[Ericus Rex]

If you like the OB sound why does it matter if it's fake or not?   

[studiotech]

One concern I'm guessing some readers may have is that with minimaly miked live-on-location recordings, all the info- instrumental form and the decay of sound in the venue- is contained in the first wave of sound and that a second wave may be redundant and addtive.  Diffusion would better scatter the back wave rather than absorb it and possibly neutralize or obscure somewhat the benefit, it seems to me.  A question some readers may have is that if all the info is available in the first wave, what is the benefit of a second wave? 

Hard to quantify when we're not talking about a specific speaker as some acoustic suspension OB's may have the bass driver enclosed which doesn't make good sense to me theoretically.  The benefit as I gauge it is in space and grandeur.  But, getting the distance from the rear wall so that you have instrumental cohesion and imagery may drive a person crazy.  Is this a possible fly in the ointment?  Comments are appreciated.

Good point.  That first, direct sound IS what contains all of the information in the recording.  To add anything to that is questionable.  Especially if it is NOT well balanced tonally.  In other words, let say you've got a typical system that shows up on this forum with an Alpha 15(or 2), a wide-range mid and then some form of helper tweeter.  Generally the tweeter is forward firing only, but woofer and mid are radiating to the rear.  You've already got an excess of energy in the bass and mids radiating into the room as compared to the tweeter.  If you place them too close to the wall, there will be some reinforcement at certain frequencies and dips at others scattered throughout the bass-midrange.  This CAN lead to a very warm or bloated midbass sound and very little real low bass.  Kind of like a typical ported minimonitor sound.

If yo build a nice system like John K that maintains it's dipole directivity pretty much all the way through the spectrum, then at least the sound added by ones own room is tonally balanced compared to the initial forward firing wave.

If you are too close to the front wall, the reflected energy is technically arriving close enough to the direct sound as to not be recognized by the ear as a distinct separate sound, but it still blurs the image focus.  Moving farther away from the walls not only delays the reflected sound, but also allows it to drop in level as compared to the direct sound.  They can both be good.  You get a more precise initial wavefront containing JUST whats on the recording.

The easy test is too walk into the listening room and just talk.  Do you perceive a certain sound added to your voice?  Is there a noticeable change in the tonality?  If so, this same sound is getting added to your music.  Seems like a bad idea to me...  Or have someone stand in place of the speaker and talk.  What do they sound like there?  It just requires some experimentation.  Same thing for the speakers.  At least get some treatments and move them around the room and behind the OB and see if you prefer that sound over naked.  Try to use good, full range absorbing too, not some lame 1-2" acoustic foam.  Use some good rigid fiberglass or Bonded Logic that has a fighting chance of evenly absorbing down into the low mids and bass region.

Greg

[Quiet Earth]

If you like the OB sound why does it matter if it's fake or not?   

I agree. These stereo imaging debates are continually reoccurring, and while I always find them interesting I usually end up in the same place.

One thing worth mentioning..... We have to stop blaming the mastering engineer, the production team, etc., for our soundstage issues. How can we impose our own set of standards on something that has no set of standards? I believe that the recording personnel do their best with what they have to work with, and that they try to get the music to translate in as many situations as they can foresee.

[Trismos]

If you like the OB sound why does it matter if it's fake or not?   

I haven't heard an OB speaker myself but there are no end of threads espousing their virtues. As mentioned, I was looking for my next build after doing the GR N3 TLs and if you look at Danny's site, the next "step up' are OBs and then there is a further upgrade in performance going with the V series which are also OB based. Then of course there are other 'ultimate' speakers like the Orion.

So. Somewhere I read what it was about the OB design that made it seam so appealing; that the rear wave reflected back to the wall and then on to the listener, arriving milliseconds later which gave the impression of a larger soundstage. There are other 'benefits' mentioned in regards to having eliminated the box, but it was this artificial creation of a bigger (or deeper or whatever it is) soundstage that had me thinking about how disparaging everyone was of Bose for this very reason.

Someone mentioned the sound from a conductors point of view in an orchestra, and indeed what about any given musician within that orchestra, never mind an audience member seated at any given location in the venue. All this talk about 'they are here' or 'you are there' is merely ones individual perspective (or perception).

