Open baffle speaker design

[Cosmik]

The back wave is inverted with respect to the front, and a boundary (wall) sure enough inverts the wave so now it is no longer inverted with the front wave

This seems to be a very pernicious pervasive myth!

 

[Cosmik]

Either way (whether we believe the reflection=inversion myth or not), the assertion is that we can take two transducers, one of which releases only monopole pulses into the room, and one which releases a mixture of positive and delayed inverted pulses into the room, and that both are audibly indistinguishable and both are 'correct'.

Well, I think that one is clearly more correct than the other.

It's fascinating, in a world where people debate the audibility of DAC artefacts at -110dB, that people think that dipoles are anything but a way of avoiding extra woodwork.

 

[Deleted member 2944]

Yeah, I dunno about that...

I owned 3 different Martin Logan electrostats for over 10 years. I've since gone back to unipole dynamic speakers.

Dipoles are pretty impractical in certain scenarios, such as near field listening or DAW work.

Also, you have a "circle of confusion" issue in that pretty much zero recording studios use dipoles, so using a dipole is putting you farther away from what the recording engineers heard and mixed for.

Near field listening and DAW work are different applications than we're talking about here, yes? You're most likely in the professional world with those.

The "circle of confusion" issue is an interesting premise though. That home speakers for reproducing should be the same type as those used for recording/mastering studio work is logical, I suppose, but are recordings made in a studio with dozens of channels, pan-potted, added effects, etc, etc, some sort of "reference" that needs to be adhered to? I don't think so.

Dave.

 

[watchnerd]

Near field listening and DAW work are different applications than we're talking about here, yes? You're most likely in the professional world with those.

The "circle of confusion" issue is an interesting premise though. That home speakers for reproducing should be the same type as those used for recording/mastering studio work is logical, I suppose, but are recordings made in a studio with dozens of channels, pan-potted, added effects, etc, etc, some sort of "reference" that needs to be adhered to? I don't think so.

Dave.

That's my point. Dipoles aren't inherently better -- different applications require different tools.

As for a reference -- that's a complicated topic and 2 channel home audio has never been calibrated to the extent that other formats have. Even reference levels are undefined.

But one thing is for sure is that mixing and mastering engineers aren't using dipoles. So by playing back on them, you're adding an unforeseen element to the original intent of the artists.

Whether that's aesthetically good or not is a matter of taste.

 

[Deleted member 2944]

Just to be clear, I didn't say they were better. I said they had less trade-offs.
Also, what guarantee is there the mixing/mastering engineer is trying to recreate the original intent of the artist??

It's very important to realize that the only proper reference is live un-amplified music. If that music is well/faithfully recorded in a venue where the ambient cues are encoded, then a mastering engineer should have a very simple job.

Dave.

 

[watchnerd]

Just to be clear, I didn't say they were better. I said they had less trade-offs.
Also, what guarantee is there the mixing/mastering engineer is trying to recreate the original intent of the artist??

It's very important to realize that the only proper reference is live un-amplified music. If that music is well/faithfully recorded in a venue where the ambient cues are encoded, then a mastering engineer should have a very simple job.

Dave.

There are only less trade offs if what you value most is what dipoles are good at.

If you value super high efficiency, or small size, or the ability to hang on a wall, or soffit mounting, or approximating a point source, etc, etc.....they're not the best choice.

 

[watchnerd]

It's very important to realize that the only proper reference is live un-amplified music. If that music is well/faithfully recorded in a venue where the ambient cues are encoded, then a mastering engineer should have a very simple job.

Dave.

As for this...

Yes, that's the classic Harry Pearson definition of 'the absolute sound'.

But the logical holes are legion:

1. I can record a purely acoustic event and have it sound different depending upon the microphones I use, each of which have their own sound signatures and radiation patterns. Which one is correctly capturing the un-amplified sound?

2. If I use even a simple set up, 2 stereo mics on elevated stands, what the mics are hearing is not what the audience is hearing. Which is my reference? The mics or the audience? Which seats in the audience?

3. Unless I was physically present at the event, how do I know what it sounded like? I only have the recording.

4. Even if I was present, how do I account for the fading of auditory memory?

5. If I can't fit a grand piano in my listening room, how do I know what a grand piano is supposed to sound like in my room? And a symphony can't fit in my room, so all I'm left with are artistic simulacra that are supposed to invoke the ambience of an event -- none of them can actually reproduce it.

