What uncontroversial audible differences cannot be measured?

[fas42]

A somewhat important one for me is the measuring of what qualities are sufficient for a system to have 100% invisible speakers; that is, it becomes impossible to audibly detect the drivers working, no matter where in the room you choose to listen. This is rarely experienced, because the level of audible anamalies has to be very low - but what numbers are applicable? Key types of distortion must be extremely low, all interference effects must be strongly attenuated, the speaker must be physically very stable within the listening area - these parameters should be measurable, but no-one has attempted to do so - I am also none the wiser as to how to put numbers to it.

[fas42]

5 hours ago, watercourse said:

"Image density" as I have heard it, can be described as giving the listener an impression of solid objects in the reproduced soundstage. In my experience, systems that have some leanness, e.g. lack midbass or have emphasized treble frequencies, will have less image density.

 

"Image specificity" means instrument(s) or voice(s) are more easily discerned and/or located in space (in the soundstage). This may have something to do with system self-noise and/or ambient noise levels, and likely treble reproduction characteristics.

 

I think I'm seeing these two as again likely based on spectral characteristics, and therefore likely measurable.

 

 

Both of those terms relate to what I call competent playback, and IME have nothing to do with FR. One can say that system self-noise is an issue, in the sense that low level detail in the recording itself is masked by low level reproduction artifacts, making it impossible for the brain to decode the recording data fully, and then the potential "density" and "specificity" is compromised.

 

"Rich 3D dynamic" sound is actually the true nature of recordings, and this is quite often masked by non-optimal playback.

[fas42]

8 minutes ago, GUTB said:

One aspect that's interested me lately is audio imaging. I don't know if there any objective means to measure it. I know there is theory on the topic, but nothing as well documented / studied that would allow you to objectify it. I know that many of you reading this thread actually have no idea what I'm talking about, and think a stereo image is left, right and center. After spending close to 2k in room treatments and re-arranging things dozens of times, including a bunch of money on measurement equipment, I've finally arrived at the "next level" of imaging. Sometimes sounds come from several feet beyond the edge of speakers, and even looking directly at the speaker doesn't totally collapse the illusion. Speakers have literally disappeared from the center, cymbals will envelope as opposed to eminate. Instruments in high quality recordings exist as unique entities in space. 

 

Seperating the sound from the speakers and unfurling a sound stage turned out not be easy for inexpensive. If there was a way to objectively measure it, it would undoubtedly greatly improve the accesability of this hobby.

 

Count me in as one who understands! Yes, "seperating the sound from the speakers and unfurling a sound stage" is hard - but doesn't have to be expensive! I first experienced a full-blown version of this 30 years ago, through great attention to detail - but still find it very difficult to achieve in a particular, new situation.

 

Measuring such would be ideal - but I still haven't achieved that level of understanding.

[fas42]

2 hours ago, watercourse said:

 

I've heard some small monitors exhibit image specificity, so I agree that it is not necessary to have full range frequency reproduction to image well. Perhaps it is only due to lack of experience that I have not heard bass-shy or tipped-up speakers exhibit image density, but I haven't heard it (or at least I can't recall that I have). If it is the case that limited range speakers can and do exhibit image density, what would you say about this quality then that you can measure?

 

I will disagree with the second paragraph, for instance, some of my favorite punk, early jazz, and ethnic recordings will never have "rich" or "3-D sound", yet I love them just the same, and don't need to hear them on the best systems to enjoy them fully.

 

Possibly because the amplication chain was not sufficient, regarding getting density. It appears to be a psychoacoustic factor, because a bass-shy speaker will deliver a subjective impression of deep, intense bass if driven with a high quality signal - the harmonics convey the information which the brain then reconstructs as the "correct note" - I have yet to hear a recording I have of the Sydney Opera House pipe organ being played on a system which has all the bass drivers necessary to get the job done, belonging to someone else, being delivered with the majesty and sheer 'grunt' that I have heard on my own systems, using only modest bookshelf sized speakers. I put this down to the quality of the sound, which allows a correct interpretation of the sound field to be made - IOW, very low levels of audible anomalies; how to precisely measure this I have yet to determine.

 

"Rich" and "3D" again comes from adequate quality; it may take quite a bit of effort to get the necessary performance to deliver on the sort of recordings you mention - but, it is possible. True mono recordings won't have left/right, but will be highly layered in the depth sense - subjectively, there will be plenty of apparent space with them.

