[Carl V]

Why do speakers for the most part image & soundstage behind the plane of the speaker baffle? 
 
Looking at polar response plots of speakers & drivers I find this puzzling.  I have an appreciation for room & system
setup----and how that effects the sonic panorama.  Not too mention the
basic recording techniques which artificially 'enhance the depth or spread.

cheers

carl

[Scotty]

Carl V,In part,speakers do what they do. You build four pairs of loudspeakers with different drivers
and identical frequency response at the listening position and the same power response into the room and all four pairs may have different depth reproduction capabilities. The one with the deepest soundstage may also not be the the one that is the most accurate either. The other half of the equation is that the speaker can only reproduce what you give it to work with. In my own system I will occasionally have images that appear between me and the loudspeaker in front of the plane defined by the speakers. The amount of depth that the system will reproduce is determined by the source material and some recordings
don't have a lot of depth. Also if every recording you playback has a whole lot of depth there may be cause to wonder if you have a dip in the response curve in the  midrange.
It should also be noted that lower fidelity systems will tend to image only within the plane of the speakers and sometimes they will sound like musical wallpaper.
Scotty

[Steve]

One of the things I look for is the front to back ratio. I found one recording that is useful is the Stereophile CD3, track 10. It is a soundstage recording and can give a sense of how one's system is performing in terms of front to back and side to side.

[jon_010101]

Maybe my system/room has phase problems, but much of my "image" is consistently in front of the speakers    Drum kits and such tend to be a few feet behind, but the rest of the junk is usually a couple feet in front. 

[rabpaul]

Hi,

Its not just the speakers but also the source, amplication that influence imaging. The room also plays a part. If there is a lot of space behind the speakers you will notice imaging tends to be in that space. Its only not quite right if you consistently have imaging behind, on the same plane or in front of your speakers for all types of music.

I was made to understand the classical recordings are supposed to give the impression you are in a concert hall and these almost always have little or no stereo manipulation done to them. You will find most of the music is always behind the speakers. All recordings (including classical ones) you will have depth and you will be able to detect that something e.g voice or instrument is behind or in front of something else.

There is also a difference in perception with eyes open and closed when listening to music. Since stereo effects are created in your brain (Haas effect), IMHO you will have the best imaging with eyes closed and when your eyes don't overule your ears.

You are there as opposed to they are here is to describe a concert hall as opposed to say a jazz club. The first has imaging far from you (behind the speakers) while the second has imaging in front of you.

Rgds

[G Georgopoulos]

Room acoustics together with volume and speaker position can have
a big impact on the soundstage imaging, always experiment a bit with
speaker positioning and sound propagation axis for the best results

cheers

[andyr]

The amount of depth that the system will reproduce is determined by the source material and some recordings
don't have a lot of depth.

Scotty

Hi Scotty,

While I certainly agree with the thrust of your proposition, your comment that "the amount of depth that the system will reproduce is determined by the source material" is not true!!   

IMO, the same source material through different amps will certainly produce different soundstage depth! 

I had a very interesting exposition of this when I listened to some 'normal' ss amps through some speakers, and then with some SETs powering the same speakers (with the same source and preamp).

With the SETs, the singer was so much more "into the room" it was just amaaaazing!   

Regards,

Andy

[95bcwh]

With the SETs, the singer was so much more "into the room" it was just amaaaazing!   

Regards,

Andy

"Into the room" - do you mean "right on your face?"

Actually, if you understand that not all speaker/amp/preamp produce the same frequency response in your room then you wouldn't be surprised by the fact that they produce different depth. But Scott was right that it all started with the source material, the recording must be done such that each instrument can be heard in different distinct location.

With my Tact preamp, I can change the target curves such that the singer can be singing right into my nose, or she can be 5 ft behind the speaker (into the wall). You don't really need SET amp if what you're after is soundstage depth... SET amp is supposed to give you something else.

[miklorsmith]

What else is a SET supposed to give?

I find my 45 SET amp is defined by its presentation of space.  In fact, this is where it most distinguishes itself over everything else I've heard.

[PEB]

There is a lot that can be said about this.
First, there is one premise that speakers can emulate the action of a microphone, only in reverse.  If the sound being recorded is distant from the microphone, then so will be the sound coming from the speaker.  You are simply hearing the original depth of sound stage.  The best way to check how much spacial depth is in the recording itself is to listen to the track on a good set of headphones.

However, like other sonic aspects, depth of sound stage is a fragile thing, IMO.  It is difficult to preserve it to its fullest.  Speaker design, location and room acoustics all gang up to continually reduce the depth of sound stage.  When it’s very good, you should be able to hear sounds being created from both close by and distant.  So it should also be possible that the speakers can project sound that appears to come from the plane of the baffle. 

