Pin point imaging isn't for everyone

Hi Everyone,
Lots of very interesting reading going on here and in the related thread. I really want to thank everyone for listening, participating and letting me know your own personal experiences, especially when they aren't like mine!

Also to Tom for reminding me of my own advice!!

I've learned a lot, and it will take me a while to digest it all. :)

I still think Neo6 is pretty cool, as is a center channel in HT, but I also don't think they are make/break items for systems. I keep trying to convince myself to go back to HT and listening to my 2 channel I can't baby, I just can't.


Thanks again, and look forward to even more contributions from all of you.

Best,

Erik

Oh, you are most welcome:)

Mike

Go figure. They are absorption. These are the ones I use. Dirt cheap.
https://www.parts-express.com/sonic-barrier-fwp122-studio-acoustic-foam-wedge-panel-12-x-12-x-2-black-12-pack--260-547
Remember I have Acoustat 2+2s 8 feet tall and twenty inches wide. I put a single vertical row of seven tiles alternating the pattern. They are placed at the deflection point on the wall. The easiest way that I know of to find it is stand right up against the back of the speaker right in the middle. Have someone move a mirror back and forth horizontally across the wall slowly and have them stop when the reflection is centered on the listening position. Mark that point on the wall. That is the deflection point and your tile pattern should be centered there. Height and width are up to you and depends on your speaker's dispersion. 
I first tried double sided carpet tape to stick the tiles on the wall. The tape would not stick to the foam. Next I put a drop of viscous cyanoacrylate glue in each corner and right in the middle, sprayed the wall with accelerator and slapped the tile to the wall. Worked great! I had marked out the wall with pencil and a 4 foot level so I knew where each tile would go. If you ever want to take the tile down the residue will sand right off.

Mike

Mijostyn wrote:

"Sure Duke but I think there is one caveat. You don’t want reflected energy off the front wall coming right back at you."

You are absolutely correct!!

"I wish I could draw a picture here but essentially you want the reflection to take the long way around the room. "
YESSS!!!

"So with a properly toed in dipole the rear sound would head towards the front wall angled towards the side wall. Then it would bounce off the side wall and head towards the rear wall to your side around you."

That’s what I do, whether it be a dipole or one of my quasi-bipolar horns. With my current generation of quasi-bipolar horns, the "backwave" energy is angled up towards the ceiling, further increasing the reflection path length, and allowing good results even when the speakers are quite close to the front and/or side wall.

"This gives you that late reflection from around the room that makes you think the room is bigger."

Right on!! The reflections need to come from all around, not just from the same general direction as the main speakers (which is actually the worst possible direction). And once you have the long time delays from these long path lengths plus the reflections coming from all around, the ear/brain system is really good at picking out the "hall ambience" reflections on the recording.

(Some people mistakenly think this is just a room effect, but it cannot be because how can a modest home listening room sound like it is the size of a concert hall? It must be that the concert hall ambience on the recording has been unmasked, rather than that the small room’s signature has been enhanced.)

"If sound heads toward the center of the front wall and bounces back right at you it really confuses the image just like a blurry photograph. It also diminishes the sensation of a 3rd dimension. I place acoustic tile on the front wall to prevent this reflection towards the center. It only works for frequencies above 250 Hz but that is enough to do the job."

Now you are teaching me something I had not thought of! What you describe makes sense, and I will give it a try next chance I get. THANK YOU!!

Are your acoustic tiles absorption or diffusion?

Duke
learned something new today - THANK YOU Mijostyn!

Sure Duke but I think there is one caveat. You don't want reflected energy off the front wall coming right back at you. I wish I could draw a picture here but essentially you want the reflection to take the long way around the room. So with a properly toed in dipole the rear sound would head towards the front wall angled towards the side wall. Then it would bounce off the side wall and head towards the rear wall to your side around you. This gives you that late reflection from around the room that makes you think the room is bigger. If sound heads toward the center of the front wall and bounces back right at you it really confuses the image just like a blurry photograph. It also diminishes the sensation of a 3rd dimension. I place acoustic tile on the front wall to prevent this reflection towards the center. It only works for frequencies above 250 Hz but that is enough to do the job. This is the only place I use room treatment. 

