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Re: I'm just not sure about one thing

Posted by morricab (S) on November 20, 2006 at 08:50:46

In Reply to: Re: I'm just not sure about one thing posted by Pat D on November 17, 2006 at 22:58:54:

Well the fact that you have difficulty understanding some generally accepted audio language makes this discussion rather difficult, or are you merely being obtuse? I assumed that at least some of these definitions are obvious and at least a few have been explained and discussed enough that you know what I mean.

However; I will address the points and give you what I am thinking about when I use these terms.

1) I never said even frequency response wasn't important, just less important than you give it credit because of its relative ease of correction. With modern DSP, FR is the least of a speaker designer's worries.

2) Transparency "a piece of optical imagery, not really very clear in its application to audio"

You are the only one who would question this. Yes it is an optical analogy but one that is quite clear (no pun intended) to most people because the auditory equivalent is the feeling that there is nothing between you and the original sound. It mainfests itself in that on recordings with natural acoustic one can hear the ambience in the recording clearly, for example. In this sense it is related to low level resolution but low level resolution also includes clearly perceiving subtle dynamic shifts at low levels, not simply did you hear the sound or not. Does the character of the instrument retain the correct timbre and expression at that low level or is it indistinct?

3) Coherency: The sense that the sound is coming from a unified source and not multiple sources. Nearly every box speaker betrays the drivers it uses to make sound. This is due to crossover anamolies, differing driver materials, sharp cutoff, cone resonances etc. Time coherence is another matter and why I put it in parenthesis. It has been my experience that speakers which are time coherent (for example full-range electrostats or a speaker like the Thiel CS3.6) are also more coherent in the first sense of the word. An example of one of the least coherent speakers I know is the B&W 802N. This speaker uses a different material for each driver and high order slopes. Hearing the transition between drivers is painfully obvious as a change in the coloration of the timbre of instruments. It has very little to do with FR.

4) Low level resolution: see point 2 above. I will repeat, it is not just if you can hear a soft sound or not (although with some speakers and systems this is an issue) but if that soft sound retains the complete characteristics of the thing making the sound, including dynamics and timbre. MOST speakers in the world have problems at the low level sounds. Nearly all conventional medium to low sensitivity speakers fail miserably.

Example: Some friends of mine have Apogee Scintillas. These are very high resolution speakers; however they are a bit old and one friend has had them rebuilt and the other has a stock pair. They did a speaker cable test (quite important with a 1 ohm speaker) comparing the Speltz anticables to some DIY silver cables. They did this test on the rebuilt Scintillas that have the same DIY silver cable as internal wiring. They had a track of a new woman singer from Norway done in what seems to be a home studio. On one track they noticed very quiet in the background a dog barking(presumably outside the studio). They had not noticed this with the anticables but it was clearly audible with the silver cables. When they went back to the anticables and listened carefully for the dog THEN they heard it. However; it was much less distinct and barely noticable as a dog. Back to the silver cables and the dog was distinct with timbre of its voice and probably even would be recognizable to the owner. Oh they were using only 1/2 meter long cables and this was still obvious.

The other friend took the recording home on his stock Scintillas, which are wired with 20 year old Monster cable and he has 3 meter speaker cables. He couldn't hear the dog at all!!! It was simply not there no matter how hard he tried to hear it and even knowing exactly where it came in. Clearly information was being lost and now he is going to have his speaker cables shortened and rewire his speakers. This is an obvious example of what I mean by low level resolution.

5) Dynamics. This has nothing to do specifically with bass. Does a trumpet's blast rely on bass response? What about a Cymbal crash? Dynamics has to do with a speaker's or system's ability to go from one level to another level with lifelike speed and in the case of big amplitude shifts do so at ALL frequencies equally and without compression. Not just bass. Speakers that are restricted in dynamics in some frequency band will exhibit a certain "character" that is not obvious from a FR measurement (same is true for amps and sources). If a speaker sounds "dark" even though the FR is nearly flat then it suggests that the high frequencies don't have the same dynamic character as the mids or bass. If it sounds bright and the response is relatively flat then it is possible that the bass driver has begun compression whereas the mid and tweeter have not.

