SDA-2B Consensus on Modifying the Crossover's
Comments
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Set up correctly, SDA's shouldn't have any toe in. I would think off axis would be just as important, if not more important in this case."He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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Agreed. Of course there is going to be a very strong correlation between on-axis and off-axis, so speakers with very good on-axis tend to behave well at moderate off-axis angles. The better metric may in fact be the average of +15, 0, -15. Sadly my notes from the lecture are not perfect so I think some of the more subtle details I've forgotten. The Harmon FR measurements for each speaker included on-axis, two off-axis, directivity and power response. The on-axis response is also obviously brighter because the speaker is radiating in the forward direction.Set up correctly, SDA's shouldn't have any toe in. I would think off axis would be just as important, if not more important in this case. -
That seems to be the consensus amongst many top designers and certainly anyone associated with the NRC,ie.Toole,Barton, Voecks and the likes of D'Appolito ,Theil etc.Its not even arguable, its a fact
I bet that was interesting and informative.I drove to LA earlier this week to listen to this lecture:
Thus making that the on axis or prefered listening position on which the response should be optimised.Set up correctly, SDA's shouldn't have any toe in. I would think off axis would be just as important, if not more important in this case. -
Totally OT but I had a girlfriend in the 80s who worked summers for the NRC in Ottawa. Great memories ... I'd love to go back again and visit.That seems to be the consensus amongst many top designers and certainly anyone associated with the NRC
Yes, precisely. I believe Olive is a protege of Toole. Hosers.,ie.Toole,Barton, Voecks and the likes of D'Appolito ,Theil etc.
It was extremely interesting. Olive is a great speaker with a dry wit that had people chuckling for about 2 hours straight. At Harmon/Infinity they are able to do super-accurate anechoic SPL measurements and boy did he trash some "audiophile" speakers. In my notes, I have a direct quote from him: "you can't get good sound without measurements".I bet that was interesting and informative. -
Yes some of our hard earned tax money helps to fund loudspeaker research.Totally OT but I had a girlfriend in the 80s who worked summers for the NRC in Ottawa.
In part I guess it has contributed to our fledling speaker industry.
I believe Harman recruited and were successful in enticing both away from the NRC.:frown:I believe Olive is a protege of Toole.
He even named names?.. and boy did he trash some "audiophile" speakers. -
He had slides with "Competitor A", "Competitor B" and so on. He also had additional slides with photos of the speakers. A few times he joked "oops, wasn't supposed to say that was A"He even named names? -
At Harmon/Infinity they are able to do super-accurate anechoic SPL measurements and boy did he trash some "audiophile" speakers.
In Olive's tests, did he mention that he understood the design goals of the speaker designer and were the test results interpreted within that context?
I ask because many audiophile loudspeakers are optimized for a particular type of room, a particular type of music, a particular type of amplifier, etc. If a speaker is tested or auditioned in an environment for which it was not designed, it is not difficult to understand how poor results might be obtained.
For example, when I was shopping for loudspeakers many years ago and mentioned jazz was my primary listening preference, SDA's were recommended as one of the best speakers for reproducing jazz. In fact, SDA sales brochures mentioned that SDA's excelled at reproducing simply mic'ed jazz. If I liked classical music, I would probably have different speakers and different electronics.In my notes, I have a direct quote from him [Olive]: "you can't get good sound without measurements".
No rational person would disagree with this. However, I think we must not get carried away and think that measurements tell the whole story. Measurements have to be considered and understood within the context of the design goals of the loudspeaker.
Due to the non-linear, non-flat nature of human hearing response, it is possible for a loudspeaker to measure poorly in some area(s) and still sound quite good.
