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post #511 of 554 Old 09-12-2019, 04:41 PM
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RAAL Fatigue - Not Likely

I suspect that most believe that measurements tell you a lot, but not the whole story. Generally, it seems that if a speaker measures poorly, it is less likely to sound good. And, not surprisingly, if it measures well, it is more likely to sound good. One clarification…good is as per the ear of the listener.


It has also been fairly well documented, at least anecdotally, that two speakers that measure similarly, may not sound so similar…hence, RAALs, diamonds and Be measure well, but don’t deliver music in exactly the same way.


This is where the ear and the experience of the loudspeaker designer are so important…which tweeter blends with which other drivers and when put in the proper box with the proper crossover can be voiced to deliver the sound that they think best reproduces music correctly. Dave, Jim, Dennis and Phil are experts at this, they have the option to use the RAAl which they frequently do and to use other tweeters…and sometimes do. And if you read through various threads, while they all measure, the final product is based on tuning by ear.


And then there is that all important “room” which most people can’t, won’t or don’t treat. Not so much of a problem if it is a big room with high ceilings…much more of a problem if it is a small room, square and has low ceilings. You can put a great speaker in the wrong room and it will disappoint.


As for music, if you listen to Led Zeppelin at 95db 15’ back, I’ll go out on a limb and say that there may be more satisfying choices than one of the RAAL options. But, if you want the open, spacious, dimensional and tonally precise sound of one of the better planars or ESLs with the punch of a dynamic speaker, then one of the RAAL offerings by any of the guys listed above will probably shock you…especially if you crave the lifelike sound of pianos, horns, voices, and acoustic guitars and even more so if you listen in the 70-85db range
.
Full disclosure, I’m somewhat biased. I own a pair of Salk Veracity STs which feature the RAALs, Seas midwoofers and a transmission line design. Their sound is detailed, delicate, dimensional, airy, and captivatingly realistic…as though you are sitting at a front table in a moderate size club and the performers are right there in front of you…and if you are hearing any “bite” at all, it’s not the RAAL…start looking into your source/DAC and/or room…and then your amp/preamp.


Finally, I suspect that the RAAL as implemented by Dave, Jim, Dennis and Rick is NOT fatiguing in any of their offerings that use the RAAL….but in the wrong room…or fed by a poor source….or played loud to the point of pain…yes, it may be fatiguing; but then, what wouldn’t be?
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post #512 of 554 Old 09-12-2019, 07:27 PM
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One of the aspects I love about the RAALs in my Sierra-2s is the lack of exaggerated sibilance. My Axioms were the worst at this. But even my Salk bookshelf speakers (which have an excellent soft dome tweeter) had more noticeable sibilance. Some of you guys are saying the Sierra-2 has a dip around 2-3khz and rising response above that. I'm pretty sure sibilance is somewhere in the 4-8khz range, maybe higher. If the Sierra-2 has a rising response above 3khz, it would seem they would have more sibilance, not less. So what's the explanation for this?
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post #513 of 554 Old 09-12-2019, 09:19 PM
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Originally Posted by xcjago View Post
One of the aspects I love about the RAALs in my Sierra-2s is the lack of exaggerated sibilance. My Axioms were the worst at this. But even my Salk bookshelf speakers (which have an excellent soft dome tweeter) had more noticeable sibilance. Some of you guys are saying the Sierra-2 has a dip around 2-3khz and rising response above that. I'm pretty sure sibilance is somewhere in the 4-8khz range, maybe higher. If the Sierra-2 has a rising response above 3khz, it would seem they would have more sibilance, not less. So what's the explanation for this?
It doesn't really "rise" until after 10 kHz.

http://www.ascendacoustics.com/pages...rm2exmeas.html

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post #514 of 554 Old 09-12-2019, 09:39 PM
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Originally Posted by xcjago View Post
One of the aspects I love about the RAALs in my Sierra-2s is the lack of exaggerated sibilance. My Axioms were the worst at this. But even my Salk bookshelf speakers (which have an excellent soft dome tweeter) had more noticeable sibilance. Some of you guys are saying the Sierra-2 has a dip around 2-3khz and rising response above that. I'm pretty sure sibilance is somewhere in the 4-8khz range, maybe higher. If the Sierra-2 has a rising response above 3khz, it would seem they would have more sibilance, not less. So what's the explanation for this?
They are flat on-axis, the slight dip and rising response after the crossover only happens off-axis due to the wide dispersion. Because of that, how they sound as far as being bright, neutral, sibilant, etc would be highly dependent on your room, if you have treatments or a lot of thick curtains, furniture, etc, you might not notice it.
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post #515 of 554 Old 09-13-2019, 01:25 AM
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Xcjago,

Sierra-2EX does not have a rising response after the slight crossover dip. Aarons continues to make up answers to suit his narrative.

