Point-source and the argument of less ways= coherency

[Juhazi]

Binaural sound localization accuracy depends on frequency/wavelength and interaural distance (which is pretty constant for adult humans). Because our ears are at same horizontal plane, our vertical accuracy is very poor. Minor head movements improve accuracy a little (But take a look at how birds and cats listen...)

In regard to listening to loudspeakers at home, sound reflections from adjacent surfaces have major importance, and a large multiway speaker is different to coaxial or fullrange in this respect.

More about this
http://www.davidgriesinger.com/overvw1.pdf
http://www.linkwitzlab.com/TMT-Leipzig'10/TMT-Hearing spatial detail.pdf
Spatial hearing and hearing aids

 

[celef]

Binaural sound localization accuracy depends on frequency/wavelength and interaural distance (which is pretty constant for adult humans). Because our ears are at same horizontal plane, our vertical accuracy is very poor. Minor head movements improve accuracy a little (But take a look at how birds and cats listen...)

what does that mean, that we are insensitive to reflections from above and below the ears?

In regard to listening to loudspeakers at home, sound reflections from adjacent surfaces have major importance, and a large multiway speaker is different to coaxial or fullrange in this respect.

yes, reflections seems to be very important, with to much damping in the listening room there will be "black spots" in the sound field, with reflections the spots will be filled in, i am leaning more and more to that it is better to minimize the damping, or maybe the old live-end/dead-end can work?

More about this
http://www.davidgriesinger.com/overvw1.pdf
http://www.linkwitzlab.com/TMT-Leipzig'10/TMT-Hearing spatial detail.pdf
Spatial hearing and hearing aids

cool, can you summarize? or give some great rules of thumbs

 

[Juhazi]

Not insensitive, but poor, more poor than horizontally. Vertical localization happens by analyzing reflections in the ear's pinna, which means it happens only with high frequencies (>4000Hz), but still this is not a totally solved question.

Most hearing tests are done with simple test signals or speech. Music is always multitonal and even a single instruments's sound often covers several octaves of harmonics that give the timbre. A kick drum or organ's pedal notes are examples of "pure bass sound" in music. So this "vertical localization in small rooms" is a very difficult question. Visual information helps hearing a lot, and when we see a large speaker with the woofer down low, that sets some guidelines to our brains!

Google - hearing localization vertical

The Aging Auditory System - Google-kirjat

 

[Bergfinn]

Broadband drivers have some charm, but is not good enough for the high and low end.

Later this month I will try this horn;
Yuichi A290FL

with this comp.driver;
Celestion AXi2050

..in a 4-way active setup.
I think the most importent area to get a point source like sound are in the 4-500 Hz up to 10 kHz.
Sorry my english

 

[Juhazi]

I went walking with my dog and the cut the lawn. I was thinking about this height localization and got even more convinced of the importance of visual cues and learning.

Most dogs aren't interested in birds or squirrels and even don't look up in trees at all. Only people with audiophilia nervosa know what a woofer is and detect the height of bass sound of loudspeakers...

Here is my woofer barking at thunder! Shared album - Juha Sirkka - Google Photos

 

[GM]

i am leaning more and more to that it is better to minimize the damping, or maybe the old live-end/dead-end can work?

I've been 'leaning' towards using/recommending it ever since I experienced one ages ago, but the problem for most folks is attaining a sufficient decay in the [mid] bass to get a sense of having no walls. Only built one in a below grade basement, but well worth the cost/effort of building a lossy room within a room.

GM

 

[Patrick Bateman]

The point is not whether they disappear, but how coherent they are, i.e. do you perceive a horizontal piano, harp or a vertical one? Or worse, one that moves in both planes.

This is what drove me nuts with a large/tall full horn system that only the DSL Unity/Synergy concept horns solved, so for me, anything less is just mid-fi at best unless one sits far enough away for them to appear as a single point source.

GM

I told this story on another thread, but here goes:

I have Bill Waslo Cosyne Unity Horns at home. A couple of weeks ago, I was watching some trashy reality TV. I was seated equidistant between the speakers.

I could've *sworn* that the right speaker wasn't on.

As in, I literally had to get up and walk to the speaker to convince myself that it was on.