 

It's one of the criteria I use to evaluate systems - how well can they recover "rich 3D" from "unpromising" recordings ...

[fas42]

1 hour ago, Fokus said:

 

And listener.

 

It is largely a learned skill.

 

I find that pretty bizarre ... I hear the qualities that matter in live, acoustic sound; and I look for the same in reproduced sound - I can't see where "learning" comes into this ...

 

[fas42]

1 minute ago, esldude said:

And you don't do reality checks do you?

 

Meaning?

[fas42]

3 hours ago, esldude said:

See the original post in this thread.  All your conclusions are from sighted evaluations.

 

Quote

(that stand up to various reality checks like blind testing, etc)

 

Various? Do we have anything other than blind testing?

 

Achieving completely invisible speakers is quite easy to test "blind" - simply close your eyes, move around a bit, at random, and then see if you can locate the speakers using your ears only. This is something I did instinctively when I first experienced this behaviour, to confirm what was happening - it's a very straightforward sensory experience; it either happens or it doesn't, there's no "I want it to happen" or "I'm not really sure".

[fas42]

10 hours ago, semente said:

So, the way I see it, in a way 3D "effects" and "timbre" correctness are inversely proportional.

 

 

As far as I know, there's only so much "ambience" that an adequately positioned mic setup can pick up from a live unamplified performance with vocals and acoustic instruments.

If that is not enough for you then you'll need to add your own "spices".

 

Actually, you can get it all - 3D, imaging, timbre. Simple reason being, that all the information is on the recording, it just has to be "processed" correctly, with minimal tampering while passing through the playback chain - the ear/brain then has enough detail to decode what's going on. A simple live analogy is a single person playing some instrument; you can place that musician in the most acoustically challenging places, listen to them from almost anywhere in the vicinity, from a couple of rooms away - and it's obvious always what's going on, you never lose the sense of someone playing that particular instrument.

 

This is what happens when a playback system is lifted to a sufficient level of competence; you experience the same sensations as when listening to live. And, many recordings have huge spatial enhancements encoded on them - these override the listening space, dominate completely - you're "transported to the recording environment".

[fas42]

6 hours ago, Albrecht said:

Hi,

No. I don't think that people mean that they cannot measure everything. What they mean is that the measurements are inadequate. Either the tools used are not sensitive enough to accurately measure, or not enough measurements are taken and then combined together to reflect the entirety of what's going on. Or, the wrong TYPE of measurements are taken.

 

Yes. I was fortunate enough to have very high quality sound fall into my lap, many decades ago - and I had plenty of time and opportunities to explore this, because my system would enter this "mode" and then slip out of it, over and over again. This was 100% repeatable, for as long as I wanted to play with it - so, what was changing? Nothing whatsoever to do with the room, or FR, or how the equipment was set up, or "tuned" - it had to do with very low level distortion which was being injected into the electronics side of things, as it stabilised after being switched on - switching off, and switching on again reset this behaviour, every time.

 

Would I have been able to measure what the artifacts were that were critical here? Theoretically, yes; practically, not a chance - even now I would be unable to suggest what the right way of detecting those anomalies would have been, if I could go back to that system.

 

[fas42]

1 hour ago, Sal1950 said:

Most likely the result  of alcohol/drug induced delusions. 

 

Tsk, tsk ... alternative definition of insanity: Being made aware of some aspect of how the world works again and again, but refusing to accept it because it doesn't fit in with one's mental picture of it.

[fas42]

3 hours ago, mourip said:

 

I have seen this effect also. In my case adding in an isolation transformer cleaned up the sound to be much more consistently satisfying.

 

I did not have a way of knowing that this would help or any way of measuring it except for reading a few really helpful posts from John Swenson and a few others regarding the effects of clean power and the elimination of ground loops.

 

Thanks for the post.

 

Pleased to hear that you had a similar experience!

 

Yes, eliminating interference effects is a key part of achieving this goal - clean power, optimum earthing arrangements, it's a list of "little things" that can make all the difference ...

 

[fas42]

1 hour ago, semente said:

I wonder what effective measurements would one use to determine the resolution of a loudspeaker driver at low levels...

