Interesting in this discussion is that virtually no mention is made of that nasty stuff, "distortion", by name. My experience is that ALL systems distort, some nicely, adding a soothing patina to the sound, but the majority inject varying amounts of relatively low level, edgy, unpleasant and irritating distortion which then overloads the ear and brain when you turn the volume up. I'm talking here of non-linear distortion, not frequency or phase response effects.
As mentioned, many musical instruments are naturally LOUD, but nasty, amusical, low level distortion is not part of unamplified sound. If you eliminate the majority of the unpleasant stuff from a system, which is typically very difficult to do, then even a very ordinary setup can sound hugely realistic.
One easier way to get there, as some know, is to use highly efficient speakers with powerful amplifiers; if the components are virtually idling when in normal use then you have a much better chance of keeping "bad" distortion at bay ...
Frank |
>I would think high efficency speakers with powerful amps >would make distortion and noise worse -- no?
No, systems typically either use powerful amps and low efficiency speakers, or low powered amps and high efficiency speakers. The outcome is roughly the same in each case, the setup runs out of puff at a certain point -- think of a small, light car with low capacity engine as compared with an SUV with a big V8, their maximum rate of acceleration would be roughly the same; any really decent performance vehicle is always about a light body propelled by a high powered engine. Of course, in this analogy, the combination has to be carefully matched and tuned to realise the potential performance and prevent problems, but this is just engineering!
The analogy follows into the audio world -- I once had fun in a large, noisy electicals store: hooked up a fairly mediocre but high wattage Japanese HT receiver to a good pair of Klipsch main speakers, wound up the volume, the sound was clean as a whistle and cut right through the store; a store bloke came running from the other side, yelling turn it down, not because it was distorting but because it was so dynamically loud ...
Frank |
Weseixas, the term "ear splitting" immediately gives away the game -- what you are referring to here is a system that is overloading, lots of nasty system generated distortion hammering away at your ear drums, of course it sounds terrible! The other giveaway is "effortless power", so to translate:
System A: "alive", with size and effortless power - equals x dB's, by sound meter, with MINIMAL audible distortion.
System B: ear splitting SPL - equals precisely the same x dB's, by sound meter, with SIGNIFICANT levels of EXTREMELY unpleasant distortion injected.
As to an efficient speaker requiring lots of power, not true. Take a 96dB sensitive speaker, which is also an easy 8 ohm load (Klipsch again!), and an amplifier of capable of a clean 120 watts RMS. You get an extra 3dB volume for every doubling of 1 watt power, which means the speaker can produce 96 + (3 * 7) = 117dB at 1 metre. Considering you have two such speakers, then at a couple of metres you will have all the dynamics you need, PROVIDED the system is adding only low levels of distortion. Then, the clean "percussive energy" you speak of will be there in spades ...
Frank |
Weseixas, in your last response to Atmasphere you acknowledge that 110dB peak is easily attainable at the listening position, which is exactly what my figures were pointing to. My 117dB number was peak, not DIN, average, RMS or anything else. By the way, the level drops 6dB per doubling of distance, not per metre, so 117dB at 1m, 111 at 2m, 105 at 4m. And, that is only one speaker, the stereo setup nominally adds 6dB to those figures, plus the listening space normally is not open; further back, reflections from side and back walls complicate any simple maths.
The end result, as Atmasphere points out, is that well over 110dB PEAK sound at 3m with the right combination of hifi gear is easy to get. To now get that in perspective, a study of the sound levels experienced by members of an orchestra, not the audience(!), playing "heavy" music only momentarily went a db or so over 120dB peak in the worst possible case. Many audio people would suggest orchestral recordings are the hardest to get "right", but from the point of view of the dynamic capabilities of the system it should be no problem at all.
So, why don't orchestral recordings typically do it (sound real)? Again, as I mentioned earlier, the answer is distortion -- the two common ways of reproducing sound both have failings.
The audiophile way: make sure at low levels that the sound is "pure", that is, low levels of unpleasant distortion, but run out of grunt and it starts to compress and fall apart as the volume increases.
The pro way: plenty of grunt from the word go, but the effort has not sufficiently gone into eliminating the subtle mechanisms that inject relatively low level but nasty distortion into the sound, at any volume -- the too frequent PA setup, BIG sound hammering at you, impossible to tolerate for anything but a short period.