Sierra-2EX simply has wider off-axis horizontal dispersion (thanks to the RAAL ribbon), and it does not precisely conform to what he feels is the ideal soundpower response based on his rather limited knowledge of acoustics. Unless a tweeter has some type of dispersion lens or poorly designed faceplate, it is basically not possible for it to produce more energy at on off-axis angle than on-axis at a specific frequency or range of frequencies. What Aaron fails to understand is that in soundpower measurements, the 70 measurements are averaged such that the further off-axis, the more that measurement is weighted. The extreme off-axis response counts more.

Had he understood the polar response of the S2-EX, he or anyone can clearly see how the range ~5kHz-9kHz remains at or near the same amplitude as it does on-axis. That is not a rising response, that is a flat response with very wide horizontal dispersion (something it took me writing a novella to explain to him)

When he doesn't have an answer to something - he reaches, because he fails to understand that there just might be more to it than he comprehends. We have sold many thousands of pairs of Sierra-2, the majority of our customers do not have room treatments and yet it is exceedingly rare to find anyone complaining of sibilance - in fact, for our RAAL ribbon based speakers, I generally advise to not overdo it with room dampening. By Aaron's own logic with this post, he is stating that speakers that then conform to his ideal soundpower response would then sound dull and never sibilant in a damped room (because they display less energy in their soundpower response at this frequency range) - which also isn't true....

Aarons, it's enough - stop commenting on a speaker you have absolutely zero experience with.

David Fabrikant

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post #516 of 554 Old 09-13-2019, 02:13 AM
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Why not simply look at the directivity indices?
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post #517 of 554 Old 09-13-2019, 05:19 AM
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Aarons, it's enough - stop commenting on a speaker you have absolutely zero experience with.
Dave - Just ignore. I still remember the night I got my upgrade kit to convert a pair of 1s to 2s. Once done I spent the rest of the evening listening to some of my favorite SACDs with a big grin. Anyone can figure out there is an agenda here, but I've enjoyed reading your comments along with those from Dennis and Rick. I plan on ordering a pair of S2-EXs later this fall to go with my HTM-200s, S1s, S2s and Horizon center (with RAAL). While I am fortunate enough to be in a position at this point in life to buy just about anything out there, why would I deviate from giving my business to a company that makes great sounding speakers.

Thanks for the ten plus years of enjoyment listening to Ascend speakers. The value proposition is just icing on the cake.
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Dave - Just ignore.
Unfortunately, Dave, Dennis, and Rick are in between the proverbial rock and hard place here to some extent. They provided numerous worthy responses that SHOULD have laid the discussion to rest and they shouldn't need to respond to additional foolishness. But the nature of the Internet and small ID businesses model, leaving some seemingly legitimate criticism unanswered makes it APPEAR as if they have no answer. That plays into the hands of those with an agenda who wage a "war of attrition" with such posts.
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post #519 of 554 Old 09-13-2019, 06:54 AM
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Aaron - the horse is dead, get off it.
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post #520 of 554 Old 09-13-2019, 07:02 AM
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RAAL Sibilance??

I'm in the camp of the RAALs are detailed but without sibilance....for those that might be concerned...as has been said, they have wide dispersion which would allow you to "tune" for any suspected brightness as well as center image and holography by angling them in, out or straight to suit your own desired characteristics.


Another thing...and admittedly its anecdotal, you almost never see RAAL loudspeakers...nor Ohm Walshes for that matter, on the resale market....it seems that people buy them, love them and keep them....I think that says a lot.
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post #522 of 554 Old 09-13-2019, 07:14 AM
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Quote:
Originally Posted by TimVG View Post
Why not simply look at the directivity indices?
Below is an excerpt from an interview with David Smith. He's an engineer who has worked with several speaker companies, including JBL, Snell, KEF, McIntosh, and PSB.

