Imaging ?

[lbjazz]

I have been wondering lately about how a speaker creates an "image." I have listened to many speakers and noticed the differences in their imaging. Some have large soundfields, others' only extend to the edges of the speakers, some only seem to image in the midrange while the highs seem very directional, etc. etc. What acoustical process causes a speaker to image? What characteristics of a room, placement, speaker design, materials, etc. are neccessary? Also, how does an engineer "place" the insturments and vocals in the mix to define the image in the first place?

Thanks.

 

[ChrisJam]

Renewing an old thread

Hi,

In my quest to learn more about my new hobby, I'm slowly working my way through old threads. There are some good questions in this one--at least to my newbie eye.

I know now that my speakers don't have a great soundfield, but that might be because they're placed in less than ideal spots, which can't be changed right now.

But I've noticed that some speaker pairs have better imaging than others, so what causes one pair to outperform another?

Chris

 

[j_garcia]

The overall design of the speaker - in other words, the person/people who designed it, is/are going to play probably the largest role in how a given speaker images. The drivers chosen and their respective quality, the crossover design, the cabinet design and the relationship of the drivers within the cabinet, all factor into how well a particular speaker will image.

 

[silversurfer]

Placement and room acoustics also have a lot to do with imaging.

Having a big screen TV between the speakers is one of the worst things for imaging.

 

[Jack Hammer]

Placement and room acoustics also have a lot to do with imaging.

Having a big screen TV between the speakers is one of the worst things for imaging.

Having just added room treatment, I can tell you that for me it really made a huge difference. I had read that adding acoustic panels was one of the biggest bang for buck improvements to a system, but hadn't really appreciated it until I added some acoustic panels to my room. They really opened up the sound for me.

Jack

 

[JoeE SP9]

Room treatment and proper placement of speakers will enhance whatever imaging the speakers are capable of giving. Almost any speaker will give reasonably decent imaging when placed properly. A room that has been treated will give even better imaging with those same speakers and positions.

 

[j_garcia]

It didn't sound like he was aksing what makes better imaging, it sounded like what is it IN A SPEAKER that makes it have better imaging vs another speakers. Of course setup is also critical, but if the speakers themselves don't image, then even the best placement isn't going to make them better than they are.

 

[ChrisJam]

It didn't sound like he was aksing what makes better imaging, it sounded like what is it IN A SPEAKER that makes it have better imaging vs another speakers. Of course setup is also critical, but if the speakers themselves don't image, then even the best placement isn't going to make them better than they are.

You're right, I was asking about the technical things in a speaker design that make one pair image better than another.

And to update where I am, I learned about a month ago that tweeter placement--how far front or back it is in relation to the woofer cone(s)--can make a big difference in sound. B&W, for example, puts its tweeters an inch or so back, and on top of the cabinet in its better lines. Other companies, Amphion for example, will hollow out the front of the speaker cabinet and have a recessed tweeter in there, so it's in line with the woofer. These are the kinds of things I'd like to learn about.

I've read that some speakers image better than others and some have bigger soundstages. Why?

As for speaker placement and room treatment, that's good to learn, too, though that won't affect me now. We don't have a bright room--drapes on all the windows, wall-to-wall carpet, bookshelves with books, and a big Middle Eastern carpet hanging behind the couch that spans the couch and runs almost from the top of the couch to the ceiling. Our mains point to the wall with two medium-sized draped windows and the wall behind the couch with the heavy wool wall hanging. While I recognize that our speakers aren't placed in the optimal positions--they're too high and placed on their sides--we just have to live with that for a while.

But as I audition speakers over the next couple years, I'd like to know what to look for in speaker design--or company policy--that makes a speaker have much better than average imaging.

On a related note, I've heard that some speaker companies produce speakers with better dispersion than others. Paradigm is supposed to be one of these. What causes this difference? And does dispersion have anything to do with large imaging?

Chris

 

[JoeE SP9]

The set back tweeters are supposed to time align the tweeter with the woofer and midrange. The idea being that if the signal reaches each voice coil at the same time they should be physically aligned so there is no difference (time wise) when the signal gets to your ear. Theil speakers are constructed this way and have a reputation for great imaging. My ESL's produce sound from one diaphragm and in the sweet spot produce very good imaging. Of course my ESL's have relatively poor dispersion. It would seem that wide dispersion and imaging are not necessarily related. In my experience true omni directional speakers (very wide dispersion) tend not to have great imaging. They do have other points in their benefit such as large open soundstaging.
The only way to get what you want is to listen to as many speakers as possible. I realize this goes against common practice nowadays. Many people buy speakers over the web without hearing them. This is a practice I don't understand. Reading a review and listening to another's opinion is useless. You have to please your own ears. If you buy speakers without hearing them first you don't know what you're going to get. What sounds good to me may not to you.

