graaf said:
Hi Graaf,
I can hear a slight difference when removing the absorbers, not very big. I think I prefer with them... some measurements would remove the doubts and make it all more objective!
You lifted very interesting points in your last posts, I hope Earl will answer you.
By the way, this set up is not a disaster, it is quite good!
I put my speakers back in the front firing position some days ago. After about 3 songs, I moved them back lying along the walls. It really surprised me!Regards,
Etienne
I don't know if you are aware if it but Earl has a powerpoint on his website about small room acoustics. It is an interesting document.
From page 8, you can read that VER below 1ms are far more perceptively important than a spectral analysis of their effects would indicate. This could explain the problems Earl has with the side walls reflections of our set up. But at the time the powerpoint was written (2005) the statement above comes from a paper that would be published.
Earl, was the paper approved and thus published?
Do we have a better understanding of the situation with VER below 1ms today?
Regards,
Etienne
From page 8, you can read that VER below 1ms are far more perceptively important than a spectral analysis of their effects would indicate. This could explain the problems Earl has with the side walls reflections of our set up. But at the time the powerpoint was written (2005) the statement above comes from a paper that would be published.
Earl, was the paper approved and thus published?
Do we have a better understanding of the situation with VER below 1ms today?
Regards,
Etienne
Etienne88 said:
I hope so too
It would be great because I consider Dr Geddes an authoritative source
He is also a person who has all facilities and knowledge to do and interpret necessary measurements
How am I suppose to do an impulse response measurement in my living room?
I am not a technical person, I am a music lover
desperate because of suckyness of loudspeakers money can buy on the market, even big money
I have no my own speaker laboratory nor factory
all I am able to do is experimenting with positioning of a simple fullrange loudspeaker (anything more complicated is beyond my DIY abilities)
all I have is intuition and all I can do is simple calculations of triangles, Pythagorean theorem
Etienne88 said:
By the way, this set up is not a disaster, it is quite good!
well, but perhaps we have impaired hearing or just a taste for bad sound?
we cannot exclude those possibilities, "brain-ear reference" is constantly misleading us
for the time being all we have is an objective assesment of a genuine expert that "is is a disaster"
best,
graaf
Etienne88 said:
Yes, I know this
therefore I asked Dr Geddes all those questions
because I think that what was covered by Dr Geddes' research was diffraction on edges, especially on horn throat or a waveguide edges
diffraction produces very specific VER, it is frequency dependent and its frequency content is concentrated in the highs
it is like having an array of small delayed tweeters around the loudspeaker, many vertical and lateral reflections in every plane
this is exactly why I asked specifically about our specific case and the answer was that "we don't know" because "experiments were very simple"
BUT "probably it would be wise to minimize them"
BUT we can say that "there would likely be very few VERs above 1 kHz in that setup"
so the question is - what do we really know?
best,
graaf
Let me quote from Dr Geddes’ presentation:
"diffraction" AND "wall reflections < about 10ms" - two separate problems?
"diffraction", "diffraction effects", " all horns have diffraction effects", "near field diffraction from the cabinets, any waveguide devices, or nearby structures"
well, isn’t it clear from the above that the research concerned not the problems of all sort of "reflections <1 ms" but rather the problems of "< 1ms diffraction effects"
this was researched, this was part of research into horns, waveguides and cabinet diffraction effects
then we have a kind of generalization in statement that, let me quote again:
well, important question - can a frequency independent reflection off the wall be treated as the same as frequency dependent "DIFFRACTION from a NEARBY STRUCTURE"?
this is the question
the initial response of Dr Geddes regarding our specific case was "we don't know" but all that can be said is that "there would likely be very few VERs above 1 kHz. in that setup"
BTW one more quote from Dr Geddes' presentation :
therefore we shouldn’t be worried by relatively early reflection off the opposite wall in our setup
best,
graaf
"diffraction" AND "wall reflections < about 10ms" - two separate problems?
"diffraction", "diffraction effects", " all horns have diffraction effects", "near field diffraction from the cabinets, any waveguide devices, or nearby structures"
well, isn’t it clear from the above that the research concerned not the problems of all sort of "reflections <1 ms" but rather the problems of "< 1ms diffraction effects"
this was researched, this was part of research into horns, waveguides and cabinet diffraction effects
then we have a kind of generalization in statement that, let me quote again:
well, important question - can a frequency independent reflection off the wall be treated as the same as frequency dependent "DIFFRACTION from a NEARBY STRUCTURE"?
this is the question
the initial response of Dr Geddes regarding our specific case was "we don't know" but all that can be said is that "there would likely be very few VERs above 1 kHz. in that setup"
BTW one more quote from Dr Geddes' presentation :
therefore we shouldn’t be worried by relatively early reflection off the opposite wall in our setupbest,
graaf
graaf said:
I agree on that.
The reflections I was referring to in post #162 are the ones of the side wall closest to the speaker which are delayed by 0,5ms in my case.
graaf said:
I would say no since the wall has no sharp edges... Unless you have a very nearby frame or shelve.
Regards,
Etienne
You guys are taking everything out of context and bending the words to suite you position. Your not trying to learn whats right, only prove your own opinions.
The research that you are quoting WAS only about diffraction, because the research on reflections had already been done. And yes the two things are different, but the ear doesn't really know that and hears them about the same.
The research that you are quoting WAS only about diffraction, because the research on reflections had already been done. And yes the two things are different, but the ear doesn't really know that and hears them about the same.
gedlee said:
well, what can I say?