Speakers with poor phase response, veiled components, and sometimes steep filter alignments exhibit a shallow depth of sound stage.  By going to the trouble of setting up your system outdoors, you can evaluate how well the speaker itself reproduces depth.  Make sure the source is mono, and you play just a single speaker.

Overly tilted voicing can lead to the subjective impression of an overall forward or distant stage, akin the a closer or farther seat in the audience. 

The Master Handbook of Acoustics is a good source to read up on phantom sources, which explain how the early reflections affect the perceived sound stage depth (front wall reflections), width (side wall reflections), and distance.

[prokennex]

I also find that most of the music I listen to comes from behind the speaker plane. The room is 13.5 feet in width and 26 feet long. I have martinlogan sl3s pulled a third into the room approximately 8 feet. with 32 inches to the sidewalls. Although I do get images that extend outside the edges and in front of the speaker plane on the outer edges, I don't get  center images extending in front of  the speaker plane.

The front wall is treated with eight nerve adapt 2, but no first reflection treatments. Regardless of the electronics I still have this effect.

Could someone list more recordings with some having images which should be placed more toward the rear of the speakers and some recordings with images place infront of the speaker plane.

Tks
Ray

[jon_010101]

"Into the room" - do you mean "right on your face?"

I've had the "right on your face" effect a few times when using a Foreplay preamp with wayyy too much gain for my power amps.  Everything I listened to, the music felt like it was trying to smack my nose.  Vocals were within a foot of my face.  It just sounded effed up, but it was fun for a few tracks.  Clearly a case of fun/extreme distortion, although I have no idea what kind of distortion that might have been 

[aerius]

Could someone list more recordings with some having images which should be placed more toward the rear of the speakers and some recordings with images place infront of the speaker plane.

Tks
Ray

Sarah Harmer - I'm a Mountain  "Salamandre" will put a mandolin in front of the speaker plane while the other songs will put various instruments in front and behind, but mostly behind.

[kirch]

Could someone list more recordings with some having images which should be placed more toward the rear of the speakers and some recordings with images place infront of the speaker plane.

Ray - not sure what kind of music you like, but for just plain ole' soundstaging front to rear, over your head, behind you, left to right, you name it, is Roger Waters "Amused to Death".  For me, it's good music and especially fun to listen to!

[prokennex]

Tks I'll give those suggestions a listen once I pick them up. I like a little of everything. Eva Cassidy, Lyle Lovett (Joshua Judges Ruth), Diana Krall, Eagles, some of Mahler symphonies etc..  but no Brittany Spears.

Ray

[andyr]

Ray - not sure what kind of music you like, but for just plain ole' soundstaging front to rear, over your head, behind you, left to right, you name it, is Roger Waters "Amused to Death".  For me, it's good music and especially fun to listen to!

Good choice, kirch!     One of my favourite LPs.

Have you read the great write-up about "AtD" which you can use to see how your system measures up? (Mine, for instance, doesn't seem to deliver the really low bass on the "Genie" track and I don't get all of the soundstaging effects.  )

If you don't know this article and want to read it, send me an email in a month's time and I'll be able to give you the URL.  The article is in the jacket of "AtD" and all my LPs are currently in storage ... but we move back into our house in a couple of weeks time and I will then unpack them all.  My email address is: redwood dot andrew at gmail dot com.

Regards,

Andy

[konut]

There is a lot that can be said about this.
First, there is one premise that speakers can emulate the action of a microphone, only in reverse.  If the sound being recorded is distant from the microphone, then so will be the sound coming from the speaker.  You are simply hearing the original depth of sound stage.  The best way to check how much spacial depth is in the recording itself is to listen to the track on a good set of headphones.

However, like other sonic aspects, depth of sound stage is a fragile thing, IMO.  It is difficult to preserve it to its fullest.  Speaker design, location and room acoustics all gang up to continually reduce the depth of sound stage.  When it’s very good, you should be able to hear sounds being created from both close by and distant.  So it should also be possible that the speakers can project sound that appears to come from the plane of the baffle. 

Speakers with poor phase response, veiled components, and sometimes steep filter alignments exhibit a shallow depth of sound stage.  By going to the trouble of setting up your system outdoors, you can evaluate how well the speaker itself reproduces depth.  Make sure the source is mono, and you play just a single speaker.

Overly tilted voicing can lead to the subjective impression of an overall forward or distant stage, akin the a closer or farther seat in the audience. 

The Master Handbook of Acoustics is a good source to read up on phantom sources, which explain how the early reflections affect the perceived sound stage depth (front wall reflections), width (side wall reflections), and distance.

