What speaker measurement references how good imaging will be?

[Swerd]

Well, that's the thing about time alignment- it works for a limited space and only for that space. There's not a great way to cover a large area AND have the sound from various drivers reach the ears at the correct time. Thiel speakers are/were time-aligned, too- they don't sound like most speakers but again, the listener can't expect to move around the room and hear the same sound at all locations.

It's been my non-scientific observation that it's the 1st order crossover that creates the image perception over such a narrow space, <1 SC.

At the crossover frequency, the drivers will be properly aligned with time & phase. But a 1st order crossover allows the drivers on either side of the crossover to produce sound over a wide range of at least 2 octaves above & below the crossover frequency. That allows plenty of opportunity for the drivers' sound to get out of phase or time. In contrast, 4th order crossovers only allow drivers to audibly operate within 1 octave of the crossover frequency.

That is enough to explain (in theory) how Vandersteens require audiophile head-vises. Time alignment may have nothing to do with good imaging. That question might be settled by listening to two identical speakers, in physically time-aligned cabinets, where one had a Vandersteen-style 1st order crossover, and the other had a 4th order L-R crossover. I'm certain I'm not going to do that. Where are all those eager DIY builders when they're most needed?

The part about carefully selecting drivers and other components- some companies don't seem to be as interested in sound quality when the bean counters pipe up with "That's good enough!".

I can't think of a better example than B&W. Their 800 series speakers make it clear that the speaker designers do actually know how to design & build good speakers. And all their other speaker series make it clear that the bean counters rule over the designers.

 

[highfigh]

It's been my non-scientific observation that it's the 1st order crossover that creates the image perception over such a narrow space, <1 SC.

At the crossover frequency, the drivers will be properly aligned with time & phase. But a 1st order crossover allows the drivers on either side of the crossover to produce sound over a wide range of at least 2 octaves above & below the crossover frequency. That allows plenty of opportunity for the drivers' sound to get out of phase or time. In contrast, 4th order crossovers only allow drivers to audibly operate within 1 octave of the crossover frequency.

That is enough to explain (in theory) how Vandersteens require audiophile head-vises. Time alignment may have nothing to do with good imaging. That question might be settled by listening to two identical speakers, in physically time-aligned cabinets, where one had a Vandersteen-style 1st order crossover, and the other had a 4th order L-R crossover. I'm certain I'm not going to do that. Where are all those eager DIY builders when they're most needed?
I can't think of a better example than B&W. Their 800 series speakers make it clear that the speaker designers do actually know how to design & build good speakers. And all their other speaker series make it clear that the bean counters rule over the designers.

The head vise sounds like something from Spinal Tap- "Don't move, don't even blink".

I don't know if you have listened to Dynaudio speakers, but they use low-order crossover slopes and they sound very good- the listener isn't pinned to a single location.

 

[TLS Guy]

It's been my non-scientific observation that it's the 1st order crossover that creates the image perception over such a narrow space, <1 SC.

At the crossover frequency, the drivers will be properly aligned with time & phase. But a 1st order crossover allows the drivers on either side of the crossover to produce sound over a wide range of at least 2 octaves above & below the crossover frequency. That allows plenty of opportunity for the drivers' sound to get out of phase or time. In contrast, 4th order crossovers only allow drivers to audibly operate within 1 octave of the crossover frequency.

That is enough to explain (in theory) how Vandersteens require audiophile head-vises. Time alignment may have nothing to do with good imaging. That question might be settled by listening to two identical speakers, in physically time-aligned cabinets, where one had a Vandersteen-style 1st order crossover, and the other had a 4th order L-R crossover. I'm certain I'm not going to do that. Where are all those eager DIY builders when they're most needed?
I can't think of a better example than B&W. Their 800 series speakers make it clear that the speaker designers do actually know how to design & build good speakers. And all their other speaker series make it clear that the bean counters rule over the designers.

I have been through that period. The trouble with first order time aligned crossovers, is that you end up with quite a few drivers to cover the spectrum. Also you need really small drivers close together. This minimizes the time shift with changes in position. In addition the axis is downwards, so the drivers have to be fairly high to properly align at the listening position. So the speaker has to be tall or upside down. I went through this phase, at the same time as Dynaudio. They chose the upside down approach with the tweeter on the floor. When I listened to them I could not escape feeling that the orchestra was playing through the floor. I was in contact with the good folks at Dynaudio at that time and we were shooting ideas.

Anyhow, I decided not to be quite so hair shirt, and the speakers, now my rear backs, were time aligned above 180 Hz. That is a third order active, crossover to maintain a 15 degree downward axis, the others are first order at 900, and 5000 Hz.

