What is the prime determinant of sound quality?

[speaker dave]

Oddly your arguement confirms my case: Electro Voice countersued and won based on the obvious prior art of the Olson/Preston patent (you really should read it). I agree that it was wise of Vilcher not to further pursue it.

As to the tweeter patent, I don't see any mention of being a dome as a unique claim. It is a patent on a unique magnet structure and suspension. Apparently Vilchur didn't believe he had invented the dome radiator.

Theory (see Beranek and Olson) says that dispersion is primarily determined by drive unit diameter. You can dabble with breakup modes and try and get a different effective area, but I don't know of any designs that look smaller than they are over any significant range. To claim that AR achieved wider dispersion than anyone else is to fall for their marketing. They had wider dispersion than the horns and larger cones that preceeded them. Not wider than later designs with similar sized domes.

Wide spread beliefs aren't always factual.

David S

[Carlspeak]

Here's a link to a study I did comparing a 1" dome (HiVi Q1R) to the original 3/4 inch AR dome. Obviously, this is an apples and oranges comparison. However, I don't know of any currently commercially available 3/4 inch domes that have similar dispersion characteristics to the AR; including the classic Scanspeak D2010 (improved D2008) which I have installed in a few 3a restorations.

http://www.classicsp...er&fromsearch=1

Below are some off-axis scans of the no longer available D2008 deliberately located close to a Seas midrange in an AR1W modded with a Super-Mod install. These do not match up well with the AR 3/4 inch results shown in the above linked paper.

[speaker dave]

Hi Carl,

Thanks for the curves. Besides the diameter difference the HiVi unit has a short flare that will narrow its dispersion from what its size might suggest. (Although we should ponder why manufacturers would add flares that narrow directivity if wide dispersion is such a key parameter.)

A better comparison might be the KEF T27. It is closer in diameter and has a flat mounting plate with no wave guide. (Not a perfect unit in other regards.) AR did have one advantage in that they tended (in the early days) to use domes with no surround and that would keep the effective diameter right to the VC diameter.

David S.

[Carlspeak]

Hi Carl, Thanks for the curves. Besides the diameter difference the HiVi unit has a short flare that will narrow its dispersion from what its size might suggest. (Although we should ponder why manufacturers would add flares that narrow directivity if wide dispersion is such a key parameter.) ...............

That's a big "if" that seems to reside almost exclusively here at CSP. I'm a member on a number of other speaker forums and from what I read there, narrow disp./high directivity has become the 'flavor of the month' for some time now.

[Mach3]

Interesting phenomena here - and a constantly recurring one in human behavior - when confronted with data to the contrary some people will simply not change their position ignoring said data. In fact a fellow named Thomas Kuhn wrote a book about this inability to observe any data that is outside an individual's apriori conclusions. See "The Structure of Scientific Revolutions" - one of the items that Kuhn noted was that "two scientists who witness the same phenomenon and are steeped in two radically different theories will see two different things."

Speaker Dave - your mind is made up and nothing - even Divine Revelation - will ever change it. Such is fine by myself. But rest assured that for many, many people - Villchur did invent the priniciple of air suspension AND the dome direct radiator.

Villchur went on to invent a great turntable - that Ivor Tiefenbaum of "Linn" fame effectively copied. Later, after selling AR to Teledyne Villchur went into hearing aid research wherein upon he discovered the principle of multi-channel compression. Villchur did NOT patent this idea - instead he made it freely available for the wide benefit of all hearing impaired (and it is employed by every hearing aid that is made currently).

This behavior - in re the hearing aid research - should give you some idea of Villchur's internal processes - he didn't want to spend time arguing and being surrounded by legal eagles - he wanted to make the world somewhat a better place. This reflects on his air suspension patent - he knew that he had invented it (the other two guys never, ever actually built anything) but was adverse to stupid pointless arguments.

As I am to this one.

[Gerry S]

Yes, but what speaker characteristics make it sound 'right'? Toole is pretty much an axial FR, first-arrival guy. Do you agree with that as being what makes a speaker sound like it sounds?

Steve F.

I'm trying to "stay on topic" instead of going into fine technical details many may not comprehend or care about.

"Right' for all intents and purposes is ENTIRELY SUBJECTVE in my opinion. And "accurate" is impossible to "quantify" regardless of how many sophisticated acoustic measurements one makes. Why do I say this? I will list them.

1. ALL speakers interact with the room they are played in. Move the speakers to another room and you will change the sound,

2. Using the same room but re-locating the speakers will change the sound.

3, Keep the speakers in the original room and original placement but re-locate your listening position and you will change the sound.

