Open baffle speaker design

[Cosmik]

If I invert one ear's signal relative to the other in headphones I get the well-known 'Whooah..!' effect where mono sound goes 'stereo' (kind of), accompanied by a sensation of head-spinning nauseousness. I just tried it for about a minute using Audacity to invert one half of a mono track duplicated to stereo and I still seem to be suffering from the effects 10 minutes later..!

Clearly, (and I've only just thought of this) if other people also experience this, it proves that hearing is not just a phase-free Fourier Transform analyser as claimed by many people, because otherwise it would not be able to distinguish between inverted and non-inverted conditions when listening with headphones (where there is no acoustic comb filtering/cancellation). Instead, sound is correlated in some other way that is discombobulated by inverted polarity.

The effect also happens with stereo speakers wired in anti-phase - quite strongly I would say. But... I went to an audio show a few months ago where an expert was talking to the audience about speakers he had re-built, and joked that he had had a 'Golden-Ears' in that morning who had spotted that he had wired one of the speakers backwards. So it seems that such a strongly-negative sensation for some people might not be a problem for others.

Is this happening with dipole speakers and their inverted reflections that reach the listener's ears via different paths? Some people (me) find them at some level nausea-inducing, but maybe others hear only a widening of the stereo, or a funky surround sound effect.

 

[Wombat]

Open waffle..

Concise description of most audio forums.

 

[Wombat]

If I invert one ear's signal relative to the other in headphones I get the well-known 'Whooah..!' effect where mono sound goes 'stereo' (kind of), accompanied by a mild sensation of head-spinning nauseousness. I just tried it for about a minute using Audacity to invert one half of a mono track duplicated to stereo and I still seem to be suffering from the effects 10 minutes later..!

Clearly, (and I've only just thought of this) if other people also experience this, it proves that hearing is not just a phase-free Fourier Transform analyser as claimed by many people, because otherwise it would not be able to distinguish between inverted and non-inverted conditions when listening with headphones (where there is no acoustic comb filtering/cancellation). Instead, sound is correlated in some other way that is discombobulated by inverted polarity.

The effect also happens with stereo speakers wired in anti-phase - quite strongly I would say. But... I went to an audio show a few months ago where an expert was talking to the audience about speakers he had re-built, and joked that he had had a 'Golden-Ears' in that morning who had spotted that he had wired one of the speakers backwards. So it seems that such a strongly-negative sensation for some people might not be a problem for others.

Is this happening with dipole speakers? Some people (me) find them at some level nausea-inducing, but maybe others hear only a widening of the stereo, or a funky surround sound effect.

Blind testing required hear(here).

 

[Burning Sounds]

.

Is this happening with dipole speakers and their inverted reflections that reach the listener's ears via different paths? Some people (me) find them at some level nausea-inducing, but maybe others hear only a widening of the stereo, or a funky surround sound effect.

I know what it is - you've been listening to electrostatics arcing haven't you? - it's that pesky ozone that's making you feel nauseous...

 

[Frank Dernie]

I used Apogee Diva panels for about 8 years. I loved the sound and the spacious stereo image but I always had the impression that they added rather more of my room acoustic to the sound than box speakers, but that could be expectation bias. In the end I sold them because in my new room the speakers have a window behind and they pretty well cut out all the light, probably not an ideal surface either but I didn't keep them there long.
I have listened to electrostatics quite often but never owned any.
The latest large Quads, which are basically just bigger bass panels above and below an ELS63 concentric ring panel, were superb at the Scalford show a few years ago.

 

[DonH56]

If I invert one ear's signal relative to the other in headphones I get the well-known 'Whooah..!' effect where mono sound goes 'stereo' (kind of), accompanied by a sensation of head-spinning nauseousness. I just tried it for about a minute using Audacity to invert one half of a mono track duplicated to stereo and I still seem to be suffering from the effects 10 minutes later..!

Clearly, (and I've only just thought of this) if other people also experience this, it proves that hearing is not just a phase-free Fourier Transform analyser as claimed by many people, because otherwise it would not be able to distinguish between inverted and non-inverted conditions when listening with headphones (where there is no acoustic comb filtering/cancellation). Instead, sound is correlated in some other way that is discombobulated by inverted polarity.

The effect also happens with stereo speakers wired in anti-phase - quite strongly I would say. But... I went to an audio show a few months ago where an expert was talking to the audience about speakers he had re-built, and joked that he had had a 'Golden-Ears' in that morning who had spotted that he had wired one of the speakers backwards. So it seems that such a strongly-negative sensation for some people might not be a problem for others.