RA: There has been a lot of research with regard to psycho-acoustics and Toole's book is a great summary of this research. You have not only worked with some of the leading researchers but also contributed to the research itself. What is your take on the findings and how they apply to the home environment?

DS: Toole’s book is a groundbreaking work, worth reading over and over. It summarizes his decades of research on the subject of loudspeakers, their measurements and the applicable psychoacoustics. I think it is the new bible on sound system priorities, covering the audibility of the many measurable aberrations found in loudspeaker, including the effects of the room. If we place a speaker in the typical lively room and do a high resolution measurement, the result is such messy resonant picture that we can’t possibly discern whether it should sound good or not. Over the years we’ve developed a lot of approaches to smoothing out the view to simplify the picture, but without having any real justification for these approaches.

Toole’s classic paper, published in 2 parts in 1982 (part 1 and part 2), had a carefully run listening panel rank order 20 loudspeakers for preference and quality and at the same time made a large variety of measurements on them. It showed which measurement correlated with listener preference and which didn’t. This is great stuff for a speaker designer because you can ask: “what should I concentrate on when designing speakers”. Everything costs money and it is a competitive market. Should I spend money to get the phase response flat? Should I add extra components to flatten the system impedance curve? How low does distortion need to be? In other words, what measurable parameters correlate with our subjective impression?

This is a fundamental difference between commercially built speakers and DIY efforts. The enthusiast constructer can pick any design aspect and beat it to death. But if you are trying to survive in the market place you need to think about “bang for the buck”. Do your cost choices give the end user an audible benefit? Or are you creating straw men to knock down, say, reducing distortion to levels way lower than audible, over a misguided belief that that aspects overrides others.

Well, what I think Toole’s early research shows is that axial frequency response is the number one criterion. Power response, or overall directivity, seems to be a poor correlation with subjective impression. Why this is important is because it shows how room curves (strongly influenced by later arriving off axis response) can be misleading. The larger the room the more power response determines the room curve and the more misleading they will be. Still, I think he has drifted slightly from some of his earlier findings. In spite of what Toole’s early works clearly showed he is now placing importance on room curves and extending that from small rooms to large rooms as well.

I’m currently on one of the SMPTE committees that is looking to replace the X Curve approach to Cinema equalization. For years we’ve known that going into a large space, plunking down a microphone, feeding pink noise into the speakers and adjusting to flat response gave bad results, it is always too bright.

Now what does that mean? Something that measures flat sounds too bright? This isn’t an issue with amplifiers or record/playback systems, where flat sounds flat. I think there are a lot of clues to the reason for this, it is tied into human hearing and our ability to focus on earlier arriving sounds while ignoring later arriving sounds, but this is still a new concept to many in the industry.

With domestic listening rooms, the difference between the anechoic performance and the steady state, in-room performance is fairly minor for upper frequencies. But as the room gets to auditorium or cinema size, the differences enlarge and the steady state curve becomes very misleading.

There are a number of studies, by Kates, Salmi, Lip****z and Vanderkooy, Bech and others, that suggest that we judge frequency balance with largely a time windowed approach. Late arriving sound is ignored. Also, this time window is long for low frequencies and short for high frequencies. In effect it is the steady state or room response for low frequencies and typically just the direct (anechoic) response for high frequencies. At mid frequencies it might contain the first floor or back wall bounce, but later reflections are generally under the level required for audibility.

"Wouldn’t it be nice to have a measuring system that perfectly mimicked human hearing and the way we perceive frequency response? It could take all the subjectivity out of it."
Viewing perception this way answers a lot of questions, including why we need to roll off the response of a system in a large room: the early response is inherently brighter than the later response, due to rising speaker directivity, rising room absorption, even the absorption of the air. Flat steady state response would give very bright early sound, and so we reject it.

