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In Reply to: RE: Ideal frequency response curve posted by throwback on June 16, 2015 at 06:03:35
If your system is doing damage to the sound at low levels bringing the levels even lower than you would normally hear in nature. Since the sensitivity with level affects YOUR hearing and not the sounds per se it means you have the same bias with real live sounds.
However, if your stereo is not sensitive to small fluctuations at lower levels (most low sensitivity speaker systems suffer a "drop out" below a certain SPL) then it will sound lacking in both bass and highs compared to "the real thing". This is one of the biggest problems in audio and its affect on realism, IMO. It also manifests itself at higher volumes when a soft sound is trying to be discriminated (my late friend Allen Wright called it DDR, downward dynamic range).
A proper compensation would need to see how much of a deviation is being made and applying that dynamically with each change in level. The compensation would NOT be to the Munson/Fletcher curves but to whatever the systems original target curve would be at say 85db.
The problem is that you are always correcting what has already come before with a feedback system. With high dynamic music you might be applying the right curve correction at the wrong time!! A proper system would need to have the right response measured for a given speaker/amp combo and that file loaded into memory. THEN for the music being played the system would need to analyze the WHOLE recording in advance to be able to apply the right correction at the right time. Of course the listener would have to include their target reference level (min, mean and max SPL levels) or else it would STILL be incorrect with a random volume level selected.
A non-trivial problem IMO but still solvable.
Follow Ups:
Morricab:
We may be talking about two different things. Or are we? I was talking about the phenomenon that a system that measures flat at the listening position will sound bright to the ear at normal listening levels. If I read Fletcher-Munson right, as one reduces the volume the measured response will remain the same but both the highs and lows will drop off as perceived by the ear.
Tricky stuff, eh what?
Well, in that case you are talking about power response vs. on-axis response in a room. A truly flat measuring speaker will sound bright if the dispersion is even and wide and you have reflective surfaces. In a large room or with a speaker that has quick rolloff in off-axis measurements, it is less likely to sound bright.
If you are listening to a recording at lower than natural volume levels then to get a "live" feeling there would need to be boost because of your changing perception and the fact that it is not at the natural level for that given performance (really only applicable with uncompressed acoustic music). Enter the loudness button, however, the bigger problem is how stereos handle low level signals and as you lower the volume then subtle sounds will simply drop out because the system cannot generate such small responses.
"the bigger problem is how stereos handle low level signals and as you lower the volume then subtle sounds will simply drop out because the system cannot generate such small responses.""because the system cannot generate such small responses.".
Show me. This is easy to prove. Is the signal there, or, is it not there?
I understand that your friend believed it, and that you believe your friend. The emotional factor is huge in situations like this, so it's essential to do our best to eliminate personal bias.
Moving on...
If one plays a recording of an orchestra where the live peaks were 105 dB, and sets the playback volume to, for example, peaks of 80 dB (a reduction of 25 dB), minute details will obviously be lost. This is common, and, to be expected.
Often, it's a result of hearing acuity and/or the ambient noise level in the playback environment.
You'll have to provide some evidence that the signal simply isn't there, and that it's not because the listener couldn't hear it.
Your're a smart and experienced guy, but your argument that the system can't reproduce very low level signals is suspect.
:)
Edits: 06/22/15
It is not if the signal is there or not it is if the driver that is supposed to reproduce it will respond to it or not. Below a certain level there are resistive forces (mostly mechanical) that will resist motion and the drive from the electrical signal will be insufficient to overcome those forces. Then you start to get drop out of signal.
It is not just belief, it is empirical experimentation. It can easily be heard with the decay of sounds in a real acoustic environment and then the reproduction of that environment will often entail a truncated decay. The further that decay is captured the better the low level performance of the system and the better a system can capture that decay when there are other louder sounds also being played (like decay of a piano while the next notes are being played...with a real piano you can hear the decay of the previous notes even when the next notes are flowing onward...with hifi this is often difficult to hear).
"If one plays a recording of an orchestra where the live peaks were 105 dB, and sets the playback volume to, for example, peaks of 80 dB (a reduction of 25 dB), minute details will obviously be lost. This is common, and, to be expected. "
For sure, and why some kind of compensation to return things to a more lifelike level without actually turning up the volume is perhaps interesting. THis is because it is clear that wide dynamic range music loses interest when not played at the realisitic volume usually. However, there is a HUGE difference between systems on how well that 25db reduction is handeled and some lose much less than others. The Acoustats I had (Spectra 2200s) EXCELLED at retaining the detail of the low level information even when the peak level was reduced by a large amount and thus kept the music more interesting. The only speakers I have had that are as good are the horns i have now, Stax ESL F81s and AudioStatics. My Apogees, as good as they were, could not do as well in this test nor could the Infinity Betas or the Genesis VIs.