(Which, by the way, is why I shudder at the thought of seeing a live show these days: once or twice in my experience the sound people knew what to do, but, as an example, for me Phantom of the Opera at the premier city production was a nightmare, at the end of the evening my ears felt like they had been bludgeoned to death!)
But, there is a third way, as some people have discovered: put together efficient speakers and reasonably powered, high performance amplifiers with a decent level of care and fastidiousness and you should have an excellent chance of getting close to the "real thing".
And, for the people who claim it is all about room treatments and precise positioning of the speakers, in my experience this is wrong too. The ear brain combination is extremely capable and tolerant; if you give your head half a chance by supplying a sufficient amount of CLEAN sound information, then it can decipher what is going on and generate the experience of "being there". What the treatment and positioning thing helps to do, I believe, is to reduce the obviousness and impact of the distortion components in the sound, a sophisticated equivalent to specialised ear plugs.
Finally, I believe firmly in the LIAR (Listening In Another Room) test -- if the system fails this then it certainly won't sound like the "real thing" anywhere ...
Frank |
Pubul57, it is quite remarkable the enormous number of terms used to describe system sound, which ultimately are only ways of categorising the types of distortion, or lack of it, being generated. To me, micro dynamics simply means, as in real life listening to everyday sound, that you can hear the fine details of a subtle, low level sound occurring at the same time as louder background sound. For example, jingling of change in your hand while a heavy truck thunders by. Likewise, macro means the rich, bass rumbling of that truck passing is fully sensed, or the crescendo of an orchestral climax seems to wash over you with tremendous force, with no sense of discomfort.
It's all about distortion, the amp that sounds better to you is producing less of the distortion, at that particular moment, that you're sensitive to.
Frank |
Shadorne, your Sheffield labs drum track test would be a very good one, but as regards the sound meter reading you refer to a "SUSTAINED 108 to 112 db" value, which would not be the same as the the actual peak dB reading. From Wikipedia: "'Peak sound pressure level' should not be confused with 'MAX sound pressure level'. 'Max sound pressure level' is simply the highest RMS reading a conventional sound level meter gives over a stated period for a given time-weighting (S, F, or I) and can be many decibel less than the peak value".
I would suggest that that the peak dB level in the test you describing would be well over 120dB at 1 meter -- I don't want to destroy the bass driver's suspension!!
Frank |
Weseixas, I'm sorry but my figures correlate very closely with Atmasphere, 96 versus 98 sensitivity, 120 versus 140 good watts, my sound level of 117dB at 1m, his of 110 at 3m. Check out a text book, you lose 6db per doubling of distance -- from 1m to 2m down 6dB, from 2m to 4m (a doubling) down another 6dB, total 12dB. Remember, a 3dB difference is only just detectable by ear.
I also pointed out previously that the 10 to 20 times power is completely unnecessary IF the system is not distorting. I thus agree, that if the system is poorly engineered then you would need a very large "safety" margin, to compensate for the inadequacies of the setup.
Finally, the room size has nothing to do with it. Having personally experienced what is possible with a nominally mediocre setup, which has been tweaked in every which way, in a very nondescript normal room, I say that with total confidence.
Frank |
Pubul57, it gets tricky talking about different powered versions of particular amp types, it's almost a how long is a piece of string conversation!
Theoretically the higher powered amp SHOULD be better because its power supply needs to be bigger, and it is working more within its limits. Unfortunately, manufacturers change a whole lot of things going for bigger power, and quite often these are backwards steps in terms of maintaining quality. For example, a small amp may be fully hard wired with very direct connection paths. The bigger unit is made up of modules, with wiring harnesses with push on connectors for ease of manufacture, and bang, there goes your quality in one hit! In other words, the actual quality of the engineering of the particular component is far, far more important that the nominal power rating.
A 60 watt amp and 89dB sensitive speaker will do a very, very nice job IF everything is optimised, and the amp does produce genuinely clean 60 watts -- class A is a relatively easy engineering way to do this, of course.
Frank |
Timlub, as notes of interest I have had almost the same number of years as yourself wrestling with this bizarre and at times excrutiatingly frustrating "addiction", and also my room is almost a perfect size match to yours.