Now, obviously, that's nonsensical. If the speaker was actually off, it would sound like everything was coming from the left speaker. But the Cosynes throw up such a convincing "center channel", it often seems as if the sound isn't coming from the speaker at all.

In this case, I think a lot of the blame was with the source, basically reality TV shows don't have a big budget, and I think they recorded that scene in mono. Hence, the sensation that the "speakers weren't on." It seemed as if the only source of sound was a phantom mono speaker.

 

[Juhazi]

^ I listen to radio broadcast every day, as well as TV using my stereo speakers. Speech and old mono music recordings are good material to check the symmetry of loudspeaker positioning/reflections in the room. You should immediately recognize a monaural recording!

But for tv/movies, center channel speaker gives precise centering even if one sits off from center axis.

 

[ICG]

The main thing regarding point-sources and off-center multi ways is, do you regard coherency/homogenity higher than linearity?

If you do, fullrange and coax are probably the way to go. Room impression and stage positioning is very good to excellent on these.

However, linearity, dispersion pattern and distortion are taking an impact because of the coaxial (or fullrange) constelation. Linearity will have a great impact unless you are taking up a generous divertion of it or use numerous of correction EQs, which will likely apply to a small range of dispersion but will get different results on other angles. Often it's better to optimize for a 15-30° angle than 0° but it will perform great in linearity only in a small disperson pattern.

I, personally, use 12" fullrange drivers at the moment (got other speakers at hand too though). They got a great spl, excellent room impression and great dynamics. I despise two thing though, they are very narrow in dispersion and (okay, for me a less major issue) they don't deliver the linearity to replicate a lot of instruments realistically. The dynamics of impacts (drums, guitar, bass) and realistic reproduction of voices and them being in a certain room are extremelx impressive though.

In the end it only matters if a coax or fullrange will serve you better in your room and with your listening 'parameters' and if they can fulfill your other criterias. And, to extend that and use the advantages, it's very helpful to accept a subwoofer or even a woofer to the system to keep the advantages of a coax or fullrange driver without dealing all the disadvantages.

 

[youknowyou]

What do you guys think of Geithain like arrangement?

yes, coaxial are used by many (genelec, kef, ect), but as far as I see, Geithain arrangement is basically never used. why? In theory, Geithain arrangement seem to be the ideal compromise between coaxial (with its own set of compromise) and a point source like presentation using the Geithain arrangement.

My only concern in building a 3 way using a 15 inch + 6.5 inch+ 1.5 inch tweeter in a Geithain like arragement is the bass driver firing right into the back of the midrange driver...

 

[ICG]

What do you guys think of Geithain like arrangement?

yes, coaxial are used by many (genelec, kef, ect), but as far as I see, Geithain arrangement is basically never used. why? In theory, Geithain arrangement seem to be the ideal compromise between coaxial (with its own set of compromise) and a point source like presentation using the Geithain arrangement.

My only concern in building a 3 way using a 15 inch + 6.5 inch+ 1.5 inch tweeter in a Geithain like arragement is the bass driver firing right into the back of the midrange driver...

Geithain got a lot of paradigms right, dispersion control by waveguides, crossover frequencies at critical points, precise impulse answer and flat response. They don't leave much to be desired.

You are asking why the 15" bass does not have much impact on the midrange? See, that's a complex answer. At first, the back bass impulse does not much to the low mid membrane, at bass frequencies 'float' around certain obstacles. The objects it has to go around is very small compared to the wavelength of the bass. To get you a comparison: You can put a garbage can in front of a bass driver and it doesn't change the response but if you put a singe match in front of a tweeter, it ruins the perfomance completely. Yes, the bass impulse moves the membrane of the free air low mid driver a bit but it doesn't impact it much because it's size doesn't take up enough energy for a serious excursion, most of the kinetic energy goes around the membrane. The mid drivers are built for that excursion and the low HF crossover prevents it from having a Doppler effect on it or increase the distortion much. You'll see that is the basic principle of most of the gaithain speakers.

The downside of it is that the speakers can't take much of excursion of the low-mids. Their speakers perform remarkably well up to a certain spl, after which they sheer explode in distortion. That doesn't make the speakers bad, the limit is very high and up to that point they perform perfectly, but that's the limit of the construction. It either increases the distortion, impacts the linearity or the maximum spl and/or the dispersion.