@david_ten wrote: " Duke, thank you so much for your detailed posts. Very helpful!"

Thank you David, my nerdy tangents aren’t always welcome, very glad to hear you found these helpful!

@mijostyn wrote: "This is a major reason line source dipoles sound the way they do. They minimize reflected energy in a way no other type of speaker can match."

Imo line source dipoles have many things in their favor, and minimizing early reflections is certainly one of them. Imo their backwave energy is also uniquely beneficial.

First off, the backwave of a dipole is spectrally correct, which is a really good start. Then assuming the speakers are fairly far out into the room, the backwave can actually REDUCE the small-room signature I alluded to earlier! Let me explain:

The ear/brain system judges the size of a room by the time delay between the first-arrival sound and the "center of gravity" of the reflections. When we have a significant path-length-induced time delay on the arrival of the backwave energy, the ear/brain system interprets that as "we’re in a pretty big room". So less "small room signature" is super-imposed on the soundstage in the recording! Imo this is an example of "reflections done right".

(The highly counter-intuitive implication here is that MORE reflections [in this case the backwave energy], done "right", actually result in hearing LESS of the room you are in and MORE of the soundscape on the recording!)

Mijostyn again: "Horns can be made to do almost the same thing by controlling their directivity."

Yes! Horns can definitely reduce the amount of energy in the early reflections AND generate a spectrally-correct reverberant field, through uniform pattern control. (Imo gotta use the right kind of horn the right way to avoid audible colorations.)

I really like the liveliness of good horns but probably like the timbral richness and sense of immersion in the recording’s soundscape from a good dipole speaker even more. So my best horn systems have a rear-firing array dedicated to generating a spectrally-correct, relatively late-onset approximation of the backwave of a dipole speaker. There are still things that a good line-source dipole does better, but imo the additional "backwave" energy tightens the race in some areas.

Duke

You bet Duke. This is a major reason line source dipoles sound the way they do. They minimize reflected energy in a way no other type of speaker can match. Horns can be made to do almost the same thing by controlling their directivity. It seems harder to do with standard dynamic drivers. Their directivity changes continuously with frequency getting narrower as the frequency increases. Dispersion is not uniform and I would think this would cause problems.

@audiokinesis   Duke, thank you so much for your detailed posts. Very helpful!

Instruments are always louder at the sides than in the center.

@erik_squires I’ve listened with attention regarding what you posted... for over two days now AND:

I am not hearing any of this across a wide range of randomly chosen as well as Roon Radio queued up tracks.

No issues whatsoever.

Two albums stood out in this evaluation. Calle 13’s ~reggaeton~ "Residente o Visitante" and the OST from "Slumdog Millionaire"

I mention the above two albums because each contains copious amounts of musical information on the Left, Right and Center with strong volume levels across.

All of my listening was 2Ch PCM Native.

"I’m a little curious about when they were aware of it though."

My recollection is that the other listeners didn’t confirm that they were aware of the sounds off to the sides being not as loud as they were used to. So I don’t think it was obvious. Must admit I did not notice it, but the guy who did is extremely observant and I would trust his ears more than my own.

"Having had a HT system with and without a center, the benefit of the center was much better than I had expected."

I’ve gotten mixed feedback on center channels.

I have several customers who started out with center channel speakers in their home theater systems, then they bought a pair of my controlled-pattern, strongly-toed-in speakers, and felt the sound quality (using phantom center mode) was better than when using the center channel, so they sold their center channel speakers. I presume this was because the center channel speaker did not sound as good as - and/or did not blend well with - the main speakers, and also because in this case the phantom center image remained fairly well centered even for off-centerline listeners. (These were not cheap center channel speakers being unseated - they cost more than one of my main speakers).

So IF the center channel speaker sounds as good as the left and right speakers, or close enough, it is probably a qualitative improvement. (As an aside, I have yet to hear a conventional sideways MTM speaker that I really enjoyed listening to.) But if the left and right speakers sound better and produce a solid center image from all the seats in the audience area, then adding a center channel speaker may not be a net improvement, with this exception:

IF there are listeners with a hearing imbalance (one ear hears better than the other), THEN a dedicated center channel speaker is needed to anchor the dialogue onscreen.

