comparing live and reproduced sounds in near real-time) is still an excellent way to actually test and develop new speaker systems. If the speaker is capable of sounding like the real thing, it's doing it's job, whether or not the acoustic signal at your ear bears any resemblance to the electrical signal in the speaker wires.
When it comes to listening for enjoyment, however, our new artificial world no longer has a "real thing" to compare with, so almost all of us, almost all the time, are automatically reduced to using the "it sounds good to me" standard.
-Gnobuddy
For me the enjoyment of doing my own design is fun. It's also a unique product. I also learn new techniques, which is usually always the goal in anything I do.
Plus I get to buy new tools.
EDIT: I will add, that I do not go to DIY forums like I used to because it has become such a circle jerk over the last 10 years. Any forum, not any one in particular. No one really cares are about just fostering the willingness to do something yourself. It's all about proving how knowledgeable you are by talking down to anyone that asks a question or wants to start a project. The secret is.....they won't hear the difference....unless they think they should or are told they should. So just let them build something and learn.
Plus I get to buy new tools.
EDIT: I will add, that I do not go to DIY forums like I used to because it has become such a circle jerk over the last 10 years. Any forum, not any one in particular. No one really cares are about just fostering the willingness to do something yourself. It's all about proving how knowledgeable you are by talking down to anyone that asks a question or wants to start a project. The secret is.....they won't hear the difference....unless they think they should or are told they should. So just let them build something and learn.
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My experience too! Fortunately not so (much) with DIY forums.. hence I ignore all others these days.
The definitions are from today's WIKI. If you think they need to be updated, go WIKI and update them. 🙂
Thank you very much for that link. What a treasure! Papers on audio and audio reproduction, written by actual researchers, at a time when actual scientific research methodology was the primary tool used to gain additional understanding.
That 1933 demonstration was over eighty years ago. Our human hearing system hasn't changed in tens of thousands of years, so we are certainly not capable of hearing what people couldn't hear in 1933.
In fact, these days, most of us have worse hearing than our ancestors did, as our increasingly loud societies inflict hearing damage on most of us before we're out of our twenties.
These days, we certainly have more experience with the artificial reproduction of sound, and perhaps that will make some of us more discriminating about the quality of audio reproduction.
But in an actual live vs recorded comparison, conducted along the same lines as that 1934 experiment, we certainly don't have any more ability than our 1934-era parents, grandparents, and great-grandparents did.
All this suggests that those ancient research papers are probably almost as relevant today as they were in 1934.
It's fascinating, though, to see things like loudspeakers with drastic treble roll-off, combined with microphones with even more drastic treble boost. Either one of those by itself would certainly sound "not Hi-Fi". Put together, though - the papers speak for the results obtained!
-Gnobuddy
Agreed, but the guy who coined the phrase, Hi-Fi did not say anything about eardrums. He said the reproduction system should not add or take away anything from the input signal. And he said that in the context of output of the speakers as being the last part of the reproduction system he was referring to.
Ah, the tools. DIY sex toys. I even have a special saw for cutting off the bottoms of doors to clear the carpet. 😎
Except maybe for the slight problem that amplifiers and speakers have improved dramatically, so it's possible to hear things now that were buried in gross distortion before.
In addition, medical research methodology and biostatistics knowledge have improved dramatically over the years. Any idea even today that some electrical engineers are qualified to DIY in that area without professional collaboration with other experts would be almost certain folly.
Back in 1934, nobody knew how to do human subject research anywhere near as well as it can be done today, so its hard to see how 1934 research would likely be able to stand up to today's standards. If someone thinks it can, then some replication studies would be in order to prove that whatever results they produced way back then still remain robust today.
Even today with the best of modern human subject research, replication is always needed to verify important results. It would be very surprising if people here never heard of medical research that later turned out to be wrong.
Woah, damn. It's good to be back.
Edit:
Does anyone perhaps by experience know if the ratings on PartsExpess' bassBox6Pro fields are including or excluding driver displacement?
Talking about this:
Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)
Sealed Volume 1.54 ft.³Sealed F3 40 Hz
Vented Volume 4.63 ft.³Vented F3 20 Hz
http://www.parts-express.com/dayton-audio-rss315hfa-8-12-reference-hf-subwoofer-8-ohm--295-445
Edit:
Does anyone perhaps by experience know if the ratings on PartsExpess' bassBox6Pro fields are including or excluding driver displacement?
Talking about this:
Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)
Sealed Volume 1.54 ft.³Sealed F3 40 Hz
Vented Volume 4.63 ft.³Vented F3 20 Hz
http://www.parts-express.com/dayton-audio-rss315hfa-8-12-reference-hf-subwoofer-8-ohm--295-445
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Those highlighted in red have been addressed earlier on this thread more than once. Hint, "perfect-fi", in case you don't recall.
No, that is a German specification with much lower requirements,
"Frequency response is specified as 40Hz to 16kHz with permissible deviations (at 6dB below full power output) of ±1,5dB for non-equalised inputs and ±2dB for equalised inputs. Tone controls may be adjusted to secure the best response characteristics and volume controls can be fully advanced."
The BR EN spec was 20Hz to 20KHz IIRC.
They were comparing the actual live sound with the reproduced sound, and finding convincing similarity. Ergo, there was no audible distortion.
Today some of us might think 0.5% THD is "gross", because we've bought into the bizarre claim that 0.0003% THD is audible. But if people couldn't hear 0.5% THD in 1934, we can't expect to hear it today, either.
Not my area of expertise, but I'm willing to believe the claim.
That would be nice, yes. Additional confirmation is always a nice luxury to have.
Of course, there were in fact multiple studies along similar lines (comparing real vs reproduced sound) done over the decades after the 1934 experiments. Eventually the studies petered out, largely because most of the basic requirements for Hi-Fi were already quite well studied and confirmed by multiple experiments by multiple organizations, from Wharfdale to Bell Labs.
Those old 1934 papers state that 15 kHz was found to be an adequate upper frequency limit; I don't think that's likely to have changed significantly, even today, though saying so would cause a storm of protest in any group of audiophiles. In my teens I tried surreptitiously inserting a first-order, 10 kHz low-pass filter into the audio chain while friends were listening to music. To my surprise, nobody ever noticed, unless I pointed it out to them. It was audible if you paid close attention, but most people didn't pay close attention, and didn't notice.
Agreed. Of course, as mentioned, 1934 was hardly the last time someone did a controlled "is it live or is it reproduced" study.
Some things have changed since 1934. Leopold Stokowski's love for larger-than-life dynamic range didn't survive the test of time (supposedly audience members sometimes fled during the performances). I expect we would probably be happy with considerably less dynamic range today, compared to what was specified in those 1930's papers.
I guess the nutshell version of what I'm trying to say is this: in our current era of often utterly ridiculous audio-related claims, I find those old 1930's papers a very welcome counter-balance. A breath of sanity in a world largely gone insane.
-Gnobuddy
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