Is this happening with dipole speakers and their inverted reflections that reach the listener's ears via different paths? Some people (me) find them at some level nausea-inducing, but maybe others hear only a widening of the stereo, or a funky surround sound effect.

Yes, comb filtering is a known issue with dipoles, since the back wave hits the wall behind, inverts, and recombines with the front. I do not like it at all as it really wreaks havoc with FR and imaging. It drives me nuts, but it's a short drive. That is why I routinely damp (ro diffuse) the back wave unless they are far enough away from the wall behind that the cancellation is low enough in frequency and delayed enough to not be a problem. That has rarely been the case in the rooms I have had through the years. The same thing occurs with conventional speakers, natch, due to first reflections. Planer dipoles do not radiate much off the sides and top/bottom over the bass region (below they start to look more like a point source) so first reflections are rarely an issue -- except for the back wave.

I have many times pointed out the effects of comb filtering to folk who did not realize what they were hearing. It is very obvious once you know what it is and can be very annoying depending upon how low it starts. And that may be part of the issue; it can start pretty low for dipoles firing into an untreated back wall, whereas conventional speakers may exhibit it to a lesser degree due to position, room treatment (or just things hanging on the walls), and their intrinsic radiation (dispersion) pattern.

I have never espoused that phase in Fourier transforms can be neglected, especially gross phase shifts leading to cancellations (naturally). Music is not really steady-state and phase matters IMO, though studies (see Toole's book) have shown frequency response dominates. But, a lot of the highly-regard room correction systems (e.g. Dirac Live, Trinnov, DEQx IIRC) tout their phase corrections and time-domain improvements.

FWIWFM - Don

 

[Blumlein 88]

If I invert one ear's signal relative to the other in headphones I get the well-known 'Whooah..!' effect where mono sound goes 'stereo' (kind of), accompanied by a sensation of head-spinning nauseousness. I just tried it for about a minute using Audacity to invert one half of a mono track duplicated to stereo and I still seem to be suffering from the effects 10 minutes later..!

Clearly, (and I've only just thought of this) if other people also experience this, it proves that hearing is not just a phase-free Fourier Transform analyser as claimed by many people, because otherwise it would not be able to distinguish between inverted and non-inverted conditions when listening with headphones (where there is no acoustic comb filtering/cancellation). Instead, sound is correlated in some other way that is discombobulated by inverted polarity.

The effect also happens with stereo speakers wired in anti-phase - quite strongly I would say. But... I went to an audio show a few months ago where an expert was talking to the audience about speakers he had re-built, and joked that he had had a 'Golden-Ears' in that morning who had spotted that he had wired one of the speakers backwards. So it seems that such a strongly-negative sensation for some people might not be a problem for others.

Is this happening with dipole speakers and their inverted reflections that reach the listener's ears via different paths? Some people (me) find them at some level nausea-inducing, but maybe others hear only a widening of the stereo, or a funky surround sound effect.

When has anyone claimed ears are phase free. We know phase is very perceptible until 1500 hz. Then becomes less important as you move higher in frequency.

 

[Cosmik]

When has anyone claimed ears are phase free. We know phase is very perceptible until 1500 hz. Then becomes less important as you move higher in frequency.

It's an idea that pervades all of laptop & mic-oriented audiophilia.

People believe that humans are frequency response analysers and that if there's a time-of-arrival element to what we hear, it is the alignment of similar spectrograms rather than anything directly in the 'baseband'. Room acoustics are analysed in terms of smoothed frequency responses with the assumption being that human hearing smooths frequency responses too - and that this is all it hears.

The inverted backwave from a dipole would be assumed to be just another source of 'frequency matter' whose effect on the frequency response is a few modified notches and peaks in the general chaos that our hearing just smooths away.

Didn't someone post a few overlaid, smoothed in-room responses a while back, the implication being that if the smoothed frequency responses all look about the same, the speakers must sound the same? This implicitly assumes that the listener is a phase-free frequency response analyser and that they could not possibly be able to tell that part of the picture is timing, phase and polarity.

Most people would say that a source of delayed inverse waveform shows its presence in the way it affects frequency response (too complex for the ear to register explicitly especially after a delay), rather than the possibility that the listener can identify a reflection by its 'baseband' similarity to the original sound. This denies that inverting a reflection would create any sickly 'Whooah!' anti-phase effect, because its effects on the frequency response are just 'chaos' and are smoothed away in both the plot and our hearing.

