Speakers that throw images outside the speaker boundaries: a puzzling comparison

[Deward Hastings]

That's what I'm trying to figure out. It just doesn't seem to be as cut-n-dry as "this one has less higher order harmonic distortion therefore it is better". There's gotta be more to it.

Of course there is ("more to it"). At root here, I think, is the gross oversimplification of cone breakup as being merely one (or perhaps a couple) simple resonance(s), with it's only significant effect being "harmonic amplification". There is a lot more going on than "shows" in simple single-tone response and distortion tests.

[Deward Hastings]

I think Pallas is probably on the right track. Sound power is key. This will not change in any environment. Whatever a speaker's sound power is, you can expect it to correlate in any environment. If there's a 'hole' in the response, it'll show up even after reflections are taken in to account because it wasn't there to begin with. IMHO, the soundstage and everything else about a speaker is rooted in sound power.

It is significant even if not "key" . . . in most listening situations the "off-axis" radiation provides most of the sound that we hear, and "first reflections" can either mask or augment localization cues in the recording.

Power response isn't everything, and I really don't think it comes into play here.

Power response is significant in perceived "tonal balance", it's the nature and direction of the "off-axis" response (and associated room reflections) that influences "image". As several (game and synthetic music) examples above indicate it's easy to fool the ear by phase manipulation . . . such tricks are not applicable to concert recordings, but may be used for mixer-assembled studio tracks. In the concert hall ORTF micing generally gives a wider "sound stage" while Bleumlein stays "between the speakers", as do most "multi-mic" placements.

If you want a "wide image", though, you can always "do a Bose" and turn your speakers to face the walls . . .

[ErinH]

But that's the recording.

I agree entirely.. a speaker should replicate what the recording is. But, is that the way this thread is trending? Honestly, I was still focusing on how one speaker performs better in this regard to another. And, then, I go back to sound power (due to its interaction with the room).

[Bob Brines]

So when you get right down to it, imaging is really a figment of the engineer's imagination. If he screws with phasing etc sound extends beyond the speakers, if he uses a two mic setup, the imaging will be what you would hear at that point in space, and if he is doing a multi-mic mix-down of different tracks laid down at different times, all bets are off!

Bob

[Face]

That's a given.

What I and some others are wonder is, how come some speakers do this better than others...

[Pallas]

180 degree waveguide? Wouldn't that be a flat baffle?

Yes. However, referring to it (correctly) as a 180deg waveguide points out what a poor surface a flat baffle is to constrain the tweeter's directivity at the bottom of its passband. That failure inexorably leads to a parade of sonic horribles.

[COLOR="red"]Ok, then why to the same speaker throw the same image in multiple, very different rooms?

Um, because its power response doesn't change?

***If you've never played a first person shooter like Call of Duty, then you don't have a clue at what can be done with a recording to fool you into thinking things are happening all around you, when only two little, crappy, speakers ahead of you are doing the work.

Well, I don't play those kinds of video games (I am, after all, an adult) but the nearfield is a different ballgame, generally speaking.

If the recording has it, then the speakers should reproduce it. If speakers will not throw an image outside their position, regardless the recording, they're not very good speakers.

I think many other attributes are more important. Such as getting the timbre of the midrange right. But those are preference things. Reasonable people can disagree on issues of preference.

I've read a lot of great research from Toole that first led me to see if this held up... and I think it did. Or, maybe I was just influenced psychoacoustically by the reading (I'm half serious).

Point well-taken on the potential of being influenced in one's perception by knowledge of the relevant research. I've read the same stuff, and that's what led me to check my assumption about the Q900's pattern by asking for a measurement of the "waveguide" (cone) angle.

Power response isn't everything, and I really don't think it comes into play here.

You're conflating two analytically distinct things with your talk of computer speakers and children's toys: far-field listening and nearfield listening.

Yes, even in the farfield, some speakers that sound like crap because they have fairly large midwoofers and tweeters plopped onto 180deg waveguides can do imaging tricks. However, in the relevant frequencies, their directivity is quite wide. Wide directivity, of course, leads to lots of early reflections.

[Face]

And it's no surprise why more aren't chiming in...

[Deward Hastings]

Yes. However, referring to it (correctly) as a 180deg waveguide points out what a poor surface a flat baffle is to constrain the tweeter's directivity at the bottom of its passband.

But the 180deg waveguide is not a "problem" (and works just fine) as long is it is what is determining the polar for all the drivers through the critical range. The "problem" is allowing drivers on that waveguide to establish their own independent radiation patterns . . . the patterns will likely not agree at crossovers (and typically get wonkey at "baffle step" as well).

The ultimiate beaming of the tweeter turns out not only not to be a problem but, properly managed, to be a benefit as the recorded sound "translates" to the typical listening room (where most listeners favor a falling power response at the higher frequencies).

You shouldn't blame the waveguide for designers not using it correctly . . .