 

Effective, but not measurement, method for evaluating the system, not just the speaker, is to listen to a driver as if it were a side of a headphone; that is, put your ear just a few inches from the surface of the radiating surface: do you hear the driver working, are you aware of its presence as the source of the sound; or are you only able to perceive the recording presentation?

 

This was a method I started using decades ago, and has proven to be ideal for the job - if you can't "hear the speaker" even in this "extreme" circumstance then the system is in a good place.

[fas42]

1 hour ago, Fitzcaraldo215 said:

Yup, like me and others who are drifting seriously off topic, we still got nothin', boss.

 

Have a room with a grand piano, and quality hifi: either have a skilled pianist play the instrument, or play recordings of the same pieces on the system. Have the door to the room open, and allow people to come up to that door without being able to see inside: ask, is that a real piano, or recording? If they're nearly always correct, what is the measurement that gives it away?

[fas42]

56 minutes ago, STC said:

 

Anyone you know done this? If the difference is audible than it is measurable. But this experimentation depends on so many variables. You must play the sound of the grand piano captured in anechoic chamber. 

 

No. It's been suggested many times that the quality of "aliveness" can't be replicated by audio playback, that there is always some giveaway in the sound field which betrays its origin - hence my putting this forward, as a possibe detectable variation, which is not readily measurable.

 

By all means, do whatever one thinks necessary to give the recording the best chance of being undetectable.

[fas42]

16 hours ago, STC said:

 

I find " aliveness" that you talk about is not clear from what I read so far. For the record, animal which life depends on acute hearing sensitivity couldn't distinguish playback from from real voice. And the challenge for the penguins in the experiment was to find their chics with thousand other chics making very similar noise to we humans at the same time. And we are  having trouble focusing to a conversation in a noisy restaurant. 

 

Let's say a lot of money was depending on whether you got it right or wrong - IOW, strong motivation meant that you weren't going to make it an idle guess - would you nail it most times?

[fas42]

Regarding having a speaker devoted to each instrument, this, as esldude eludes, is what happens subjectively from stereo when the quality is sufficiently high - the system playback creates "virtual speakers" corresponding to each sound element in the mix; this is particularly obvious when listening to complex studio productions - Michael Jackson's "Bad" is an example that comes to mind here.

 

Why should this happen? If there are real speakers corresponding to each sound element then it seems fairly obvious why the perceived sound field should have these individually identifiable sources within it; but it only occurs because the detail of information from each speaker is well formed, the acoustic clues as to what is going on are clearly presented, and our hearing makes good sense of it.

 

And this is what happens with adequate resolution of conventional stereo playback: the acoustic clues locating each sound element in the mix are reproduced to such a level of clarity that our hearing mechanism has no trouble decoding the information; we always "know" where a particular sound within the sound field is coming from, irrespective of our position in relation to the left and right speakers.

[fas42]

6 hours ago, Jud said:

Something I don't know that we've talked about much is the analogy between circuit components and system components.  There are two potentially fruitful lines of inquiry here that I can think of:

 

- Can you (has anyone) simulated system components using something like SPICE, to try to get a better handle on the complex interactions in a system with multiple components and interconnections?

 

To a small extent, yes. Simulations of amplifiers using, say LTspice, my choice, typically assume everything around it is perfect, including power supplies - which leads one to a fairy land of performance numbers. By adding a real world mains supply, and typical component power supply made up of Spice parts with all their parasitic behaviours, I was able to see the high treble distortion of a decent amplifier design increase by the order of a 100 times - why? Because the linearity of the amplifier was compomised by the design's feedback having to deal with the non-ideal voltage rails; the complex, and real world, electrical environment ensured that the amplifier performed nowhere near as well as assuming ideal operating circumstances.

[fas42]

55 minutes ago, Jud said:

 

I was wondering if/hoping that ground/leakage currents and other such bothersome stuff could be modeled.  Finding such stuff going on inside a design without having to waste time hunting around, is, after all, one of the reasons to run a simulation.

 

It all could be modelled, if one knew what all the sources of the "bothersome stuff" were. There are always extremely critical areas in a design - for example, it's vitally important that the feedback loop in an amplifier be implemented in an as "perfect" a way as possible; simulating some interference source within this path shows how damaging the impact would be. Other parts of the circuit are extremely robust, innately having very high levels of rejection of outside signal - just putting all the bits of a design on a board so that it "looks pretty" is not a good approach.