Were the speaker tests referenced in Olive's workshop done in mono, stereo or both? I ask because Olive, and his mentor Toole, preferred to do the vast majority of their speaker tests in mono...although they did do some stereo testing. Toole has gone so far as to state his disdain for the stereophonic format because he believes it to be inferior and a "step back" from mono.Proud and loyal citizen of the Digital Domain and Solid State Country! -
Both. From my notes: "good mono implies good stereo". I think its pretty hard to imagine a great mono speaker that is not a great stereo speaker, or the converse. Near this comment is the comment that "Harmon tests listeners for normal hearing". In a somewhat wider context, he speculated that perhaps the reason why audio reviewers were poorer listeners (in terms of performance on complex listening tests) than audio retailers was that their hearing had degraded with age. Funny guy.DarqueKnight wrote: »Were the speaker tests referenced in Olive's workshop done in mono, stereo or both? -
The stated goal of most loudspeaker designers is accuracy and having good frequency response measurements most certainly contribute to that goal.There certainly exists speakers that while exhibiting some response anomalies can still sound musically pleasing. However I suspect it a rarity that a speaker with an excellent set of FR measurements is be found highly coloured and unlistenable.DarqueKnight wrote: »In Olive's tests, did he mention that he understood the design goals of the speaker designer and were the test results interpreted within that context?
I'm sure someone of Mr Olive's experience can ascertain enough about a particular design so as to not misrepresent it. -
Not in most cases. In the general case (mostly, almost always, normally, etc), when you see weirdness on the FR trace, you know somebody made a mistake. There was a trace from a Polk LS-series speaker with a nasty spike in the 200Hz range, which I suggested to Olive was a cabinet resonance. He responded by saying something approximately like "yeah, cabinet's buzzing there". While I acknowledge very specialized and intentional FR shaping like a carefully crafted BBC dip or a smooth downward tilt of the FR curve may be preferrable sometimes, nonflatness of the FR is almost universally just bad design. Period. End of story.DarqueKnight wrote: »Due to the non-linear, non-flat nature of human hearing response, it is possible for a loudspeaker to measure poorly in some area(s) and still sound quite good.
Olive has mountains of post-Y2K data that was used to derive statistical models that predict how a listener will rate a speaker. The model metric is based almost entirely on flatness and smoothness of on-axis FR. He made a comment about the FR of the $11k Martin Logans (Speaker of the Year according to one magazine) and its resemblance to the Rocky Mountains. When the listening wasn't blind, people seemed to tolerate it (IIRC) but when the testing was blind, everybody (trained and untrained) ranked it worst. Before he revealed the speaker identity, I accused of him of using some kind of white van speaker. Even the most incompetent novice designer would be hard-pressed to make a speaker with FR that bad. It was almost unbelievable. -
While I acknowledge very specialized and intentional FR shaping like a carefully crafted BBC dip or a smooth downward tilt of the FR curve may be preferrable sometimes, nonflatness of the FR is almost universally just bad design. Period. End of story.
Chapter 19 of Dr. Floyd Toole's book, "Sound Reproduction, The Acoustics and Psychoacoustics of Loudspeakers and Rooms" is entitled "Psychoacoustics-Explaining What We Measure and Hear".
He goes into some detail explaining that a loudspeaker's measured frequency response does not always correlate to what is heard. From page 449:
"Reviewing these data, it is clear that neither the measured amplitude of the spectral aberration nor the duration of the ringing is a direct correlate of what we hear. So let us enjoy those attractive waterfall diagrams. Use them as evidence of the presence of resonances, but don't rely on them as indicators of audibility. Our ability to hear a resonance depends on the ability of the driving signal-the music or movies-to excite it. If the signal is at the correct frequency and lasts long enough, one can hear high-Q resonances; if not, we don't.
The amplitudes of the resonances shown in frequency responses are the steady-state measured changes in the playback system caused by the presence of the resonances that have been adjusted to the detection threshold level while listening to different kinds of program. This is not the amplitude of the output from the resonance when listening to musical program material because music is not a steady state signal. That amplitude is likely to be much lower. The fact that the resonant peaks are higher for the chosen pop/jazz examples is a reflection of the fact that the program material exhibits a lower probability of exciting the resonance than pink noise, a spectrally dense, steady-state signal."