Over in the audio-only realm, one of my colleagues was using an extremely high quality trinaural processor to derive a center channel signal, and his center channel speaker was identical to his left and right speakers. He has since gone back to conventional stereo using speakers that pay a lot of attention to room interaction, in part because he finds the soundstage depth and sense of detachment from the speakers better with the stereo configuration, in this case at least.

So I think I appreciate the arguments for using a center channel and they are very compelling, but ime two-channel can, under some conditions, compete, with this caveat: Two channels cannot provide a reliable, solid center image for listeners with a significant hearing imbalance.

I have toyed with the idea of doing a somewhat unorthodox high-end center-channel speaker.  Probably not a good idea... unorthodox is a hard enough sell in the two-channel world. 

Duke

I'm also thinking of early sympohonic recordings which used the 3 microphone approach, which were down mixed to 2 channel stereo.

Duke,

I'm a little curious about when they were aware of it though.

Having had a HT system with and without a center, the benefit of the center was much better than I had expected. I wonder if that's because the HT system at the time didn't do more than a simple split of the center signal?

Best,
E

Erik, that primary 2 kHz comb-filter crosstalk notch is something recording engineers have to be aware of. When listening nearfield to mixing monitors in a fairly dead room, the notch is not significantly filled in by the reverberant field, so the engineers need to take it into account. Fortunately it is NOT some great mystery, the professionals all know about it, and in fact often use it to precisely locate the exact center of the sweet spot!!  

Duke

Duke:
That's very interesting! :) I'll have to cogitate on this for a bit. :)


Thanks so much for the detailed background information.

Best,
Erik

@erik_squires posted an interesting observation:

"Even with very good imaging I notice the following: Instruments are always louder at the sides than in the center."

Several weeks ago I had the privilege of setting up a set of my speakers in a world-class dedicated home audio room. My speakers were not replacing the excellent speakers already in the system, but the owner was kind enough let me set up my speakers in his system for my own education.

I solicited criticism from those present, because I learn more from my critics than from my fans. One listener noticed that instruments were not as loud at the sides as what he was used to hearing! In other words, he was hearing the exact opposite of what you describe, when using my speakers.

I think the difference was this: My speakers were fairly directional and toed in aggressively, so they were generating a very weak reflection off the nearby side walls. The room owner’s speakers had a much wider radiation pattern and were only toed in a little bit, so they were generating strong sidewall reflections.

I’m not saying this is the whole story on why "instruments always sound louder at the sides than in the center", but it may be part of it.

(I am well aware of the inevitable comb filtering in the phantom center image, which is one of the reasons why I do my final crossover tweaking listening to a mono signal over a single speaker.  Comb filtering of the center vocalist could sucker me into making the 2 kHz region too loud.)

Duke

@david_ten poses a very interesting question:

"Do differentials in volume guide perception of distance (of the performer) relative to the listening position?."

Volume plays a role, but it is my understanding is that reflections play the primary role in the perception of distance. Two of my kids are amateur musicians and on their recordings they often manipulate the perceived distance of a voice or instrument by adding the appropriate reverberation. When done right, timbre is enhanced as well.

So we have the reflections on the recording, and then we have the reflections of the recording within the listening room.

Unfortunately the speaker/room interaction usually results in "small room signature" cues which tend to be dominant, and which overlay or degrade the soundstage depth that was on the recording.

If the setup does not superimpose a strong "small room signature" atop the the recording we are more likely to hear its inherent soundstage well, including distance of the performers (depth).

At the risk of over-generalizing, early reflections are the ones most responsible for a "small room signature" which (among other things) degrades soundstage depth. And it seems that the ear is able to extract beneficial depth and ambience information present on the recording from relatively late reflections, so apparently late reflections do not convey a dominant "small room signature".

Managing the room reflections well (a complex topic, and something easier said than done) can allow you to readily hear the different soundscapes from one recording to the next, giving you a good excuse to rediscover your music collection, and giving you new appreciation for really good recordings.

Imo, ime, ymmv, etc.

