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Hi-Fi An accidental discovery!, I made my speaker "disappear".

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TSVagueConcerns
post Oct 2 2015, 03:29 AM, updated 9y ago

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I'm up late, I'm bored, and so I decided to design another enclosure. I removed one of speaker drivers to put them in the new enclosure I'd be making tomorrow.

I rested it on a tall basket with a rug on top, and naturally they pointed up. I had the TV hooked up to them, and it was as if the sound wasn't coming from the driver! Usually with many speakers I'd have to close my eyes to fool myself. If I look directly at a pair of stereo speakers, I can tell even with a strong centre audio playback as if the stereo speakers are two mono sources.

But in this case, I am 3 feet away and I couldn't tell that the driver is making the sound. I have to have my face right up to it to break the illusion. I moved about in the room, sitting and standing and it's still invisible. Without the enclosure it was plasticky and thin, but the illusion is fantastic! Tried it with the other one but it didn't work. I suspect he position was off, and the condition wasn't correct. So the effect I got from the other driver is a fluke. Still though, I would like to recreate it again, in a multi-way configuration, like Linkwitz's Pluto.

If I could get it to work in stereo I wonder how the soundscape will be portrayed?
TSVagueConcerns
post Oct 2 2015, 05:09 PM

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Hehe. I couldn't sleep so I decided to fool around the house, making new things. I just cut the wood for the new speakers just now. All I tried to do was take the dimensions of the speaker driver, and I found that, of course I'm excited. biggrin.gif

There it was sitting 3 feet away from me and I'm staring at it convincing myself that it's the driver! This isn't "disappear" as in correct tonality, big soundstage, real instrument and vocal sounds, etc. I have heard those. This is none of those, it just achieved a certain sound dispersion/directional characteristic, but with none of the Hi-fi sound quality.

It's kinda like an open baffle, but with the null region pointed at the listener instead of the speaker cone itself. I have mounted them on an open baffle for burn-in a year ago (40cm x 130cm) before the baffle was cut to size. The effect didn't happen then. I didn't try pointing the null region pointed at me though. I could try once I acquire more wood in a few days. biggrin.gif
TSVagueConcerns
post Oct 2 2015, 07:24 PM

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QUOTE(penmarker @ Oct 2 2015, 05:20 PM)
I remember one time a year or so ago, it was in Asia Sound Equipment in Amcorp Mall, 1st floor.

There was a turntable setup playing a lady blues singer. The speakers completely disappeared. It literally sounded like a woman singing in front of my face. As if her face is in front of my face.

I walked towards the turntable and the closer I got to it, the closer her face is to my face. My brain cannot process that, and it was out of my mental capacity to digest that a voice is there but a body isn't.

I tell people that and they don't get it. They can't imagine that, I myself can't imagine that, but it happened. Can you imagine your brain short circuiting because you're hearing a physical voice without a physical body?
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That's exactly the experience. There was no speaker, just an invisible singer somewhat. laugh.gif

Anyway, I have posted the same thing over at diyaudio, and a forumer pointed me to a thread. The builder had his speaker driver setup very similar to my accidental setup. He had an 8-inch Fostex full range that is mounted in a small enclosure (looks to be sealed), but only 8 inches high from the floor and pointed up. It wasn't an open baffle though, but the speaker's placement and design was to produce VERY early reflections. It was essentially coupled to the floor, and the very early reflections allow minimal colouration (by not having them too out of phase/time to the original wavefront I would imagine, I don't know, probably). The design goal was to have the loudspeaker fit the room, instead of modifying the room for the speaker, and to reproduce a sound people would expect when played in a real physical world.

That forum can be ridiculous most of the time, but you can learn a lot from those guys. Seems that quite a lot are skeptical that it would work, but if I can do it accidentally, then I think there's some merit to that design.

Being so sensitive to positioning, no wonder I didn't get it for the other one.

This post has been edited by VagueConcerns: Oct 2 2015, 07:50 PM
TSVagueConcerns
post Oct 3 2015, 03:04 AM

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Thanks for the suggestion.
I'l have fun experimenting. biggrin.gif
TSVagueConcerns
post Oct 4 2015, 04:06 AM

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QUOTE(fx20 @ Oct 3 2015, 10:40 PM)
Research reported this phenomenon is all due to how your brain perceive the sound wave.
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Of course it is. It's how to trick our brains into falling for it is the difficult part (even more so making the sounds "accurate").
The timing and intensity etc. of the entire frequency range has to be correct in order for our brain not to be able to triangulate the sound source.

