Direct or Reflect ... What's your flavor


Was thinking about this from another thread. When we think of a basic speaker we usually think of monopoles. That is, speakers with a single baffle or plane from which sound emanates out of to the room, but as long as I can remember there are examples at all price ranges of speakers designed specifically to reflect, or whose basic construction forced rear or side reflections. Among the "forced to reflect" categories:

  • Electro static speakers (Martin Logan, Sanders, etc.)
  • Open Baffle / di-pole
Then we have ambient reflectors, which I include:
  • Bose 901 and smaller direct/reflecting models
  • Snell with their rear tweets
  • Wilson 
  • Probably numerous others
Let be clear though, NONE of these ambient reflectors are accurate. None of these latter elements can be called a way of credibly and accurately increasing the transmission of information from the recording to our ears. To my mind these are all in the land of bass shakers. They add some pizzazz and excitement, and perhaps an illusionary venue.

So, still, for your music and tastes, who has gone with di-poles or ambient reflecting speakers and never looked back?
erik_squires
I never look back. Someone might be gaining on me. But if you ever do, remember Meatloaf: speakers in the rear view mirror may appear closer than they are.
Erik, I have been using dipole line sources exclusively since 1979 including ESLs, ribbons and planar magnetics. I have come to the conclusion that ESLs are the best. My next and probably last set of speakers is going to be Sound Labs Ultimate 845s. I have absolutely no interest in dynamic speakers other than the Sonos units I use for background music and the old Mirage speakers I use in my workshop.
I find horn speakers intriguing but I have yet to hear a set that really wow me out. It is difficult if not impossible for a dynamic loudspeaker to match the accuracy of an ESL. But, the cheapest full range ESL is $14K and they are big things that will totally dominate the environment. It is a shame Acoustat went under as they produced ESLs at a price most of us could afford. Having said that the most expensive Sound Labs are about 50K. Given that there is no loudspeaker at any price that a good number of us would prefer makes them an extreme value. Why anyone would spend $250K on Wilson's or Magico's is totally beyond me. 
millercarbon, there is a great white about to bite you in the a--. 
Eric......If I may......Bose 901s are not ambient reflectors, as 89% of their output was purposely sent to the back wall. Then you have speakers designed by Stewart Hegeman, and all of the manufacturers who use his design ( s ), ( look them up ). Tweeters on the rear of a box, yes. And talk about ambient retrieval ? This can be done electronically, or, with other speakers placed about the room. It is my contention ( however, no arguments, please ), that recordings have ambience, and I want to hear all of it, before any additional reflections of the room. This is my preference, and feel, there is no right or wrong, as long as the listener is happy. Panels, omnis, box, horns, whatever, is no different, than ice cream flavors. Same with analog vs digital, tubes vs solid state. Most folks know what I like, but, the important thing, and this should be with every one, that when you find what you like, good for you, and no one can say different. Enjoy ! MrD.
@mrdecibel 

OK, maybe the 901s were not, but a lot of future Bose speakers were. :)
Eric, don’t you hate it when some [email protected]$$ comes along and argues with the facts? Well, today it’s my turn to be that guy.

"NONE of these ambient reflectors are accurate. None of these latter elements can be called a way of credibly and accurately increasing the transmission of information from the recording to our ears."

This statement makes intuitive sense. How can adding something which wasn’t on the recording to begin with (the additional in-room reflections) possibly increase accuracy? I know what you’re thinking... "Duke, right about NOW would be a good time to stop typing"...

I’m not going to argue in favor of every single technique for deliberately adding reflections; rather, I’m going to argue that DONE RIGHT can be a worthwhile net improvement, especially if we are designing for ears rather than for test instruments.

Perhaps our first question ought to be, are reflections ever benefical in a home audio setting? Since anechoic listening is not a desirable goal, the answer must be "yes".

Next question: Are all reflections equally desirable? Apparently not, else acousticians would be out of work.

What, then, makes reflections desirable? This is a complicated subject so I’m just going to focus on one aspect for now: Reflections should sound like the direct sound. That is, they should be spectrally correct. The more they sound like the direct sound, the more beneficial they are likely to be. And the less they sound like the direct sound, the more detrimental they are likely to be. (Things like timing and level and diffusiveness and arrival angle and decay rates all also matter, just for the record.)

