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Open baffle speaker design

Sal1950

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Thread Closed For Further Comment.
 

Cosmik

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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.
But of course music isn't steady state and comprises asymmetrical transients, so an inversion is real, and not just a change of relative phases of sine waves. If your hearing expects a time domain similarity from a reflection, the inverted version is genuinely different in the time domain and, who knows, may even seem like a different source.

So if your hearing is deciding on a likely location for a source (even a phantom source) and you shift position a few inches or turn your head, which is more likely to be easier to interpret: the source that radiates positive only and the reflections thereof, or the source that sprays some positive and some negative? If the answer is "I can't see any inverted stuff in the frequency response" then that is missing the point I would say. And ditto for "Everything reflected is chaos, so it's just a question of the balance and smoothness of the collected 'frequency matter'".

Our hearing clearly picks up more than just the balance of 'frequency matter' (the headphone experiment shows this because the frequency responses and timing between the channels are identical but we still hear a clear difference when the inversion is present).

But anyway, I'll shut up about it. It's another thing to add to the list of things where simplified audiophile hardware gives arbitrarily complicated behaviour, and complicated hardware (with a bit more woodwork to do in this case) gives simple, straightforward behaviour. I like to keep it simple, anyway :)
 

Fitzcaraldo215

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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.

What? You actually tried and believe a sighted, uncontrolled listening experiment you yourself conducted on yourself? We all know well from you that any results derived from listening by others is all easily dismissable garbage, even if done scientifically and carefully controlled. How can this mundane listening possibly compare to your infallible simple logic derived from your own infallibly selected assumptions? Are you perhaps changing your tune, or at least, changing it only when you, yourself, are the listener? I mean, I thought from you, we could just reason all this audio stuff out in pure theory, and there was no need to actually listen or to conduct controlled empirical studies gathering data from all those arbitrary, impertinent human subjects.
 

palamudin

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What? You actually tried and believe a sighted, uncontrolled listening experiment you yourself conducted on yourself? We all know well from you that any results derived from listening by others is all easily dismissable garbage, even if done scientifically and carefully controlled. How can this mundane listening possibly compare to your infallible simple logic derived from your own infallibly selected assumptions? Are you perhaps changing your tune, or at least, changing it only when you, yourself, are the listener? I mean, I thought from you, we could just reason all this audio stuff out in pure theory, and there was no need to actually listen or to conduct controlled empirical studies gathering data from all those arbitrary, impertinent human subjects.
 

Blumlein 88

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But of course music isn't steady state and comprises asymmetrical transients, so an inversion is real, and not just a change of relative phases of sine waves. If your hearing expects a time domain similarity from a reflection, the inverted version is genuinely different in the time domain and, who knows, may even seem like a different source.

So if your hearing is deciding on a likely location for a source (even a phantom source) and you shift position a few inches or turn your head, which is more likely to be easier to interpret: the source that radiates positive only and the reflections thereof, or the source that sprays some positive and some negative? If the answer is "I can't see any inverted stuff in the frequency response" then that is missing the point I would say. And ditto for "Everything reflected is chaos, so it's just a question of the balance and smoothness of the collected 'frequency matter'".

Our hearing clearly picks up more than just the balance of 'frequency matter' (the headphone experiment shows this because the frequency responses and timing between the channels are identical but we still hear a clear difference when the inversion is present).

But anyway, I'll shut up about it. It's another thing to add to the list of things where simplified audiophile hardware gives arbitrarily complicated behaviour, and complicated hardware (with a bit more woodwork to do in this case) gives simple, straightforward behaviour. I like to keep it simple, anyway :)

Okay, what about real sources that have inversions of polarity about a symmetric axis? Dipolar sources in other words. Like I don't know......maybe....a kick drum. Other drums and percussion gear, sometimes oriented in various angles from the listener. Yet we don't have an ear malfunction unable to hear those or where they occur. We seem to be able to listen thru the reflections just fine. Do drums become distorted in a way that invalidates seal box speakers for reproducing drum sounds in a room? Would only panel speakers be appropriate for drums?

Further perhaps figure of 8 or dipolar microphones should only be used for recordings that will be played back upon dipolar speakers. Or maybe dipolar sources, dipolar microphones and dipolar speakers have to go together.
 

rebbiputzmaker

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Further perhaps figure of 8 or dipolar microphones should only be used for recordings that will be played back upon dipolar speakers. Or maybe dipolar sources, dipolar microphones and dipolar speakers have to go together.
And maybe only for listeners suffering from bipolar disorder.
 

Wombat

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And maybe only for listeners suffering from bipolar disorder.

Making a joke like this one shows a lack of compassion for the suffering of others.
 
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rebbiputzmaker

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Making a joke like this one shows a lack of compassion for the suffering of others.
Are you sure about that? Can you provide objective data, to support your comment?
 
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Wombat

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Are you sure about that? Can you provide objective data, to support your comment?


See post #87.

FYI: Heightened intolerance to sound is one of the distressing symptoms of bipolar disorder.
 
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Wombat

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Blumlein 88

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Making a joke like this one shows a lack of compassion for the suffering of others.
I'm okay with that.

Not that I lack compassion. Would I say that next to a person with the disorder? NO. OTOH, on an open public forum, if someone has the disorder I don't think they get to prevent all mention of it which isn't geared toward displays of compassion or help with the disorder. That becomes ridiculous.

Otherwise I would also ask for moderation if people speak disparagingly of my panel electrostats like has happened his in this thread. Do you people lack compassion for us dipolar owners? Don't be ridiculous.
 

Wombat

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I'm okay with that.

Not that I lack compassion. Would I say that next to a person with the disorder? NO. OTOH, on an open public forum, if someone has the disorder I don't think they get to prevent all mention of it which isn't geared toward displays of compassion or help with the disorder. That becomes ridiculous.

Otherwise I would also ask for moderation if people speak disparagingly of my panel electrostats like has happened his in this thread. Do you people lack compassion for us dipolar owners? Don't be ridiculous.

No, I don't have bipolar disorder but I have known some who did. Terrible affliction, often fatal. Not funny. Enough said by me.
 

SIY

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Otherwise I would also ask for moderation if people speak disparagingly of my panel electrostats like has happened his in this thread. Do you people lack compassion for us dipolar owners? Don't be ridiculous.

A random question: should dipolar be the polar pattern of choice for speakers reproducing a recording made with figure 8 mikes, and point source be the polar pattern of choice for recordings made with omnis or cardiods?
 

Jakob1863

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What? You actually tried and believe a sighted, uncontrolled listening experiment you yourself conducted on yourself? We all know well from you that any results derived from listening by others is all easily dismissable garbage, even if done scientifically and carefully controlled. How can this mundane listening possibly compare to your infallible simple logic derived from your own infallibly selected assumptions? Are you perhaps changing your tune, or at least, changing it only when you, yourself, are the listener? I mean, I thought from you, we could just reason all this audio stuff out in pure theory, and there was no need to actually listen or to conduct controlled empirical studies gathering data from all those arbitrary, impertinent human subjects.

Maybe i´m mistaken, but i think you misinterpreted his statements in this regard.
Cosmik would probably dismiss more easily a "scientific listening test" using a panel of "middle aged men" but did acknowledge that "informal" listening usually played a role.
 
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