gedlee said:
Dear Dr Geddes
well I don't like to force anyone to do anything but here is an exception
I'm really happy that You have finally taken a specific position
beacuse it seems that there is at least "hope" for "typical living room" and for omnidirectional designs
and that there is probably no "diversified opinion" between Dr Geddes and Dr Toole as to good or bad effects of early reflections on imaging/soundstaging
and between Dr Geddes and Dr Toole and the rest - Watkinson, Moulton, Carlsson, Manger et alia
after all this 2 ms corresponds to a distance of just about two feet
no practical problem in positioning the loudspeakers in a typical room at all, at least with respect to room walls, what remains is a problem of a reflection off the floor - it is the most early and typically within those 2 ms
and what is above is neutral or even beneficial (more and more as milliseconds go by) to imaging/soundstaging i.e. creating spatially realistic sound picture
the separate problem is coloration of course but that was never questioned and omnidirectional designs having 360 degrees flat horizontal polar response seem to have an advantage in that regard?
and especially in Carlsson (a guy from Royal Institute of Technology in Stockholm, Sweden, +1997) approach where additionally the problem of reflection off the floor is effectively addressed
thank You Dr Geddes very much for Your time and patience!
I've been perhaps a little aggresive and/or emotional in my previous posts
I apologize!
I have to admit that these posts were intentionally provocative.
I don't like that kind of discussion tactics, nevertheless I think that it was all worth in that case i.e. worth the answer You have finally given
best regards,
graaf
graaf said:
I'm really happy that You have finally taken a specific position
beacuse it seems that there is at least "hope" for "typical living room" and for omnidirectional designs
and that there is probably no "diversified opinion" between Dr Geddes and Dr Toole as to good or bad effects of early reflections on imaging/soundstaging
and between Dr Geddes and Dr Toole and the rest - Watkinson, Moulton, Carlsson, Manger et alia
after all this 2 ms corresponds to a distance of just about two feet
no practical problem in positioning the loudspeakers in a typical room at all, at least with respect to room walls, what remains is a problem of a reflection off the floor - it is the most early and typically within those 2 ms
the separate problem is coloration of course but that was never questioned and omnidirectional designs having 360 degrees flat horizontal polar response seem to have an advantage in that regard?
First, when I talk about time delays I mean time DIFFERENCES between direct and reflected, NOT total travel time. A difference of 2 ms or 2 feet IS an extreme issue if you plot out the actual lines. I think that you are missing this critcal point. Putting speakers 2 ft. from something will not necessarily delay the reflection/diffraction by 2 ms. It could be much less.
As far as I am concerned omni-directional speakers are the completely wrong thing to do for all the reasons that I have stated. Please don't take away from this discussion that I am saying anything to the contrary.
As to "diversified opinions", Dr. Toole and I don't really have many major ones, but I do have major differences with most of the others that you mention.
Graaf,
When I wrote that summary I had read everything posted on this thread including lots of extra stuff subsdiary to the reference URL's everyone had posted, and then I distilled it down to what practical approach which could work with least cost in time and money, and give the speaker operator the most freedom both in terms of electrical operation and acoustic remedy.
Well, how can possibly horizontal polar response of a omnidirectional design look alike?
Like this. :
http://www.moultonlabs.com/more/new_loudspeaker_design/P1/
See figure 3.
I finally did find one on Moulton's site (I never did find one for that German speaker).
although I also note he says his speakers work better if they're moved away from the walls
Where does he say that? I would be happy to see this statement in its context.
In his discussion of desirable characteristics of domestic listening room Moulton says,
# loudspeakers need to be at least 6’ from the nearest wall or else installed in the wall;
This isn't surprising because in the next point he says,
loudspeakers need to have broad and uniform lateral high frequency dispersion
Previously, on the same page just above this, he also says,
Early reflections will begin to arrive at listeners in the optimum listening area approximately 10-15 ms. after their direct predecessors, and will build up over the next 40 ms.
See here:
http://www.moultonlabs.com/more/design_considerations_for_an_idealized/P1/
I read elsewhere on that site, (I can't find it now) that he prefers operating his speakers well away from the wall. This certainly was not clear in the interview.
When I look at the graph and and read the discussion in the two papers it's very clear to me he wants those lateral reflections diminished and delayed, relative to the direct signal.