And therefore you are absolutely correct: what does it matter as long as you find what you are seeking?

[Bob in St. Louis]

If you like the OB sound why does it matter if it's fake or not?   

Agreed.   

After four pages, this very thought has been creeping into my head more and more since this thread started. At the end of the day, my 100% Open Baffle system is what makes me happy and I have zero plans on changing anything whatsoever that effects the sound that emanates out of those paper cones in front of me.

Bob - OB fanboy

[Quiet Earth]

Well Trismos, now that you have done all of your academic research on open baffle speakers the only thing left for you to do on the subject is to go somewhere and hear one. If you can make a hifi show in your area you will be able to hear several of them.

After that you will have a much better idea of what it sounds like and maybe even a few more questions.

[Tyson]

OB's mimic how music sounds in a live acoustic space more closely than other speakers do.  From a strictly acoustical standpoint, this direct plus reflected sound combination sounds very close to how live music sounds. 

So, I say again - box speakers replicate the recording more precisely, while OB speakers replicate the sound of live music better.  Which do you prefer?  Well, that's up to you....

[Quiet Earth]

Box speakers must be the correct choice for home stereo then, since all we have to play are recordings. 

[Tyson]

Ideally, we would all listen exclusively to headphones, since they give direct monopole sound at all frequencies, and remove the room from the equation entirely. 

[fredgarvin]

Trismos makes a good point about DSP and other methods (more sophisticated than OB) to add to and expand the soundfield. Ultimately in all of these imaging is a challenge.

[doug s.]

OB's mimic how music sounds in a live acoustic space more closely than other speakers do.  From a strictly acoustical standpoint, this direct plus reflected sound combination sounds very close to how live music sounds. 

So, I say again - box speakers replicate the recording more precisely, while OB speakers replicate the sound of live music better.  Which do you prefer?  Well, that's up to you....

i must respectfully disagree w/the statement that ob's more closely mimic how music sounds in a live acoustic space.  not to my ears anyways.  as far as whether or not "box speakers" replicate the recording more precisely, i simply don't know...  i suspect they might, simply because i find the overblown soundstaging of dipoles to be so un-natural, i can't imagine that's what it sounds like when the recording is being made.

as far as "which do you prefer"?  that, i agree with 100%!   

ymmv,

doug s.

[Russell Dawkins]

I've mentioned this perhaps three times over the years, each time to zero response, but here goes again, anyway.

There is one way to take the guesswork out of determining which speaker set up is most true to the source (at least, spatially) and that is by "calibrating" the mono image. The narrower the mono image, the more accurate and the more you can trust that what you are hearing in stereo is what was intended.

If you are comparing two or more sets of speakers and one set produces a more diffuse mono image - i.e., one with lateral smearing - that set will be less accurate, even if it is more fun to listen to because it "widens the soundstage".

This is an easy and accurate guide to speaker choice and placement.

[fredgarvin]

I've mentioned this perhaps three times over the years, each time to zero response, but here goes again, anyway.

There is one way to take the guesswork out of determining which speaker set up is most true to the source (at least, spatially) and that is by "calibrating" the mono image. The narrower the mono image, the more accurate and the more you can trust that what you are hearing in stereo is what was intended.

If you are comparing two or more sets of speakers and one set produces a more diffuse mono image - i.e., one with lateral smearing - that set will be less accurate, even if it is more fun to listen to because it "widens the soundstage".

This is an easy and accurate guide to speaker choice and placement.

That is a good point and worth mentioning again. Really it seems to me the one place one should be concerned with a good point source is in nearfield listening. Otherwise, tweeter dispersion, or even smearing as you mention, makes a wider and more satisfying soundstage. It's about the balance of various speaker characteristics, I suppose.

[JohnR]

A question some readers may have is that if all the info is available in the first wave, what is the benefit of a second wave? 

Jim, all speakers have a "second wave." Why do you think people obsess so much about putting absorbing material on the side walls? With a dipole, you point the null at the first reflection point on the side wall - problem solved. Instead, you have a (full-spectrum) "wave" at the rear, so different approaches are needed - as per the recommendations by Linkwitz. Have a look at the article by Duke that I linked earlier, to see some discussion about what you do want to happen to reflected sound in the room.

