The tubes are made of transparent PVC in rolls 1000 mm high and 0.25 mm thick. It is for sale in meters in the bricocenter. In the cut the thickness of the double-sided adhesive used to fix the edges of the cylinder must be added to the circumference of the loudspeaker. The longest part of the work is to prepare a frame that holds the flaps in place during gluing.
If you do not have to reproduce the bass is also good cardboard 250-300 g/sqm.
The general issue is addressing the rear wave by sequestering or otherwise re-introducing it to the music room without harm to the front wave. I've come to believe that tuned systems* which are the dominant approach today, while very satisfying conceptually playing around with T/S parameters, are by no means the wisest approach.
Which leads me (and anybody who uses dipole speakers) to point out that a major benefit of long tubes of vinyl or concrete-forms is that they release the rear wave quite a distance - physically and room-acoustically - from the driver.
Famous Nelson Pass had a tall music room ceiling and made a 12-foot tube and published favourable comments on it. Right!
B.
*which includes QWTLs and the like as understood today but not really "labyrinths" or leaky boxes
Which leads me (and anybody who uses dipole speakers) to point out that a major benefit of long tubes of vinyl or concrete-forms is that they release the rear wave quite a distance - physically and room-acoustically - from the driver.
Famous Nelson Pass had a tall music room ceiling and made a 12-foot tube and published favourable comments on it. Right!
B.
*which includes QWTLs and the like as understood today but not really "labyrinths" or leaky boxes
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I love writing about my projects, helping me to rearrange ideas and foster their development. If I exaggerate with the space dedicated to the answer, report it.
A premise, the 665g project already works better than any of my optimistic initial predictions. It had to be a simple and inexpensive liquid music speaker for use with my students. After the work I have done in five years I am not able to propose a model that describes the sound reproduced. I only have work hypotheses that could be changed in the future.
I think the sense of hearing has evolved to recognize sounds and at the same time have information about the environment in which the listener is. Listening is pleasant if the sound reproduced is recognizable and compatible with the characteristics of the environment unconsciously reconstructed from the information contained in the reflections.
If the environment has a bad acoustics, even the musical instrument listened to live will cause annoyance. In the case of a reproduction trying to optimize it is simply a lost battle.
In the case where the live instrument can feel good in an environment, then you can try to reproduce it just as well. A perfect system could reproduce the reflections of a totally different environment from the listening room. The brain will struggle to decode where it is. As if faced with a translucent mirror, by adjusting the focus, one sees something or another, the doubt will be: I have to follow the reflected image or the one in transparency.
Assuming you have a perfect system you can pursue two goals:
1 - I want to reproduce also the reflections of the environment used in the recording to get the impression of attending the event,
2 - I want to feel the instruments as if they were in front of me in my room.
In case 1, direct emission speakers are used and the room must be treated to avoid excessive reflections that make the original image confused. The exact position of the instruments can be identified.
In the case 2 dipole or omnidirectional diffusers are able to reconstruct a coherent perception of room, thanks to the wave fronts sent on the walls and subsequently reflected and perceived late by the listener.
The listener must decide whether to close his eyes and believe he is sitting at the theater or invite a jazz band to the living room. It's a matter of personal taste. I prefer to invite the jazz band in the living room. The abundance of reflections generated by the walls can enrich the listening experience and facilitate the recognition of sounds. By correctly positioning the dipole or omnidirectional loudspeakers, the listener after the first wavefront receives a series of reflections that if consistent with the original help to perceive the characteristics of the environment and recognize the sounds. In particular, the 665g speakers add to the first wave front a series of delayed and coherent secondary waves that reach the listener before the reflections generated by the walls.
In summary I think that the presence of delayed and consistent signals improve the quality of listening. Facilitates the recognition of sounds and makes their perception compatible with that of the environment.
A premise, the 665g project already works better than any of my optimistic initial predictions. It had to be a simple and inexpensive liquid music speaker for use with my students. After the work I have done in five years I am not able to propose a model that describes the sound reproduced. I only have work hypotheses that could be changed in the future.
I think the sense of hearing has evolved to recognize sounds and at the same time have information about the environment in which the listener is. Listening is pleasant if the sound reproduced is recognizable and compatible with the characteristics of the environment unconsciously reconstructed from the information contained in the reflections.
If the environment has a bad acoustics, even the musical instrument listened to live will cause annoyance. In the case of a reproduction trying to optimize it is simply a lost battle.