4. Keep speaker/ room / seating a "fixed constant" but add or remove furnishings and you will change the sound.

Use a SINGLE scenario from the above list and assume it "perfect" from the user's standpoint. BUT, it is "perfect" for a few recordings. Other recordings will deviate from sounding "right" to some extent (sometimes enormously). This assumes a SINGLE genre (jazz, pop, folk, rock, country, reggae, hip-hop, rap, chamber music, large orchestral works, "audio books", studio recordings, live broadcast, recordings using "purist miking" or "muti-mike" techniques, etc.

And now for the subject of "accuracy", which in my opinion highly influences our decision to buy a speaker based on "specs' (manufacturer's published). OR the "measured specs" acquired from "technically competent" reviewers from "underground", "mainstream" or "lunatic fringe" publications.

Much has been said about AR's famous "live vs. recorded" demos (both the AR3a and the AR 10pi). But look at the ENORMOUSE resources and technical expertise required to pull this off. In the "real world", NONE OF US have that degree of control over all the "ingredients" to do this consistently IN THE HOME.

Many on this forum would argue that "live classical music" is the ONLY "valid" reference for determining "accuracy". I don't agree with this because I feel it to be "elitist". Even If I DID agree, our "memory" of ANY acoustical event whether "live" or "recorded" is extremely brief. I could attend a "live concert", then immediately rush home to play my "best" recording of that concert to determine "accuracy". I personally couldn't tell you whether my "best cost-no-object system" even remotely resembles what I heard "live" hours earlier. I doubt if anyone else here could either.

As for "accuracy" regarding playing "recordings" of any kind, it's only possible to be 100 percent "accurate" if your listening room was an EXACT replica of the environment/equipment in which that recording was mixed. That’s highly unlikely for any of us. The best any of us can do is recreate some facsimile of what we THINK is how closely it resembles what WE prefer the recording SHOULD sound like.

And now, finally to the topic Steve F mentioned; near field "first arrival" and "power response" in the far-field (reverberant field). Both are critical in determining what sounds "right" and/or "accurate". Depending on all of the variables I just described, it’s the proportion for any given listener that’s important.

This is a "speaker forum". Unlike headphones, speakers are used in rooms. Headphone listening does not involve a far field; just ‘first arrival". Maybe that’s why the "I-Pod generation" with their "ear-buds" is the norm today. If they were to stumble across this page, they would think all of us "nuts" bordering on the "lunatic fringe" category. Frankly, there have been many moments in my own pursuit of "sonic nirvana" where I would agree with these "young ones" !

　

　

[speaker dave]

Interesting phenomena here - and a constantly recurring one in human behavior - when confronted with data to the contrary some people will simply not change their position ignoring said data. In fact a fellow named Thomas Kuhn wrote a book about this inability to observe any data that is outside an individual's apriori conclusions. See "The Structure of Scientific Revolutions" - one of the items that Kuhn noted was that "two scientists who witness the same phenomenon and are steeped in two radically different theories will see two different things."

Speaker Dave - your mind is made up and nothing - even Divine Revelation - will ever change it. Such is fine by myself. But rest assured that for many, many people - Villchur did invent the priniciple of air suspension AND the dome direct radiator.

......but was adverse to stupid pointless arguments.

As I am to this one.

On the other hand I enjoy the odd "stupid pointless arguement".

Regarding the invention of dome loudspeakers here are a couple of patents you should look up:

2237298 and 2442791

http://www.google.co...%20dome&f=false

http://www.google.co...2442791&f=false

Baumzweiger shows a dome radiator from 1941. By the way he talks about it as a microphone but in the preamble says that all are reversible transducers and equally valid as "receiving apparatus or transmitting apparatus". Baumzweiger later changed his name to Ben Bauer.

Wente shows a nice dome radiator with an accordian shaped suspension in 1948 (applied 1945).

My point was that Vilchur was careful to patent his suspension and magnet structure invention. A dome diaphragm would have been disallowed by the patent office due to the prior art.

Now, as to the "invention" of the turntable...

Regards,

David S.

[Steve F]

Re: Villchur and the 'invention' of acoustic suspension: EV worked on a prototype, and pulled his protoge Henry Kloss into the process that brought their experiment to success. Had EV already known about RCA's prior investigation and writings about high compliance drivers and an airtight box supplying a linear restoring force?

It's tough for any of us to say with certainty.

My own purely subjective take is that EV--regardless of whether he was aware of RCA's theoretical investigations or not--put the thoughts into physical action by building the prototype and proving that the AS principle worked. EV's actions constitued the "invention," to my mind.

