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Old 22nd June 2007, 03:48 AM   #1221
gedlee is offline gedlee  United States
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Default Re: Re: Re: Re: Re: Directionality

Quote:
Originally posted by DDF



The floor reflection one surprised me. However, read it for yourself before you form conclusions:
"Effect of early reflections from upside on auditory envelopment", Journal of the Acoustical Society of Japan, 16, 2 1995
This paper shows vertical images are spread if a vertical reflection is delayed by at least 10 ms, and the reflected power is at least 1/2 the incident.

We'll have to respectfully agree to disagree on the front wall.

But a floor reflection delayed by 10 ms !!! Thats way beyond what it would be in a small room. What you are quoting does not apply.

Using a term like RT60 implies a quantifiable reverb time, and in a small room it is so short that these concepts don't apply.

Virtually none of the concepts and research from large room acoustics applies to a small room. I hope that you are not making the mistake of thinking that they do.
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Old 22nd June 2007, 03:53 AM   #1222
AJinFLA is offline AJinFLA  United States
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It would be nice if the moderators could shift these last exchanges to this thread The Objectives of a Loudspeaker in a Small Room

cheers,

AJ
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Old 22nd June 2007, 04:06 AM   #1223
DDF is offline DDF  Canada
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Default Re: Re: Re: Re: Re: Re: Directionality

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Originally posted by gedlee



But a floor reflection delayed by 10 ms !!! Thats way beyond what it would be in a small room. What you are quoting does not apply.

Using a term like RT60 implies a quantifiable reverb time, and in a small room it is so short that these concepts don't apply.

Virtually none of the concepts and research from large room acoustics applies to a small room. I hope that you are not making the mistake of thinking that they do.

No, I'm well aware of the differences.

Perhaps I am guilty of stretching the application of the vertical reflection study though. However, it could reasonably apply to vertical ceiling reflections. Either way, it doesn't substantively change my argument that the floor cue is important if the goal is to create a believable ruse that the players are in your room.
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Old 22nd June 2007, 05:13 AM   #1224
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Quote:
Originally posted by DDF



The Toole School has been very vocal popularizing their philosophy, of very even response over wide dispersion angles, with the top end tailing off as you move off axis. Idea is flat long term integrated power in room with a gentle low pass shelf characteristic.

How would you describe the BBC and old KEF school?

The BBC/old-KEF constants I've seen over the years are a softer top end, and crossovers that aren't designed to be in phase at xover. Many years ago, the various KEF papers and the BBC designs seemed to sport mainly odd order acoustic xovers with their well known pros and cons: no reverse null here. These "uncorrelated" xovers certainly have a place in the trick bag and I've been getting superior results with them in some applications, especially ones where drivers are extremely close together.
I assess the "school" by the sound of their graduates. Although the NRC/Toole folks have been effective advocates, and there are many commercial speakers that now represent their approach, I haven't been dazzled by the results.

To me, the ones I've auditioned - at a range of price points - sounded OK. Not bad, not great, as if they were designed by a focus group to satisfy most listeners. A bit like the food in a good-quality chain restaurant. Pleasant, but ...

By contrast, the speakers I heard at the BBC Research Lab, aided by a Studer 1/2" tape recorder playing a first-generation quadraphonic mastertape, was possibly the finest and most lifelike, you-are-there sound I've ever heard. I have also had this sensation listening to Quad ESL57's with a high-quality analog system. There were moments with the Bastani Apollos that were really quite something, along with moments with the Linkwitz speakers.

When something really grabs my attention, I start asking why. I'm very Buddhist that way: I trust my perceptions, but I also want to know why I've perceived a certain set of sensations. This makes me a very dangerous reviewer: I either like or dislike a product, and if I like it, I immediately start back-engineering it and finding out what made it sound that way. This is not fair to the manufacturer, so I resigned as a Positive Feedback reviewer in the early Nineties.

Speakers are remarkably flawed in so many ways, the real question is what to optimize, and what parameters to relax. It will be a very long time until we get speakers that measure like amplifiers, so you have to pick and choose. Where the "objectivists" and I disagree is using personal esthetics to guide the choice - until some kind of audible perfection is within reach, I believe in speakers that reflect a certain esthetic, that is designed to accomplish certain goals while setting aside others.

I think that perfection is a long, long way off. Every time I go to a live concert (no amplification, thank you very much) I can't listen to hifi - any hifi - for at least a day or two afterward, the contrast is so great and so unflattering to the mechanical reproduction system.