So if reflections are going to happen, and if they can be a good thing, does it not make sense to MAKE them as beneficial as we reasonably can?

Let’s look at how we might accomplish this. Suppose we start with a good wide-pattern conventional speaker. The speaker’s pattern averages perhaps 160 degrees wide over most of the spectrum, narrowing considerably in the top octave as the tweeter starts to beam. The spectral balance of the first-arrival sound will be the on-axis response (or close to it), while the spectral balance of the reflections will be dominated by the off-axis sound, and because of the tweeter’s beaming, it will be weak in the top octave or so.

Now suppose we were to take this speaker’s 160 degree pattern and chop it in two, with 80 degrees firing forward and 80 degrees firing backwards. Each half gets its own tweeter so the highs hold up better out to the sides of each 80 degree wedge. Now let’s mentally examine the spectral balance of our reverberant energy, and which includes a backwave identical to the frontwave, and we’ll see that there is much less spectral discrepancy between the first-arrival sound and the reverberant sound. The overall loudness of the revereberant sound relative to the direct sound has not changed, but its spectral balance has been significantly improved.

This is but one example of a way that intelligent manipulation of the reverberant field can be benefical. (Note that virtually everything a professional acoustician does falls into the category of "intelligent manipulation of the reverberant field".)

"They add... perhaps an illusionary venue."

In a home audio listening room there is, in effect, a competition between the acoustic signature on the recording (whether it be real or engineered or both), and the acoustic signature of the playback room. At best, in home audio we are presented with a poverty of recording venue cues, compared with actually being there. Still with a good recording and good system setup, we are often able to perceive a plausible illusion of the recording venue. The trick is to effectively present the cues on the recording while simultaneously minimizing the inherent "small room cues" which our playback room super-imposes atop the recording. This is a complicated topic which I will go into more detail about in another poster’s thread, entitled "The "They are here" vs "You are there" sound topic".

But imo this is another instance where intelligent manipulation of the reverberant field can pay significant dividends. By way of a quick anecdotal example, consider the experience of countless Maggie and Martin Logan and Acoustat and SoundLab and so forth owners with pulling their speakers out into the room: With sufficient distance from the back wall (i.e. sufficient time delay on the backwave energy), they hear significantly more variation in acoustic signature from one recording to the next.

So in my opinion, "done right" (which includes appropriate set-up), a good polydirectional speaker gets some things more correct than a conventional speaker does, particularly from a perceptual standpoint. 

Duke
speaker manufacturer
What did they call those iddy biddy Bose speakers? The little white cube ones? Two of em one right on top of the other? With of course a "sub". Everyone knows you have to have a "sub".

Because there was this one guy, a regular at The Alehouse, he had em. And he was telling me how crappy they were, no imaging whatsoever. And no he didn’t say imaging. Already said, regular, bar, try and keep up okay? So that was me. What he said was man its all vague and stuff. (I know what you’re thinking but this is Redmond, mile from Microsoft, guys in bars know words like vague. Most of em.)

I said yeah because stupid Bose makes wife speakers, don’t sound good nowhere but sounds about the same level of not good everywhere, which is what women want, it don’t mess up their chit chat so much.

And yeah I talk that way in a bar, you wanna make somethin of it? So anyway like I said the guy is a regular and so next time he sees me he’s all hey you were right! And I’m like yeah tell me bout it. And so if you could just fill me in on which Bose that was then we could get down to the next order of business tracking this guy down to let him know how helpful his opinion has been filling out this little poll.
Erik

I have Matrix 800's in Room 1.

I have WPK Quad 57 (set up high physically) with dual Dynaudio 12" subs set up near field in Room 2.

Objective 1 was make Room 1 (Midrange and High Frequencies) sound like Room 2. 
 
Objective 2 was make the bass in Room 2 sound as good as the bass in Room 1.

You can click on W. E. Coyote to see the Room pics.

Cheers Chris

I wish somebody would come out with a contemporary version of the Definitive Technology BP 20.

A *bipolar* speaker design in a heavy large tower cabinet with awesome bass and soundstage even at low volumes.
@audiokinesis

I read no argument there.  The truth is we are all here to figure out what kind of illusions we like the most. Then we argue what measurements and tools make this illusion more easy to define and achieve.