Duke

Here's an interesting write-up, pay attention in particular to section 1.4

http://www.sfxmachine.com/docs/FixingThePhantomCenter.pdf

@ieales

I’m going to have to listen for a while, in most recordings they don’t actually move around.

Probably going to have to find some choral works. :)

There is by the way quite a body of work on HRTF and how the phantom center can’t compensate for it, which is related to what I’m discussing, and I think a lot of people will have trouble hearing it if they’ve spent decades listening to 2 channel stereo. You don’t notice it until it’s gone.

Kind of like recording a room of people talking. You listen with headphones on and suddenly the acoustics of the room become glaringly obvious.


But again, please put this along with geek curiosities. I'm not going to bang a drum that we must all do something differently. I'm an apartment dweller living happily with 2-channel for now. I learned all of this while having a HT set up and listening to the difference between a real center speaker and phantom, and listening to music with and without a center. It's curious and interesting, but not worth upending how we enjoy music.

Best,
E

@erik_squires 

Instruments are always louder at the sides than in the center

In the few [under 5] times I've listened to compressed music, I would agree there is a hole in the center. On well recorded material on my systems, never.

Most music, live or recorded is pretty static.

Can you give an example of uncompressed material where a horn on the side is quieter in the center?

@erik_squires   Erik, I'm glad you clarified you were referring to volume vs. a centre image as I thought you meant 'image.'

Off memory (and even as I'm listening right now) this isn't the case (re. volume falling off in the center) BUT I will pay attention to it!!!

Appreciate your response and take on the topic.

As I evaluate, I have an additional question for you and others:

Do differentials in volume guide perception of distance (of the performer) relative to the listening position? Thank you.

Hi David.

Listen for a while to your 2 channel. Even with very good imaging I notice the following:

Instruments are always louder at the sides than in the center.

A horn playing hard left will get softer when it is in the center. Neo6 seems to really help that, and I never heard anything negative using it.

However, lets be clear, I don’t have a HT processor right now, and I’m not going to sit and bang a drum for it. :D :D

I was just pointing out that even with the best systems, the center instruments seem lower in volume than the sides. Neo6 corrects this and you notice it when it’s gone.

I repeat: This isn't about imaging, it is about relative volume. We're so used to it we don't notice it.

Best,

E

it did a really good job of filling in the center, an area where traditional 2 channel playback is lacking, but we are so conditioned to hearing it we don't notice.

@erik_squires   Can you explain? This statement is a head-scratcher for me at the surface. Thanks. 

[Emphasis on "filling in the center, an area where traditional 2 channel playback is lacking"]

@erik_squires 

filling in the center, an area where traditional 2 channel playback is lacking

A friend once said "It's like Joe Pass is sitting right there." No system I've ever owned or used in the studio had a center hole.

If there is a hole in 2 channel play back, it's improperly set up or the speakers are deficient.

I don't recall the track, but I when I first heard Neo:6, I left the demo. IMO, it's unbearable on music I know and downright annoying on music I don't.

People say there is no pinpoint imaging in a big concert hall. But if you were standing at the conductor’s place, you would hear pinpoint imaging and soundstage depth. That’s where the microphones often are too, a bit behind the conductor, above his/her head.

Hi @ieasles,
I also worked in theater sound equipment.

I find your statement a little hard to read.

My experience with Neo6 and classical or Jazz was that it did a really good job of filling in the center, an area where traditional 2 channel playback is lacking, but we are so conditioned to hearing it we don't notice.

Best,
Erik

Neo6 music mode

now there’s an oxymoron if ever there was one. [I worked for dts]

Multichannel processor playback is only suitable for phase mangled mp3, AAC et al. when out of the room or otherwise disinterested as in background in a noisy party. Otherwise the image wander and egregious level and phase distortion forces me to ask that it be turned off or I must leave the room. I literally feel ill with continued exposure.

See http://ielogical.com/Lossy/

Speaking of 3 mike recordings, for those of you with a multi-channel setup, I strongly suggest you try the Neo6 music mode if you can. It’s really pretty good.

Yes the "Decca Tree" technique was a three mic boom (left centre right) over the orcheschra which captured those early Decca recording imaging properties when listen to with good speakers like Quad 57’s, but sadly the image got splashed all over the place, with things like Klipsch Horns ect.
And it’s still used today in live recordings, but with more mics in between the main three to get even better imaging.