 

[Rob Babcock]

I agree that room treatment improves imaging a lot, and every other area of sound, too. While I can appreciate imaging it's not all that high on my list of audio "fetishes."

 

[svaudio]

Like Joe says there's a difference between imaging and soundstage.

Mirage induces dispersion with the omniguide on top of the mid and tweeter to extend the soundstage.

I can't say that I have noticed any issues with the Mirage's imaging but that is knock on the omni directional speakers. Also my placement probably isn't the best but they do seem to project well for small speakers.

 

[j_garcia]

Listening to a set of speakers is the only way to tell what kind of imaging and soundstage they have, and what you ultimatley like the best may not have the best imaging. There isn't a definitive way to look at a speaker or a manufacturer and get an idea of how good or poor the imaging will be.

 

[Rob Babcock]

Fwiw some of the best imaging speakers I've ever heard were Onix Reference 1's. There's something about a small 2-way with relatively narrow baffles. Those little guys imaged spectacularly, and were absolutely beautiful to look at. Overall I didn't think I could live with the sound long term, as they sounded a bit bright in my system (a bedroom system with plaster walls & no room treatments, so take that with a grain of salt).

 

[ChrisJam]

It would seem that wide dispersion and imaging are not necessarily related. In my experience true omni directional speakers (very wide dispersion) tend not to have great imaging.

That's interesting! Gives me more stuff to research, thanks.

Reading a review and listening to another's opinion is useless. You have to please your own ears.

True, but if knowledgeable people can give me a heads-up or two, it helps me learn what to look for. For example, I know many people like the B&W 705. When I auditioned it recently (I'll post something about this in the speaker forum soon), I didn't like it, even though I recognize it's well-engineered.


Follow-up question, please. You said

My ESL's produce sound from one diaphragm and in the sweet spot produce very good imaging.

When I buy a new set of speakers in a couple years--this is after we get a different house--I wouldn't want mains that produce good tone/imaging just to a small sweet spot. If we have guests sitting on the couch and surrounding chairs, I'd like them to hear the speakers' imaging, too. Yes, I know that some of this will depend on how far the speakers are from the sitting area, and other variables. But basically, I'd like mains that have good imaging, and not just to a small sweet-spot. Is this too much to ask for?

If not, what do I look for? How can I test this in a showroom, especially a small showroom?

Chris

 

[ChrisJam]

Fwiw some of the best imaging speakers I've ever heard were Onix Reference 1's. There's something about a small 2-way with relatively narrow baffles. Those little guys imaged spectacularly, and were absolutely beautiful to look at. Overall I didn't think I could live with the sound long term, as they sounded a bit bright in my system (a bedroom system with plaster walls & no room treatments, so take that with a grain of salt).

Thanks, Rob, I appreciate the info. Onixes are on my list of speakers I'd like to audition. I appreciate your brightness comment. It's something I'd watch for.

Chris

 

[mtrycrafts]

I have been wondering lately about how a speaker creates an "image." I have listened to many speakers and noticed the differences in their imaging. Some have large soundfields, others' only extend to the edges of the speakers, some only seem to image in the midrange while the highs seem very directional, etc. etc. What acoustical process causes a speaker to image? What characteristics of a room, placement, speaker design, materials, etc. are neccessary? Also, how does an engineer "place" the insturments and vocals in the mix to define the image in the first place?

Thanks.

Why not start here towards your quest.

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Or, you may want to call a speaker company known to be consumer friendly

http://www.axiomaudio.com/tips_biwiring_and_biamping.html

While the link is to another issue, use the links there to inquire and don't hesitate to send them an email with your question as it is very specific technically.

 

[svaudio]

Then Chris depending on your budget you might want to look at something like the high end of the Mirage line. Sounds like you are looking for that bigger soundstage that an omnidirectional speaker can give you.

http://www.miragespeakers.com/v2/product_page.php?open=lines&subid=666&id=667

Here's a quote from the audioholics review of the Omnisat FS, which is Mirage's cheaper line and the speaker pictured in my previous post.

