[skrivis]

However, I did get a laugh out of the "discussion" of time coherence on the Meadowlark site. I didn't learn anything.....except about "how the nature connects the stars to my soul." I feel like a beer.

In and amongst the mysticism, there was some good info. I just didn't like having to wade through the malarkey to get to the info...

[John Ashman]

Don't you mean Meadowlarky?  

[skrivis]

I am in no way able to comment technically on crossover design. I can only tell you that out of all of the speakers I've ever heard, only ones with 1st order crossovers, wired in phased, with sloped baffles, give the actual space, image density, and soundstaging that are essential parts of the puzzle for me. It just doesn't make much sense to me to have multiple drivers starting and stopping at different times, on purpose. I know that no speaker design is perfect, but time and phase coherent speakers just sound more real to me. Just my 2 cents.

I agree with this. Speakers like this also seem to do dynamics better.

[skrivis]

So, first order, time aligned, phase correct speakers have the following problems:

1. Increased cabinet costs
2. Extremely poor vertical dispersion
3. High cone woofer/midrange cone resonances
4. Increased driver distortion for midrange/tweeter
5. Limited dynamic range
6. Very limited sweetspot, vertically and horizontally
7. Increased crossover complexity and expense.
8. Limited choice of appropriate drivers for good performance

1 - Not always. A sloped baffle isn't that hard (you can just tilt the whole box back on stands if you want to do it that way) and an non-rectilinear cabinet (with slope built-in to the cabinet) may be less likely to have resonances.

2 - Simply reduces size of sweet spot

3 - I don't quite get this. If you're talking about cone breakup and such, good drivers would lessen this.

4 - I assume this, like 3, is related to the shallow slope allowing significant "out of band" output. Good drivers lessen this problem.

5 - Again, good drivers lessen this problem.

6 - Is this actually a problem? As long as the user is aware of it...

7 - I've seen 1st-order series x-overs that weren't complex at all. In fact, higher-order x-overs should be _more_ complex. I would have to assume that you feel that shallow-slope x-overs put more demands on the drivers, so you have to build a more complex x-over network to keep the drivers from getting into trouble.

8 - This gets back to using the proper drivers. If the drivers are good, many of these "drawbacks" go away. You can also do some control of the drivers with enclosure design to get around some limitations...

These types of system require a lot more work on the part of the designer, so they're not for everyone.

When done well, you get a very seamless presentation and can't tell that there's a woofer, mid, and tweeter. Dynamics are excellent because there's no smear.

Maximum SPL may be more limited than with higher-order x-overs, but the good dynamics at everything but max level seem to compensate for increased levels.

It's possible that 1st-order x-overs make a system more fragile than with higher-order x-overs. I don't feel that they're necessarily so fragile as to be unusable.

If I were selecting a system for use in a large room where I might be listening from a number of places, I'd probably choose higher-order x-overs, and I'd want higher max SPL. (This quickly leads you into PA speakers. LOL)

For a more intimate setting, or even a more restricted listening area within a large room, more delicate speakers seem to perform better.

I've had a pair of speakers with 1st-order series x-overs, sloped baffle, transmission line enclosures, etc. for the past 15-20 years and haven't been particularly gentle with them. I haven't seen any problems so far.

[skrivis]

That's definitely pushing my limits of understanding!  Everything, really, affects linearity if you think about it.  I suppose it depends too on where you define the signal in/out point.  If you say at the binding posts, then definitely everything matters.  That's why a digital speaker will be far more linear than a passive one even though they're not directly affecting the motor structure of the driver.  But for instance, I don't know if the box volume of a sealed speaker creates a more linear output at on ...

If the air in the enclosure provides a significant part of the driver's suspension, then you'd very definitely see non-linearities.

[John Ashman]

Skrivis, with my above commentaries, simply insert the phrase 'all other things being equal'  That pretty much addresses your commentary.

[skrivis]

I guess one of the things that has puzzled me over the years is that drivers are supposed to have this pistonic motion to them. Now when I think about a piston I think about what happens inside an internal combustion engine where the piston is moving in a very precise chamber in a very contolled fashion.  Now when I look inside a loudspeaker and look at the inside of the box I don't exactly get the impression I am looking inside a very precise chamber. Am I missing something here?
Maybe someone could explain that to me.
                       d.b.

With regards to loudspeakers, pistonic refers to the driver diaphragm (cone, dome, etc.) tracking closely the motion induced in it by the voice coil. Ideally, the entire area of the diaphragm would react instantly and evenly to an input by the voice coil or motor.

Grab a piece of cardboard at an edge and start waving it. It flexes and part of it will be going up while your hand goes up, part down, possibly even part sideways if it's floppy enough.

Now take a sheet of plywood and do the same thing. The plywood comes closer to pistonic motion.

However, the plywood probably has more mass, so it starts effecting the motor (your hand). You'd need a more powerful motor to compensate.

We want a diaphragm that's extremely stiff and extremely low mass. Real materials conform to this in various ways, with each having drawbacks. There have been a number of designs that use honeycomb materials to give good stiffness with low mass. (The actual materials used do still make a difference though, so nothing's perfect.)