For me, when the system is working correctly, i.e., low levels of distortion, the auditory experience is that the end wall completely dissolves and the room becomes attached to the location where the recording was made, the "window" experience, I guess. If a large scale orchestral, then exactly if one were sitting in a private stall in the concert hall. It is no longer that of a musical event in a room, the sensation is that the whole house has somehow been transported and is sitting next to where the musical event is happening, and is a mere extension to the "soundstage". Very hard to get to happen, but very much worth it!
Frank |
Timlub, glad to hear how you're doing! If anyone here could see my current setup they would laugh hilariously, it looks a mess... Speakers roughly 2 ft from back wall, about 6 ft apart.
What I learned to concentrate on, is eliminating all, and I mean ALL, unpleasant distortion from the system, and this can be very, very difficult to do. Everything matters, as they say, and if you don't fix everything then you are making it very hard to get it to happen for yourself.
How low should the distortion be? A simple test, when the system is working flat out on a "difficult", or any recording, is that a speaker completely disappears. That is, standing a foot away directly in front of one (left or right) speaker and in line with the tweeter (or high end reproducer) your ear/brain cannot pick that the sound is coming from the drivers. "Believe it or not ..." as I think someone once said ... :-)
Why this can happen is that the ear/brain compresses the loud sound, rather than the system. This is what happens naturally; how else can a player in an orchestra tolerate the sound level around him if this didn't happen ...
Frank |
Weseixas, " ... has a Holodeck" -- nicely put :-)
Timlub, unfortunately the key phrase in your comment is "distortion is so far below our hearing that it was unconceivable to hear" -- of course distortion is easy to hear! My system distorts, your system distorts, everyone's system distorts. That is why every system sounds different from every other system, every time you change something in a system it sounds different, because you have changed the distortion component. If you have two widely differing systems that don't distort then they must sound identical.
I think the problem area is in the use of this word "distortion". One dictionary says "a change in the wave form of the original signal", which sounds fair enough to me. The argument would then be how MUCH change is allowed before you would call it distortion; I would say only so much that you can hear a difference between the original signal and the distorted one: if you can hear a difference between the original and the altered signal then you can hear the distortion! Two systems sound different, which is the distorting one? Both, of course, as compared to the original waveform.
Another way of looking at it, is that there are 2 tiers of distortion, let's call it "macro" distortion and "micro" distortion -- sounds familiar ... :-). Everyone knows macro distortion: boomboxes overloading, speaker cone rattling, treble ripping layers of skin off your eardrum, you could even include really bad digital playback here; all very easy to pick.
Micro distortion unfortunately is everywhere, it's all that low level stuff that makes one system sound different from the next. But everyone normally calls it the million and one other things, see J. Gordon Holt's Audio Glossary. Interestingly he includes "distortion" in its own right, firstly as a "true" definition: "1) Any unintentional or undesirable change in an audio signal." and then to highlight most people's concept of "macro" distortion: "2) An overlay of spurious roughness, fuzziness, harshness, or stridency in reproduced sound." But in the majority of the other, sound related terms in his glossary he specifies virtually every other type of "micro" distortion: dry, forward, haze, liquid, etc, etc. Talking of THD and IMD, these are just straightforward ways of putting numbers to the distortion in a very specific setup, somewhere between maximum "macro" and minimal "micro" ...
So, what to do? My "solution" is to eliminate, obviously, "macro" distortion, and then as much of the unpleasant, AUDIBLE "micro" distortion as I possibly can, which is, very, very difficult. How do I know I've got there? When I can change something on the system and from the point of the auditory experience nothing changes! And, at this point the sound becomes "real" ...
Frank |
Mapman, -- "not all distortion is necessarily unpleasant" , I agree with your comments 100%. And, there is definitely "nice" distortion, which is quite easy to do, and is a perfectly valid way of obtaining listening pleasure. One of my earliest high end experiences was listening to a dealer's highly tweaked in home setup, we are talking here of Goldmund Reference TT, Audio Research D250, Infinity columns: of course the playback on a selected LP was absolutely stunning. He didn't like CD, of course, but had a CAL, so I tried one of my "test" CD's. The experience was bizarre, sounded smooth and pleasant enough, but half the sound content had disappeared! My half reasonable setup of the time at home absolutely walloped his in terms of conveying the musical message on that particular CD.
So "nice" distortion works, but it is "horses for courses" ...
Frank |
Weseixas, Timlub, thanks for your reaction and comments to Atmasphere and Mapman, they are coming from very close to what my take on the situation is.