[JohnR]

The narrower the mono image, the more accurate and the more you can trust that what you are hearing in stereo is what was intended.

I believe this contradicts research by Toole - I'll try to look it up later.

[John Casler]

Whew!   

Lots of interesting comments and just the kind of stuff I have contemplated for the last 40 years in Audio.

It has to be known and assumed that each of us will have reasons and preferences to the SOUND we like.  This will be shaped by the recordings we listen to, the speakers and systems we employ, and just simply what floats our individual boats.

It is also important that we understand what is occurring psycho acoustically in our ROOM/SYSTEM that we like or want to change.  This in itself is exceptionally complex due to the incredible number of factors that affect sound from recording to reproduction.

So in discussing this topic it is valuable to understand your biases, and preferences and then proceed to understand them and why others may not have the same as you.

I have been very lucky enough over the last several years to have taken part in a yearly TEST of how to record, replay and compare LIVE music on a great system.  This in itself is a MUCH more difficult task than one might think. 

In all the previous discussion, I don't think I saw where anyone has actually had the opportunity to record a LIVE performance and then "in the EXACT same space" play it back on a high quality system.  I think the value of this is that you find out a lot regarding the "you are there" and "they are here" situation. 

What I have learned, is that ANYTIME you have sound coming from your speakers, and it is "reflected" to you from the rooms surfaces, it is a distortion to accurate reproduction of what was recorded. 

Will it, or can it sound good?  Yes. 

Will it or can it sound real?  Yes.  But if it was NOT in the recorded event, then it is a distortion to the reproduction of that event.

I have also learned that if you record a LIVE event, you DO record all those live reflections and they ARE NOT distortions since they were part of the event.  If you then replay them in the same venue/space, your enemy to accurate reproduction is that the venue/space will add more of its reflections, overlaying the ones originally recorded and you will then in essence have 1 performance and 2 sets of reflected sound.  The first set is the natural and real one, the second are the distortions added at playback.

So there can be lots of discussion regarding different designs of speakers and handling room related reflections, but once you have wrapped around what is actually happening if you are trying to record and reproduce a LIVE performance it begins to take shape and make sense.

Now my post is just scratching the surface relative to what might be the best (your opinion/my opinion) way to deal with all the myriad of elements that will at some point in the performance, recording, and reproduction chain, affect the accurate reality of what you hear. 

Let me assure you it is not as simple as just a speaker design issue.  Some of the most liked speakers (supposedly due to their ability to sound REAL) rely on an interactive level of reflected (distortion to the actual recording) which sounds pleasing and realistic to our biases and preferences.  This does not mean they don't sound wonderful, and maybe EVEN BETTER (like Kodachrome) than the reality.

In any event, since I was lucky enough to have had these experiences, thought I might mention them and what I have personally concluded regarding how they "fit" in our quest to enjoy the hobby.

[JohnR]

What I have learned, is that ANYTIME you have sound coming from your speakers, and it is "reflected" to you from the rooms surfaces, it is a distortion to accurate reproduction of what was recorded. 

That is incorrect. If it were correct, the anechoic chamber would be the ideal listening room.

[Trismos]

That is incorrect. If it were correct, the anechoic chamber would be the ideal listening room.

Interesting. Speakers are tested in anechoic chambers. Why would't this be the ideal listening room? Sound engineers do not anticipate someone / anyone has a given room. Is this not why headphones are so ideal?

[John Casler]

Interesting. Speakers are tested in anechoic chambers. Why would't this be the ideal listening room? Sound engineers do not anticipate someone / anyone has a given room. Is this not why headphones are so ideal?

It is the most accurate for both testing and distortion free reproduction.

There are many elements that make up what one might call the ideal listening room, and they relate to our listening preferences and bias.  If that preference and bias is to hear the original recorded signal without any room interaction (which can only be distortion to the original signal) then it is true an anechoic chamber is the most accurate.  In reality no one could actually stop all room interaction (particularly in the bass regions) so it would only be to approach non-reflective conditions.

[Tyson]

Or you could listen outside, in a field.