[fas42]

49 minutes ago, jabbr said:

 

That's what cascodes are made for  

 

Yes, there are always ways of improving behaviour - that's what good engineering is about. So then the question is, how much does it have be "improved", to reach the point where further improvement doesn't yield any audible benefit, under all possible conditions?

[fas42]

46 minutes ago, STC said:

 

I am lost here because I don't know what you are referring to. Give me some examples of "Aliveness" because I don't get it from the Youtube links your provided. Since I don't understand the concept of "aliveness" that your are alluding to realism, could you provide some examples of it? 

 

It is always going to be a problem providing examples of such, because the quality necessary will always depend on the full chain that's in action at the time when you're try to evaluate it. In this case, the chain includes the YouTube encoding, the downloading mechanism your system is using, and the playback chain on your PC, including the speakers or headphones used.

 

The best strategy, if using YouTube, is comparing a clip of a live recording of an instrument, to a clip of an equivalent recording of the playback of an optimum capture of that instrument - confused enough?! If a very good match in key areas then you have something to go on ...

 

The intention of the YouTube channel is to provide snippets of where I've been, and progress to date - they are miles from being perfect examples of what I'm talking about, for various reasons. However, for me they contain signature elements of what I look for in reproduction, and which are usually missing in recordings of other playback.

 

The "realism" sensation can only come about when the actual acoustic event that your ears are registering at that moment is of sufficiently high quality - for me, the key marker then is that the speakers in use become impossible to locate, no matter how close you move an ear to a driver; the illusion of a musical event occurring in a space separate from the playback system is rock solid, at all times.

[fas42]

21 hours ago, STC said:

I personally made recording of my son playing classical guitar and compared with playback. It never occurred to listen from outside the room to guess the source of the sound. Will try that later. But it was quite close. But inside the room the difference was there but I would not say too much.

 

This is the situation I was referring to, regarding being motivated to always pick the difference.

[fas42]

39 minutes ago, lmitche said:

This would be the basis for a research tool to determine what really matters in the reproduction chain.

 

What really matters in the reproduction chain is a very old cliche, but is still exactly the right answer - "the quality of the weakest link". That will always determine whether a convincing illusion will be thrown up or not - I've spent decades foolin' around exploring this, and the answer has not changed, one iota, in that time.

[fas42]

55 minutes ago, STC said:

 

With respect, you were able to determine AVshowroom certified accomplishment as, and I quote you " This includes a long segment at the end of the clip of the speakers in operation - and, it is relatively easy, even on a YouTube video(!), to hear that the sound is deficient - it has a "shouty", uncomfortable quality to it, which seems to get worse as the clip progresses ... what is happening?" .

 

The video clip wasn't excellent but despite so many words I don't see any concrete method to show your method could work because I don't think Peter is so deaf not to hear the deficiency when he awarded the certificate of accomplishment.

 

I have pointed to other YouTube clips at various times, which capture systems which show no obvious audible flaws, via my YouTube replay - if the playback shows obvious problems in the quality, as does this one to me, then I mention such - if someone walked into your room while you were playing that YouTube clip at high volume, and you said that was a real group in action, rather than a hifi, do you think they would believe you?

 

[fas42]

... typo post ...

[fas42]

19 minutes ago, STC said:

Ok, this I understand. So far, you have explained about what to listen for. I am going back to your blog to start from your first post. Unfortunately, I am told that no secrets will be revealed. Could you confirm that your method:-

 

1) Involves only two speakers.

 

2) No phase manipulation.

 

3) No crosstalk cancellation.

 

5) No DSP modification.

 

Thanx.

 

Correct. The only exception is that the Philips HT rig used a single, active, subwoofer which it came with.

 

Why there are "no secrets" is because my method is all about troubleshooting - every system will have strengths and weaknesses - I leave the strengths alone, and just concentrate on eradicating where the setup shows problems. This is how I fluked getting my first decent audio combo working at a high level - by trial and error I determined what was causing issues in the sound, and either fixed them or organised a work around.

 

In that first system the power supply of the amplifier was non-optimal; only after many modifications of that was I happy with its behaviour; in my current rig, in the NAD combo mentioned in my blog, it was the over-complex circuit, saddled with poor quality switches, that were a major problem. The 'secret' is that I take educated guesses as to what needs to be looked at, and proceed with investigating, and then resolving issues in a low cost manner.