Why this has always fascinated me as a speaker designer is that it holds out the promise of our being able to design speakers that are perfectly balanced, if only we can figure out how our hearing works. Remember, if we accept as our goal that the speaker shouldn’t add anything, it should be a neutral lens for the recorded sound to come through, we still have to figure out what neutral or flat means? Is it flat anechoic response, flat in-room response, flat power response, flat time windowed response? In smaller domestic listening rooms the direct response from the speaker and the room response (including all reflections and reverberation) aren’t that far apart, perhaps 2-3dB of shelving in the room response when the direct component is flat. As rooms get bigger it becomes a major issue and steady state curves need to roll about ten dB (the Cinema X Curve).

My current approach is to design for flat anechoic response for midrange and up and then see how the low end interacts with the room, do a lot of listening and fine tuning until it seems right across a broad spectrum of software. Still, there is always a feeling that a little more tweaking could give a better result, and a suspicion that I am tuning to give a pleasant result with music I like, rather than achieving verifiable accuracy. Wouldn’t it be nice to have a measuring system that perfectly mimicked human hearing and the way we perceive frequency response? It could take all the subjectivity out of it.
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post #523 of 554 Old 09-13-2019, 07:17 AM
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Originally Posted by TimVG View Post
Why not simply look at the directivity indices?
Well for one look at the ER index, I've said multiple times that it should be the inverse of of the ER curve if the listening window is flat, but it's not. Do you or anyone agree/disagree?
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post #524 of 554 Old 09-13-2019, 07:41 AM
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Originally Posted by Ascend View Post
Xcjago,

Sierra-2EX does not have a rising response after the slight crossover dip. Aarons continues to make up answers to suit his narrative.

Sierra-2EX simply has wider off-axis horizontal dispersion (thanks to the RAAL ribbon), and it does not precisely conform to what he feels is the ideal soundpower response based on his rather limited knowledge of acoustics.
I said the response was due to wider dispersion of the RAAL, it doesn't matter why but it is there. I also explained to you that the overall sound power is probably the least important curve( no one is using Sierra 2 in a huge room) but you keep bringing it up. I thought we were almost in agreement after my last post but the only thing that remains is the early reflections curve is a very close predictor to in-room response and it is pretty clear that the ideal room response is a gently falling curve from the bass to the treble of about .4-.5 db.octave. The Sierra 2 ER curve is going to show a bump from 4-10k assuming it matches the ER curve pretty closely. Whether someone describes that bump as detail or brightness is going to depend on a lot of things.
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post #525 of 554 Old 09-13-2019, 07:43 AM
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Quote:
Originally Posted by Rick Craig View Post
Below is an excerpt from an interview with David Smith. He's an engineer who has worked with several speaker companies, including JBL, Snell, KEF, McIntosh, and PSB.

RA: There has been a lot of research with regard to psycho-acoustics and Toole's book is a great summary of this research. You have not only worked with some of the leading researchers but also contributed to the research itself. What is your take on the findings and how they apply to the home environment?

DS: Toole’s book is a groundbreaking work, worth reading over and over. It summarizes his decades of research on the subject of loudspeakers, their measurements and the applicable psychoacoustics. I think it is the new bible on sound system priorities, covering the audibility of the many measurable aberrations found in loudspeaker, including the effects of the room. If we place a speaker in the typical lively room and do a high resolution measurement, the result is such messy resonant picture that we can’t possibly discern whether it should sound good or not. Over the years we’ve developed a lot of approaches to smoothing out the view to simplify the picture, but without having any real justification for these approaches.

Toole’s classic paper, published in 2 parts in 1982 (part 1 and part 2), had a carefully run listening panel rank order 20 loudspeakers for preference and quality and at the same time made a large variety of measurements on them. It showed which measurement correlated with listener preference and which didn’t. This is great stuff for a speaker designer because you can ask: “what should I concentrate on when designing speakers”. Everything costs money and it is a competitive market. Should I spend money to get the phase response flat? Should I add extra components to flatten the system impedance curve? How low does distortion need to be? In other words, what measurable parameters correlate with our subjective impression?

This is a fundamental difference between commercially built speakers and DIY efforts. The enthusiast constructer can pick any design aspect and beat it to death. But if you are trying to survive in the market place you need to think about “bang for the buck”. Do your cost choices give the end user an audible benefit? Or are you creating straw men to knock down, say, reducing distortion to levels way lower than audible, over a misguided belief that that aspects overrides others.