There are entire genres of music that just don't work with hifi at any level of performance, modern classical being one. I was moved to tears listening to the Seattle Symphony perform Stravinsky's "Rite of Spring", a piece that is horribly dissonant on any hifi system. In performance, with a good orchestra in a good hall, it is inexpressibly beautiful. I never knew. None of my records or CDs sound remotely like what I heard in Seattle - and I know if I listened to a top European orchestra this piece would be even more intense and powerful.

I am dumbfounded when I hear people compare any hifi to live music. They sound completely different, as different as real-life is to a movie.

Given this vast gulf, I aim for a subjectively pleasing sound that has qualities similar to the real thing. That sounds pretty modest, and I guess it is - but even something as modest as that is pretty hard to do. Just getting rid of the grossest and most irritating colorations, along with the extremely unnatural spatial presentation of 2-speaker stereo, is no small challenge.

When I listen to controlled-directivity speakers, I hear a very closed-in, unnatural, and artificial perspective. Other people hear something completely different, and enjoy the sound of controlled-directivity speakers. I can force myself to ignore it, but the unnatural quality never goes away, and substantially detracts from my enjoyment.

In terms of spatial perspective, the most realistic sound I've heard has come from BBC-design direct-radiators or Quad electrostats, in 2 and 4-channel playback from mastertapes and occasionally LP's. Most digital seems to have a spatially truncated perspective - but high-resolution 96/24 or higher PCM seems to get closer to the mastertape sound. I'm still reserving judgement on SACD/DSD - there seems to be something wrong with single-bit conversion.

As for room size, I dunno. Bigger rooms help, but I have heard remarkable sound in small rooms, too. I really dislike dead rooms, though - they sound grossly unnatural to me. Any room where your own voice sounds weird is NOT going to be a good room for hifi listening. Conversely, if a real musical instrument, like a violin, sounds good, it's a good room.

As for the readers with small rooms, I'm actually optimistic. I've heard ESL57's sound exceptionally good in rooms that were ridiculously small, where you were practically on top of the speaker (think of the typical Brit living-room right after the war).

As for crossovers, it was Laurie Fincham that personally instructed me on the importance of phase-tracking through the entire crossover region. I take this seriously, and try and keep phase angles very carefully controlled, since this has such a strong influence on timbre, naturalness, and spatial quality. I feel this is underestimated in most commercial high-end speakers, with the result of somewhat phasey images and odd colorations in the vocal region. The fad for cookie-cutter image quality has greatly undermined the overall spatial perspective, which I feel is much more important, since it conveys a sense of "being there".

Minor Point: Floor reflections are typically delayed 3~3.5 mSec, with ceiling and sidewall reflections taking somewhat longer. And don't count on carpeting to "absorb" the floor reflection - when I measure the floor reflection by itself, it's very similar to the direct sound, with a gradual rolloff starting around 8 kHz. It takes a LOT of damping material to get a 20 dB reduction in a reflection.

MLSSA pix are here.
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Old 22nd June 2007, 05:49 AM   #1225
kevinh is offline kevinh  United States
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Hey Lynn I am very interested in the direction you are going with the OB design, I'm also taken by your comments on the Quads. Have you ever heard the LArge Sound Labs/ If so what were your impressions?
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Old 22nd June 2007, 06:03 AM   #1226
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Originally posted by kevinh
Hey Lynn I am very interested in the direction you are going with the OB design, I'm also taken by your comments on the Quads. Have you ever heard the LArge Sound Labs/ If so what were your impressions?
I've heard them locally at a Denver audiophile's house and a truly gigantic system at the last RMAF. Each speaker must have had a surface area the size of an SUV - it was huge partially cylindrical array, each side powered with a giant stack of Krells. I was told the system cost more than a million bucks.

Sonically? Ehhh, only just OK. Timbres sounded kind of pale, diminished and flattened out - and dynamics, despite the immense size, were just so-so, typical dynamic-speaker fare. Symphonic music just didn't have the sparkle and immediacy I expected, given the tremendous resources thrown at this system. But in all honesty, I don't think it's at all fair to assess Sound Labs based on the crazy, over-the-top RMAF demo in a huge hotel ballroom, big enough to park a semi-truck in.

(I don't think any kind of audiophile speaker works in theater-size spaces - that's what prosound systems are for.)

As for the Sound Labs at a local audiophile's house, I dunno. I didn't hear the sparkle I expected - I was a bit surprised, actually. By "sparkle" I don't mean HF extension, more a quality of liveliness and expressiveness, those little quirks of performance that makes music so enjoyable. I'd have to characterize it as a very "audiophile" kind of sound - take that for what you will.