Toole's observations above relate to what I said earlier about understanding the design goals of a particular speaker. On paper, a given speaker's FR might look obnoxious. However, that speaker might be designed to play a style of music that does not objectionably or audibly excite the peaks seen in the FR plot. If that same speaker is auditioned with a different style of music, and/or placed a room with unfavorable acoustics, unpleasant things might be heard.Proud and loyal citizen of the Digital Domain and Solid State Country! -
I just deleted my response to this in an effort not to waste my time and yours. Cheers.DarqueKnight wrote: »Chapter 19 of Dr. Floyd Toole's book, "Sound Reproduction, The Acoustics and Psychoacoustics of Loudspeakers and Rooms" is entitled "Psychoacoustics-Explaining What We Measure and Hear". -
... oddly enough they gave away a free copy of this book to a randomly-chosen AES member. I was only 6 tickets away from winning :frown: Nevertheless, in deference to my countrymen I've ordered a copy.DarqueKnight wrote: »Chapter 19 of Dr. Floyd Toole's book, "Sound Reproduction, The Acoustics and Psychoacoustics of Loudspeakers and Rooms" -
There are two fundamental reasons for wanting to keep the stock crossover in my opinion: (1) so that you'll have a 100% stock crossover for posterity, (2) so that you'll have a fully-intact reference crossover.
Seriously :rolleyes:Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
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Something's not right with you.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
In my notes, I have a direct quote from him: "you can't get good sound without measurements".
I would say, "you can't get good sound without good sound." After all, it's the "sound" produced through the air you are hearing, not the numbers. I haven't heard a number produce any sound, let alone good sound. Granted, to a certain extent numbers and sound can be related, but numbers don't always correlate to what you hear (as has been pointed out on numerous occasions).
Greg
Taken from a recent Audioholics reply regarding "Club Polk" and Polk speakers:
"I'm yet to hear a Polk speaker that merits more than a sentence and 60 seconds discussion."![:\](https://forum.polkaudio.com/resources/emoji/confused.png ":\")
My response is: If you need 60 seconds to respond in one sentence, you probably should't be evaluating Polk speakers.....
"Green leaves reveal the heart spoken Khatru"- Jon Anderson
"Have A Little Faith! And Everything You'll Face, Will Jump From Out Right On Into Place! Yeah! Take A Little Time! And Everything You'll Find, Will Move From Gloom Right On Into Shine!"- Arthur Lee -
For those interested some of the material from the book has been posted here.... oddly enough they gave away a free copy of this book to a randomly-chosen AES member. I was only 6 tickets away from winning :frown:
http://www.eetimes.com/design/audio-design/4210985/Loudspeakers--Objective-evaluations---Part-1--Sound-source-radiation-patterns?Ecosystem=audio-design -
I am NOT a big believer in measured specifications as a tool to predict how something will sound. It certainly is important to take measurements and use those as a guide or a tool to get the final product.
I have heard a lot of what measurements indicate should sound good, in the end sometimes the specs have no correlation to the end sound at my ears. There is a lot that happens between the point the sound is originated and when it finally reaches my ears and then for my brain to process.
Ultra low distortion and flat response can be overrated and people who constantly chase those kind of specifications religiously are really missing out. Use the specs as a guide, but be sure to get your ears on a lot of different gear to be sure you settle on something your ears like, not the black and white print of a test report or manufacturer derived data.
As indicted by this quote:
Despite its mediocre measured performance, I thought it sounded quite good. I still had some misgivings about taking it to market
Many tube amps measure poorly. Or not as good as most sand amps. Even so—or because, at least in part—they often sound from good to terrific.
"A poster of Einstein once said, things should be made a simple as possible but no simpler. This can apply to audio amplifiers but if they are evaluated subjectively, the simplicity thing can get a little out of hand. Of itself, minimalism exerts a strong aesthetic attraction and there is a reasonable belief that fewer components in the signal path allow more information to get through with less coloration. If like me you are interested in understanding how we hear distortions with our brains—instead of our meters—you might appreciate that simple circuits help isolate these phenomena. I listen to all sorts of flawed circuits because I enjoy hearing the differences and it helps to train my ears. In this regard, reducing the number and types of flaws makes it easier to tweak a single parameter and hear the difference. I think it's also true that simple distortions are often more forgivable in a listening situation and create less fatigue."
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
The discussion is in regards to loudspeakers not electronics.Trying to correlate the SQ with measurements in loudspeakers vs those of electronics are two completely different kettles of fish IMO.Most competently designed audio electronics will perform well on the test bench (ie. with ruler flat FR,low THD etc.)However with speakers the FR can have variances of +or-several db over parts of their operating range.These large depatures from flat should be very audible and will give the speaker it's own charateristic sound.