Otherwise, as Toole points out in that paper I posted in a previous reply to you, the fat lady is going to be very fat and sound quite unlike she does in real life, or in the recording studio, or through head phones.
Because it's what happens prior to those 10 - 15 ms that matters:
Since the wall is a radiating surface, the closer the omni speaker is to the the wall, then the more extremely (greater SPL) the wall will behave like a slightly delayed copy of the speaker, which our perception will attach to the direct signal. And so we introduce to our perception colouration of the sound which was not present in the signal which left the loudspeaker. Also, the high SPL of that early reflection from the too-close-to-the-wall omni speaker causes our hearing to mask low SPL musical information. Thus we create two kinds of distortion: colouration, and loss of some of the information in the signal transmitted by the speaker.
This is why a room suited for speech intelligibility may not be suited for music.
This is why Moulton says six feet - almost two meters. Like everyone else who's sharp, he's going to avoid those loud, early reflections but he's going to have an acoustically treated, lively room so he can hear all the music.
The difficulties of operating speakers in a small room which is not only a listening room but also a living room, a family room, should not be made more extreme - by, for instance, putting speakers six feet from the walls in a 12' X 20' room. Building speakers into the wall or even on the wall are not non-trivial projects and much of the time impossible for many - for example, folk who live in multiple dwellings.
....................................
Operating speakers in small rooms has a chain of constraints: pyschoacoustic processes -> small room characterisics <-> capabilities of operator -> speaker characteristics .
I think we have to work our way through these constraints in the direction of the arrows:
The psychoacoustic processes are immutable;
the room has to conform to them;
the room characteristics and operator capabilities are perhaps modifiable, hence the two headed arrow;
the speaker (including crossover, amplifier, etc) has to conform to all the foregoing.
A speaker with well controlled directional capabilities and a smoothly falling off-axis response gives the operator the most flexiblity in terms of their placement and space requirements, room modification, and listening positions. And it's far more accessible to most people, especially DIYers, than the extremely expensive devices produced by B&O and MBL.
When I wrote that summary I had read everything posted on this thread including lots of extra stuff subsdiary to the reference URL's everyone had posted, and then I distilled it down to what practical approach which could work with least cost in time and money, and give the speaker operator the most freedom both in terms of electrical operation and acoustic remedy.
Well, how can possibly horizontal polar response of a omnidirectional design look alike?
Like this. :
http://www.moultonlabs.com/more/new_loudspeaker_design/P1/
See figure 3.
I finally did find one on Moulton's site (I never did find one for that German speaker).
although I also note he says his speakers work better if they're moved away from the walls
Where does he say that? I would be happy to see this statement in its context.
In his discussion of desirable characteristics of domestic listening room Moulton says,
# loudspeakers need to be at least 6’ from the nearest wall or else installed in the wall;
This isn't surprising because in the next point he says,
loudspeakers need to have broad and uniform lateral high frequency dispersion
Previously, on the same page just above this, he also says,
Early reflections will begin to arrive at listeners in the optimum listening area approximately 10-15 ms. after their direct predecessors, and will build up over the next 40 ms.
See here:
http://www.moultonlabs.com/more/design_considerations_for_an_idealized/P1/
I read elsewhere on that site, (I can't find it now) that he prefers operating his speakers well away from the wall. This certainly was not clear in the interview.
When I look at the graph and and read the discussion in the two papers it's very clear to me he wants those lateral reflections diminished and delayed, relative to the direct signal.
Otherwise, as Toole points out in that paper I posted in a previous reply to you, the fat lady is going to be very fat and sound quite unlike she does in real life, or in the recording studio, or through head phones.
Because it's what happens prior to those 10 - 15 ms that matters:
Since the wall is a radiating surface, the closer the omni speaker is to the the wall, then the more extremely (greater SPL) the wall will behave like a slightly delayed copy of the speaker, which our perception will attach to the direct signal. And so we introduce to our perception colouration of the sound which was not present in the signal which left the loudspeaker. Also, the high SPL of that early reflection from the too-close-to-the-wall omni speaker causes our hearing to mask low SPL musical information. Thus we create two kinds of distortion: colouration, and loss of some of the information in the signal transmitted by the speaker.
This is why a room suited for speech intelligibility may not be suited for music.
This is why Moulton says six feet - almost two meters. Like everyone else who's sharp, he's going to avoid those loud, early reflections but he's going to have an acoustically treated, lively room so he can hear all the music.