[johnastockman]

And it's no surprise why more aren't chiming in...

I was wanting to add in some of my experiences also, but your post was quite correct. What does being an adult have to do with whether or not you enjoy a good-quality video game experience? Many folks I know think I'm childish because I listen to music more than watch TV and the fact that I don't watch any major or minor network talking-head news program.

The main noticeable factor when I built those Speakerlab S2's in '77 was the imaging and the lack of ear fatigue from the mids and highs. Something even casual listeners noticed immediately and an attribute that critical listeners who had brand-name speakers commented on first. While the side-by-sides I did at my home and at others houses were not "scientific" or by-the-book A/B comparos, the SQ and imaging differences were so obvious everyone had a new skepticism about the claims of OEM speakers. Now, there were some of the Dahlquist open-back designs, B&W, RTR, AR, and others of that same quality that were superior in the areas of balance, resolution and imaging. To this day, I still get skeptics bringing their speakers over to prove that the brand of their choosing is "better" than something I can build from a plan. Kinda like if you're a doctor...folks find that out and the proverbial "I have this pain..." comes out. Some are curious, others have a chip on their shoulder and want to prove me wrong. I haven't had any Thiel, IRS, Philharmonics, Wilson, Vandersteen or other esoteric brands show up here. But just about any popular brand you can think of, vintage to new, and many white-van varieties have come through the door.

I wish I was more knowledgeable about some of the physics at work with the topic, but I learn much from you guys that can discuss these things rationally. So thanks to you and others that have enlightened me in this area. I know when I hear it, and I just don't hear it with a majority of the OEM brands. Neither do friends and family, as evidenced by how many of the Speakerlab models I made enclosures for back then and the numerous DIY designs I've done in the past 15 years to replace or re-purpose their retail brands.


John A.

[mzisserson]

But the 180deg waveguide is not a "problem" (and works just fine) as long is it is what is determining the polar for all the drivers through the critical range. The "problem" is allowing drivers on that waveguide to establish their own independent radiation patterns . . . the patterns will likely not agree at crossovers (and typically get wonkey at "baffle step" as well).

The ultimiate beaming of the tweeter turns out not only not to be a problem but, properly managed, to be a benefit as the recorded sound "translates" to the typical listening room (where most listeners favor a falling power response at the higher frequencies).

You shouldn't blame the waveguide for designers not using it correctly . . .

This about sums up home speaker design for me! Well stated!

[Pallas]

And it's no surprise why more aren't chiming in...

Whatever. As far as I'm concerned, the question has been answered: the KEF Q900's simply throw a wider pattern than I had assumed. (Though Erin's point about personal bias stemming from knowledge of research results was, I think, a useful caution.) My assumption was reasonable, based on the size of the midrange and the claimed crossover point. It just turned out to be wrong. That 1.5" dome tweeter must be really stout, to play low without steep slopes or much loading from the cone at the bottom of its passband!

So they do not violate the received wisdom about "outside the speakers" imaging and directivity.

Though perhaps I should add "adults who waste their time playing video games" to the "what are you a snob about" thread.

But the 180deg waveguide is not a "problem" (and works just fine) as long is it is what is determining the polar for all the drivers through the critical range. The "problem" is allowing drivers on that waveguide to establish their own independent radiation patterns . . . the patterns will likely not agree at crossovers (and typically get wonkey at "baffle step" as well).

I agree with all that.

The problem with it is, by definition then the overall directivity has to be 180deg through the midrange. That can be done in a 3-way, with a small flange tweeter butted up against a small midrange. It can also be done in a 2-way with a small and stout mid-tweeter crossed to a woofer where it is still more-or-less omnidirectional, such as in your Linkwitz Pluto (or clone). Though that does lead to a price in dynamic shading, because power compression is fairly high. (Remember that I've been using the Aura Whispers since about 2004, well before SL released the Pluto design. I know their thermal/dynamic limits well.)

The ultimiate beaming of the tweeter turns out not only not to be a problem but, properly managed, to be a benefit as the recorded sound "translates" to the typical listening room (where most listeners favor a falling power response at the higher frequencies).

Again, I agree. Both with the conclusion and the analysis.

[GranteedEV]

Though perhaps I should add "adults who waste their time playing video games" to the "what are you a snob about" thread.

Lord forbid adults with "time wasting hobbies" like, reading novels, building explicitly controlled directivity diy speakers, installing speakers in their 1960s Citroen cars, playing video games, listening to music, visiting internet forums, playing sports, shopping, drinking scotch.

The only things adults should be allowed to do, is work to make money, and work out in the gym, and eat dinner after praying with their family of exactly four at 6PM so that their children are raised well enough to procreate and follow this exact path. As far as DIY goes, only fixing the house is acceptable.

Reality is, your hobbies are no more productive than anyone else's hobbies. There is nothing that defines a hobby with respect to age demographic.

[mzisserson]

Nevermind...