Re: AR and the dome tweeter, it is my understanding that the dome tweeter and midrange of the AR-3 in 1958 constituted the "invention" of that device. I know University had their "Sphericon" tweeter (my uncle had a pair of University speakers), but I believe the AR-3 made its market appearance first.

Re: dispersion, I agree with Speaker Dave in that it is my understanding that the major factor in a given driver's dispersion is that driver's effective radiating diameter compared to the frequency being reproduced. That's the major factor. Minor factors may be things like breakup modes/diaphragm stiffness, shape, etc. Also note that small "semi-horns" or "flares" will increase the driver's efficiency in a lower band at the expense of widest dispersion in the uppermost octave. The AR-2ax had its 3/4" dome inexplicably mounted in a recess that caused diffraction/interference to its HF dispersion, thus mostly negating the supposed dispersion advantage of the small radiator. The 3a and 5 didn't have the baffle board recess around their 3/4" tweeters, but their cabinet edges were still quite intrusive. The 10 Pi/11/12, and the Verticals (9, 90, 91, 92), and the later 9LS, 98LS, and 78LS had 3/4" domes, unfettered by cabinet "blinders" or other obstructions.

However, AR's own internal data shows that while the 11's soft cloth 3/4" tweeter is both more efficient and goes appreciably lower in frequency than the 3a's hard paper 3/4" dome (the 11 and 10 Pi could have easily crossed over at 3.5-4kHz instead of 5kHz), the 3a's hard paper 3/4" dome had measurably better dispersion than the 11's dome, thus giving credence to the thought that it's more than just radiator diameter that affects dispersion. Remember, AR measured their drivers on a 2 Pi flat baffle, so the 3a vs. 11 tweeter comparison is absolutely apples to apples. I'll dig out the graph if people are interested.

I'm not addressing whether HF dispersion is a major contributing factor to perceived sound quality or not. I'm just adding factual historical data to the discussion about AR's domes.

Steve F.

[speaker dave]

Re: Villchur and the 'invention' of acoustic suspension: EV worked on a prototype, and pulled his protoge Henry Kloss into the process that brought their experiment to success. Had EV already known about RCA's prior investigation and writings about high compliance drivers and an airtight box supplying a linear restoring force?

It's tough for any of us to say with certainty.

My own purely subjective take is that EV--regardless of whether he was aware of RCA's theoretical investigations or not--put the thoughts into physical action by building the prototype and proving that the AS principle worked. EV's actions constitued the "invention," to my mind.

Steve F.

I've already conceeded that Vilchur was the first to market an acoustic suspension system as we know it, the modern middle efficiency sealed bookshelf speaker. The question of invention though is really down to the patent office and the application dates. Even if Vilchur arrived at the notion independently to RCA (which happens frequently), RCA has the prior art and can claim the legitimate right of invention.

It is also not like the case of Armstrong and DeForest, where DeForest stumbled across something and only Armstrong understood its worth. Olson and Preston talk of the benefit of very low driver responance, of letting the cabinet be the primary restoring force, and of the improved linearity of the resultant system. They understood acoustic suspension.

The high compliance radio speaker that they based the patent on was also a production item, so they did take actions to put their theory into practice.

As much as we applaud the many achievements of Vilchur, he lost the patent case with EV because there was clear prior art.

David S.

[Gerry S]

The question (and original topic) seems pretty "straight-foward". "WHAT IS THE PRIME DETERMINENT OF SOUND QUALITY" ?

So why aren't people giving a straight-foward answer ? Is it frequency response, power response, a particlar "contour" to either first-arrival or total reverberant field energy? Extended bass ? Extended treble? Low IM distortion? Low harmonic distortion? Transient response? Group delay? Phase response? The ability to reproduce a square wave somewhere? Resonances (or lack of) in the cabinet ? Lack of thermal compression @ "realistic" levels? Directivity ?

Is it one of the above? None of the above? A combination of them? if so, in which order (ranking)? The word "prime" to me infers a SINGLE "determinant" that overwhelmingly overides all others. I believe the question as originally stated is too restrictive and narrow to be answered . "Sound quailty" is IMO still primarily a SUBJECTIVE term that engineers attempt to "quantify" scientifically.

I've already stated that the most "simplistic" answer for ME is "frequency response" coupled with "power response" (and the ratio between them). What do others feel ? Why do they feel that way ? What type of music are you using as "a source" when making your evaluations ? THAT'S what I want to hear from others here; NOT who first invented the dome tweeter or "acoustic suspension".

[HarryM]

Ok,I think I finally came up with an answer.Clarity.As in,can I hear the differences in the notes clearly or can I hear each drum beat.Can I hear sounds roll off or echo that sound like they belong.To me that is the single largest difference between a crappy sound system and a very good sound system.