6. What's the proper reference for an electric guitar? A Hammond B3 organ?

7. What's the proper reference for electronic music?


etc etc

 

[Deleted member 2944]

There are only less trade offs if what you value most is what dipoles are good at.

I'm not going to play silly premise word games with you. I certainly understand your point of view on this. It's one that I've heard for many many years.
Have a good weekend.

Cheers,

Dave.

 

[watchnerd]

JIf that music is well/faithfully recorded in a venue where the ambient cues are encoded, then a mastering engineer should have a very simple job.

And what about the mixing engineer who works on the recording before the mastering engineer?

 

[watchnerd]

I'm not going to play silly premise word games with you. I certainly understand your point of view on this. It's one that I've heard for many many years.
Have a good weekend.

Cheers,

Dave.

I think the silly premise is asserting that dipoles have fewer trade-offs.

They have *different* trade-offs.

 

[Wombat]

As for this...

Yes, that's the classic Harry Pearson definition of 'the absolute sound'.

But the logical holes are legion:

1. I can record a purely acoustic event and have it sound different depending upon the microphones I use, each of which have their own sound signatures and radiation patterns. Which one is correctly capturing the un-amplified sound?

2. If I use even a simple set up, 2 stereo mics on elevated stands, what the mics are hearing is not what the audience is hearing. Which is my reference? The mics or the audience? Which seats in the audience?

3. Unless I was physically present at the event, how do I know what it sounded like? I only have the recording.

4. Even if I was present, how do I count for the fading of auditory memory?

5. If I can't fit a grand piano in my listening room, how do I know what a grand piano is supposed to sound like in my room? And a symphony can't fit in my room, so all I'm left with are artistic simulacra that are supposed to invoke the ambience of an event -- none of them can actually reproduce it.

6. What's the proper reference for an electric guitar? A Hammond B3 organ?

7. What's the proper reference for electronic music?


etc etc

Exactly.

Then there is all that twiddle-twaddle, tweak and fiddle with no substantive reference.

However, should 'audiophiles' see this, their raison d'etre evaporates - thus all of that mind-numbing,
'state of denial rhetoric', that infests audio forums with no rational support other than " but I hear it".

 

[watchnerd]

Exactly.

Then there is all that twiddle-twaddle, tweak and fiddle with no substantive reference.

However, should 'audiophiles' see this, their raison d'etre evaporates - thus all of that mind-numbing,
'state of denial rhetoric', that infests audio forums with no rational support other than " but I hear it".

Even a simple survey of the some of the most cherished classical recordings that are highly regarded by audiophiles present a set of paradoxes.

Take, for example, the Mercury Living Presence recordings made by Bob Fine and Wilma Cozart Fine:

1. Many were originally recorded in 3 channels. So any 2 channel version has already had an 'artistic intervention' in the form of mixing decisions.

2. The microphones used were mostly Telefunken U-47, tube condenser microphones, which are still in production and regarded for their "vintage" sound and their air on top. In other words, they're far from flat, reflecting another artistic decision upon the part of the recording engineers:

3. Sometimes Bob Fine used 1 single microphone -- in the case of Kubelik's "Pictures at an Exhibition", he suspended the U-47 25 feet above the conductor's podium....an acoustic point of view that an audience member would never have.

4. Components of Mercury's recording of the 1812 Oveture were recorded on 3 different occasions, in 3 different venues -- 1 for the orchestra, 1 for the church bells, 1 for the cannons. It was all stitched together in post production. No human being heard a live, un-amplified acoustic event that represents what is in that recording.

 

[HammerSandwich]

This seems to be a very pernicious myth!

Persistent, certainly.

DonH, et al., how would a solid surface convert a wavefront from high pressure to low? Where are all those tightly packed molecules going when they hit the wall?

After explaining this, please help me understand the mechanism behind pressure-vessel bass boost below a room's lowest fundamental. Thanks!

 

[watchnerd]

Persistent, certainly.

DonH, et al., how would a solid surface convert a wavefront from high pressure to low? Where are all those tightly packed molecules going when they hit the wall?

The molecules aren't going anywhere, but kinetic energy is lost upon any kind of reflection. How much depends on the surface.

 

[Wombat]

Persistent, certainly.