The KEF B 139 are in a TL and so is the 6" mid, but it is totally damped and not a speaking pipe.

This speakers where a nightmare to get right, but in the end they turned out to be really good speakers. But I did learn the lesson not to do it again.
I got to visit with the folks from Dynaudio and heard their contour, apart from the weird image it was a good speaker.

So these speakers are still giving good service, and have a really good accurate bass response. Just by dumb luck they are ideal for this application, as the three upper drivers are above the seat backs and the axis down to the listening position.

This is the FR.

There is a shallow null in the 900 Hz crossover region, but not too bad. Most first order crossovers look a lot worse than that. You can see the impulse response is excellent.

Anyhow I have not gone down this road again.

Even if you use DSP, you still do not change the driver spacing issue. That is why there really is a crying need for much wider bandwidth drivers. That is the real solution.

Ted Jordan knew that, and it was his life's work, and he moved it forward more than anyone else.

By the way you miss spoke in another post. Sealed enclosures roll off LF 12 db. per octave and not 6 db. Vented B4 boxes roll off 24 db. per octave and not 12 db. per octave. Passive radiator boxes roll off 36 db. per octave generally. Aperiodic TLs roll off 12 db. per octave as a rule, the mass loaded 24 db. per octave.

 

[dlaloum]

Hmm Imaging, is driven by the direct signal from the speakers - it can with the right decoding, be extended to three channels (L/C/R). In pure stereo mode, it can be very difficult to get pinpoint imaging away from a very limited sweet spot. - Using 3 channel stereo, the illusion of imaging can be expanded to a much larger listening area.

Soundstage, is more a matter of the reflected ambient sound of the room - it is to do with reflections, delayed sound that bounces off surfaces before hitting your ears - and works best when the delay is sufficient to ensure that your ears/mind do not confuse it with the primary Image / Imaging.

If the reflections arrive too early, they will smear the imaging, in which case you can still get a large, soundstage, but the palpable illusion of sounds in space will be lost.

The measurements that are most critical will relate to how the speakers activate YOUR ROOM - so it isn't one measurement, but a series of measurements, and how those interact with your room - a speaker that works well in my room, may not work well in yours.

Wide dispersion, bipole/dipole or omnidirectional speakers can sound fantastic in large rooms - where there is sufficient space for the speakers to be positioned so reflections are sufficiently delayed, not to smear the imaging... - they can get into trouble in smaller rooms, or when positioned next to reflective surfaces, where the resulting reflections arrive at almost the same time as the direct signal, and therefore smear the imaging! (Bipoles/Dipoles, can be positioned close to side walls, as they put almost nothing out to the sides...omni's need more "breathing room")
And of course, you can adjust the room to improve imaging - if you know a particular surface is too close to the speaker, you can put absorbing, or dispersing materials on that surface to treat the reflected sound - sometimes something as simple as a heavy curtain can do magic!

Frequency response, and such, alter the tonality of the speaker - but don't affect the imaging - although you do want the various frequencies to arrive at your ears at the same time... you don't want an instrument to sound as if the lower frequency part of it is in one place, and the high frequency part of it is in another!

Another thing to watch out for, is speaker resonances - parasitic sounds, emitted by the speaker that should not be there - the ones that really bug me, are those generated by "boxes" - can be an issue with larger floor standers, without sufficent bracing and damping, bookshelf speakers, due to their smaller size, are naturally less prone to this, and funky shapes are often used as a way to eliminate many of these issues.... hence spherical speakers tend not to suffer from these, and of course panel speakers, not having a "box" or "case" at all, completely eliminate that type of flaw.
Depending on the resonance, and its time/frequency relationship to the image, it may or may not affect imaging...
So I would watch for these, but they are not prime indicators... there are some speakers that have substantial resonances, yet still image very well.

 

[MrBoat]

Good afternoon, I'm still new to this. What could it be if the speakers are tapping intermittently? Like something moving around inside? Can it be fixed or do I need a replacement?

Could be any number of things from a blown or loose driver, or a detached crossover board or a child's toy that made it in through one of the ports. What kind of speakers? Do you push them to extremely loud levels? Chances are, if you can't readily identify the type of sound it is (many experienced people can tell what these different distortions are from) or aren't very mechanically inclined, you would have to bring it to someone who is.

 

[Eppie]

Good afternoon, I'm still new to this. What could it be if the speakers are tapping intermittently? Like something moving around inside? Can it be fixed or do I need a replacement?

Remove the grills and listen from a close distance to determine whether the sound is coming from one of the drivers or from inside the cabinet. You can remove the screws securing the woofer to look inside for any loose components (as MrBoat suggested). If you can find the source of the noise then members can suggest a possible remedy.