[Pete B]

I've already stated that the most "simplistic" answer for ME is "frequency response" coupled with "power response" (and the ratio between them). What do others feel ? Why do they feel that way ? What type of music are you using as "a source" when making your evaluations ? THAT'S what I want to hear from others here; NOT who first invented the dome tweeter or "acoustic suspension".

Gerry, the reason that invention of the dome tweeter and acoustic suspension come up is that we want to get the facts straight and I agree completely with Dave, speaker dave.

What is very clear is that most people here have not read the classic literature on the subject, Dave is the exception, excuse me if I missed anyone else. I just pulled one of my many notebooks from the shelf and I have copies of probably 10-20 AES papers on the subject. There was a time, for example on the old Bass List when I would list them all but often people don't care to read the research that has already been done so I don't bother anymore. Were any people here on the old email Bass List from the mid 1990s?

It is fairly well accepted that smoothness and an appropriate shape in the on axis frequency response is the most important factor for sound quality as long as other factors such as distortion, dispersion etc. are good enough. From memory I'd say that this was fairly well accepted by the mid-late 1970s or perhaps a bit later. It was later confirmed in studies at the NRC, Harmon, and probably others. This is a question where the answer has to have a factor of "it depends". It depends on the bandwidth of the source material that a listener plays, how loud they want to play it, etc. Systems with serious flaws in the midrange response will never sound real or convincing to a critical listener and this is the basis for the smooth frequency response answer. There are also psychoacoustic considerations that can make a "flawed" speaker sound quite good. The Dynaco A-25 has a dip near the BBC dip frequency and I believe that this is part of their appeal. It is a complicated question and there is no simple answer. Less critical listeners may favor low bass response where they want to hear that low bass line down to 42ish from the days of 4 string basses and perhaps 32ish today when 5 string basses and very heavy bass lines have become more popular - it depends. I personally add to the smooth frequency response requirement, low distortion and low SPL compression. Few people have heard truely low distortion systems at realistic levels with low dynamic compression.

Two things that I have found annoying for many years are speakers that sound boxy, speech sounding like it is coming from a box. The other is when a center placed performer sounds like they spread from speaker to speaker, or move from one speaker to the other when the listener moves their head. It is shocking to hear speakers that overcome these issues while meeting other performance requirements. I noticed these two issues as a young teenager and I'm surprised that they are not discussed more in the literature. These are both mainly frequency response "issues" that involve interaction with the room, the home listening environment, and perhaps psychoacoustics.

[Carlspeak]

I think Pete summed it up pretty nicely.

If you want to read more about it, download Tools's "Loudspeaker Measurements and their Relationship to Listener Preferences parts 1 & 2". This landmark work may have been referenced in an earler post, but is worth repeating here.

[Gerry S]

I agree with Pete and Carl ; very neatly summarized too. It IS a very complicated question. The "all things being equal" is key because it never is. The wider the age range and musical genres included , the more complex the answer. Having voiced many produccts to compete against competitors, I can see (hear) their design philosophy and understand why they chose that route. The terms "accurate" and "sound quality" don't necessarily go hand in hand.

In my brief career, I have heard many "pleasing sounding" speakers that don't partuclarly "measure well". My approach is to make it measure as best as possible, and then LISTEN to it REPEATEDLY. It's a pretty exhausting process, must do this multiple times before "signing off" . It's especially difficult if the product is to appeal to a 'broad" audience at any given price point.

[Pete B]

I don't recall exactly who the pioneers were for that early conclusion about on axis response but I certainly should have mentioned the BBC research labs and probably work done at KEF, B&W, etc.

Carl, you bring up Toole again, my point was that there are many other contributors having done research in this area - nothing wrong with Toole's work just making the point that there were/are others. Here are links to the Toole papers and I bring them up to point out that there are 83 references in the first paper and over 50 in the second:

http://www.harman.com/EN-US/OurCompany/Technologyleadership/Pages/ScientificPublications.aspx?CategoryID=Scientific%20Publications

Certainly people here know to go look up the references or at least the best or most relavent ones to do even more research. I have over 25 years of the AES Journals in my library and I'm told that you can get a CD from the AES covering many years in case anyone is interested.

[xpat]

As all of us are unique individuals with specific tastes, I don't believe the question can accurately be answered. It seems if the music engages or moves you to joy or tears, that is what matters.

[Gerry S]

As all of us are unique individuals with specific tastes, I don't believe the question can accurately be answered. It seems if the music engages or moves you to joy or tears, that is what matters.