"You'll have to provide some evidence that the signal simply isn't there, and that it's not because the listener couldn't hear it."
I never said the signal isn't there, I said it is not being reproduced or reproduced increasingly inaccurately. It is also possible to get burried in the electronics noise floor as well, especially if the piece of gear has a high negative feedback that creates a signal correlated "noise" floor. This was demonstrated by Crowhurst back in the 1950s. Of course it is also possible that the listener is not able to hear it below a certain level but I think it is more often system related because in a good acoustic environment with live, unamplified music you can hear these things (or at least I can) clearly.
"I never said the signal isn't there, ..."
Yes, you did. You wrote:
"...subtle sounds will simply drop out because the system cannot generate such small responses. "
You're mincing words. "Drop out" and "isn't there" both mean it isn't there, and isn't that what you're saying?
First, you were talking about "the system", which you later modified to "the speakers". There's a difference.
This makes me wonder about all those reports and reviews of systems (er, loudspeakers, er, amplifieers, er, preamps, er, sources, er, interconnects, er...) where the writer talks about it reproducing the most subtle nuances and details of the recording, and having such wonderful "air". You know exactly what I'm talking about. They must have been playing the system at "concert level" (or louder?).
I've already asked you for data. I'll ask again.
If your assertion is correct and you have empirical evidence, cite a reference or two (preferably three), or point me to where I can find it. Anecdotal "evidence" doesn't count.
In any case, there are at least two factors which make the "problem" moot:
1. At "low" (define that) listening levels, subtle detail is lost in the room's ambient noise.
2. You still haven't provided evidence.
Let's not forget that audio level compression and limiting has been around since darn near forever. This is not news. The problem of low level playback compensation was addressed many decades ago, by many companies. Probably not to your liking or approval. Google "Gain Brain" and "Kepex" and "LA-4".
:)
By "system" I meant loudspeakers in that particular case but it can also apply for electronics but in their case it is more that the signal is dropping below either a true noise floor or a signal modulated one.
"drop out" and "isn't there" don't really mean the same thing. Drop out means something that is there but below the capability of the system to produce the sound. Isn't there means its somehow missing from the music content and that is not what I am saying.
"First, you were talking about "the system", which you later modified to "the speakers". There's a difference"
I agree, the confusion is first I was mainly referring to speakers but it can also apply to electronics although the reasons why are completely different between the two. I ended up sort of mixing the two together (in my mind they both impact the low level resolution and dynamics though).
"They must have been playing the system at "concert level" (or louder?)."
Often the case and many of my audiophile friends listen a lot louder than me.
"I've already asked you for data. I'll ask again.
If your assertion is correct and you have empirical evidence, cite a reference or two (preferably three), or point me to where I can find it. Anecdotal "evidence" doesn't count."
I'm sorry, what exactly am I supposed to be proving to you? Not that I am in any way obligated to do so since you have a keyboard and google as well.
Those compressors and booster are to compensate (inadequately because they are not level dependent) for the drop out that I speak. It is not just the hearing that is changing but the speakers and amp capabilities as well.
There is a good reason why a horn or electrostatic speakers continue to sound lively, detailed and with good ambient retrieval at far lower average listening levels than a conventional, low sensitivity speaker. This alone gives a clear indication that some speakers "drop out" low level sounds earlier than others. You can further easily hear the influence of the electronics on this with a given speaker. I am giving you firsthand experiment observations but I am surely not alone in this. Electrostats give a great insight into the effect of electronics on the whole low level resolution issue. Horns as well but some of them have colorations and resonances that mask information too.
"I'm sorry, what exactly am I supposed to be proving"
You are kindly asked to provide data/references which support your assertions.
Too bad that live sound is not typically EQ'd or "corrected" according to individual listeners acoustical vantage point.Because everyone hears live sound differently, it is therefore crucial that live music be loaded into our memories for proper reconstruction at some later point in time. For it is written, "The best hifi system is the one in my head."
And so it may be that the best hifi system transmits as much of the electrical signal as cleanly as possible while also helping us to construct or recreate some musically IDEAL vantage point, for ourselves. We must all find our own EQ curve. EQ according to memory.
Edits: 06/21/15 06/21/15 06/21/15
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