Best,

Erik
I wish somebody would come out with a contemporary version of the Definitive Technology BP 20.


You know, I'm kind of surprised no one is making add-on speakers to turn any speaker into a bipolar.  Self-powered, self calibrating accessories that would do more for you than a lot of tweaks. :)
For overly dry close mic recording, many of the small Tulip DG variety, I just walk a few feet and activate the rear firing 100% distortion rear firing tweeter on my Vandersteen.... they are there for a reason.... 89% of the time they are switched OFF

who knows, perhaps tone controls and a stereo blend control are next...
@Tomic. 
I just walk a few feet and activate the rear firing 100% distortion rear firing tweeter on my [email protected]
I don't understand what you are saying. The rear tweeter is 100% distortion?
Bob

Duke made at least one great point (there is more than one, but I’m focusing on the one): the off-axis response of a loudspeaker is ideally the same as it’s on-axis response. When accomplished, the total in-room power response (direct sound, reflected sound) is uniform, irrespective of frequency. Danny Richie discusses this important design consideration (as well as add-on tweeters and other related issues) in one of his Tech Talk Tuesday videos.

One other point needing to be made is that monopole loudspeakers (forward-firing enclosure designs) are monopoles at only certain frequencies---where the individual drivers begin "beaming" (a function of wavelength vs. driver diameter). Below the beaming frequency, the sound coming out the front of the speaker wraps around the enclosure and propagates towards the back wall, just as does the sound coming out of the rear of a dipole.

I know one Maggie owners who uses heavy absorption behind his MGIIIa’s, due to room constraints. He accepts the lack of a rear diffused sound field, preferring in some ways the more "direct" sound of a forward-only planar. Each to his own.

One other point needing to be made is that monopole loudspeakers (forward-firing enclosure designs) are monopoles at only certain frequencies



We're now conflating dispersion with speaker topology, which I was trying to get at. Besides, even when the driver is significantly narrower than the frequency so as to cause wide dispersion, the dipole still behaves very differently.

Best,

E

Of course, Erik. The point I was making is that even direct radiators create front wall (behind the loudspeakers) reflections. Dipoles/planars do at all frequencies, direct radiators at bass frequencies up into the midrange (depending on driver diameter).

And that is just 1st wave sound. That front wall also reflects sound reaching it from the rear wall, side walls, and the ceiling.

Yes a rear firing tweeter is 100% distortion 
Part of fixing crappy recordings involves picking distortion your ear brain likes
And the big baffle is just like moving the rear wall forward
Anybody move the chair forward yet to change the direct vs room response but NOT get entirely in the near field ? Granted it takes more effort than typing..,
On beaming... that’s why every Vandersteen midrange is.... drumroll... the same size... ditto for the height of the acoustic lense... 
Part of the problem of the over damped rear wall is the lack of uniform absorption, especially below 1k. At the dealership where I worked out high end room before we moved was over dampened, a better solution is treat the bounces w absorption ( including floor or ceiling ), add diffraction to match AND realistic furnishings, and plants!!!
@tomic601  
Anybody move the chair forward yet to change the direct vs room response but NOT get entirely in the near field ?

Yes, if I am visiting a friend who has a shared music room - living room. You know - gear stacked up against the front wall. The first thing I ask .... as an experiment ....lets put the speakers & a chair  in nearfield first.....just to see how good it can be.

They hear that ......then know after that setup .....everything that follows is a compromised illusion. The discussion that follows is usually about putting the speakers on some type of rollers, to allow them to be pushed against the wall again when his wife is home.

@ct0517 a man of action and results you are!!!!
^^^^
@tomic601

Tom

thx but oh...I hope my wife never finds me here. If she did, and saw your comment, she would create an AudioGon account just so she could blast me with a post. 
You see I recently chose an Electrostatic Speaker Repair Project in priority, over fixing the shower stall, and painting the house.
Can’t stand painting, but can’t stand paying someone else to do it more.
Cheers Chris

I like Hazelnut gelato.
I like omnis. They put the music in the room the most realistically.  Period.
@mapman,

Do you find they pose any challenges to the room?