Edit: I agree with the 1500 Hz figure - if I do the inversion experiment on high pass filtered material, 1500 Hz is about the limit at which I still notice it on music.

 

[RayDunzl]

The inverted backwave from a dipole would be assumed to be just another source of 'frequency matter' whose effect on the frequency response is a few modified notches and peaks in the general chaos that our hearing just smooths away.

Frequency Response, In my room, at listening position.
Blue - curved dipole
Red - conventional with waveguide - positioned a bit high and outboard of the dipole

Blue - curved dipole
Red - conventional cone and dome 3-way - positioned directly in front of the dipole

Same general hash, a little different, because a different set of reflections.

 

[Cosmik]

Frequency Response, In my room, at listening position.
Blue - curved dipole
Red - conventional with waveguide

What is the point you are making there, Ray?

 

[RayDunzl]

What is the point you are making there, Ray?

It bothers me when people keep saying "inverted backwave" when talking about dipoles. You aren't alone in that.

The phase of the recombination of the backwave and directwave at the listening position (I assume that is where it matters to the listener) is dependent upon the distance to the reflector and wavelength of the sound. I don't see the backwave as being inverted any more than I would see the recombination of a bipolar wave as not being inverted, nor the recombinations of a conventional speaker's side/ceiling reflections as having some preferred phase.

If the backwave is a problem with a dipole speaker, my feeble measurements and tin-eared listening conclusions indicate to me it is less of a problem than with a conventional wide-dispersion speaker, that (in my opionion) creates more reflections at higher levels off of more surfaces, resulting in more "chaos" we are supposed to "sweep away" when listening.

I don't have a deadened room, and everybody's mileage varies.

 

[rebbiputzmaker]

What is the point you are making there, Ray?

1. The difference or lack thereof difference in room between box and dipole speakers. 2. Or that blue and red are pretty colors. I would pick number one.

 

[DonH56]

The back wave is out of phase with the front wave, so I guess that would be "inverted", though I used the term to speak of the polarity inversion that occurs when an audio wave hits a hard surface and reflects.

I be an engine-ear, ain't no good with semantics, English, and all that jazz.

Whatever - Don

 

[RayDunzl]

JBL's dark red.
ML's blue.

JBL - light red
Infinity - dark red
ML - blue

 

[Blumlein 88]

JBL - light red
Infinity - dark red
ML - blue

So 50% correct and one choice short of perfection.

 

[Thomas savage]

1. The difference or lack thereof difference in room between box and dipole speakers. 2. Or that blue and red are pretty colours I would pick number one.

Fify

 

[Thomas savage]

Imo we have discovered the issue with ‘ spin o rama’ yes 90 folks vs 30 folks might prefer ‘whatever’ but those other 30 are all wrong ?

Oh well...

Most folk love crap tv and have no idea of anything other than their immediate self so forgive me for not giving two ‘ raspberries ‘ about what ‘someone on paper’ says they think.

 

[Thomas savage]

The moral of the storie is ‘ humans ‘ are weak , pathetic, hopelessly compromised and can’t tell you why they like the sound of this or that so best do a @Cosmik and leve those sorry meat sacks be and rely on what we know humans can hear.

Congratulations to all those scientists that think the sum of human expressed preference is truth .., without knowing the workings it’s all rather folly imo.

 

[Sal1950]

Imo we have discovered the issue with ‘ spin o rama’ yes 90 folks vs 30 folks might prefer ‘whatever’ but those other 30 are all wrong ?

Oh well...

Most folk love crap tv and have no idea of anything other than their immediate self so forgive me for not giving two ‘ raspberries ‘ about what ‘someone on paper’ says they think.

The moral of the storie is ‘ humans ‘ are weak , pathetic, hopelessly compromised and can’t tell you why they like the sound of this or that so best do a @Cosmik and leve those sorry meat sacks be and rely on what we know humans can hear.

Congratulations to all those scientists that think the sum of human expressed preference is truth .., without knowing the workings it’s all rather folly imo.

WTF are you talking bout? Have you forgetten to take your meds today?

 

[Thomas savage]

WTF are you talking bout? Have you forgetten to take your meds today?

If you can’t account for a state of mind don’t relay on ‘anything ‘ your told.

It’s ok , we can leave it all behind given we know how to reproduce sound fields and what happens when sound is fired into small spaces..

No need to ask 100 random folks what they think they like, it changes with the wind. Unless you can explain the mechanism behind preference your shooting blind.

Oh but we twice got 70 30 preference, congratulations lol imo it means nothing and could do more harm than good.