Well, what I think Toole’s early research shows is that axial frequency response is the number one criterion. Power response, or overall directivity, seems to be a poor correlation with subjective impression. Why this is important is because it shows how room curves (strongly influenced by later arriving off axis response) can be misleading. The larger the room the more power response determines the room curve and the more misleading they will be. Still, I think he has drifted slightly from some of his earlier findings. In spite of what Toole’s early works clearly showed he is now placing importance on room curves and extending that from small rooms to large rooms as well.

I’m currently on one of the SMPTE committees that is looking to replace the X Curve approach to Cinema equalization. For years we’ve known that going into a large space, plunking down a microphone, feeding pink noise into the speakers and adjusting to flat response gave bad results, it is always too bright.

Now what does that mean? Something that measures flat sounds too bright? This isn’t an issue with amplifiers or record/playback systems, where flat sounds flat. I think there are a lot of clues to the reason for this, it is tied into human hearing and our ability to focus on earlier arriving sounds while ignoring later arriving sounds, but this is still a new concept to many in the industry.

With domestic listening rooms, the difference between the anechoic performance and the steady state, in-room performance is fairly minor for upper frequencies. But as the room gets to auditorium or cinema size, the differences enlarge and the steady state curve becomes very misleading.

There are a number of studies, by Kates, Salmi, Lip****z and Vanderkooy, Bech and others, that suggest that we judge frequency balance with largely a time windowed approach. Late arriving sound is ignored. Also, this time window is long for low frequencies and short for high frequencies. In effect it is the steady state or room response for low frequencies and typically just the direct (anechoic) response for high frequencies. At mid frequencies it might contain the first floor or back wall bounce, but later reflections are generally under the level required for audibility.

"Wouldn’t it be nice to have a measuring system that perfectly mimicked human hearing and the way we perceive frequency response? It could take all the subjectivity out of it."
Viewing perception this way answers a lot of questions, including why we need to roll off the response of a system in a large room: the early response is inherently brighter than the later response, due to rising speaker directivity, rising room absorption, even the absorption of the air. Flat steady state response would give very bright early sound, and so we reject it.

Why this has always fascinated me as a speaker designer is that it holds out the promise of our being able to design speakers that are perfectly balanced, if only we can figure out how our hearing works. Remember, if we accept as our goal that the speaker shouldn’t add anything, it should be a neutral lens for the recorded sound to come through, we still have to figure out what neutral or flat means? Is it flat anechoic response, flat in-room response, flat power response, flat time windowed response? In smaller domestic listening rooms the direct response from the speaker and the room response (including all reflections and reverberation) aren’t that far apart, perhaps 2-3dB of shelving in the room response when the direct component is flat. As rooms get bigger it becomes a major issue and steady state curves need to roll about ten dB (the Cinema X Curve).

My current approach is to design for flat anechoic response for midrange and up and then see how the low end interacts with the room, do a lot of listening and fine tuning until it seems right across a broad spectrum of software. Still, there is always a feeling that a little more tweaking could give a better result, and a suspicion that I am tuning to give a pleasant result with music I like, rather than achieving verifiable accuracy. Wouldn’t it be nice to have a measuring system that perfectly mimicked human hearing and the way we perceive frequency response? It could take all the subjectivity out of it.

Interesing read, which I completely agree with. Thank you. I have to say though, my comment refers to the discussion about the response rising or not. Simply look at the directivity indices to see what is going on.


Quote:
Originally Posted by aarons915 View Post
Well for one look at the ER index, I've said multiple times that it should be the inverse of of the ER curve if the listening window is flat, but it's not. Do you or anyone agree/disagree?
I'm trying to figure this one out. It should be the difference between the listening window or on-axis response and the early reflection response.
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post #526 of 554 Old 09-13-2019, 07:54 AM
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Originally Posted by Rick Craig View Post
Now what does that mean? Something that measures flat sounds too bright?
Exactly right, which is why you want to follow the Harman target in-room response curve.