Cheers George

This Stereophile article may interest some:    https://www.stereophile.com/content/stereo-image

Call it pinpoint, realistic sounding  imaging and soundstage or any other fancy name, the bottom line is that when we sit and listen to the music, we want it to sound as natural as possible. Rarely that is the case, due to the many limitations we have to deal with, from (1) the recording environment, (2) the recording engineer/equipment, (3) equipment used to reproduce and (4) the listening environment. Some (item 3-4) we can influence, others not. Forums like this are mainly established to address the items 3-4, as there are many ways to come closer to the desired end product, and certainly not always money related. For those who say it is not that important to them, they can save themselves some money, as you only need to buy one speaker ;)

There is a point when listening to music becomes "more"than simply an auditory experience.When you can see the event as well as hear it,suspension of disbelief becomes easy & we are transported into the event..For example a live Rush recording where 2 guys who whistle REALLY loud interact from what appears to be about 300’ apart.Or a bootleg recording of a Janis Joplin demo tape where a secretary madly types away about 25’ behind Janis as she belts out "I Need A Man".Or even an obscure recording of Mozart’s Gran Partita,from a small church in Germany with a U shape,multi level layout that has the Woodwinds & horns moving back & forth over a 3’ height difference with about 50’ between the sections.
If the truest representation of the recorded event,weather live or studio is the eventual goal of our hobby then sound staging & pinpoint imaging are critical to a complete "picture"of the musical event.

If your system can't let you see movement of artists, especialy with Reference Recordings like Douge McCloud where you can even see left and right head movements while he sings/talks, then you don't have a good imaging system and should not even coment on this subject.

So pinpointing recording hall ambience is desired over musician placement? It's kind of hard to localize a moving target. Approximate, maybe, but going for an accurate gestalt of a room or venue and replicate it in your own room?

I'll take musician placement for 500, Alex.

All the best,
Nonoise

Cleeds you have to be kidding me. Can somebody help me out here?
What you just said is my living room is symphony hall. But, then it is Skuller's (a jazz club) and next it is an open amphitheater. It morphs into anything that is on the record label. Wow am I impressed. How the hell did I design a living room like that. Must be a genius. 

mijostyn

The information that provides the ambient characteristic of the room/hall the recording was made in is in the recording not in the room you are playing it back in. All your Hi Fi room can do is add distortion ...

That might be true if you were referring to a binaural recording intended to be heard on headphones. Or it might be true for a recording intended to be heard in an anechoic chamber. But a conventional recording is intended to be played in some sort of acoustic environment, so your claim makes no sense. And that is all part of what makes our hi-fi hobby so tricky because, of course, those making the recording can't possibly know in what sort of environment it will ultimately be heard.

I also think Mr. Allison is a bit off base.

I have had several speakers with ’pinpoint’ (precise) imaging, without a strict sweet spot. I have a pretty broad listening area, with precise imaging.

When it comes to accuracy, in almost every way (timbre, dynamics, detail, attack and decay, etc), I am all on board.

But if pinpoint or precise imaging, is considered inaccurate, I have no problems with that sort of inaccuracy. I am not willing to give up accuracy in those other aspects, for more precise imaging, but that does not seem necessary with many speakers. 

After all, I’m sitting a smallish sound room, that is almost impossible to recreate an orchestra, or jazz quartet, rock band, etc, with completely accurate scale or power, so a little extra exaggerated imaging helps fill in the gaps for me. It servers to help suck me into the performance just a bit deeper.

I am afraid Mr Allison is OTL or as Eric Dolphy would say, "out to lunch."
The information that provides the ambient characteristic of the room/hall the recording was made in is in the recording not in the room you are playing it back in. All your Hi Fi room can do is add distortion. Most experts like Earl Geddes believe the best way to deal with this is to limit the dispersion of the speakers to limit room reflections instead of burying yourself in room treatments. Omni directional speakers are passe. 

