xpert said:
A standard FR measurement tells us nothing about this stuff, it is far too course grained. What i want to see, is how these things affect the response some 40 dB down (nominal). Plug that into you calculator and tell me how a FR measurement is going to tell us anything.
I'm pretty sure i know where you are coming from -- if the only tool you have is a hammer, you treat everything like a nail.
dave
xpert said:
You keep saying this and its incorrect. It's ONLY true if 1) the system is minimum phase (which in acoustics in generally NOT true) or 2) you also have the phase response. The "response curve" is generally not shown with phase and even then non-minimum phase aspects (which are audible) are often impossible to detect visually.
You claim such supreme eXPERTise, but you get even simple stuff like this wrong.
gedlee said:
If You would have read my posts You might have seen that I always mentioned the linear regime in ONE word as to say
A) group delay
and
B) amplitude response
That is what I meant could haven been understood as what I mean with "response curve". I wrote it so often in the lenghty way that I had the hope that including You everybody even if of minor expertize would simply know. You may think of it as me trying to set a standart in understanding the word: linear response.
And - I do not claim that "expertize". You get it wrong. What I do is to show weaknesses in marketing claims. That doesn't need to much brains.
gedlee said:
As I really am a challenge for Your understanding please let me referre to my posting #135:
http://www.diyaudio.com/forums/showthread.php?postid=1837922#post1837922
From that on the talk concentrated on how to identify linear distortion and not to characterize it. Identification could be done with soley amplitude.
'Think we've got it now.
dlr said:
I listen to music, and way down is where the subtle details of the music live, the subtle details that really help with verisimilitude. On the other side the removal of grunge that hides this stuff relieves our flight/fight reflexes from having to work as hard. We are more relaxed and enjoy the music more.
dave
planet10 said:
You should be above that first part that is a not very subtle attempt to belittle. I won't get into a debate about who listens to what and how. It's pointless and a bit conceited.
Grunge isn't a very well defined term. I suspect that no two people would define it the same way. I cannot infer any clear meaning of your definition of it and I doubt that it's quantifiable. How can one argue for/against an ambiguous term?
As for the rest, it doesn't provide anything not explained by changes in the linear part of the system response. Small crossover changes can provide changes in the perception that you describe. Painting dots or stripes on a driver make a measurable change in the frequency response that may be perceptible (or not). And I can't recall reading any references you might make to the distortion profile, so it seems fair to assume that you are referring only to the linear response and not any non-linear distortion.
Dave
gedlee said:
Doc...
Arguments of expertise are a fallacy. I have no 'credentials' per se (beyond some years of experience) but can assemble a decent argument on many of the points under discussion.
Ignoring "Xpert" is the best route if you're bothered by his behavior. Anyone who uses such a moniker seems to me to be too arrogant for their own good. There's a saying, "The more you know, the more you realize how much you have left to learn" (it's been paraphased dozens of ways).
Regarding level perceptibility, testing I've seen was done with non-music signals. That alone separates the test from the usage environment, like a wind-tunnel vs. a racetrack vs. a road with cars. I do a number of tests when testing small items. One of the most important is long-term behavioral. Do I still enjoy the item in question after the novelty has worn off? Do I find myself focusing on one aspect of the sound? Do I listen to more or less music?
Obviously it's not an easy test to perform with multiple subjects, and has many factors applied, but that's why it must be longer duration. If my longer-term musical satisfaction increases, more attention is spent on the whys and wherefores. If I find my rig less enjoyable, the change is reversed, or further investigated.
Blind testing is an important validation step... sometimes. Just as with the THD wars, the ears have it all over the microphones, as far as musical enjoyment goes.
Daveplanet10 said:
I think this a mistatement of the issue. The issue is not listening to low level signals, say 50 dB down, its listening to aberations that are 50 dB BELOW the signal. Thats a vastly different thing. Its this masking that I contend makes the enclosure aspects inaudible despite the fact that you can do all kinds of things to make them audible, but only if you surpress the signal content!
There are few things where credentials don't matter and experince is a credential. I would say that they are "necessary but not sufficient".badman said:
badman said:
Agreed, I will go back to doing that.
badman said:
I think that your procedure for listening evaluations is much like mine. Where we might disagree is on cause and effect. I never accept anything that I think that I can hear until I can measure it. That IMO is a necessary requirement to establishing cause and effect. I was never able to measure enclosure effects even though I too belived in them initially. Then when I reduced the enclosure structural aspects and the sound remained just as good, that kind of closed the loop for me. I do not say and have never said that ANY cabinet is fine, only that in extensive evaluations I find that my cabinet construction is sufficient. But its not up to many people standards - that, I claim, is unjustified.
....so on and so forth.
Yes, and what about a listening room aberration that happens to reduce the amplitude of the initial wavefront by, say, 15 db and another listening room aberration that emphasizes the contribution of the panel resonance by, say, 10 db at some hypothetical frequency? Suddenly, the delayed coloration is louder than the initial sound. It appears such considerations have so far been outside of your intellectual envelope.
Deleted some OT posts. Keep it to the technical discussion, folks.
gedlee said:
But, given a well-behaved time-domain from the drivers themselves, any enclosure ringing that remains when the excitation drops off suddenly will be dramatically higher in relative amplitude. It's not during the dynamic transients- it's immediately after, where the source material is relatively quiet and consists of resonance within the instruments and environment of the recording... resonances with (likely) similar characteristics to those of the enclosure, and with much closer amplitudes.
gedlee said:
I think it's flipsides of the same coin. It's a subjective rather than an objective determination of which dataset is more valuable, data vs. hearing. When building something, it's very difficult to disassociate your prejudices from the evaluation. We're agreed that a 4" thick steel enclosure isn't necessary. But, an easily implemented set of shelf braces sure can go a long way.