 

[Brett]

Later this month I will try this horn;
Yuichi A290FL

Good flare. I built some about 16 years ago and used them with some BMS 4590 in a 5 way system, from 600Hz or so up.

 

[bbutterfield]

what does that mean, that we are insensitive to reflections from above and below the ears?



yes, reflections seems to be very important, with to much damping in the listening room there will be "black spots" in the sound field, with reflections the spots will be filled in, i am leaning more and more to that it is better to minimize the damping, or maybe the old live-end/dead-end can work?



cool, can you summarize? or give some great rules of thumbs

Reflections from above and below are difficult for our ears to decipher from the original sound, so instead of being perceived as discrete reflections, they are more likely to cause a shift in perceived timbre. Since the interference pattern includes constructive and destructive interference at different frequencies, these reflections degrade the balance of otherwise good speakers. A better solution is to mitigate the reflections, though one may be inclined to apply a gentle downward slope after doing so, to account for the loss of low frequency reinforcement.

Lateral reflections on the other hand are a major source of our perception of spaciousness during playback, which adds to the realism of the experience. Since we have two ears and are capable of using binaural unmasking, these reflections don't typically degrade our perception of detail. However, you do want some separation between your source and the reflections. 20 or 30 degrees should be sufficient, though distance will play a role as well. In general, the greater the angle difference and the greater the travel difference the better.

 

[Brett]

Surrounds?! What are the mains?

A pair of AE TD15S each side with a Lambda Unity in between them. Active of course. Plus there are subs below the 15's.

I suppose the problem with the bigger coaxial (12-15+ ) would be crossing the tweeter low enough with limited horn area....I know the woofer cone is part of the waveguide but somehow that seems prone to inaccuracy

Larger cones provide larger waveguides to potentially cross the tweeter lower, but all coax cones should move as little as possible so as not to modulate the tweeter output. That's why the 8" coaxes in the surrounds cross steeply at 300Hz; barely any cone movement at less than ear bleed levels.

 

[GM]

What makes Geithain special? All I saw was vintage tech drivers.

GM

 

[ICG]

What makes Geithain special? All I saw was vintage tech drivers.

Geithain got very good controlled dispersion on their monitor speakers and they are (semi-) co-/triaxial. Excellent nearfield monitors.

 

[AllenB]

Don't you find that Z-axis offset co-axials diffract off the small baffle, are reinforced by the cone behind them, and this produces delays that are comparable to a typical baffle to begin with.

In fact why is this thread about inter-driver offset when baffle edges can be a greater, point source related, issue.

 

[ICG]

Don't you find that Z-axis offset co-axials diffract off the small baffle, are reinforced by the cone behind them, and this produces delays that are comparable to a typical baffle to begin with.

No, the driver behind it does not reinforce it.

In fact why is this thread about inter-driver offset when baffle edges can be a greater, point source related, issue.

That's a non-issue with the Geithain since they are all active with a dsp and they do delay the drivers.

 

[celef]

Reflections from above and below are difficult for our ears to decipher from the original sound, so instead of being perceived as discrete reflections, they are more likely to cause a shift in perceived timbre. Since the interference pattern includes constructive and destructive interference at different frequencies, these reflections degrade the balance of otherwise good speakers. A better solution is to mitigate the reflections, though one may be inclined to apply a gentle downward slope after doing so, to account for the loss of low frequency reinforcement.

Lateral reflections on the other hand are a major source of our perception of spaciousness during playback, which adds to the realism of the experience. Since we have two ears and are capable of using binaural unmasking, these reflections don't typically degrade our perception of detail. However, you do want some separation between your source and the reflections. 20 or 30 degrees should be sufficient, though distance will play a role as well. In general, the greater the angle difference and the greater the travel difference the better.

for the lateral reflections, in a equilateral triangle stereo setup the side reflections should come from 50-60 degree off axis? what about reflections from the wall behind the listening position, is there any rules of thumbs?

 

[Brett]

what about reflections from the wall behind the listening position, is there any rules of thumbs?

Yes; keep the LP as far away from the wall as possible or use a 4" thick OC703 (or something with similar acoustic qualities) behind the LP. Former is better.