"Anyway, I listen well within the dynamic limits of my speakers"

Do you? Probably if you listen only to compressed music then you are right. If you listen to relatively uncompressed jazz or classical then I doubt it.

Let's be clear: Dynamic range is not just about how loud something can play. It is also about how SOFT a speaker can play and retain the correct character of the instruments (see my thoughts on low level resolution). The key word here is RANGE. From soft to loud not loud to louder. If you listen to an orchestra at REALISTIC levels then how good is your system through the soft passages and does it make it through the loud ones uncompressed? That is what I mean by dynamics and dynamic range.

6) Freedom from compression: Soundstage's measurements are steady state and not necessarily indicative of dynamic conditions.
I have seen studies that show 86 db/watt drivers that begin to show the effects of thermal compression as low as 90 db. Normally, doubling the power gets you 3db more output from the speaker. What they found was that above 90 db or so they were getting only about 2 db per doubling of power and then at higher levels only about 1 db. Eventually the driver will cease to get louder and you will probably melt the voice coil. VCs can heat up very quickly on big sudden peaks and are relatively slow to cool down thus affecting the signal that follows the big transient. This is called hysteresis and its reality is that big dynamic peaks DO compress for most drivers and at lower volume levels for lower sensitivity drivers. Tweeters are often much higher sensitivity than woofers in normal speakers. Many speakers get edgy sounding when pushed. Is it distortion?? Maybe. Cone breakup? maybe or maybe its also a momentary imbalance between the outputs of the drivers due to thermal compression.

7) Low coloration: This has very little to do with FR so I am not sure why you bring it up. Coloration is the sound the speaker makes by itself when the drivers are in motion and is correlated with but not a part of the actual signal that was put into the speaker and what the drivers are putting out. This manifests itself as: Harmonic distortion, driver flexing colorations, cabinet energy storage and release, crossover anamolies, resonances etc. This altogether can be thought of as "self-noise" or the noise the speaker makes itself that is not part of the original signal. It rides typically 10-30 db BELOW the main FR and rarely, with exception of strong resonances, makes a noticeable impact on the FR. However; it is most definitely audible and probably one of the main reasons that two speakers, even perfectly corrected for FR can sound very different (along with dynamic behavior).

Often, the lower the speaker's "self-noise" the better that speaker will retrieve low level information while retaining the proper character of the sound. Transparency and natural soundstage will also improve (assuming the recording is made in a natural space). Most speakers are so "noisy" that most people don't even realize that all that garbage is riding along until most of it is gone. This relative lack of "self-noise" (all speakers have some) is one of the reasons (along with freedom from compression and dynamics) why big Wilson speakers (like the MAXX and X2) can sound quite lifelike despite their relatively poor FR.

8) "Resolution is something you also mention: it's also an optical image whose applicability to audio is again not too clear. I suppose it means one can hear what's on the recording."

See points 2 and 4 its not just what's on the recording but if the correct character of that thing is properly preserved. When I say high resolution I am also including the other points like dynamics, coloration, and transparency. Clearly there is some overlap in the terms and some terms are used in the definition of others. We use optical analogies because they are ones that are easier to understand. It is not easy to describe hearing phenomena.

""Gear differences become so obvious that you wonder why others even argue about it."

Gee, I want to listen to music, not gear differences. "

This is a disingenous statement and a cop out because obviously in this discussion we are talking about how the gear affects our perception of music. A high resolution speaker will give you insight into which gear and cables are giving you the full information and which ones have audible problems. However; if the speaker is mucking things up too much then the ability is flawed. You can still hear differences but it becomes more difficult to tell different from right or wrong.

The right speaker and right gear will give you more of what is on the recording and presuming the recording is a good one then more music.

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