In the case where the live instrument can feel good in an environment, then you can try to reproduce it just as well. A perfect system could reproduce the reflections of a totally different environment from the listening room. The brain will struggle to decode where it is. As if faced with a translucent mirror, by adjusting the focus, one sees something or another, the doubt will be: I have to follow the reflected image or the one in transparency.
Assuming you have a perfect system you can pursue two goals:
1 - I want to reproduce also the reflections of the environment used in the recording to get the impression of attending the event,
2 - I want to feel the instruments as if they were in front of me in my room.
In case 1, direct emission speakers are used and the room must be treated to avoid excessive reflections that make the original image confused. The exact position of the instruments can be identified.
In the case 2 dipole or omnidirectional diffusers are able to reconstruct a coherent perception of room, thanks to the wave fronts sent on the walls and subsequently reflected and perceived late by the listener.
The listener must decide whether to close his eyes and believe he is sitting at the theater or invite a jazz band to the living room. It's a matter of personal taste. I prefer to invite the jazz band in the living room. The abundance of reflections generated by the walls can enrich the listening experience and facilitate the recognition of sounds. By correctly positioning the dipole or omnidirectional loudspeakers, the listener after the first wavefront receives a series of reflections that if consistent with the original help to perceive the characteristics of the environment and recognize the sounds. In particular, the 665g speakers add to the first wave front a series of delayed and coherent secondary waves that reach the listener before the reflections generated by the walls.
In summary I think that the presence of delayed and consistent signals improve the quality of listening. Facilitates the recognition of sounds and makes their perception compatible with that of the environment.
Nice post, to my mind very well expressed. Personally I prefer the "they are here" approach, and yes, I feel more comfortable with that. I would just like to add that I think the alternative, in practice, is a losing game in the normal home listening environment
I had look at the DIY info for building this DIY Thanks for making it public.
I'm not sure where I could buy the specified plastic film locally, but I get the general idea. It would be interesting to use a set of nested pipes to tune the length as well as amount of top diffuser exposed.
That is an interesting explanation. I use both a HT 5.1 system and an 2.1 Omni system in an manner that's consistent with that description. I prefer #2 for music.
Claudio's analysis of room sound is quite brilliant and deserves wider attention through a thread of its own.
The familiar, if naive, argument for "you are there in Carnegie Hall" (option 1) really depends on a substantial suspension of all the many cues discrepant with Carnegie Hall and supporting the perception of your little music room with speakers. Anybody ever confused a photo of a cow in a field with looking at a cow in a field? BTW, one of most dramatic system spatial demos I ever heard was a system played behind a curtain. No kidding.
The second option, "they are playing in your little room", leading to endorsement of omnidirectional speakers is curious and not something you'd believe off-hand because it is counter-intuitive to the Blumlein model, eh. Wouldn't most people assume a perfect point source is the ideal? As a full-range electrostatic speaker enthusiast for the last 40 years, I find that dipoles produce the best stereo sound; I need to keep my panels quite close together in order to avoid noxious ping-pong effect.
B.
The familiar, if naive, argument for "you are there in Carnegie Hall" (option 1) really depends on a substantial suspension of all the many cues discrepant with Carnegie Hall and supporting the perception of your little music room with speakers. Anybody ever confused a photo of a cow in a field with looking at a cow in a field? BTW, one of most dramatic system spatial demos I ever heard was a system played behind a curtain. No kidding.
The second option, "they are playing in your little room", leading to endorsement of omnidirectional speakers is curious and not something you'd believe off-hand because it is counter-intuitive to the Blumlein model, eh. Wouldn't most people assume a perfect point source is the ideal? As a full-range electrostatic speaker enthusiast for the last 40 years, I find that dipoles produce the best stereo sound; I need to keep my panels quite close together in order to avoid noxious ping-pong effect.
B.
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Ben - since that last sentence above was the first time I think I recall you mentioning spacing of your ESLs - have you ever posted a picture of them, or at least mentioned their placement with respect to the dimensions of the room and primary listening position?
Chrisb - my bad for tossing that out without more detail. Many snowstorms from my Toronto home just now, so no pix.
Panels about 40+40 degrees from my seat, walls about 12 feet apart, stereo stage sounds good about only 2 feet gap between (which leaves edge of each panel maybe 2-3 feet off from adjacent wall) And maybe 2-3 feet from their behind-wall, as usual with ESLs.