What I hope to inject into this conversation is something that for me has been very intriguing and frustrating over many years. That, which all hard core tweakers know, is that fiddling with any and everything makes a difference, and my reaction has been, what the hell is going on ?? Agreed, the topology, or circuit type of the amplifier can make a big difference, but once you improve your amp, then you more clearly hear the effects of making changes to other components, and the impact of everything else becomes more significant. Hmmm... not sounding too good at the moment ... gee, I wonder if that fluorescent light outside in the garage is on or off?
The trouble is, that last sentence is NOT funny, because it's true! Again, everything matters, and why does it matter? Because all the little, little things alter the makeup of my "micro" distortion, and the ear/brain has no trouble, no trouble at all picking up the change. It may sound better or worse, but it will definitely sound different!
Distortion can be linear, that is, altering the frequency response and phase angles, or nonlinear, which is everything else. The latter is the "baddy", big time: my experience is that if you minimise nonlinear distortion then linear distortion becomes totally benign, and the ear/brain can dismiss it as irrelevant. I've had a very ordinary amplifier (Sony) with classic tone controls, and managed to get the overall system working extremely well; then wound the bass and treble fully up and down, and I couldn't hear anything happening to the sound! Why, because the ear/brain could reject those changes as being unimportant to the musical message, enough "good" information was coming out of the speakers to compensate for a change that would normally be very obvious.
Yes, feedback is somewhere in there. But there is correct feedback, and "bad" feedback! If feedback was inherently not good then no piece of recorded music could ever be made to sound good, since every recording device and studio is riddled with feedback design techniques and circuitry, going back to almost the very start of electronic recording.
The quip earlier about the light points to a key factor that people play around with: power supply quality, or maybe, maybe it's RFI!? The trouble is, it's all very messy, but it ALL has to be taken care of!
Why should one? Because, if you do, then the level of "nasty", NOT "nice", micro distortion is reduced to the level that the ear/brain says "Yes! I can now accept this as being a thrilling experience, I won't be fatigued no matter how long I listen, it's magic, it's real!". And the convincing soundstaging, etc, automatically follows ...
Frank |
Irvrobinson, I would agree with you about those distortion levels, but certainly would not blame the speakers directly. I would suggest rather that the combination of equipment and setup is allowing other distortion mechanisms to intrude, into the electronics of amp and CD player, say. Typically the power supplies of much equipment are pretty hopeless in suppressing interference into sensitive areas, and this is the sort of thing that normal THD measuring never captures.
So, either you boost the quality of the power supply, as, say Naim does, or you cotton wool the power being fed to the gear with filters, special power cords, etc, etc.
Frank |
Kirkus, thank you: your statements, "it takes just ONE instance of having experienced reproduced sound as being real" and "been dumbfounded by amazing experiences from really crappy stuff, and also underwhelmed by my experiences with some really beautiful machinery", is precisely where I'm coming from. My particular angle, "obsession", etc, for many years has been to work out, and am now repeating myself, what the HELL IS going on!! I have been attempting this essentially by the process of elimination, and for me the answer is (drum roll ...) the glib statement, Everything Matters! I've found unless one becomes totally anal (sorry!) about the whole kit and kaboodle, or you fluke it to some degree, then it won't happen, it won't be "real"!
To whip out yet another analogy -- love those things :-) -- take a typical commercial passenger aircraft. To me, the audio industry is full of people who say, for example, it's all about the engines, you've gotta have turbines using this very special metal, and the fuel lines going to them have to be made out a really esoteric plastic, don't worry about the wings or landing gear, any old stuff will do. Another says, no, no, no, it's all about the cockpit, unless you get this set up perfectly it's hopeless, what's used in the rest of the airframe is pretty irrelevant ...
Would you fly in a plane designed or maintained by these people? No, I don't think so ... and for me that's what it's all about in hifi too, to get the experience of a system sounding "real" each and every time you listen to it, you have to fussy about EVERYTHING ...
Frank |
Atmasphere, unfortunately the way you present the concept of feedback with the term "propagation delay" helps to 'propagate' (sorry, couldn't help it ... :-) ) a misconception about negative feedback. Yes, "negative feedback is always lagging behind" but it is still able to "correct the signal it was supposed to". If it ends up lagging by 180 degrees, half a wavelength, with gain still happening, then you have positive feedback, and an oscillator, and fried tweeters!