DonH, et al., how would a solid surface convert a wavefront from high pressure to low? Where are all those tightly packed molecules going when they hit the wall?

After explaining this, please help me understand the mechanism behind pressure-vessel bass boost below a room's lowest fundamental. Thanks!

It is the soundwave that travels. The air molecules vibrate around a basically stationary point, passing energy to adjacent ones.


Refer To Lesson 1: https://www.physicsclassroom.com/class/sound

 

[Cosmik]

Persistent, certainly.

I just woke up thinking I'd used the wrong word (I'd been to the pub), but you got there first.

But either way, an inverted impulse doesn't matter in the world of the steady state frequency domain. If one believes that human hearing works solely in the frequency domain, and that transients can be represented in the frequency domain through the mathematical 'trick' of pretending that a window repeats forever, and that humans are insensitive to phase, and that a visual representation of in-room phase response corresponds to what we hear (it's just chaos and therefore 'de-correlated') then of course a delayed phase-inverted transient is nothing to get worked up about.

But if you believe that hearing also works on the basis of correlation of the shape of one-off events in the time domain, an inversion may be significant in messing up that mechanism.

It's all about not second-guessing how hearing works in order to justify post hoc a speaker technology that has an arbitrary characteristic that you would never have designed into it deliberately. Just to save on the woodwork

 

[Theo]

This seems to be a very pernicious pervasive myth!

Just to clarify, you are right, the pressure pulse stays with the same polarity after being reflected. However, as the wave travels in the oppposite direction, the particle movements are actually opposite when it comes back. As the original pulse was emitted in opposite directions, a movement sensor located in front of the speakers will record a pulse with the same polarity whether it is the original wave or the reflected one. Difference will be the amplitude (attenuation when reflected) and, of course, time of arrival.

Either way (whether we believe the reflection=inversion myth or not), the assertion is that we can take two transducers, one of which releases only monopole pulses into the room, and one which releases a mixture of positive and delayed inverted pulses into the room, and that both are audibly indistinguishable and both are 'correct'.

Spot on again, the dipole emission, unless placed in an anechoic chamber will create a maze of reflected wave, ie producing a reverberation effect, clearly distorting the original signal. Then, as people like harmonics added, some like reverb effects added to the music they listen. Question of taste, I guess.

 

[watchnerd]

Spot on again, the dipole emission, unless placed in an anechoic chamber will create a maze of reflected wave, ie producing a reverberation effect, clearly distorting the original signal. Then, as people like harmonics added, some like reverb effects added to the music they listen. Question of taste, I guess.

+1

People may find this reverb effect pleasing, but to claim it is an inherently superior or less compromised design seems to conflate preferences with technical superiority.

 

[DrTebi]

A friend of mine has been a recording engineer for over 25 years. He doesn't use dipoles in his studio.

But when he was at my house some month ago, listening to my dipole speakers, he was literally amazed at how good they sounded, how clean, how detailed, how well different instruments etc. could be distinguished.

Just my 2 cents in regards to recording engineers

 

[Burning Sounds]

Yeah, I dunno about that...

I owned 3 different Martin Logan electrostats for over 10 years. I've since gone back to unipole dynamic speakers.

Dipoles are pretty impractical in certain scenarios, such as near field listening or DAW work.

Also, you have a "circle of confusion" issue in that pretty much zero recording studios use dipoles, so using a dipole is putting you farther away from what the recording engineers heard and mixed for.

IIRC I think Peter Aczel listened to his Linkwitz Orions and LX521s nearfield. It's not my preference but they worked fine for me when I tried it.

Issues with control room use I can understand, and although certainly in the minority there are studios using dipoles. I do know Siegfried Linkwitz worked with a recording engineer (I don't know who) when he was refining the LX521.

Barry Diament uses Maggies.

Although his Soundkeeper recordings are not my particular musical taste the recordings sound good to me and if you would like to check on soundstage and imaging you might like to try the samples from the album Americas by Paul Beaudry and use the photos on the webpage to compare the musicians' position on the soundstage against what you are hearing from your speakers. I would expect most decent speakers to position them correctly in the soundstage. My LX521s do with solid images of each musician.

BTW if you like reggae Barry Diament's remastering of the Bob Marley Island albums is exceptionally good with outstanding clarity and dynamic range.