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-   -   How do you get good imaging? (http://www.diyaudio.com/forums/multi-way/137646-how-do-you-get-good-imaging.html)

MtBiker 30th January 2009 08:34 PM

How do you get good imaging?
 
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?

gainphile 30th January 2009 08:52 PM

First of all, an adequately-sized room. Meaning a room which speakers are away from walls.

Then speakers with uniform response and this arguably are dipoles and omnis. I've playes with waveguides and they have the "direct to your face" type of sound. Good for textures and details, not good for soundstage/image/illusion.

my 2 hz worth :)

LineArray 30th January 2009 10:40 PM

Quote:

Originally posted by gainphile

...speakers with uniform response and this arguably are dipoles and omnis
...

Hi gainphile,

i tend to agree. Uniform angle of radiation vs. frequency
( i guess this is what you meant ?) is
very important to get good imaging.

Some people say that omni sources can tolerate near walls
(distance <=1m ) better than dipoles. From my experience i
agree to that too.

To me good imaging is the result of a speaker with good
habits in "all" disciplines you can imagine.

A speaker with nasty peaks in the presence or brilliance region
will tend to produce an "out of the box" sound. A speaker which
suffers from cabinet resonances will produce a different
"out of the box" sound.

In short: A good speaker will produce believable imaging with
good recordings. It is really that simple ...

Of cause room resonances and reflections have to be tamed.

Cheers

Rudolf 30th January 2009 10:45 PM

I believe it is symmetry (in a wider sense) in the first place. Let me explain:

First: Room conditions left and right outside the speaker base should be equivalent. If first reflections off the sidewalls are very different in timing, imaging will suffer. And if one sidewall is all thick rug and the opposite one is all glass, it will not help either.

Second: Speakers should have controlled directivity. It may not be constant directivity a la Geddes, but off-axis radiation should fall off smoothly at all frequencies compared to on-axis.

Third: Your listening position has to be in the stereo triangle. You can not have good imaging outside the sweet spot.

I dont see baffle step and power response as critical factors for imaging. They are only important for an even and natural frequency response IMHO.

Drew Eckhardt 31st January 2009 12:38 AM

Quote:

Some people say that omni sources can tolerate near walls
(distance <=1m ) better than dipoles. From my experience i
agree to that too.
I've built both Linkwitz Orions and Linkwitz Plutos.

The Orions are _MUCH_ more tolerant of objects between them along with side-wall proximity. I had one room with the left speaker 2' from the side wall and the right speaker over 10' off with a center image that stayed parked with frequency.

You can add extra toe-in to the dipoles so they minimally illuminate the side walls. Even with my Orions aimed straight at the listener in my original room, I calculated a first side wall reflection about 10dB down from a less directional speaker.

tinitus 31st January 2009 12:39 AM

Re: How do you get good imaging?
 
2 Attachment(s)
Quote:

Originally posted by MtBiker
What is the key to good imaging?

Does a wide baffle render all other efforts useless because the baffle step occurs at a frequency critical to imaging?


Good imaging ?...just imagine it :D

Joke aside

Small 2ways have always been known to do it well

But not much music supports it

I prefer to focus on ambience, tonality, coherency and ... "focus" :)

I bet this new one from Troels will be good at it!

gainphile 31st January 2009 08:29 AM

Re: Re: How do you get good imaging?
 
Quote:

Originally posted by Drew Eckhardt

The Orions are _MUCH_ more tolerant of objects between them along with side-wall proximity. I had one room with the left speaker 2' from the side wall and the right speaker over 10' off with a center image that stayed parked with frequency.

This is my finding too. The pluto simply cannot live in small room, 3x4m in my case. They just don't sound right. Bass gone, FR not smooth etc. all the things you can think of bad speakers. I know SL say otherwise. The dipoles are somewhat OK but much better than pluto in small room.

Both require large room to sound great.


Quote:

Originally posted by tinitus


I prefer to focus on ambience, tonality, coherency and ... "focus" :)

I bet this new one from Troels will be good at it!

I like these too, so I also have a set of fullrange speakers for my small room :)

LineArray 31st January 2009 09:51 AM

Quote:

Originally posted by Drew Eckhardt


I've built both Linkwitz Orions and Linkwitz Plutos.

The Orions are _MUCH_ more tolerant of objects between them along with side-wall proximity ...


Maybe my former post was too sloppy ...

The dipol 08 speakers (own dipole design) i use in my room,
have very asymetric distance to the side walls.
I have to compromise the speakers position, because there
is a support (column) in the middle of my listening rooom.

Dipoles can tolerate that, because there is less energy radiated
towards the sides. Concerning a wall behind the speaker, a dipole
will not work well, when distance drops below say 1,2m.

If you cannot avoid a wall near behind the speaker, an omni is
more tolerant IMO. This is often the case for small rooms.
I would not use a dipole in a 3x4m room, because the listening
area gets too small, when the dipoles are placed far enough from
the wall behind.

But i am not a "sweet spot listener". I designed my speakers
for a listening area as large as possible.

I often sit slightly shifted from the middle when listening. I vary
the distance too. With some music (chamber music, some kinds of
electronic music) i sit 2,5 to 3m away from the speakers.
With orchestral music i choose up to 6m sometimes, depending
on my mood and the spatial quality of the recording.

But my speakers have more directivity than most designs,
so i can afford listening at larger distances.

Most speakers "live up" in a larger room. I think one reason
for that is, that balanced bass response and deep bass is difficult
in small rooms. Mode density in small roooms is too small at
LF. Balanced and deep bass is very important for imaging too
IMO.

Cheers

Tenson 31st January 2009 01:07 PM

I think many confuse imaging and soundstage. To me they are very differnt. Soundstage is about how well the speakers fill the room and the space between them. Imaging is how well they suspend a sound in an exact point of space.

In my experience small speakers have a good soundstage but not such good imaging. I put this down to the high baffle step frequency. The wider dispersion produces more reflections and diffuse sound so it gives a bigger sound with more ambiance. I think wide baffle speakers tend to have good imaging for exactly the opposite reasons. They are more directive and so you get fewer reflections to muddle the minds localisation abilities, but by the same token you have less ambiance.

I think soundstage and imaging are partly exclusive of each other, although of course you can have some of both.

Even off axis response is important in call cases. Good integration of drivers acting as a point source for good phase alignment is also important.

tinitus 31st January 2009 02:33 PM

Quote:

Originally posted by Tenson


I think soundstage and imaging are partly exclusive of each other, although of course you can have some of both.



Soundstage and imaging goes very well hand in hand

Its a matter of crossover...and I admit, its tricky
:)


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