Funny you ask, on my bucket list is a total wall of ESP panels. (I have them in a large box right now.... as soon as I figure out how to matrix the L and R among the cells.)
B.
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The distinction of my previous post is to explain which environments are suitable for 665g speakers. My evidence shows that the 665g speakers work well if the wall reflections can be easily perceived by the listener. The same behavior I believe is common for omnidirectional systems.
In environments treated to eliminate most of the reflections 665g speakers are not recommended, they lose in the high band. The sound becomes too soft. In the loudspeakers, the emission of high-frequency energy is concentrated in a frontal lobe. The same speaker in omnidirectional configuration redistributes the energy to 360 degrees decreasing by a few dB the acoustic pressure compared to that present in the frontal lobe. Further attenuation caused by walls treated with absorbent materials may be excessive.
An environment where 665g speakers sound good is visible on the page
misure
The empty rear wall behaves like an acoustic mirror, the same applies to the 3 meter high ceiling. The room is about 4 x 4 meters. Sitting in front of the monitor or on the sofa on the opposite side, listening is good. The system also liked people playing the piano, they appreciated the fact that even at close range the point origin of the sound was not perceived.
Applying my logic I think that the electrostatic dipole speakers should work well in reflective environments but it is only my hypothesis, I do not have the support of a direct experience.
In environments treated to eliminate most of the reflections 665g speakers are not recommended, they lose in the high band. The sound becomes too soft. In the loudspeakers, the emission of high-frequency energy is concentrated in a frontal lobe. The same speaker in omnidirectional configuration redistributes the energy to 360 degrees decreasing by a few dB the acoustic pressure compared to that present in the frontal lobe. Further attenuation caused by walls treated with absorbent materials may be excessive.
An externally hosted image should be here but it was not working when we last tested it.
An environment where 665g speakers sound good is visible on the page
misure
The empty rear wall behaves like an acoustic mirror, the same applies to the 3 meter high ceiling. The room is about 4 x 4 meters. Sitting in front of the monitor or on the sofa on the opposite side, listening is good. The system also liked people playing the piano, they appreciated the fact that even at close range the point origin of the sound was not perceived.
Applying my logic I think that the electrostatic dipole speakers should work well in reflective environments but it is only my hypothesis, I do not have the support of a direct experience.
For dipole speakers Linkwitz recommends that the reflections are not absorbed but rather defused, I have not experimented with this as my front wall, like yours is more like a mirror. It is generally accepted that they should also be delayed by a minimum of 6mS, which means having them at least 3 feet from the wall. The reduced 90 degree dipole radiation also minimises the first reflection from the side wall which can help as this is often slightly too early.
Have you experimented with your speakers farther from the walls?
Have you experimented with your speakers farther from the walls?
updates 665g
Hello to all
I want to report some updates to my project 665g.
I have worked on a new type of support that improves the soundproofing between the loudspeaker and the worktop
DIY
I made measurements in two different rooms
misure
Other material for DIY:
home,
desktop,
installazione.
Claudio
Hello to all
I want to report some updates to my project 665g.
I have worked on a new type of support that improves the soundproofing between the loudspeaker and the worktop
DIY
I made measurements in two different rooms
misure
Other material for DIY:
home,
desktop,
installazione.
Claudio
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
MDD Multi Delays Difraction
Hi everyone
in the new site: Claudio Gandolfi - MDD I published the projects of the new prototypes: 439h, 419h and 227h derived from the old models 665g, 621g, 666g, 667g and 669g.
These are acoustic speakers that use the Huygens principle to spread all spectrum frequencies at 360 degrees.
With a series of waveguides of different lengths, secondary and consistent sound waves are emitted at different points in the space.
I called this technique MDD Multi Delays Difraction.
Soon the old robinsrl.it site will be decommissioned, the contents of the main pages will remain available for download in pdf files at the end of the contact page: contatti.
Claudio
Hi everyone
in the new site: Claudio Gandolfi - MDD I published the projects of the new prototypes: 439h, 419h and 227h derived from the old models 665g, 621g, 666g, 667g and 669g.
These are acoustic speakers that use the Huygens principle to spread all spectrum frequencies at 360 degrees.
With a series of waveguides of different lengths, secondary and consistent sound waves are emitted at different points in the space.
I called this technique MDD Multi Delays Difraction.
Soon the old robinsrl.it site will be decommissioned, the contents of the main pages will remain available for download in pdf files at the end of the contact page: contatti.
Claudio
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