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Old 4th February 2009, 06:53 PM   #21
HK26147 is offline HK26147  United States
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Quote:
The CSS FR125S in a spherical enclosure (see Avatar) creates the best imaging I ever experienced.
I was unable to find details on that model.
I used Vifa drivers ( sourced for Revel ) in 2 spherical enclosures I built, and share the same sentiment.
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Old 4th February 2009, 07:13 PM   #22
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Default Imaging, placement and orientation

This is my recipe for best spectral balance and imaging:I've been recommending this configuration since the 1970's, and it works every time. Seems to be gaining in popularity in recent years too.
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Old 4th February 2009, 09:05 PM   #23
tinitus is offline tinitus  Europe
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Speakers should point in the direction just at the back of your head, and nothing else
My own speakers sounds optimal when setup like that
I consider any other setup as being compromised
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Old 4th February 2009, 11:54 PM   #24
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Default Re: How do you get good imaging?

Quote:
Originally posted by MtBiker
What is the key to good imaging? I can find threads where people make claims regarding specific speakers, but inductive reasoning is failing me today.

Is it just using directivity and large distances from sidewalls to reduce the amplitude of reflected energy relative to direct energy? Does that mean that in-wall speakers can never image well, or only if they are placed far from a side-wall?

Will flat on-axis and even power responses guarantee good imaging regardless of the method chosen? i.e. dipole vs waveguide

Does a wide baffle render all other efforts useless because the baffle step occurs at a frequency critical to imaging?
Creating a believeable soundstage is elementary, when you think about it. The only thing that is required to create a stereo image is that the levels of the left and the right speaker are consistent, and the timing is correct.

That's it. That's all there is to it.

So why do few speakers image well? This is simple also. The sound which emanates from the cone of the loudspeaker is reflected by the cabinet, by the floor, by the walls nearby, and by objects in front of the speaker. That's why speakers don't image well.

So if you want a convincing image, all you have to do is address these issues. Treat the floor. Move the speakers away from the walls. The most difficult challenge is the cabinet of the speaker itself. When the sound from the speaker hits the edge of the cabinet, it diffracts if there is a sharp edge there. This diffraction creates a phantom image, delayed in time. This phantom image, generated by diffraction, is the primary reason that large speakers typically image worse than small ones. While small speakers suffer from diffraction, they do not suffer from diffraction to the same degree as large speakers in a conventional cabinet, and the delay is greater with a large speaker. The only solution to cabinet diffraction is a cabinet with NO SHARP EDGES. ANYWHERE. The speakers which I am listening to as we speak practically look like a bar of soap, and they use a waveguide. This attention to detail is the reason they image so well.

Click the image to open in full size.

The timing problem is more difficult, and the only real solution there is to use a minimum of drivers, and to locate them in a way that they're timing differences are minimized. The timing issue is most prevalent in the midrange and in the upper midbass. At low frequencies and at high frequencies the timing issue is not as critical.
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Old 4th February 2009, 11:59 PM   #25
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Quote:
Originally posted by tinitus
Speakers should point in the direction just at the back of your head, and nothing else
My own speakers sounds optimal when setup like that
I consider any other setup as being compromised
I agree with you that on-axis response should be flat, so having the forward axis pointing straight at you should yield good results. That's sort of the most obvious condition to me, a starting point, if you will. Most any good speaker should sound right when pointed directly at you, and if it doesn't, something is wrong.

However, this listening position - where a stereo pair of speakers cross their forward axis - defines a pinpoint spot. I think this is the optimum listening position for most speakers, and if the listener moves in any direction, sound quality degrades.

What I've described in the link above is a setup that offers good imaging over a much wider range of listening positions. It allows the listener to move in their chair without detracting from their listening experience, and also allows them to share that same good quality sound with others sitting nearby. However, one caveat is that it requires speakers that provide constant directivity.
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Old 5th February 2009, 02:42 AM   #26
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Quote:
Originally posted by Wayne Parham


I agree with you that on-axis response should be flat, so having the forward axis pointing straight at you should yield good results. That's sort of the most obvious condition to me, a starting point, if you will. Most any good speaker should sound right when pointed directly at you, and if it doesn't, something is wrong.