The CD version, of the Chesky Jazz Sampler, Vol 1:  https://www.amazon.com/Chesky-Records-Sampler-Audiophile-Compact/dp/B000003GF3   

I prefer a system "editorialize" as little as possible. The recording contains the imaging (and the instrumental and vocal timbres, etc.); the hi-fi system's (including and especially the loudspeaker’s) job is to reproduce the recording as is, not to create imaging that isn’t contained in the recording. That’s anarchy!

The following provide tests, with which one may determine whether their system actually images, or reproduces a soundstage, as recorded. ie: On the Chesky sampler/test CD; David explains in detail, his position on the stage and distance from the mics, as he strikes a tambourine(Depth Test). The LEDR test tells what to expect, if your system performs well, before each segment. The Chesky CD contains a number of tests, in addition to the LEDR. (https://cheskyrecords.bandcamp.com/album/chesky-records-jazz-sampler-audiophile-test-vol-1 ) An online resource: (https://www.audiocheck.net/audiotests_ledr.php ) BTW; The shape of your ears’ pinnae is also a variable, regarding your ability to perceive images/locate sounds. An old article, from Stereophile, regarding the LEDR test: (https://www.stereophile.com/features/772/index.html ) That article also mentions some other possible impediments, to a system’s imaging abilities. Of course; all that’s only for those interested in finding out, if their systems(and/or ears/brains) are up to the task.

@bdp24, I agree that if you are interested in a system that is accurate to what was recorded then the system should reproduce the soundstage as the studio mix intended you to hear it even though it may not be accurate to how the performers were actually arranged. That is if you have the ability to place your speakers in your room ideally. If it is a live field recording then it is how the performers were mic'd and then mixed. In both instances the soundstage could run the full gamut from pin point to diffuse. The question is do you like pinpoint positioning of the performers when listening or do you like to be washed in sound? Purchase and place your components so that they enhance your sound stage preference. Either way you still can purchase equipment / speakers that reproduce sound accurately. Accurate sound and soundstage in my opinion are two different variables that one considers when setting up a system which also must take into account the room in which you will be listening, in particular speaker positioning in regards to the room's boundaries.

The 901’s had a great run and when you consider the selection at highland electronics superstore the Bose imaged as well as the big cerwin vega or the rest of the midfi stuff of the day.

How natural is pin point imaging in acoustic music?

Varies by program, venue, instrument and seat.

so there’s something to be said for speakers with rear facing drivers

All that can be said is "Don’t use them." Bose 901’s et al are an ’instrument’ in their own right as they are incapable of presenting, and only mess up, what’s on the recording. Unlistenable.

If the recording is mixed to precisely localize, the system must. If it can’t, then more nebulous recordings become a gigantic bucket of mush.

Especially for some producers.
 I hear it on the bandstand playing acoustic or electric. Keep in mind front of house sound and live recording are usually different. 

Good topic for a rainy day. Mapman made a simple point. Play low spark of high heeled boys then play any of the Pearl Jam bootlegs. The studio recording sounds so real it’s spooky and the ‘live’ recording sounds anything but. The whole point of stereo is imaging and I think the term pinpoint in this context means accurate or precise, not pin sized or pin like. Chuckle, never can tell how the net interprets. Ive had hi end speakers that image but not sound stage and I think thats where the bass comes in, just a thought.

Sweating size of intruments in a recording is a noble effort but practically a waste of time since what you hear is more about how things were recorded than how big the intrument is/was.  

Not that practicality ever stands in the way of a dedicated audiophile.   Carry on.......  

GK brings up an interesting point, but it's more complicated than that.  On many good piano recordings you can tell from what vantage point the piano has been recorded, the two most frequent perspectives being from the side (lid open to mikes), and from the front, looking at the pianist.  Notice in this second case in how many recordings treble register appears more to the left of the sound picture and bass to the right.  Is that pinpoint? Accurate? Close?  Too close?

Great Thread!
In my opinion, it really depends upon the overall impression the speaker makes.

B

Adding extended and articulate deep bass to my system did indeed improve the sense of envelopment. Not by extending the sound stage per se, but by increasing the feeling of being in the room. The main performance is still up front with every instrument palpably positioned, especially bass and drums which are now even more palpably real than before. But there is now an additional sensation of deep bass that just feels like you are in the room. Even though the meat of the performance is still up front, its more like you are in it now.