Your answer is non-scientific, rational, and hard to refute. Therfore, I must conclude you are not really a "true" audiophile. You are probably "rare" in this regard. Audiophiles (at least the extreme ones) tend to forget that the equipment serves the music. "Devote audiophiles" often make "sound reproduction" an end unto itself (instead of a means to an end). Almost like religous zealotry !

[Carlspeak]

Your answer is non-scientific, rational, and hard to refute. Therfore, I must conclude you are not really a "true" audiophile. You are probably "rare" in this regard. Audiophiles (at least the extreme ones) tend to forget that the equipment serves the music. "Devote audiophiles" often make "sound reproduction" an end unto itself (instead of a means to an end). Almost like religous zealotry !

I guess I'm not a "true" aubiophile then. For me, as my signature line states: 'It's all about the music', unstated is what could easily follow: 'not so much the sound of the music.' When listening to music, I'm happy if instruments sound like I feel they should sound, rather than sound like they're in the same room with me. The 'they are here', 'you are there' following of (I think you meant to write 'devout') audiophiles are indeed a fringe faction whom I grow tired of constantly tweaking their's or other's systems to eek out that last bit of realism, or soundstage, or whatever etc.

I'm in it for the emotional connection - mostly. :-)

[Gerry S]

I guess I'm not a "true" aubiophile then. For me, as my signature line states: 'It's all about the music', unstated is what could easily follow: 'not so much the sound of the music.' When listening to music, I'm happy if instruments sound like I feel they should sound, rather than sound like they're in the same room with me. The 'they are here', 'you are there' following of (I think you meant to write 'devout') audiophiles are indeed a fringe faction whom I grow tired of constantly tweaking their's or other's systems to eek out that last bit of realism, or soundstage, or whatever etc.

I'm in it for the emotional connection - mostly. :-)

Me too Carl... the "you are there" or "they are playing in my home" experience is what my own goals are. Simply put, if the bulk of my favorite recordings sounds "real", than the sytem is "good" regardless of age ,price, brand, "prestige facror", industrial design , whatever !

I'm tring to get away from "home theater" because a video image removes the necessity of "quality sound" to "get the picture ". Realistic audio is much more challenging to obtain but extremelt rewarding when it is.

[Gerry S]

I guess I'm not a "true" aubiophile then. For me, as my signature line states: 'It's all about the music', unstated is what could easily follow: 'not so much the sound of the music.' When listening to music, I'm happy if instruments sound like I feel they should sound, rather than sound like they're in the same room with me. The 'they are here', 'you are there' following of (I think you meant to write 'devout') audiophiles are indeed a fringe faction whom I grow tired of constantly tweaking their's or other's systems to eek out that last bit of realism, or soundstage, or whatever etc.

I'm in it for the emotional connection - mostly. :-)

My last response was inaccurate(sorry)! The "you are there" or "they are here" IS what I strive for. That's what makes ME an "audiophile". I guess others here seek different ways to reach audio nirvana (i.e that last bottom octave)!

Not being a musician, I'm clueless as to what "real instruments" SHOULD sound like in my room. But I know very quickly when something is "reproduced" if it LACKS "sounstaging". Here is the irony: "soudstaging" as experienced through loudspeakers does not exist in the real world. But, it is necessary(IMO) to create the ILLUSION of reality.

I believe all of us ARE '"audiophiles" to some degree; just different degrees and different criteria to be met before we become satified. I must admit I no longer have the stamina to get that "nth degree" of realism. So "good enough" is something I've settled for. Leaves me more time to "enjoy the music" (or watch that DVD).

On occasion, I'll get that "itch" to tweak something: that crossover, tame that slap echo, remove that slight sibilance, etc. But not often...LOL.

[Carlspeak]

My last response was inaccurate(sorry)! The "you are there" or "they are here" IS what I strive for. That's what makes ME an "audiophile". I guess others here seek different ways to reach audio nirvana (i.e that last bottom octave)!

Not being a musician, I'm clueless as to what "real instruments" SHOULD sound like in my room. But I know very quickly when something is "reproduced" if it LACKS "sounstaging". Here is the irony: "soudstaging" as experienced through loudspeakers does not exist in the real world. But, it is necessary(IMO) to create the ILLUSION of reality.

I believe all of us ARE '"audiophiles" to some degree; just different degrees and different criteria to be met before we become satified. I must admit I no longer have the stamina to get that "nth degree" of realism. So "good enough" is something I've settled for. Leaves me more time to "enjoy the music" (or watch that DVD).

On occasion, I'll get that "itch" to tweak something: that crossover, tame that slap echo, remove that slight sibilance, etc. But not often...LOL.

Evidently, you've thought about this considerably since your last post and I agree with your latest post completely. That's just about where I am.