You might like to watch this video and see if there is anything here that might help you.
A Master Class in speaker placement - YouTube
Thanks to all who replied.
In March, here in the Mediterranean, it was Winter. The room temperature was 17K colder than it is now. That makes a difference in how the room sounds.
I listened to the video linked and discovered I am on the wrong track. I am too obstinate to keeping the speakers' distance as it is, but the expert who answered questions, was very clear about changing the speakers position to improve the room acoustics. He was very clear about having a square room. But there is hope, I can change the speakers' position using the 8:3 ratio. For other rooms there is the 1/5 rule. I will try to rearrange the room. As it is, the sound is irritating with room modes amplifying the sound well beyond +10dB. My perception of the sound loudness at room modes is more than three times!
In March, here in the Mediterranean, it was Winter. The room temperature was 17K colder than it is now. That makes a difference in how the room sounds.
I listened to the video linked and discovered I am on the wrong track. I am too obstinate to keeping the speakers' distance as it is, but the expert who answered questions, was very clear about changing the speakers position to improve the room acoustics. He was very clear about having a square room. But there is hope, I can change the speakers' position using the 8:3 ratio. For other rooms there is the 1/5 rule. I will try to rearrange the room. As it is, the sound is irritating with room modes amplifying the sound well beyond +10dB. My perception of the sound loudness at room modes is more than three times!
It's not quite like this. Modes can be a problem at any frequency and are especially audible at higher frequencies.
What happens below the Schroeder Frequecy is that the room modes become a significant determinant of the propagation, rather than free field propagation being the norm with room contributions added.
The Schroeder frequency indicates the frequency above where room modes will be (more or less) evenly distributed across the frequency spectrum. Room modes lower than the Schroeder frequency are not. As such those are recognizable, every single one, and they lead to bigger room response irregularities vs. frequency.
Schroeder frequency has nothing to do with free field or diffuse field sound propagation, although there of course is a link between the two. Free field propagation (or rather the circumstances we'd normally consider as free field propagation) is defined by the situation where free field propagation dominates over propagation from reflections and modal behavior. I believe the English expression for that is the 'critical distance' from a (singular) sound source. But I like the dutch 'galmstraal' better. 😉
Schroeder frequency has nothing to do with free field or diffuse field sound propagation, although there of course is a link between the two. Free field propagation (or rather the circumstances we'd normally consider as free field propagation) is defined by the situation where free field propagation dominates over propagation from reflections and modal behavior. I believe the English expression for that is the 'critical distance' from a (singular) sound source. But I like the dutch 'galmstraal' better. 😉
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Sorry, wrong of me, I took a consensus from a manufacture's forum that this was so and an established truth, it was not based on any personal view or work.
But I do get some weird imaging from my tweeters, up in the air and way outside the frontal imaging, sometimes at my side.
I tried to displace the speakers to various positions but failed to find a position showing any noticeable reduction in intensity of room modes. It seems without invasive changes to the room setup, there is very little probability of success. My option seems to be using something to prevent or absorb reflections at the walls. However, some sites suggest very thick foam material to absorb bass. This is expensive to do and takes up room space, and is therefore, invasive.
I am NOT after a perfectly behaving room, but after a room, which allows the enjoyment of music without too much ingredients of its own. Is this possible?
My search for room modes consists of playing an mp3 file containing a sine wave of increasing frequency. The test starts at 50Hz and ends at 20kHz. Room modes are very clearly noticeable as perception of intensity increases dramatically and then rapidly it drops.
I am NOT after a perfectly behaving room, but after a room, which allows the enjoyment of music without too much ingredients of its own. Is this possible?
My search for room modes consists of playing an mp3 file containing a sine wave of increasing frequency. The test starts at 50Hz and ends at 20kHz. Room modes are very clearly noticeable as perception of intensity increases dramatically and then rapidly it drops.
I think that the brain is very able to do quasi correction because its primary purpose is to interpret and understand, and to me the modes, at least in my lounge are not really a problem - I may be very fortunate though.
I am still currently, after nearly three years, struggling to understand the sound of new speakers because the results are so different from the norm I am used to, and this obscures the problem discussed.
I now have widely differing bass loudness on different recordings, much more than previously, and it makes me wonder if many of my previous speakers have just 'made the typical bass noise' which we have become accustomed to over the years, and which is also typical at shows.
This may be that we expect a certain 'noise' (Oh yes there it is, is it louder than usual or softer), The notes being very familiar and having become a norm to us.
My current sound is also probably the worst on speech I have ever encountered, but this does not necessarily make them wrong, they could be much more responsive to transients and eigentones caused by poor mic'ing techniques. Again, massive variation in this problem.
I am still currently, after nearly three years, struggling to understand the sound of new speakers because the results are so different from the norm I am used to, and this obscures the problem discussed.
I now have widely differing bass loudness on different recordings, much more than previously, and it makes me wonder if many of my previous speakers have just 'made the typical bass noise' which we have become accustomed to over the years, and which is also typical at shows.
This may be that we expect a certain 'noise' (Oh yes there it is, is it louder than usual or softer), The notes being very familiar and having become a norm to us.
My current sound is also probably the worst on speech I have ever encountered, but this does not necessarily make them wrong, they could be much more responsive to transients and eigentones caused by poor mic'ing techniques. Again, massive variation in this problem.
Due to the wavelengths involved, moving the speakers small distances won't make a noticable difference.
Well at least you gave it a go. When one is limited in where you can place the speakers it does make things difficult. And some times you just have to go with the best you can get, even if it's way less than you might want to have.
There was the LEDE theory, was that invalidated? I've recently seen that one pro uses alternate pads on the side walls; where there is one on say the left, there is none on the right etc.