"I’ve often found that if you weren’t sitting in the sweet spot (particularly true where it comes to systems sporting 1st order crossover networks) the sound quality suffered. With the v2s - and their ability to fill the listening space with a huge soundstage - there wasn’t a bad seat in the house, so to speak.

The seating area within this particular listening room can accommodate comfortably 10 to 15 people. With the v2s in place, watching movies had become a social experience. Gone was the situation where of the 10 – 15 listeners there were only one or two lucky enough to be sitting in the sweet spot enjoying the movie’s soundtrack to its maximum advantage."

 

[ChrisJam]

Woohoo--great link!

Why not start here towards your quest.

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Hi, mtrycrafts,

Nice to see you again in one of my threads. I give you big thanks for this great link.

Though you were answering the originator of the thread--a thread long-dead till I resurrected it--I love your link. I love experimental physics and theoretical physics and cosmology, and I know they often overlap. I'm fortunate to have many friends who are physicists (one of the benefits of living near a major university and having a gf who's a scientist). These friends have or have had local ties--some are European and have moved back to to Europe, though some of these still come back to run experiments from time to time. Most are experimental physicists, one is an astronomer whose specialty is dark matter (this overlaps with other physics specialties, of course), and one is a theoretical physicist. I've read many physics and cosmology books, and my friends are fonts of knowledge when I have questions. I've often said that if I could live my life over, I might go into one of these fields.

While I realize you were being tongue-in-cheek, I thank you for showing me a great web site.

Chris

 

[ChrisJam]

Then Chris depending on your budget you might want to look at something like the high end of the Mirage line. Sounds like you are looking for that bigger soundstage that an omnidirectional speaker can give you.

Thanks, svaudio. I have a folder on my hard drive of the Mirage line. I'd love to hear them. If my main speakers died tomorrow, I'd have to replace them with a pair under $1000. I might go with some PhaseTech PC-1.1 IIs that I heard locally a month ago, because space is limited, and the speakers would have to live on a shelf. But a couple years from now I'd have a higher budget and probably a differnt room, so my options then would be more open.

Chris

 

[JoeE SP9]

When I buy a new set of speakers in a couple years--this is after we get a different house--I wouldn't want mains that produce good tone/imaging just to a small sweet spot. If we have guests sitting on the couch and surrounding chairs, I'd like them to hear the speakers' imaging, too. Yes, I know that some of this will depend on how far the speakers are from the sitting area, and other variables. But basically, I'd like mains that have good imaging, and not just to a small sweet-spot. Is this too much to ask for?

If not, what do I look for? How can I test this in a showroom, especially a small showroom?

Chris

When I say the sweet spot for my ESL's is rather small that refers to critical listening. This type of listening is almost always for music only. The kind of imaging I'm referring to is the ability to hear real musicians playing in a large room that begins at the plane of my speakers and extends as much as 20-30 ft behind them with a lateral spread that is much wider than their positions. Within this "phantom" area I can close my eyes and place the musicians and vocalist in a precisely defined position both depth wise and laterally. This kind of imaging can only be recorded and played back when there is no multi tracking and studio "sweetening done. All multi tracked and overdubbed recordings are nothing more than multi mono recordings. It is very difficult if not impossible to get a sense of depth in a multi tracked studio recording. You can always get a sense of lateral positioning merely by using a pan pot to move a given track from left to right.
If you are at all curious about real imaging you need to listen to one of the few recordings done direct to 2 track with no overdubbing or sweetening. I recommend Jacintha -- Here's To Ben -- Groove Note GRV 1001-2. This CD demonstrates exactly what imaging can and should be. If your speakers image properly you will get a sense of musicians playing in a large room that extends 20ft or more behind your speakers and 10ft or more wider on each side. Within that area you will be able to place the musicians laterally and depth wise as they are playing. This is what imaging is. Once you have heard it you will never be fooled again.
When playing MC sources this kind of imaging is not necessary and nearly impossible to record. The small sweet spot of my ESL's is no detriment to full enjoyment of any MC source. Comments from friends neighbors and guests are usually of the "I never heard any AV system sound that good" type. These comments come from those sitting well off axis of my front speakers. BTW I use MC in phantom mode. I have found that speech seems well centered from anywhere in my room. I already have 4 full range ESL's/w 3 subs and would have difficulty placing another ESL in the center front.
I suppose what I'm suggesting is that with MC sources pin point imaging is not of primary importance or even possible. All that overdubbing and sweetening just makes them MC mono anyway.