However, this listening position - where a stereo pair of speakers cross their forward axis - defines a pinpoint spot. I think this is the optimum listening position for most speakers, and if the listener moves in any direction, sound quality degrades.

What I've described in the link above is a setup that offers good imaging over a much wider range of listening positions. It allows the listener to move in their chair without detracting from their listening experience, and also allows them to share that same good quality sound with others sitting nearby. However, one caveat is that it requires speakers that provide constant directivity.
Wayne,

I have my speakers set up in the manner described in your link. Being able to listen any where in the room is delightful. For instance, my listening room also doubles as my office, and I really appreciate being able to listen in the sweet spot, but also getting good sound at my desk which is a few behind the sweet spot. Highly recommended!

If I'm not mistaken this is also the setup described here:
http://www.gedlee.com/downloads/Cum%20laude.pdf
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Old 5th February 2009, 02:57 AM   #27
tedr is offline tedr  United States
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In the formation of the phantom image only the direct sound from the drivers is useful. Reflected energy is destructive. The reason for getting away from the walls is mainly to do with the timing of reflections not the amplitude, the ear responds to delayed reflections by ignoring them after a certain time, a few tens of milliseconds I think, whereas early reflections cause both timbre shifts and confusion of the phantom image. A symetrical room and speaker layout helps. So does listening with the speakers toed in 45 degrees each side and listening close up where the tweeter axes cross. One of the better tests for phantom image construction is mono sound played back through both channels, the desired result is that the speakers seem to disappear and the sound comes only from a point midway between the speakers.

Ted
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Old 5th February 2009, 05:01 AM   #28
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I think this is the HOLY GRAIL of sound reproduction. Taken from stereophile:

What had wowed me? A total absence of "electronica." An enormous addition of lushness, texture, harmonics, and warmth, especially in the massed strings. And, at the same time, a major extension in air, detail, and transparency, coupled with a sensation of phase coherence that I describe as "acoustic jell." Usually you can get improvements in warmth and textures or more extension, air, detail, and transparency. Here, simultaneously, were both: a gigantic floating apparition of detail, delicacy, air, and texture, and an even greater diminution of glaze, glare, etch, and artifact. Usually you can get rid of those with the tonal cover-up of a high-frequency rolloff. With the TARA Mystery Wire, the artifacts were gone, yet the top-end extension and openness were greatly increased.

Each note on the celeste became a full-fledged, tripartite event: first a fully defined, cleanly rendered attack; then a three-dimensional, body-defining sustain; and finally a cleanly defined, effervescent decay into blackness. That holy trinity of live sound—believable attack, sustain, and decay timed out to perfection—more or less describes the dramatic improvement the TARA IC had wrought in my system. That, and the pitch-black backdrops against which all this sonic drama was played out, was what had me yelling "Wow!"


You can't beat "Acoustic Jell"
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Old 5th February 2009, 05:07 AM   #29
tinitus is offline tinitus  Europe
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Quote:
Originally posted by tedr

Reflected energy is destructive. .

Ted

Yes, and NO

A small amount of reflection is good...its a matter of finding the right amount fore that particular speaker in that very room

Absorbers should be used very carefully, its NOT a matter of more is better

My previous room was quite empty, with carpet on the floor...and it still needed some carpets behind and between the speakers

My present room is stuffed with all sorts of things, that should cause lots of destructive reflections...and wooden floor with NO carpets
I dont say is optimal and couldnt be improved...but I can only say it works perfectly, no problems whatsoever

There are no general thumb rules
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Old 5th February 2009, 06:22 AM   #30
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Default one things also is how the wave react with each other

for there will be waves that will cancel each other, and you have waves that at redirecting parts of the air motion in different directions even as they come out of the speakers. I like the MTM or TMTM designs for the middle tweeter gives a good transient response that would be lacking in the true way that a high definition wave. My speakers project many mode points for imagining. I believe that is why Bose has for a long time using direct/ direct-reflecting approach. For when you are at a live performance you have sound bouncing from many directions. Plus just the movement of the air in the room like air conditioning, since it is all about how the air is vibrated.
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