Hello ThorstenL,
Thank you, I am reflecting on your comments.
As far as listening spaces in my home, one is a relatively ample HT space with large pro speakers. To keep the censor happy the other is a small would be bedroom. I often used headphones and home brew tube gear but the music was always in my head. I took off the headphones and have used Linkwitz style OB’s & Behringer 2031P’s with an M&K dual 12 sub woofer. The size of the space limits the configuration to near field. I searched DIYaudio for near field and found this ZDL thread started by Joachim. I like the idea of modular pieces-parts for swapping in and out mids, woofers and tweeters.
The near field ZDL’s will reduce the required power and reduce the strain on the drivers.
Again reflecting on your comments;
“I am there” will work.
DT
All just for fun!
Thank you, I am reflecting on your comments.
As far as listening spaces in my home, one is a relatively ample HT space with large pro speakers. To keep the censor happy the other is a small would be bedroom. I often used headphones and home brew tube gear but the music was always in my head. I took off the headphones and have used Linkwitz style OB’s & Behringer 2031P’s with an M&K dual 12 sub woofer. The size of the space limits the configuration to near field. I searched DIYaudio for near field and found this ZDL thread started by Joachim. I like the idea of modular pieces-parts for swapping in and out mids, woofers and tweeters.
The near field ZDL’s will reduce the required power and reduce the strain on the drivers.
Again reflecting on your comments;
“I am there” will work.
DT
All just for fun!
Now this is an unusual setup. The angle between speakers is commonly 60° or less. The sound stage tends to fall apart if the angle is greater than 60°.
I'm also struggling with your (and Thorsten's) definition of "nearfield". Does it represent "listening closer than usual (speakers on the meter bridge)", "listening within the critical distance (D/R=1)" or "listening within a distance where the inverse-square law isn't yet applicable"?
"I am there" and "They are here" both extremes depend also on recording and processing techniques. Normally I find the better point to be "I am right outside there and They are right outside here". In this case, I feel like I've opened a window to there while I am right in my room. This technically is also more reasonable because the original recording will contain room reflections with delay characteristics that are "there", but can never be reproduced due to the fast and higher energy reflections "here".
Now, with near field listening, as with what Joachim has envisioned, if the setup is getting pretty far away from walls, compared with the listening distance, the situation becomes better. However, not the masking effects of the head above certain frequencies become more critical.
If I use mics to do recording from the ears, and play back through earphones at the same location, the total effect of "I am there" is the most realistic I have ever expereienced. Even with people talking behind me during the recording, I tend to feel them exactly there when I listen to the playback that way.
Now, with near field listening, as with what Joachim has envisioned, if the setup is getting pretty far away from walls, compared with the listening distance, the situation becomes better. However, not the masking effects of the head above certain frequencies become more critical.
If I use mics to do recording from the ears, and play back through earphones at the same location, the total effect of "I am there" is the most realistic I have ever expereienced. Even with people talking behind me during the recording, I tend to feel them exactly there when I listen to the playback that way.
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The prevalent premise is that only a subset of cues is necessary to create a realistic virtual auditory space.
How is a "high energy reflection" defined that would prevent realistic spatial reproduction? 10dB down, 20dB down? Which arrival time? Angle of incidence? Interaural cross correlation?
I would hate to go on the assumption that only a subset of cues are necessary, rather I like to look at what is dominating. Let's say we listening to recordings at realistic level, in the original performance recording was made in a normal performance hall, the energy of the reflection would be at much lower levels and arrive at much later time than the characteristic of the listening room. Thus the listening room will mask such performance room characteristics during playback, then you lose the "I am there" perception. However, if we gradually reduce the listening level, we may gradually get the "I am there" perception back.
That is not necessarily correct. If the EQ is developed to correct the response at the listening position then at the listening position the response will be correct. If the direct sound is an impulse of magnitude 1 and a reflection of magnitude 0.5 arrives 0.5 msec after the direct sound than by adding inverse of the reflected impulse to the system after 0.5 msec then at the listening position the direct sound inverted impulse will cancel the reflection. There will be a reflection of the correcting impulse which is then canceled by another correction and so on. If the sum of the original direct plus reflected sound is minimum phase, then MP EQ will provide the necessary correction. You can check this out with the UE.
Then why do you guys concentrate on building speakers that actually increase early reflections?
This is true for one single point in space but humans tend to be equipped with two spatially separated ears. Humans also tend to move their heads while listening. How does an EQ cope with that?
Yes indeed, further back-up:
http://www.diyaudio.com/forums/multi-way/100392-beyond-ariel-126.html
Posts 1251, 1254 and 1255
DDF
V<>IR
Markus you are right. I learned that nearfied means to measure at a distance that is less then double the size of the measured radiator. If i measure further away, i measure in the farfield. I used the term nearfield when i listen closer then 2m from the radiator. That whould be inside the reverberation radius. A better term whould be freefied. Sitting further away i whould then be in the difuse field where the amount of reflected energy is higher then the directly radiated energy. This is for a point source.
My setup has the speakers quite far apart. Still i get very good image focus of phantom sources and the sound does not "fall apart". What i get is an elevation effect so that the image of central voices and music is slightly raised over the speakers. I like that effect. It remids me sitting in front of a stage with the musicians slightly elevated.
My setup has the speakers quite far apart. Still i get very good image focus of phantom sources and the sound does not "fall apart". What i get is an elevation effect so that the image of central voices and music is slightly raised over the speakers. I like that effect. It remids me sitting in front of a stage with the musicians slightly elevated.
The criteria depends on sweep spot area vs how you use the speakers. It's a choice of where the tradeoff is. For example, it's well known that I like a fast spectral decay, because this decay had higher energy than the reflection, and this is also part of the source. So if this is reduced to a certain degree, other performances are improved. Additionally, when this reaches a certain level of improvement, other areas become more important.
That depends on the frequency range in question and the speaker. I think many people would be surprised to see the extent of the listening window over which such EQ results in an improvement of both frequency and transient response. "Perfect" at only one point does not necessarily mean degradation everywhere else.
I posted this figure before to show the affect of off axis movement on on phase correction for an LR4 crossover to render it linear phase at the design point. The corrections also include amplitude EQ. Clearly neither speaker is showing the short time hash associated with diffraction in the impulse. The major degradation is due to the time misalignment of the sources as a function of off axis angle.
An externally hosted image should be here but it was not working when we last tested it.
I learned that the mic distance in a nearfield measurement should by <11% of the drivers effective membrane radius (see D'Appolito).
There is no critical distance in acoustically small rooms. All those diffuse field concepts originating from concert hall studies are misleading when talking about our domestic listening rooms.
There are strong early reflections followed by a diminished late reflected sound field (see Toole). Any loudspeaker design for home use needs to tackle that situation.
As I seid before, very uncommon setup and probably not tranferable to the majority of listeners. Nothing I want to argue about but readers should be aware of the fact before jumping to any general conclusions.
Do you have any data that shows how big that listening window is for different frequencies?
A resonance in the speaker is different from a room resonance. The arrival time of let's say a side wall reflection changes with position. How effective is an EQ in that situation?
I though we were discussing diffraction and its affect on temporally accuracy. The impulses I show give an indication of that. At 30 degrees off axis horizontally the biggest affect is the roll off of the driver's direct response. Vertically it is the the time misalignment between drivers.
Room effects are another topic.
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