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Baffle step logical error
Baffle step logical error
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Old 15th May 2019, 04:34 PM   #1
bentoronto is offline bentoronto  Canada
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Baffle step logical error
Default Baffle step logical error

The fretting about baffle step issues results from the error of "hearing" with your eyes.

When you look at the theoretical damage done by a step or edge on a freq response trace, it looks terrible. But when you are listening to music (or white noise) two things are different.

First, there is no step to hear; nothing is "happening" except some undetectable small deviation in loudness in a narrow band. Harmonic distortion is something happening and you might hear it.

Second, there is no baseline from which to hear the deviation; with your eyes, you want to see a flat line but with your ears, there is no such line, just tone colour.

Think of somebody playing a guitar. Each note has partials and other bits of grace all over the place. By eye, that would be different, but by ear just how would you know if the player was wearing a sweater while playing that day? There's no baseline.

I think things are a bit different with reflections and their timing. A thread for another day.

B.
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Old 15th May 2019, 04:58 PM   #2
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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It also depends of the ear of who are listening. For example, I am not unable to distinguish La 440 from La 432, but I can recognize small levels of distortions.
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Old 15th May 2019, 08:56 PM   #3
RobWells is offline RobWells  United Kingdom
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I'd only want to see a flat line if I was floating in space...

When you say 'small deviation in a narrow band' and it could in reality be everything under 300hz down by 6db I disagree that it is 'undetectable'

Rob.
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Old 15th May 2019, 09:53 PM   #4
AllenB is offline AllenB  Australia
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Ben, would you say the same if you were listening to monopoles?
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Old 15th May 2019, 10:01 PM   #5
bentoronto is offline bentoronto  Canada
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Baffle step logical error
Quote:
Originally Posted by AllenB View Post
Ben, would you say the same if you were listening to monopoles?
Glad to reply but what is "the same [thought]" you are referring to?

B.
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Old 15th May 2019, 10:23 PM   #6
AllenB is offline AllenB  Australia
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Designing a system to blend in with the room, against attempting to work around the room.
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Old 15th May 2019, 10:42 PM   #7
ICG is offline ICG  Germany
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Location: I had a Déjà Moo - I've seen that BS before!
Quote:
Originally Posted by bentoronto View Post
The fretting about baffle step issues results from the error of "hearing" with your eyes.

When you look at the theoretical damage done by a step or edge on a freq response trace, it looks terrible. But when you are listening to music (or white noise) two things are different.

First, there is no step to hear; nothing is "happening" except some undetectable small deviation in loudness in a narrow band. Harmonic distortion is something happening and you might hear it.
Well, the deviation in loudness in a certain frequency band (not always that narrow) actually is one (or the biggest) of the effects. It does not add distortion but it can change the room impression and dispersion pattern, depending on the frequency and the baffle dimensions.

Quote:
Originally Posted by bentoronto View Post
Second, there is no baseline from which to hear the deviation; with your eyes, you want to see a flat line but with your ears, there is no such line, just tone colour.
Well, a non-linear frequency response is a colouring of the sound. The theoretical dramatic change often does not happen that extremely in praxis. That's because of 3 things:

Firstly, the sound source isn't a point, even at fullrange or coax speakers, it's always an effective surface of a certain size, depending on the geometry of the membrane and partitial movement and frequency - membranes do not move uniform as a perfect cylinder (or whatever the shape of the membrane is) over the whole frequency range (there are a few exceptions like plasma, ESL and some foils).

Secondly, if you don't use the worst case (a round baffle with centered driver), the actually effective membrane surface got a different distance to the edge. Both 'smears' the baffle step a good way over a certain frequency range. With an exact positioned measurement microphone you can still measure it but the tonality of the sound also consists of the indirect/reflected sound in the room which can partly smooth it out a bit. That has an effect on the room impression or how some details of a voice or instrument is perceived though.
Generously rounded edges or bevels at the edge of the baffle also reduces the effect of the baffle step, sometimes drastically. Absorbent foam or fabric layer on the baffle can reduce it too (especally at high frequencies).

Thirdly, it depends on the directivity of the driver. A fullrange driver, a horn or waveguide probably already starts to beam at the frequency of the baffle step and the reflections of the sound waves are already on a lower loudness and therefore not adding much up to hardly anything.
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