Here is another video for you to watch. It is a good watch and listen. You may not be able to do this now, or ever. But since this is similar to what I do I can verify that this all works exactly as described.
Master Set & Rational Speaker Placement How To For GREAT SOUNDSTAGE - YouTube
Further testing continued to reconfirm the set of room resonances. I changed the speakers' postitioning, but the room remained loyal to its natural frequencies, although, I am noticing certain speaker positioning, is less efficient to setup strong standing waves. One particular speaker positioning, is such that, the distance from the side walls is intentionally different for the left and right speakers. Also, the distance from the wall immediately behind the speaker was made much less than before. This wall is treated for reflections, and the real wall is a heavy stone wall, the stone being globigerina limestone with each brick of about 65kg. This setup is giving me the impression it is more resilient to room resonances and the music is more naturally sounding. The only difference, is the bass now sounds far weaker than when the room was vigorously dancing at its modes. I am assuming this is to be expected.
The logic behind my experimental speaker setup:
The physics of standing waves requires, two wavetrains of the same amplitude and frequency, to travel in opposite directions and the distance between opposite facing reflections to be an integral number of halve wavelengths. My attempts are aiming to break the requirement of two wavetrains travelling in opposite directions. This is hopefully achieved by using different distances from the side walls for the two speakers. At any two intersection points at the side walls by any line parallel to the line joining the two speakers, the sound waves have to travel slightly different distances. Therefore, the waves generating a standing wave are at different phases. This, hopefully, causes the two superposing standing waves to result in a weaker resultant standing wave. All this can only hold, if the side walls lengths are comparable to the wavelengths of the room resonances. The production of pseudo wave sources at the various points of incidence on the side walls assumes diffraction is active, higher frequences cannot be affected this way.
What do you think? Is this correct or not? I am not at all experienced in room acoustics. What I wrote is plain Physics, and the real world does not tolerate oversimplication of theory.
Thanks for any helpful comments.
The logic behind my experimental speaker setup:
The physics of standing waves requires, two wavetrains of the same amplitude and frequency, to travel in opposite directions and the distance between opposite facing reflections to be an integral number of halve wavelengths. My attempts are aiming to break the requirement of two wavetrains travelling in opposite directions. This is hopefully achieved by using different distances from the side walls for the two speakers. At any two intersection points at the side walls by any line parallel to the line joining the two speakers, the sound waves have to travel slightly different distances. Therefore, the waves generating a standing wave are at different phases. This, hopefully, causes the two superposing standing waves to result in a weaker resultant standing wave. All this can only hold, if the side walls lengths are comparable to the wavelengths of the room resonances. The production of pseudo wave sources at the various points of incidence on the side walls assumes diffraction is active, higher frequences cannot be affected this way.
What do you think? Is this correct or not? I am not at all experienced in room acoustics. What I wrote is plain Physics, and the real world does not tolerate oversimplication of theory.
Thanks for any helpful comments.
I'll just go with what I think here. I just don't think you will get anywhere towards better sound with the way you are going. It's all a bit of guess and hope.
Room modes are properties of the room. As has been shown the frequencies are fairly close together. Thus far you seem to be pretty good at exciting them. So that's not where you want the speakers to sit, if possible.
Standing waves are easy to avoid. You should not have them.
If the only possible positions for your speakers excite the modes and give you standing waves, you may need to look at some kind of dsp for your speakers. That makes things a lot more complicated than just moving the speakers around a little bit.
I have a really small room, and it's nearly square in dimension. It's not symmetrical and I'm a little limited in what I can do with the speakers and where I can sit. Yet, I have great sound.
I follow along pretty much with the second video I linked to. I have experienced most everything the video guy talked about. It's easy to follow the procedure. It's not easy to find the magic spot. It took me a long time to find it.
Finding it means you don't excite the room modes. You do not have standing waves. You do have a great stereo image and you can sit in a relaxed position and just listen and not worry about anything but the music.
I found him (in the video), annoyingly verbose and not getting to the point, as I did also with another video. The under the chin lavalier mic doesn't help with the loss of sibilants and formants, and a boosted mid range, clearly audible on my £20 PC speakers.
Then I googled "speaker placement advice" and got 48 million results, looked at a few, most full of errors of communication, let alone valid knowledge, (talks like Yogi bear, Al Stewart), and am amazed at the lack of real insight and rigour involved.
Why are there so many with a limited knowledge and ability to express in clear English, without self important self aggrandising? This hobby seems to be full of this.
I want a theory supported by science, or at least validatable anecdotal evidence.
Then I googled "speaker placement advice" and got 48 million results, looked at a few, most full of errors of communication, let alone valid knowledge, (talks like Yogi bear, Al Stewart), and am amazed at the lack of real insight and rigour involved.
Why are there so many with a limited knowledge and ability to express in clear English, without self important self aggrandising? This hobby seems to be full of this.
I want a theory supported by science, or at least validatable anecdotal evidence.
This thread seems to be more about dealing with room modes affecting bass and not so much about getting good imagery. Unless you want a lot of room treatment to deal with the bass issues and/or separate bass speakers that can be positioned independently to the main speakers, you are going to find yourself making a trade off.
So, googling "science of speaker placement" gets 38 million threads.
If it is a clear science, why so many responses which vary enormously in approach?
If we google "What atoms comprise common salt" we don't, (I hope), get numerous disparate responses.
If it is a clear science, why so many responses which vary enormously in approach?
If we google "What atoms comprise common salt" we don't, (I hope), get numerous disparate responses.
Probably because there is an element of personal preference, for example, the amount and timing of reflections from the side walls.