But it's possible that you determined via (known flawed, there's no such thing as a 'perfect' measurement) measurements that the enclosure resonances were below an audibility threshold, and that influenced your listening to be willing to ignore them. This is just a flipside of the coin of hearing what you want.
I think that much of this hobby is in the finer points, and sometimes they're obscured via short-term measurements. I can't remember an album well after the first listen, or even (usually, if it's music that I deemed worth evaluating) give a good idea of whether I'll enjoy it longer-term.
Human auditory memory is known to be short.....
But that's based upon short-term testing! Perhaps auditory memory is longer with more time spent with a driver/speaker/system? I know I recognize the 'sound' of speakers and drivers I've long not-heard, if I spent enough time with them. Likewise, there are subtle bits of music that take time to pick up on, and certainly wouldn't happen in a DBT with unfamiliar everything, but once they're recognized, these (typically low-level) information pieces can be critical, and one can be aware that they're altered, even though they're very low level and the alterations even lower.
Maybe I'm just slow, but rapid fire evaluation is extremely difficult for me, but I am pretty confident in longer terms. When doing switch-based tests, I meditate before hand, to clear my mind and relax. I have to be very careful to not 'actively' listen as much as 'hear', for the low-level stuff to be clear. The correlation of these shorter-term tests to longer-term experience has only been useful when extreme care to be passive and comfortable and clear-headed are taken. However, the combination of the two gives a great deal of confidence in the results. If I listen to a specific device, swap it in and out a few times over a month or three, then do A/B/A (sometimes DBT, sometimes not) testings in the right fashion, the character I've come to know is much more apparent.
Enclosure resonances are tough to eval in this situation. My own experiment consisted of a pair of sealed 8"s, one with dowel braces much like your own bracing and 3/4" void-free ply of mediocre quality, and one with the same enclosed volume and wall thickness of better ply with a few corner chocks and shelf braces. Upon longer term swapping in and out the nicer cab was consistently preferred due to better 'clarity' and 'impact'. This included a few single-blind tests with buddies but nothing more formal.
None of this has been done with appropriate documentation, but I think you can relate to doing 'good' experimentation to satisfy your own curiousity without feeling the need to go further with it.
badman said:
As I said before IF the enclosure is going to be audible this IS where it will most likely occur.
badman said:
To me the point is that you have to do both, objective and subjective. Unless you can measuire what you hear and hear what you measure, you don;t know what you are doing. The loop has to be closed, but it makes no difference which direction you go arround the circle.
I too take a very long time to decide on anything subjectively regarding sound quality. This is precisely why I gave up going to shows. At one show some guys came into the room, sat down listening to what was probably an unknown piece of music and got up after 15-20 secconds stating "What crap!" One person wouldn't listen because the amp was so bad (although how they knew that was beyond me. I've measured that amp and it actually works quite well.) If thats the evaluation process, then I don't want to be part of it. Yes, there were several other people who spent some time and a couple of them actually bought speakers, but I still have serious concerns over that type of audition.
Unfortunately, "The loop" has open sections on both sides- the hearing mechanism fails, but so does the measurement. And they fail differently...
We're agreed regarding shows. I'm generally able to judge when there's high-quality sound but am very careful to avoid negative judgements due to show conditions, since they are unfamiliar everything, usually.
I don't bother with rooms that are really packed, either. Too much distraction and bother. I usually make the rounds many times to try to catch the rooms I'm most interested in when there's a break. And speaking of breaks.... can show organizers PLEASE stop having shows in high-rise hotel venues? It's the worst of all worlds. The old CES and THE show venues were nice because you weren't getting dry-humped by fat audiophiles in the fire-hazard overcrowded hallways. There was outdoor walking area to let your ears and mind relax between exhibits. This was a nice aspect at VSAC 08 as well, there was plenty of opportunity to chill out in the lobby or outside between rooms. I don't think I'll ever bother going to a 'nomal' hotel show again.
I've found that at these shows, also, the best sounding rooms are often speakers I wouldn't like. Dynamically restrained "soft" speakers playing the music that suits them, with lots of acoustic treatment. A little break from the pains of overblown demos from many exhibitors.
We're agreed regarding shows. I'm generally able to judge when there's high-quality sound but am very careful to avoid negative judgements due to show conditions, since they are unfamiliar everything, usually.
I don't bother with rooms that are really packed, either. Too much distraction and bother. I usually make the rounds many times to try to catch the rooms I'm most interested in when there's a break. And speaking of breaks.... can show organizers PLEASE stop having shows in high-rise hotel venues? It's the worst of all worlds. The old CES and THE show venues were nice because you weren't getting dry-humped by fat audiophiles in the fire-hazard overcrowded hallways. There was outdoor walking area to let your ears and mind relax between exhibits. This was a nice aspect at VSAC 08 as well, there was plenty of opportunity to chill out in the lobby or outside between rooms. I don't think I'll ever bother going to a 'nomal' hotel show again.
I've found that at these shows, also, the best sounding rooms are often speakers I wouldn't like. Dynamically restrained "soft" speakers playing the music that suits them, with lots of acoustic treatment. A little break from the pains of overblown demos from many exhibitors.
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