Quote:
Originally Posted by Rick Craig View Post
There are a number of studies, by Kates, Salmi, Lip****z and Vanderkooy, Bech and others, that suggest that we judge frequency balance with largely a time windowed approach. Late arriving sound is ignored. Also, this time window is long for low frequencies and short for high frequencies. In effect it is the steady state or room response for low frequencies and typically just the direct (anechoic) response for high frequencies. At mid frequencies it might contain the first floor or back wall bounce, but later reflections are generally under the level required for audibility.
I'm not sure how long ago that interview was but yes we've known this for a long time, it's why I keep saying that the Early Reflections curve is so important, if you only had a listening window and ER curve, you would have most of the information needed to tell if a loudspeaker is good or not. Good find and interesting read.
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post #527 of 554 Old 09-13-2019, 08:00 AM
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So the directivity indices are calculated from the difference between the early reflection/sound power curve and the listening window or on-axis response. The ER and sound power curves have the same power at 200Hz yet the DI's start 1,5 -2dB apart. This would mean at 5kHz they should in fact touch which seems odd. If I compare overlay the ER and soundpower curve from 4kHz up they are nearly identical in slope, yet the DI slopes show larger differences.
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post #528 of 554 Old 09-13-2019, 08:07 AM
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Originally Posted by TimVG View Post
So the directivity indices are calculated from the difference between the early reflection/sound power curve and the listening window or on-axis response. The ER and sound power curves have the same power at 200Hz yet the DI's start 1,5 -2dB apart. This would mean at 5kHz they should in fact touch which seems odd. If I compare overlay the ER and soundpower curve from 4kHz up they are nearly identical in slope, yet the DI slopes show larger differences.
Exactly! I don't think Dave can admit that someone who can't read a Spinorama spotted it and he didn't...
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post #529 of 554 Old 09-13-2019, 08:14 AM
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If we bring the ER and Sound power a bit closer together and compare with the ER and Sound power DI we see this



Not wanting to throw oil on the fire, I have no quarrel with anyone here, but it doesn't seem entirely correct as the directivity indices should follow eachother closer based on the ER and sound power curves. Something does not add up.

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post #530 of 554 Old 09-13-2019, 09:34 AM
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Of course I don’t mind!
Thanks - I waited to see if Mr. Toole would answer your question about the Ascend measurements. I don't think he ever did unless I missed it. He did respond about using automated EQ and he's absolutely right about that subject.

Dave Fabrikant really pretty much covered everything about the speaker's measurements, including using a NRC graph of one of my designs to contrast the larger RAAL against the one he uses in his new 2-way. I respect him and Floyd Toole very much as straight-up and no-nonsense people.

Some of the readers here may not realize that Floyd really helped put the Canadian loudspeaker industry on the map. His earlier work with the NRC (National Research Council) was used to increase the performance of Paradigm, Energy, Mirage, and other companies. This is one of the main reasons Harman hired him because they were losing market share to those companies. At Harman they not only used his expertise but they wanted to compare their work (Revel/Infinity/JBL) against the designs from other speaker companies.

Prior to working for Harman Floyd had selected a Mirage M1 speaker for his own system. The M1 was a bipolar design which I don't think Harman has ever made as they focus on forward-firing monopole speakers. From reading his book I believe that Harman mainly concentrated on how they fared against some of the more popular monopole speakers. There weren't many speakers with ribbons available at that time and none that popular that they might target for comparison.

Harman has a history of heavy engineering and I know some of the transducer engineers that have worked for them in the past. They certainly are capable of creating a ribbon tweeter. When they bought Infinity that company was widely known for using planar drivers, both midranges and tweeters. The planar drivers are more similar to ribbons and were abandoned by Harman.

I gave this history on Harman to help explain that their approach is to make speakers that adhere to the groundwork that Floyd laid and continues to this day led by Sean Olive. Sean was mentored by Floyd and is the driving force in Harman's research which has now shifted more to headphone design and testing.

So the question is would a company like Revel ever use a ribbon? Does it fit well with their goal of constant directivity? There are also other factors for consideration. How robust would the driver be? Is it low in compression when the speaker is played really loud? Can it cross low enough to maintain constant directivity at the crossover point? Is the off-axis dispersion smooth for constant directivity? Obviously they have decided that a dome tweeter with a waveguide / horn (or compression driver as used in the M2) is the best match for achieving their goals.