I am sorry, that was not my intention,
I was only speculating because You were not responding
perhaps it came out that way unintentionally as looking like "taking out of context, bendind" and so on
I am very sorry
absolutely not my intention
I sincerely want to learn, I have no "position" nor "opinion"
gedlee said:
can You elaborate on the topic of those <1ms reflections so that we can learn please?
or in case You haven't got time just give some references so that we can read and learn?
It would be very kind of You
best,
graaf
Sadly, I don't think we will get any more help from Earl...
Graaf, you might found the following thread of interest DIY omni directional speakers.
Regards,
Etienne
Graaf, you might found the following thread of interest DIY omni directional speakers.
Regards,
Etienne
I'm not gone, just busy, which is why I have only a limited amount of time for discussion.
Blauert calls these very early efects "summing localization" because the ear basically sums up everything. Thus one has to consider them differently from say 2ms - 10 ms reflections. Some work was done on this under the audibility of group delay, which is a sort of VER. Most studies have shown them to be benign as purely phase effects (group delay), but of course the combfilter effect is well known as coloration. Lidia and I studied these effects as they would be for diffraction. We found that audibility was very low for low signal levels, but it increased rather rapidly as the SPL levels went up. It is a nonlinear effect. So you have to talk about the SPL levels if you want to talk about the perception of VER. After "summing" occurs, the effects are pretty independent of level.
Reducing these effects is significant only up to some SPL level which depends on several paramters. At some SPL any VER will be audible. I beleive the paper is on my web site.
This is all very complicated and I have tried to give you the "answer" without the data or proof. I don't have time to do both - sorry.
Blauert calls these very early efects "summing localization" because the ear basically sums up everything. Thus one has to consider them differently from say 2ms - 10 ms reflections. Some work was done on this under the audibility of group delay, which is a sort of VER. Most studies have shown them to be benign as purely phase effects (group delay), but of course the combfilter effect is well known as coloration. Lidia and I studied these effects as they would be for diffraction. We found that audibility was very low for low signal levels, but it increased rather rapidly as the SPL levels went up. It is a nonlinear effect. So you have to talk about the SPL levels if you want to talk about the perception of VER. After "summing" occurs, the effects are pretty independent of level.
Reducing these effects is significant only up to some SPL level which depends on several paramters. At some SPL any VER will be audible. I beleive the paper is on my web site.
This is all very complicated and I have tried to give you the "answer" without the data or proof. I don't have time to do both - sorry.
Earl, thank you for taking some time to explain, it is well appreciated!
The SPL level dependency of the audibility of delays/reflections does not make it easier to understand... I will do some more readings and I will probably need some time to digest it all! Then I might come back with some questions!
Graaf, I saw you post a link to the DIY omni directional speakers thread, very good!
Regards,
Etienne
The SPL level dependency of the audibility of delays/reflections does not make it easier to understand... I will do some more readings and I will probably need some time to digest it all!
Then I might come back with some questions! Graaf, I saw you post a link to the DIY omni directional speakers thread, very good!
Regards,
Etienne
Etienne88 said:
I have started a new thread at "Full Range" too
as this new setup is most suitable for one-way fullrange loudspeakers
it won't work properly in case of multiway speaker with separate tweeter, with the exception of coaxial/coincident drivers like KEF UniQ or Tannoy Concentric
best,
graaf
Speaking about Dual Concentric from Tannoy, the CMS801 seems interesting. You can find more data on Tannoy website, look for the "specs and measurements.xls" document under the download part. The directivity changes with frequency are quite smooth and you still have 60º coverage at 10kHz.
Regards,
Etienne
Regards,
Etienne
http://www.diyaudio.com/forums/attachment.php?s=&postid=1531889&stamp=1212673118
interesting remarks from one of Dr Geddes' Summa listeners/reviewers:
Amen! Amen to that!
let me put it this way:
"loudspeaker/room equation stupid! fix that problem first!"
best,
graaf
interesting remarks from one of Dr Geddes' Summa listeners/reviewers:
Amen! Amen to that!
let me put it this way:
"loudspeaker/room equation stupid! fix that problem first!"
best,
graaf
There has been a discussion in an other thread in the fullrange forum that should belong here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=123132&perpage=25&pagenumber=2
I just put my latest fullrange driver acquisition in the lower corners of my listening room and was surprised that I only get a good spacial image when I sit excentrically, in terms that there are two sweet-spots instead of one, like Stig Carlsson proposed for his orthoacoustic speakers (link in the other thread).
Now I start working in that direction as good as possible without speaking swedish.
Regards,
Oliver
http://www.diyaudio.com/forums/showthread.php?s=&threadid=123132&perpage=25&pagenumber=2
I just put my latest fullrange driver acquisition in the lower corners of my listening room and was surprised that I only get a good spacial image when I sit excentrically, in terms that there are two sweet-spots instead of one, like Stig Carlsson proposed for his orthoacoustic speakers (link in the other thread).
Now I start working in that direction as good as possible without speaking swedish.
Regards,
Oliver
el`Ol said:
in fact not much discussion there
generally not much interest on the forum in this fundamental problem of loudspeaker/room
el`Ol said:
in my setup (two speakers against the same 5.5m long wall) I get good image when I listen on-axis but indeed the image is even more impressive, more palpable when I sit slightly off-axis
...strange
did Stig Carlsson write anything about it? I cannot find it
best,
graaf