[LordCloud]

I can't believe it makes sense to someone to have three people in a room trying to tell you the same story, at the same time, saying the exact same thing, but taking turns speaking. I know this isn't exactly what's going on in a speaker, but you can get what I'm getting at. No matter what any of you say, having multiple drivers trying to make music, a naturally coherent and in phase event, using out of phase drivers just doesn't make sense. I know there are many other factors in making a good speaker, but these are the basic building blocks in my opinion. No speaker is perfect, but if you start with a phase coherent speaker and make the best speaker you can from there, you're going to get a more believable sonic picture. And it all comes out in the listening. Other people may not think so, but that makes no difference to me, I've heard other people's systems.

[skrivis]

I can't believe it makes sense to someone to have three people in a room trying to tell you the same story, at the same time, saying the exact same thing, but taking turns speaking. I know this isn't exactly what's going on in a speaker, but you can get what I'm getting at. No matter what any of you say, having multiple drivers trying to make music, a naturally coherent and in phase event, using out of phase drivers just doesn't make sense. I know there are many other factors in making a good speaker, but t ...

Music isn't actually a coherent and in-phase event. But I know what you mean. You want to reproduce the entire spectrum observed by the microphone(s) with the proper relationships between phase, frequency, and loudness.

IMO, minimum-phase or time (phase) coherent design is a necessary but not sufficent criteria for a good loudspeaker.

[LordCloud]

I agree that time and phase coherence are not the only criteria for a good speaker.

[Shamrock Audio]

The Madisound board is also having a lengthy discussion about the matter. Ken Kantor responds to some well-educated observations here:

http://www.madisound.com/cgi-bin/discuss.cgi?read=340003

[LordCloud]

I see people speaking of measurements, but few people talking about what it actually sounds like. In my experience, phase correct speakers have always offered more depth, image dimensionality, and a better illusion of real instruments in a real space. It's far easier to lose myself in the music.

[Kevin P]

I see people speaking of measurements, but few people talking about what it actually sounds like. In my experience, phase correct speakers have always offered more depth, image dimensionality, and a better illusion of real instruments in a real space. It's far easier to lose myself in the music.

The reason measurements are nice to talk about is that they are repeatable and the same for everyone everywhere.   Subjective perception is a can of worms.

[John Ashman]

Unfortunately, it's hard to tell.  For instance, I don't think Vandersteens image/soundstage better, in fact, usually worse than a lot of speakers I've heard.  Thiels are pretty amazing generally, but they have low diffraction baffles.  They sound nothing like Vandersteens which are minimum baffle, but not really low diffraction.  I'd argue that Thiel's choice of small, wide dispersion midrange and low diffraction baffle has more to do with their imaging than anything.  I've also heard that having a little brighter upper midrange "presense" helps this.   Or you might just be hearing artifacts of the 1st order design.  If you want to do real experiments to prove this, get a DEQX processor and program the same speaker for a 2nd, 3rd or 4th order crossover and make one phase correct, the other not.  Switch back and forth in real time.  Do a blind test.  Otherwise, you're hearing totally different sounding speakers, but ascribing them the same quality.  For me, Meadowlarks, Thiels, Dunlaveys, Vandersteens all sound different, don't image a like, don't soundstage alike and I'm having a hard time believing that any person could hear these speakers and assume they have anything in common, let alone believe that the all are superior because of the time/phase design *unless* that's what you're predisposed to hear these things in said design.  Our mind is very adaptive.  Tell someone that they have been injected with a disease and they will start to feel sick.  Tell them that a speaker images better because of the design and it will probably image better.  It's the way we are.

[LordCloud]

To see someone say on a forum about LISTENING to music that listening to music is a can of worms tells me all I need to know. You may not have realized this, but EVERYTHING is about perception and everything is relative. I've heard many Thiels(which I'm not a huge fan of), Vandies, Meadowlarks, and Dunlavys. I'm not a huge fan of all of them, but the ones I do like sound more real than any other speaker I've heard. I'm not saying that time and phase coherence is the end all and be all of speaker design. I'm saying that if you really care about making music and not sound effects it's the minimum requirement.

[_scotty_]

John has pretty much hit the nail on the head, without controlled tests it is impossible to quantify what is being preferred and why.  Lordcloud  has decided what he likes and says that it sounds more real to him.  This is a personal value judgement and only applies to him and his perception of reality. It is non transferable and cannot be expanded to include other peoples perceptions of the same experience.   The point of divergence  between reality and attempts at reproducing reality is still pretty sharp.
If twenty people are in a room and a glass is dropped and shatters on the floor all twenty people can be relied upon to correctly identify what happened
and agree on what they heard.  So far as I am aware no sound reproduction system can successfully duplicate this.  Until we can sucessfully reproduce
even a simple event like a breaking glass so that the reproduced sound is indistinguishable from that produced by the real event we will be stuck with
peoples perceptions of what sounds more real to them and judgements about
how well a loudspeaker performs will remain a personal decision with little basis in reality.  This is why we must return to discussing measurements of loudspeakers because they are the only thing with an objective basis in reality.  In my personal experience no loudspeaker I have ever heard was
real sounding.  The speakers I am currently listening to are pleasing to listen to and I feel that they do a good job on all types on music.  That being said however, the chances that twenty people hearing the sound of breaking glass as reproduced by these speakers and all agreeing that they experienced the real event  is non-existent.  I like the philosophical concept of phase coherence but so far there is little concrete evidence that it must be present in a loudspeakers perfomance description before it can sound good. The room you are listening in may be much more important than how phase coherent your loudspeakers are.  Scotty