As Dave Fabrikant mentioned it would be good to see how some of the RAAL designs would compare in some blind tests. I would also like to see how some of the speakers using RAAL tweeters do with compression tests. The only one I know of is the is the NRC test of my Verita design. Maybe Dennis Murphy will post his NRC results? Dave?

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post #531 of 554 Old 09-13-2019, 10:29 AM
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So the question is would a company like Revel ever use a ribbon? Does it fit well with their goal of constant directivity? There are also other factors for consideration. How robust would the driver be? Is it low in compression when the speaker is played really loud? Can it cross low enough to maintain constant directivity at the crossover point? Is the off-axis dispersion smooth for constant directivity? Obviously they have decided that a dome tweeter with a waveguide / horn (or compression driver as used in the M2) is the best match for achieving their goals.

As Dave Fabrikant mentioned it would be good to see how some of the RAAL designs would compare in some blind tests. I would also like to see how some of the speakers using RAAL tweeters do with compression tests. The only one I know of is the is the NRC test of my Verita design. Maybe Dennis Murphy will post his NRC results? Dave?
Another thoughtful post and I agree this is why Harman most likely doesn't use a ribbon, I've heard a few people, including Kevin Voecks say that he has never heard a speaker that is well integrated that didn't have a waveguide. I never really heard what he was referring to until listening to a few Revel and KEF speakers, then the difference is crystal clear. As far as the Mirage M1, you'll note in figure 7.20 that it has a flat on axis response with an in-room response that closely matches the Harman target curve, consistent with the research. The original Salon uses a rear tweeter, other than that I don't know of any Revel that isn't a monopole.

I totally agree and I think many here would love to see some RAAL designs in blind tests. Dave is in Southern California, just like Harman, so if he were truly interested in doing this I'm sure they could make it happen. If not, we could do it on our own, blind tests really aren't that hard to pull off.
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post #532 of 554 Old 09-13-2019, 10:36 AM
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blind tests really aren't that hard to pull off.

errr not sure I agree on that one. Not if you want to do it right at least, which for a 'formal' session it should be. Just ask John Schuermann about that one..
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post #533 of 554 Old 09-13-2019, 10:46 AM
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errr not sure I agree on that one. Not if you want to do it right at least, which for a 'formal' session it should be. Just ask John Schuermann about that one..
If you're doing a large scale test like that one, then yes I agree but I mean for 1 person at a time, all you need to do is level-match the speakers reasonably well and then have a way of instantaneously switching back and forth between the 2. It may not meet the standards of Harman's listening tests but it will remove your personal biases and in my experience, it also makes differences much easier to spot doing the test blind and with a single speaker in mono.
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post #534 of 554 Old 09-13-2019, 10:55 AM
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If you're doing a large scale test like that one, then yes I agree but I mean for 1 person at a time, all you need to do is level-match the speakers reasonably well and then have a way of instantaneously switching back and forth between the 2. It may not meet the standards of Harman's listening tests but it will remove your personal biases and in my experience, it also makes differences much easier to spot doing the test blind and with a single speaker in mono.

Don't forget you need to get them in the exact same position, fair is fair afterall in the case of a 'formal' test.
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post #535 of 554 Old 09-13-2019, 11:07 AM
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What are some of the characteristic differences between the RAAL and AMT tweeters? I'm asking as i'm looking at both the Ascend Sierra-2EX and RBH SV-61R, and matching a center speaker for either pair.

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post #536 of 554 Old 09-13-2019, 12:06 PM
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What are some of the characteristic differences between the RAAL and AMT tweeters? I'm asking as i'm looking at both the Ascend Sierra-2EX and RBH SV-61R, and matching a center speaker for either pair.

Thanks,
The horizontal dispersion is better with the RAAL but the AMT can cross lower. Looking at the response curves for both speakers I would favor the Ascend.

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post #537 of 554 Old 09-13-2019, 12:36 PM
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I think this would apply as well:

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post #538 of 554 Old 09-13-2019, 12:58 PM
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I think this would apply as well:
No kidding!
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post #539 of 554 Old 09-13-2019, 01:07 PM
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Yes because the one who has compared his speakers to RAAL designs and one of the top Revels blind is the one with speaker envy lol...
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post #540 of 554 Old 09-13-2019, 01:42 PM
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