But again, limited sample size. Just because they sounded funky doesn't mean they couldn't be terrific if used in the right way, in the right environment. But I don't know what that right environment would be, since I don't hang around the S'pile crowd very much. Y'know, flat ribbon cable or 2"-diameter wires on little trestles, wood blocks on top of the electronics, that kind of thing.

I have no idea why my fave electrostats are the ancient ESL57's - the poor things certainly have enough issues, with very limited SPL, and pretty bad side-to-side venetian-blind effects. But other electrostats can sound kind of weird, ranging from edgy to muted and rolled-off. These aren't easy speakers to get right. If I had to buy new I guess I'd check out Stax or those Dutch electrostats. These days, maybe you have to go DIY to get traditional electrostat sound. It wouldn't surprise me.
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Old 22nd June 2007, 10:52 AM   #1227
Pano is offline Pano  United States
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Quote:
Originally posted by Lynn Olson
I am dumbfounded when I hear people compare any hifi to live music. They sound completely different, as different as real-life is to a movie.
Which begs the question: What do we want from Hi-Fi?
Most of us who haunt forums like this profess to want a sound as close to the "real thing" as possible. Getting close to the real thing is a true emotional thrill. Tingles up and down the spine.

But what is wrong with a Cinerama-Technicolor approach to audio? When I go to the cinema I do not expect to see a perfect imitation of real life. That's not what I'm paying for. Give me bigger, better, more colorful than real life!

One of the most beautiful things I ever saw was a 70mm print of David Lean's Ryan's Daughter. More real than real. Every rock, every plant, every moss covered stone wall and dripping wet leather fishing boat was so real that you could touch it - and so beautiful that you ached to. Much, much more vivid than life. It was art.

I've had some audio experiences like that too.

Joe public doesn't care if his audio system sounds real. He just wants it to sound cool. The same with boom-boom boy in his rolling sound palace. The emotional thrill for them is not in accuracy. Nor is it for fans at a rock concert.

Most of us following this thread know how thrilling accuracy can be, the cheap tricks don't turn us on. We crave an accurate reproduction. But getting beyond that, is a little melodrama amiss? Is a touch of hyper-realism out of place? Or is a more accurate portrayal of reality enough?
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Old 22nd June 2007, 11:27 AM   #1228
Salas is offline Salas  Greece
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I just want to do something creative, learn, experiment, and have pleasing sound that gives good clue to music as I have experienced it. I have listened to a lot non amplified music but my bulk is with amplified live and studio work. I see DIY audio as comparatively elevated amongst popular enough hobby genres. And gets you to meet good cultivated people too. All in all positive. Illusions of recreating reality are not my thing. This is for when paying grand sums as a Hi-End client and must have justification.
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Old 22nd June 2007, 12:13 PM   #1229
gedlee is offline gedlee  United States
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Quote:
Originally posted by Lynn Olson


This makes me a very dangerous reviewer

Minor Point: Floor reflections are typically delayed 3~3.5 mSec, with ceiling and sidewall reflections taking somewhat longer. And don't count on carpeting to "absorb" the floor reflection - when I measure the floor reflection by itself, it's very similar to the direct sound, with a gradual rolloff starting around 8 kHz. It takes a LOT of damping material to get a 20 dB reduction in a reflection.


I've quoted the two points that we agree on.

My floor bounce piece of carpetting is about 3" thick (I use a futon under a throw rug), because you are quite correct, it takes a lot to get 20 dB reduction.

Its too bad that you never gave my speakers a chance (intollerable electronics) because I think that they would change lot of what you say here. I simply don't belive that someone can evaluate a good sound system in a few minutes using unfamilair sources. This was what you and most everyone else heard at RMAF. Thats why I belive that type of venue is more misleading than useful. A system has to "grab" you at a show like that, and anything that "grabs" you is IMO not a good thing. It takes a lot longer to appreciate a really good system than it does to be attracted by a partcicular feature of a mediocre one.

I'm off to BKK so I don't think that I will get a chance to come back to this thread. Take care.
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Old 22nd June 2007, 12:50 PM   #1230
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Default Re: Re: Re: Re: Directionality

Quote:
Originally posted by gedlee
I also disagree about the front walls as no early reflections add anything of value to a playback system - no matter where they come from. I believe that the area behind the speakers should be fairly dead - the only place where sound absorption is advised.

Hi,

woudn't 'in wall' or very flat 'on wall' systems be a good solution to avoid front wall reflections, especially in small rooms?

best, LC
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