The Modification of Timbre by Resonances: Perception and Measurement*
FLOYD E. TOOLE AND SEAN E. OLIVE
FLOYD E. TOOLE AND SEAN E. OLIVE
-
WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
Essential AES reading for high fidelity home reproduction
- Thread starter hvbias
- Start date
ON ROOM CORRECTION AND EQUALIZATION OF SOUND SYSTEMS
MATHIAS JOHANSSON, DIRAC RESEARCH AB
MATHIAS JOHANSSON, DIRAC RESEARCH AB
On the importance of early reflections for speech in rooms
Bradley, J.S.; Sato, H.; Picard, M.
Bradley, J.S.; Sato, H.; Picard, M.
Room Reflections Misunderstood?
Siegfried Linkwitz
Siegfried Linkwitz
A New Listener Training Software Application
Sean Olive, AES Fellow
Harman International Industries Inc.
Sean Olive, AES Fellow
Harman International Industries Inc.
Perception of Perceived Sound in Rooms: Some Results of the Athena Project
Peter L. Schuck, Sean E. Olive, James G. Ryan, and Floyd E. Toole
Institute for Microstructural Sciences, National Research Council
Peter L. Schuck, Sean E. Olive, James G. Ryan, and Floyd E. Toole
Institute for Microstructural Sciences, National Research Council
Hearing is Believing vs. Believing is Hearing: Blind vs. Sighted Listening Tests, and Other Interesting Things
Floyd E. Toole and Sean E. Olive
Harman International Industries, Inc.
Floyd E. Toole and Sean E. Olive
Harman International Industries, Inc.
A Multiple Regression Model For Predicting Loudspeaker Preference Using Objective Measurements: Part I-Listening Test Results
Sean E. Olive, AES Fellow
Sean E. Olive, AES Fellow
What's that you are saying? Too many? It is just 5% of all the papers I have in my library 
.
Hence the reason I suggested reading Dr. Toole's book. It can be a challenging read but it encapsulates many of these papers.
Over time I will be doing digests on all of these papers.
.Hence the reason I suggested reading Dr. Toole's book. It can be a challenging read but it encapsulates many of these papers.
Over time I will be doing digests on all of these papers.
dallasjustice
Major Contributor
Since you mentioned stereo playback and subwoofers (my passion as well), I need to express the following sentiments:
1. Most of the standard subwoofer recommendations presuppose a rectangular room or similar.
2. There are computer generated subwoofer setups. I'm not talking about those here; just the standard setups.
3. There are many ways to set up subs and none of them are perfect. Bass is never perfect on paper.
3. The so called Welti four sub midwall setup is optimal if one seeks a very wide and even sweet spot. It can be best described as a mode redistribution method. IOW, the modes still exist but they are spread out and thereby greatly diminished and much less audible. This method is NOT a mode cancellation method. This method is more ideal for home theater setups where there will more than one or two listening positions.
4. The best subjective single listener, stereo subwoofer setup referenced in the Fazenda research, is a two subwoofer setup. It is referred to as a source/sink array and is described in detail in the paper. There's also a reference to earlier tests on source/sink. This IS a mode cancellation technique. I prefer to think of it as a length mode active absorption method because that's what it actually does. This method doesn't have as wide a sweet spot as #3 above. But, IMO, it's the "best" method I've encountered at removing length modes and filling in rearwall Allison effect. This is the method I use after having tried many other methods including #3 above. I rarely use my system for home theater and rarely have more than a couple of listeners. Most of the time I listen solo to stereo playback.
I hope this info helps.
1. Most of the standard subwoofer recommendations presuppose a rectangular room or similar.
2. There are computer generated subwoofer setups. I'm not talking about those here; just the standard setups.
3. There are many ways to set up subs and none of them are perfect. Bass is never perfect on paper.
3. The so called Welti four sub midwall setup is optimal if one seeks a very wide and even sweet spot. It can be best described as a mode redistribution method. IOW, the modes still exist but they are spread out and thereby greatly diminished and much less audible. This method is NOT a mode cancellation method. This method is more ideal for home theater setups where there will more than one or two listening positions.
4. The best subjective single listener, stereo subwoofer setup referenced in the Fazenda research, is a two subwoofer setup. It is referred to as a source/sink array and is described in detail in the paper. There's also a reference to earlier tests on source/sink. This IS a mode cancellation technique. I prefer to think of it as a length mode active absorption method because that's what it actually does. This method doesn't have as wide a sweet spot as #3 above. But, IMO, it's the "best" method I've encountered at removing length modes and filling in rearwall Allison effect. This is the method I use after having tried many other methods including #3 above. I rarely use my system for home theater and rarely have more than a couple of listeners. Most of the time I listen solo to stereo playback.
I hope this info helps.
Those settings do cancel modes Michael. For example by using two opposing subs, you cancel the mid-point null. Here is a good diagram from Dr. Toole's book:
Nice OP, hope it becomes a sticky
Last edited:
- Thread Starter
- #35
What's that you are saying? Too many? It is just 5% of all the papers I have in my library
Hence the reason I suggested reading Dr. Toole's book. It can be a challenging read but it encapsulates many of these papers.
Over time I will be doing digests on all of these papers.
Thanks Amir, I have Dr. Toole's book. I should read it cover to cover (and then do it again), I use it as a reference and pick selected topics to go through when I have time.
Subwoofers and smooth in room bass response. Optimal room dimensions (some limitations with ceiling height) are the two primary areas I'm looking to learn more about.
Ah yes, this is the setup that interested me. Thanks.
Last edited:
Yes. But it should be noted that said cancellation only occurs when the two (assumed identical) subs have signals to them that are equal in amplitude and in phase. If you use a system like SFM or MSO, which individually equalize the subs, this condition may be violated, making the situation a lot more complex.
dallasjustice
Major Contributor
The Welti 4 sub midwall method in a rectangular room doesn't cancel modes. You can cancel the so called mid point null or a 1st order mode using a single midwall subwoofer. A single subwoofer will only cancel a single mode when placed midwall. But when you add the other 3 midwall subs in the room, the modes are not cancelled. They are redistributed.
Last edited:
I just started reading Floyd Toole's book. I've had it on my todo-list for quite some time, but this thread reminded me again to do it. Surprisingly well-written and interesting!
I agree.
Similar threads