So much good info in this post. My primary intrest is in the first part refering to microphones.
"First, there is one premise that speakers can emulate the action of a microphone, only in reverse."
I'd like to try and generate a little discussion based on that premise. Firstly there are only a couple of mics that I'm aware of that are dual element ie. that use a cross over to generate electrical impulses separating the highs and lows. It would seem to me that the greatest chance of preserving spacial information(soundstaging) would be single driver designs. At the very least, a design which avoids cross overs in the frequencies where the ear is most sensative, in the midrange, and where a passive xover would have the least chance of mangling phase. A digital xover wouldn't have that problem, or so I've been led to believe.
 Secondly, since there are so many types and brands of microphones it would be impossible to have a speaker to emulate the sound, in reverse, for all recordings. For example, the complaint that a lot of vocals seem to be 'in your face' stem from the fact that a lot of vocalists favor mics that are directional, that don't pick up extranious sounds other than whats right in front of the mic element and, in addition, have a tailored frequency responce to complement the singers voice. These are designed to sound best when the lips are millimeters away from the front of the mic. Contrast that with omnidirectional mics that are used to pick up sound from all angles and are used at a distance from the sound sources. If one designed a speaker that emulated an omnidirectional mic, then those recordings that were made with close in directional mics wouldn't sound right. The obvious objection would be that those recordings using this technique are multi-track conglomerations with no inherant 'sound stage' to begin with.   
The only other designer I'm aware of that uses mic reverse emulation accomodations is Albert Von Schweikert. And he uses a rear firing 'ambient' tweeter! Is this an effort to reverse recreate the high frequency pick-up of an omnidirectional mic?

[Carl V]

If one designed a speaker that emulated an omnidirectional mic, then those recordings that were made with close in directional mics wouldn't sound right. The obvious objection would be that those recordings using this technique are multi-track conglomerations with no inherant 'sound stage' to begin with.   
The only other designer I'm aware of that uses mic reverse emulation accomodations is Albert Von Schweikert. And he uses a rear firing 'ambient' tweeter! Is this an effort to reverse recreate the high frequency pick-up of an omnidirectional mic?

Yes, if memory serves it was his VR2 idea...and I believe he was emulating
the Omni-mic ideal.  Which gets me back to the original idea of my post.
Why do some speaker designs & XOs create this Soundstage differently.

Many years ago at the SF Sterophile show  NHT had a killer demonstration.
They had live music playing in one room & you could walk into the next room
& hear the live mic feed...on their NHT 3.3 big boy speakers.  They used
crossed Omnis.  The sound & soundstage were remarkable, not live...but
a helluva lot beter than our usual recordings.   Later in the day you could listen to the raw tapes played back.  20/20 hindsight & auditory memory is not infallable....but it wasn't as good as the Live fed.
At this same Show, VR2 technology was been shown & Albert was demoing
his speakers with reference recordings & Omni mic's.  Dunlavey was sharing his own Tapes of his own reference music tapes.  And of course his idea
of  'the best way for sound reproduction"...he was also showing how his
speakers would reproduce a square wave ( & it ain't a pretty sound).

I'm aware of the Q sound techniques utilized for Amused to Death.
in fact there are quite a few pop recordings which have used this
technology or technique.  It can be quite startling.  And you don't
even need to use the out-of-phase gimmicks or novelty of AtD or
Madonna's en Vouge.  It works well for staright forward stuff.

Ambiosonics has used thier mic'ing techniques to great effect as well.
Soundtage has both Height & width....in front of the Baffle plane.
Mobile Fedility also had some compelling recordings geeky sound effects
as well as music recordings.  The playback of these recordings weren't
well served by all speakers.  I heard them on 4 AE-1's & then on 4
Theil speakers.  It was different...not night & day... but it was evident.

Cello used to have a heluva demo using their 'Pallette" pre-amp EQ.
They could rebalance a recording to better 'simulate the source' by
compensating for the less than perfect room or playback chain.  Of
course who 'truly knew' what was on the source material.  Mr Levinson
claimed to know because he used many of his own recordings as his
yardstick.  Or so he said.  And theirin lies the polemic.  What happens
when the source materail is the DG mutil mic...the Decca Tree...
the old spaced Omni...the crossed Omni...MS... or the new fangled
Iso-mic (which is amaizingly life like at times).

Harbeth once had a clever demo of their model 40 (?) where the XO
was manipulated in the presence region.  The soundstage was moved
forward & slightly narrowed.

I will obvioulsy go back to the handbook of Aoucstic and re-read Alton's
descriptions of Phantom images.  It's one of aspects of Muilt-channel
playback wher a hard center is used the Soundsage is more fragile.  It
isn't always well served IMHO.  I've listened to numerous 3-channel
source Mercury's et al., only now with our Multi-channel Dolby chips can
we hear the original 3-Ch. Tapes & 35mm recordings.  Some fo them
are revelatory. Some are ping~ponkish.  I've even heard them on a three
channel LCR dipolar set-up.

Thanks for all the ideas & thougths.

If any one has some time to kill...haul your speaker(s) out to your backyard
set them up on the lawn listen to them.  Entertaining & enlightening.

cheers