The difficulties of operating speakers in a small room which is not only a listening room but also a living room, a family room, should not be made more extreme - by, for instance, putting speakers six feet from the walls in a 12' X 20' room. Building speakers into the wall or even on the wall are not non-trivial projects and much of the time impossible for many - for example, folk who live in multiple dwellings.
....................................
Operating speakers in small rooms has a chain of constraints: pyschoacoustic processes -> small room characterisics <-> capabilities of operator -> speaker characteristics .
I think we have to work our way through these constraints in the direction of the arrows:
The psychoacoustic processes are immutable;
the room has to conform to them;
the room characteristics and operator capabilities are perhaps modifiable, hence the two headed arrow;
the speaker (including crossover, amplifier, etc) has to conform to all the foregoing.
A speaker with well controlled directional capabilities and a smoothly falling off-axis response gives the operator the most flexiblity in terms of their placement and space requirements, room modification, and listening positions. And it's far more accessible to most people, especially DIYers, than the extremely expensive devices produced by B&O and MBL.
A well thought out post. My thoughts (almost) exactly.
Six feet away from any reflecting surface - for two speakers spaced apart - is NOT a small room unless one sits close to a wall.
I cannot do anything about my hearing so I MUST sit away from the walls, preferably near the middle of the room. Now just try and place two speakers in the remaining space such that they are at least six feet from any reflecting surface and each other - the room gets pretty big - probably 20 ft by 20 ft minimum (ouch!). With high directivity the situation is dramatically improved because I can now be as close as 1-2 feet from the side walls and back wall and not have an early refection from these walls IF the directivity pattern doesn't see that wall.
High directivity gives one a far far better channce of achieving good sound in a small room than any other directivity can achieve.
The loudspeaker design is really pretty obvious if you follow through on the thought processes as done above.
Six feet away from any reflecting surface - for two speakers spaced apart - is NOT a small room unless one sits close to a wall.
I cannot do anything about my hearing so I MUST sit away from the walls, preferably near the middle of the room. Now just try and place two speakers in the remaining space such that they are at least six feet from any reflecting surface and each other - the room gets pretty big - probably 20 ft by 20 ft minimum (ouch!). With high directivity the situation is dramatically improved because I can now be as close as 1-2 feet from the side walls and back wall and not have an early refection from these walls IF the directivity pattern doesn't see that wall.
High directivity gives one a far far better channce of achieving good sound in a small room than any other directivity can achieve.
The loudspeaker design is really pretty obvious if you follow through on the thought processes as done above.
FrankWW said:
You have written above:
well, it appears that B&O/Sausalito does
what then?
well, it's "Surround Sound Playback/Performance Topology"
"surround sound"
a part of: "Design considerations for an idealized domestic surround sound listening space"
not "desirable characteristics of domestic listening room"
"surround sound listening space"
why have You omitted these two words: "surround sound "?
oh please not that "fat lady" and so on again...
I have read that Toole's marketing literature already and long ago
That is PRECISELY why I'm very interested in what is in his more recent scientific paper, which nobody knows and nobody seems to want to know
and even Dr Geddes admitted that "At greater than about 2 ms. the effects transition more to coloration than image"
So what 10-15 ms an d a "fat lady" are You talking about?
well, quite to the contrary Dr Toole says in his recent paper that "interestingly enough" they may be well suited
these were "Design considerations for an idealized domestic surround sound listening space"
that was "surround sound"
What are You suggesting?
well, I am certainly not an advocate of any commercial product, that is not my problem
I am very much an advocate of DIY approach
and let me tell You what is possible
a friend of mine (and a "diyaudio" forum user) tried yesterday at last, after much insistence from me, a sort of Carlsson approach with a small fullrange loudspeaker (Jordan JXr6HD) in a diminutive closed enclosure in a very live room
very live - huge windows, absolutely no absorption treatment or even absorptive furniture
he is quite an experienced listener
he has listened to many different stereos and is a very "HiFi guy", one of those (myself included) quite obsessed with accuracy
he attends live performances on every occasion and even makes his own recordings "Linkwitz-style"
his reference is "the real thing"
and he wrote to me that in terms of tonal character the result was quite unlistenable (certainly many factors affect that, reflections in too lively room included), very fatiguing
but in terms of spatiality/imaging he got "spectacular 3D"
all those reflections didn't spoil the sound picture at all, quite the contrary
what is important the results my friend got in his room are perfectly consistent with what Dr Geddes has written above in this thread about VER effects on imaging (beyond 2 ms beneficial in principle) and coloration (detrimental in principle), aren't they?
all I am saying is try something like that, easy and cheap, ideally suited to DIY
put all Your dogmas aside, all Your "sure is"
why not?
because those are just dogmas, nothing more
"there are still gaps in our understanding" as Dr Toole rightly points out
Can You disagree?
then why not to try something?