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I agree Fred, but that characteristic sound isn't nec. a negative if it sounds good to our ears even though there are measurable anomalies (within reason, of course) that some one says shouldn't sound good. I realize those quotes were discussing electronics but I personally feel they can apply to loudspeakers as well. We don't listen to speakers in the same manner as they are tested. That's all I was pointing out. I would never completely discount measurements, but I would never try and convince someone I could predict how something will sound solely based on measurement nor would I assume something that measures poorly automatically sounds poor unless measurements reveal it's so far from normally accepted parameters.
Just making a general observation based on my experiences over the years.
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
I completely agree with that. Friends of mine, who have more money than brains, have went out and purchased high-end speakers and electronics based on specifications. The majority of the time they were disappointed with them when they got them home. They say the sound is dull and boring. They couldn't understand why cheaper speakers could sound better. They thought spending the big bucks on the best specs would get them the best sound but that was not the case. Specs tell more about quality than good sound.Ultra low distortion and flat response can be overrated and people who constantly chase those kind of specifications religiously are really missing out. Use the specs as a guide, but be sure to get your ears on a lot of different gear to be sure you settle on something your ears like, not the black and white print of a test report or manufacturer derived data.
H9
I have never seen the "WOW factor" listed on a Spec sheet. Until they start doing that I will rely on my ears to make decisions about what I like to hear instead of what I see on paper.- SDA 2BTL · Sonicaps · Mills resistors · RDO-198s · New gaskets · H-nuts · Erse inductors · BH5 · Dynamat
- Crossover upgrades by westmassguy
- Marantz 1504 AVR (front speaker pre-outs to Adcom 555)
- Adcom GFA-555 amp · Upgrades & speaker protection added by OldmanSRS
- Pioneer DV-610AV DVD/CD player
- SDA CRS+ · Hidden away in the closet
- SDA 2BTL · Sonicaps · Mills resistors · RDO-198s · New gaskets · H-nuts · Erse inductors · BH5 · Dynamat
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As I mentioned in post #70 it is possible for speaker to have less than excellent measured response yet still sound pleasing.In fact there are many examples that have found widespread acceptance.( even some very spendy like those from a company that starts with W) .On the otherhand any speaker that measures very well in key areas is not likely be considered unlistenable or highly coloured.
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It is definitely possible for a speaker to sound pleasing if it has less than excellent measured response. For example, its possible for a company or DIYer to make a minor mistake, like not paying attention to the phase match-up in the crossover region, and still wind up with a speaker that sounds O.K. but has a measurable response irregularity. However, a better company or designer can come along, notice the irregularity, correct it, obtain a smoother response, and make the speaker sound even more pleasing.As I mentioned in post #70 it is possible for speaker to have less than excellent measured response yet still sound pleasing.In fact there are many examples that have found widespread acceptance.( even some very spendy like those from a company that starts with W) .On the otherhand any speaker that measures very well in key areas is not likely be considered unlistenable or highly coloured.
Very rarely does a non-flat FR occur by design (the exceptions are the BBC dip and slight downward tilting of the HF response). Normally they occur because of crossover-design errors, intrinsic driver problems, and the unwillingness or inability to correct them. -
What's not right is repeatedly making personal attacks instead of substantive comments.Something's not right with you. -
Ok, allow me. Something's not right with you.~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~
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I'm guessing the allure has returnedOk, allow me. Something's not right with you.
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You keyboard warriors ought to be more honest. What you don't like about me is that I don't agree with you.Ok, allow me. Something's not right with you. -
Agreed I would assume most accomplished designers would seek the goal of flat FR and accuracy.In fact even most DIY'rs will obsess over numerous iterations of xover design to get the last nth of linearity and proper phasing.Very rarely does a non-flat FR occur by design... -
Incorrect. I truly think there is something wrong with you. Apparently, I'm not alone in my observations.You keyboard warriors ought to be more honest. What you don't like about me is that I don't agree with you.
Truth be told.~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~