So, the feedback ALWAYS lags, even by some tiny amount, but that is just part of the understood design of any working circuit. You can easily buy one of those "terrible" opamps with much more global feedback then a typical audio power amp, that is working comfortably at microwave frequencies, that is, beyond 1,000,000 kHz -- not bad for such a "mediocre" part!
Global feedback in an audio device, on the other hand, with discrete components is typically rolled off (because it has to be for stability, remember the oscillator!) to become non-existent at the higher frequencies, where it is most necessary, and where the ear is most sensitive to distortion -- that is part of the real problem. Also, that is why nearly all gear has rising distortion at higher power, and higher frequencies; in other words, it is not the presence of feedback that's the problem but that at the very time it is most needed, it's done a bunk ... :-) !!
Frank |
Sorry Weseixas, re ".. can follow along ...". My earlier comment was just firstly agreeing with Kirkus that a lot of people have had special listening moments without it quite making sense why, and secondly, that my answer is to be fussy, fussy, fussy, just like people who make and look after aircraft are, which is why flying is so relatively safe, ie. equivalent to audio sounding "real".
Frank |
Irvrobinson, how does that 4ohm+ output impedance affect interaction with the loudspeakers As Atmasphere states, provided that the output impedance is purely resistive in nature, that is, it does not behave like a capacitor or coil to any degree over the frequency range mentioned, then its effect will be totally benign. Even if it were ridiculously high, say 100ohms, same applies. All the latter would mean is that the speaker would never get very loud! I also agree with Atmasphere regarding "decrease the propagation delay of the circuit", this is exactly what needs to be done to allow any feedback to do its job. Some people may not be aware that several highly regarded SS amps consisted of nothing more than an output stage driven by a high quality opamp, with, by normal standards, extremely high levels of GFB. "objectivist's" belief system usually can't include a reality outside simple regurgations of common-practice electrical analysis found in an average undergraduate EE textbook, and the "subjectivist's" belief system is so fundamentally undisciplined as to be able to include some really silly, wacky sh*t. Human ears (and brains)are complex sensors and information processors of an order far exceeding science or technologies ability to model exactly. Agree 100% with both of the above Frank |
An analogy (yet again!): if you drank red wine which was always very ordinary or even mediocre, you would or could with great conviction claim that there is no such as a truly extraordinary, supremely satisfying great red. But, if you sampled such a wine even just once only, and then returned forever more to the much lesser variety, you would always retain the memory of the experience, and know what was achievable. All obvious enough; and to me this experience or lack of such experience is at least one thing that divides people in this field of audio.
This clearly puts me on David's side, in believing in AND knowing what is possible. If you can put on the worst, I repeat, the worst recording in your collection and still be able to say it "sounds convincingly authentic to the live source" and talk of "The delight it gives me, however, comes from listening into the music" then you've arrived. The fact that this goal is not achievable by pushing some "perfectly" engineered, platinum plated button at the moment is just part of the landscape ...
Frank |
Atmasphere, The problem here is that while theorem is supposed, there are real-world phenomena that do not care about the theorem. I'm sorry, I don't quite follow. Yes, if you use Spice, say, to examine behaviour just based on straightforward theory, it will most certainly not match what really happens. However, if you add in ALL the actual parasitic behaviours of the components, the "real-world phenomena" you mention, into the Spice model then there should be very good agreement between the model (theory) and reality. After all, one of the classic nonsenses of a typical Spice circuit are the perfect voltage sources stuck where needed -- that alone guarantees that the match can be very poor. In volume three, page 26 Crowhurst ... Sorry, had a quick look, as far as I can see he is just saying, be careful with negative feedback, otherwise it becomes positive feedback and you have an oscillator -- straightforward stuff. Frank |
Atmasphere, I am adamant that the rules of human hearing trump all other considerations Agree 100%. So the effect in an amplifier with loop feedback is that low level detail will be truncated and this is readily audible (IME) as a loss of ambient and soundstage information Unfortunately, disagree 100%. IF the feedback is done badly or is extremely minimal in its effect then that may be the result. I agree that "low level detail is truncated" is often the way distortion manifests, but my experience is that this is lousy power supplies and a myriad of other subtle mechanisms causing problems, which insufficient feedback may struggle to compensate for, but only ends up making things worse. In other words, the overall engineering of EVERYTHING has to be got right, and then that "harmonic noise floor" you speak of will be reduced to a level well below audibility Frank |