You are certainly not too old to try something new, aren't You?
Or perhaps You are too sharp i.e. not open-minded enough?
gedlee said:
2 ms = 6 feet
Let me ask You again - how can it be?
well, perhaps I am really dumb
but I am asking questions and You are not answering
instead suggesting that I am "not following through on the thought processes"
well, but they say that there are no stupid questions, aren't they?
so let me ask them once again
gedlee [/i] First said:
gedlee said:
graaf said:
I've usually lived in small spaces and it's been a bit of a challenge to get them to sound good. I've learned a few tricks.
Single glazed windows can be an efficient bass trap (escape, actually) and sound good when covered with thin wood slatted venetian blinds to block the glass reflections. Foam backed vinyl roller blinds killed the glass but not quite so good for the back into the room reflections.
Book shelves work also if you leave space behind the books and put thin, unbraced wooden doors on the front for relections.
Cupboards and armoires with slatted doors and heavy winter clothes hanging in them work a treat. Woollen coats are best.
Hung a rug on the brick wall behind the speakers.
I once put up a vinyl plastic greenhouse in front of some glass balcony doors because the speakers were either side of the doors. Sounded better than the curtains but higher powers told me to put it on the balcony.
In one place I had to put speakers on the long wall and sit against the opposite wall. I put up a big unframed painting backed with polyester batting behind me and put in delayed back channels using Ratshack Minimus 7s - they were so close they didn't have to play loud even with big music and it all sounded pretty good.
The most successful were the window treatment and the rug behind the speakers..
Single glazed windows can be an efficient bass trap (escape, actually) and sound good when covered with thin wood slatted venetian blinds to block the glass reflections. Foam backed vinyl roller blinds killed the glass but not quite so good for the back into the room reflections.
Book shelves work also if you leave space behind the books and put thin, unbraced wooden doors on the front for relections.
Cupboards and armoires with slatted doors and heavy winter clothes hanging in them work a treat. Woollen coats are best.
Hung a rug on the brick wall behind the speakers.
I once put up a vinyl plastic greenhouse in front of some glass balcony doors because the speakers were either side of the doors. Sounded better than the curtains but higher powers told me to put it on the balcony.
In one place I had to put speakers on the long wall and sit against the opposite wall. I put up a big unframed painting backed with polyester batting behind me and put in delayed back channels using Ratshack Minimus 7s - they were so close they didn't have to play loud even with big music and it all sounded pretty good.
The most successful were the window treatment and the rug behind the speakers..
gedlee said:
I apologize, not my intention
simply my English skills are not very well
I find it strange
it isn't (I mean choosing like that) something normal on an internet forum, isn't it?
And You are here a forum user, just like anbody else.
I am really very sorry for asking questions
and I am really sorry for just responding to Your posts as I read them, perhaps I can't understand them well - therefore I ask more questions
but I am not sorry for mis-quoting because I didn't intentionally mis-quote You anywhere
I really try to listen - i.e. read Your posts - very carefully - I just can't understand.
Anyway
Can You tell me how is it possible that sound wave can travel two feet in much less then 2 ms? How much less?
That is most interesting.
best regards,
graaf
just to answer to this question, E. Geddes is right : what is important is travel difference which is not the same as distance from wall.
Example : if the speaker is at 2ft (0.6m) from walls and the listener at 16ft from speaker, the approximative difference between direct sound and the reflection from sidewall is about 2.1ft and the one from back wall is about 3.4ft. So 2ms is about the limit : generally speakers are not so close from sidewalls. But diffraction effects from enclosure are typically in this short time window.
oh please not that "fat lady" and so on again...
Yes! Again! The fat lady has the answer. She has amplitude....
Moulton's speakers won't work right for him unless they are a long way from the wall, just as he says, and that's whether its in a "listening room" or a "surround sound room" or a "studio."
