Acoustic Horn Design – The Easy Way (Ath4)

[Horneydude]

So a CD device that projects a narrow sound field, like f.e. a 30x40 degrees pattern is not a beaming device?
I still tend to think the difference is only in the width of the sweetspot.

 

[VoxCelestial]

I'll order filament to print two waveguides. This looks really good but if you decide to change anything there is still time.


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I'm not an expert of mabat's caliber, but doesn't it beam too much? Somewhat less than LeCleach (7 to 13 dB rise from 1 to 15 kHz vs 10 to 22 dB), but I'm not sure why one would design in such slope. E.g., ST260 has very gently rising DI of about 10 dB.

 

[camplo]

that the anechoic chamber would be the best, virtually without decay. No, it wouldn't - it sounds unnatural to have no reflections. We are used to hear reflections, all the time. We know how to deal with them. We are tuned to process reflections.

Did I actually say it was "the best" though? Nope

All I said is that the lower the reflective sound, the more you can hear the Direct sound accurately. Details can be hidden due to reflective sound, consequently, due to exaggerated duration via the room, masking the direct sound. Studios go through grave lengths to lower room sound in order to hear direct sound with clarity for the same reason.

 

[mabat]

...like in a Le'Cleach horn, then there are other ways of tuning the room for a satisfactory listening experience -but those may be more difficult indeed.

I already asked - how do you "tune" the colored reflections, lacking high-frequency energy? That can't be done by diffusion, nor absorption in any practical way. No matter what you do, you end up with lacking HF energy (unless in an anechoic room).

If you say it sounds good to me, that's all fine, but once you try to explain it, it just doesn't fit.

 

[mabat]

All I said is that the lower the reflective sound, the more you can hear the Direct sound accurately.

That immedaitely means that no reflected sound is the most accurate situation possible, right?

 

[camplo]

If you consider accuracy to mean unadulterated sound, yes

Accurate - 1. : free from error especially as the result of care. an accurate diagnosis.

In an anechoic chamber, you can hear:

• Direct sound only - without any reflections or reverberation. Sound decays very quickly once the source stops.
• Extreme clarity and articulation - since there is nosound masking or integrating over time. Very detailed.
• Lack of warmth and body - without the help of reflections to reinforce the direct sound. Can sound thinner.
• No sense of space or room ambience - just the raw direct sound, detached from any environment. Sense of space is missing.
• Apparent increase in high frequencies - due to lack of air absorption of highs that normally happens with reflections.
• Very focused and precise imaging - with no reflected sounds to smear the location of sources. Pinpoint accuracy.
• Any background noise is more noticeable - footsteps, breathing, etc with no other sounds to mask them.
• A strange feeling initially - since our brains are used to hearing spaces, not non-spaces. Can feel unnatural.

So in summary, an anechoic chamber provides a very clinical, detailed, but potentially unnatural listening experience with no ambience, just precision direct sound. It reveals detail very clearly.

 

[mabat]

but I'm not sure why one would design in such slope.

It's in the context of the @CinnamonRolls' speakers. I already tried to explain it -
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7398813
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7399191

It's just an experiment. And hopefully a very interesting one.

 

[VoxCelestial]

So a CD device that projects a narrow sound field, like f.e. a 30x40 degrees pattern is not a beaming device?
I still tend to think de difference is onlynin the wjth of the sweetspot.

No, it is not. We judge beaming, with regard to sound quality/fidelity, as a relative parameter: is beamwidth at, say, 7 kHz close to a beamwidth at 700 Hz? Or, looking at it another way, do reflections have similar spectral content to direct sound? So, I think, a 30x40 degree source would sound "right", if it's really 30x40 down to Schroeder (which is rare in practice). After all, large line sources with constantly narrow vertical directivity do sound great.

 

[Horneydude]

lready asked - how do you "tune" the colored reflections, lacking high-frequency energy

Yes it can be done with diffusion on the wall behind your listening position. The beam of high freqs passes behind you and scatters in a random way, bouncing around the room non-correlated until it decays. The result is a reverberation field that fill in the lack of reflections you get with a beaming device. You have to keep the front part of the room lively, not absorbing.

 

[mabat]

But how does that deal with the lack of HF energy, that's simply absent in virtually all of the reflections? I think it doesn't.
You can say that it doesn't matter...

 

[camplo]

Adding reverb to a recording that already includes its own reverb isn't more natural is it? Essentially, the rooms reverb changes the original space in the recording.... the recording already has space recorded in it. I guess the issue is that you may only have 2 channels in front of you.
If we have an Atmos set up in an anechoic chamber, I bet that it will sound fine. At the end of the Day, High DI in a room will never be anywhere near as dry as an Anechoic chamber. Larger rooms like movie theaters are mid and high frequency dry, compared to a living room, no complaints there. High DI makes the room sound, treated and larger.

 

[mabat]

If we have an Atmos set up in an anechoic chamber, I bet that it will sound fine.

Simulating all the reflections from different directions, yes. You can indeed simulate a (very) large room this way. You can't do that in a small room that's too lively, that's true.

 

[camplo]

I think people forget that music recordings are not dry at all and already have space recorded in them.

 

[VoxCelestial]

Yes, but should we really have more space at midrange than at HF?

 

[mabat]

It's not a "space" you could re-create with a playback in an anechoic chamber with just two front stereo channels. That's more something like a reverb.
For a real sense of space you need the reflections to come from all different directions - like also from behind you.

 

[camplo]

It's not a space you could re-create with a playback in an anechoic chamber with just two front stereo channels

Agreed.

 

[wesayso]

Even in nature, the high frequencies fall off more quickly .

A slowly rising DI would mimic nature, a flat DI would have to have a bend somewhere, because low frequencies are omni.

 

[camplo]

Don't you mean, Outside

 

[mabat]

Not as soon as for a JMLC horn

(I think that we need the reflections to be spectrally the same mainly to fool the hearing not to recognize immediately it's actually just two speakers playing a stereo track.)

 

[camplo]

(I think that we need the reflections to be spectrally the same mainly to fool the hearing not to recognize it's actually just two speakers playing a stereo track

Finally you come out with it.... you could of said that 2 pages ago

You will never submit to the experience so you will never know.... I have the horn you hate, not JMLC but Tractrix. At no point have I thought...."man, I really am lacking in HF reflections compared to the mids" or "the high frequency clarity vs what mids are doing, sure makes it sound like 2 speakers are playing".

In signal design, reverb (and volume) can be used to affect proximity now that I think about it. For that reason, I say that Constant Directivity is important..... Yet I still feel, Higher Directivity is more important, as room decay mask details. One can learn to adjust for something they do not hear correctly, like proximity or verb in a mix for example.... one cannot adjust for something that they never heard due to masking. Exaggerated Decay affects level perception. SPL is perceived more precisely with less room decay

I'm not saying Constant Directivity doesn't matter.... I am saying, for me, High directivity matters more.