This post has been edited by VagueConcerns: Oct 4 2015, 04:09 AM
TSVagueConcerns
post Oct 5 2015, 01:13 AM

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QUOTE(fx20 @ Oct 4 2015, 11:40 PM)
This "accurate" thingy is pretty subjective, especially using our ears.
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Yes, hence the quotation marks I put for "accurate".

Though we need to remember that, subjective opinions on accuracy can only be judged by people who know how something should sound in real life. For example, if you've never heard a flamenco guitar in real life and have only ever heard them through your high-end setup at home using a hi-fi audiophile quality CD, then you have no right to say of its accuracy in reproducing the sound of a flamenco guitar. Just as well, if in real life you can't differentiate between a Kapok and a Gibson, or a 6-string to a 7-string, then you still can't say anything of a setup's accuracy. So eventhough it's subjective, a judgement of accuracy cannot be made just by anyone. It's like judging Gymnsatics. It's subjective, but there are guidelines and professionalism involved.

P/S: When I say 'you', I meant putting ourselves as the subject of my example. biggrin.gif

This post has been edited by VagueConcerns: Oct 5 2015, 01:44 AM
TSVagueConcerns
post Oct 6 2015, 04:04 PM

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QUOTE(runemastertan @ Oct 6 2015, 12:59 PM)
A speaker does not need to be very high quality. Placement and environment are very important. I learn this the hard way LOL.  But yes, speaker can seems to disappear, and the singer seems to be singing in front of you. This soundstage and imaging are very important criteria. I first experience this with Aego M, such a small speaker but that feeling it gave me still stick in my mind. And to make this mind blowing, the player used on that speaker was just a low end Yamaha amp and sourced from a PC using AUDIO jack LOL. I have no idea what DAC or sound card it uses
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Yup. No need to get ultra high-end if you know what you're doing. It's integrating the speakers with the room, that's the most important thing.
TSVagueConcerns
post Oct 6 2015, 09:46 PM

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QUOTE(penmarker @ Oct 6 2015, 06:46 PM)
When I had that experience maybe the speakers are placed perfectly apart from each other, but the room itself doesn't seem to have any treatments because all around the store there are other turntables and amps and speakers. The most impressive thing was how I can walk towards the turntable and the illusion was still unbroken. The closer I went toward it, the closer I got to the singer's face. Which is amazing, because the speakers were probably only 3-4 feet high, and the image was in front of my face not at the speaker height.
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The "Tubifex" is an interesting DIY speaker that achieves that effect as well (according to the creator). Parts aren't that expensive, the instructions are clear, and the enclosure is made of PVC pipes of different sizes. I have thought about making one, but it would be a waste of money. It doesn't look like something my mum would allow in the living room, and I won't be home 2/3 of the year to listen to it in my room, and it's too big to bring to uni.

If you have a little money to spend, and you want to try out DIY, maybe this project can re-live that experience, for a fraction of the price of a commercial unit. biggrin.gif

This effect seems to be quite prominent with cleverly designed multi-ways, and/or speakers with minimal baffle area.

This post has been edited by VagueConcerns: Oct 6 2015, 09:47 PM
TSVagueConcerns
post Oct 13 2015, 12:10 AM

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QUOTE(power911 @ Oct 12 2015, 05:01 PM)
true illusion is when you're watching a ghost movie and you felt the location of the ghost thanks to your hard efforts of speaker placement
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Haha. That is the dream.
Thinking of making a pair of floor-standers for HT much much later (when I have the funds).
I'm thinking of making a 2-way, but instead of the usual tweeter+woofer combo, I'm thinking of subwoofer+fullrange(sealed). I'd call it a subwoofer assisted full-range. tongue.gif
TSVagueConcerns
post Oct 13 2015, 09:00 PM

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QUOTE(peter32 @ Oct 13 2015, 02:41 PM)
May I know how far apart did you place the speaker pointed upwards, and roughly how far away from the wall ? 

Were they close to the side wall as well ?

I happened to have a pair of unused Fostex which I maybe experimenting in the future.
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It was only with one speaker. The speaker was completely without an enclosure and pointed straight up. It was very close to the wall, about 2-3 inches away. From the side wall it's about 3 feet.

 

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