I keep telling you, and you're not listening, if you put omnis too close to the wall then you will get colouration and simultaneous masking, forward masking, and backward masking. It's possible that some masking effects can last up to a hundred ms. We are particularly vulnerable to masking effects in the 2000 to 5000 Hz range. This all has profound implications for incorrect playback presentation.
You will get fatigued because you keep trying to hear something you know should be there and is not. You will get fatigued because vocal and instrumental formants will be amplified by the "phantom speaker" enough to mask musical information arriving in the present, the past and the future. You will get fatigued by the emphasis on the formants' upper frequencies often noted as "detailed but fatiguing sound" - some vocalists, woodwinds, and esppecially violins and brass have truly wicked formants. You will even get fatigued because you will hear rhythm with subtle inaccuracies - the attack will be "smudged". You might get frustrated or bored because it doesn't sound "real."
Correct playback presentation has to arrive to our ears at the right levels and in the right order. Putting omnis too close to the wall messes that up.
This is what the fat lady is trying to tell us.
Yes! Again! The fat lady has the answer. She has amplitude....
Moulton's speakers won't work right for him unless they are a long way from the wall, just as he says, and that's whether its in a "listening room" or a "surround sound room" or a "studio."
I keep telling you, and you're not listening, if you put omnis too close to the wall then you will get colouration and simultaneous masking, forward masking, and backward masking. It's possible that some masking effects can last up to a hundred ms. We are particularly vulnerable to masking effects in the 2000 to 5000 Hz range. This all has profound implications for incorrect playback presentation.
You will get fatigued because you keep trying to hear something you know should be there and is not. You will get fatigued because vocal and instrumental formants will be amplified by the "phantom speaker" enough to mask musical information arriving in the present, the past and the future. You will get fatigued by the emphasis on the formants' upper frequencies often noted as "detailed but fatiguing sound" - some vocalists, woodwinds, and esppecially violins and brass have truly wicked formants. You will even get fatigued because you will hear rhythm with subtle inaccuracies - the attack will be "smudged". You might get frustrated or bored because it doesn't sound "real."
Correct playback presentation has to arrive to our ears at the right levels and in the right order. Putting omnis too close to the wall messes that up.
This is what the fat lady is trying to tell us.
Hmm, I think the Beo Lab 5 speakers should show some diffraction artifacts. Having listened to a pair a few years ago, the imaging and certain roughness in the sound was a little fatiguing. The looks was good.
Small rooms really need to have good sound absorption in the front half of the room forward of the listener.
Small rooms really need to have good sound absorption in the front half of the room forward of the listener.
FrankWW,
Yes, exactly. There is one spot, in a normal room, that allows correct timing /summing of all signals to arrive to the listening position and be correlated by our threat assessment system as a "correct" sound. This is a relationship between walls and drivers and once obtained, will free the listening area up from tight locational requirements, so long as you have actual Omni's or even wide dispersion speakers. Even Romy the Cat, the most argumentative voice in audio, will agree that this is true.
Bud
Yes, exactly. There is one spot, in a normal room, that allows correct timing /summing of all signals to arrive to the listening position and be correlated by our threat assessment system as a "correct" sound. This is a relationship between walls and drivers and once obtained, will free the listening area up from tight locational requirements, so long as you have actual Omni's or even wide dispersion speakers. Even Romy the Cat, the most argumentative voice in audio, will agree that this is true.
Bud
jlo said:
well, rather it os You who is right and I agree
but Dr Geddes has written something different, let me quote him:
Can You see the difference?
He didn't write that "travel difference is not the same as distance from wall".
He wrote that "time delays I mean time DIFFERENCES between direct and reflected [is not] NOT total travel time".
And that is very interesting.
is Your normal "listening position" really two feet from the side-wall facing the speaker along the wall? and what about the other speaker?
or are You joking?
FrankWW said:
well, I give up
it is hopeless
all I feel obliged to say is that You clearly don't know what You are talking about
simultaneous masking, forward masking, and backward masking, hundred ms, profound implications, incorrect playback, fatigueing omnis...
sorry, that' s to much for me
maybe I was not listening to You carefully enough but fortunately I have listened to omnis and also to relatively close to wall omnis (read: much less the 6 feet away from walls) many times, and not only me, and I have to say say that all You have to say about this only proves that You haven't
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