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TOPIC: new type omnidirectional loudspeaker 665g

new type omnidirectional loudspeaker 665g 1 year 8 months ago #34816

  • claudiogan
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Hello
I'm Claudio Gandolfi I want to report my project "665g". My English level is lower of Google Translator. I used it for this message.

The prototype "665g" is visible on the website
www.robinsrl.it.
in a desk configuration.
Replica for personal use is allowed for do-it-yourself.

Use
www.robinsrl.it/diy_10.html
(pictures and instructions for DIY)

The main technical characteristics of the 665g loudspeakers are:
- emission of coherent and delayed secondary sound waves without the use of electronic circuits and / or multiple loudspeakers,
- single driver with Fait Pro 3FE25 broadband speaker,
- omnidirectional in the horizontal plane,
- no internal sound reflection.

In environments with acoustically absorbing material, omnidirectional emission reduces the level of high frequencies. To compensate for the attenuation use a DSP.




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new type omnidirectional loudspeaker 665g 1 year 1 month ago #37971

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The 669g project upgrade the 665g project, the acoustic screen is rigid and the acoustic transformer use paper. More bass, less distortion.
The 669g loudspeaker is a single-driver with multiple section acoustic load.

At link www.robinsrl.it more information and more projects 621g 665g 666g 667g.

All distortion and frequency response measurements are done with miniDSP UMIK-1 Omni-Directional USB Measurement Calibrated Microphone.



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new type omnidirectional loudspeaker 665g 1 year 3 weeks ago #38111

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Very interesting theory and for trying something new! We ought to read a bit more so we understand here.. :-)
What's lowest frequency you can down before these paper assembly start to resonate? (i.e. paper is quite flexible.. :-)

DevTeam
MiniDSP, building a DIY DSP community one board at a time.
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new type omnidirectional loudspeaker 665g 1 year 3 weeks ago #38119

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The folded paper is flexible and inelastic, in the 669g diffuser it replaces the dampening material used in the TL cabinet ducts, at:
www.robinsrl.it/misure_8.html
you can see the effect on the impedance of multiple paper ducts in projects 669g, 667g and 666g.
The resonance damping of the rigid part of the TL is increased by the use of waveguides of different length in parallel.


The paper as an inelastic damping element does not have a minimum operating frequency.
The reproduction quality remains excellent as long as the section deformation is linear with respect to the acoustic pressure.
The limit is not in Hz but in dB. The maximum SPL depends on the precision of the construction and the quality of the gluing.

The 669g project shown in the photos is made by hand with the help of a frame and works well at 90 dB in a 4 x 4 x 3 m room.

A secondary effect of the paper tubes is to increase the average length of the TL and reduce the reproducible minimum frequency.
It can be verified by comparing the frequency response graphs of the 666g, 667g and 669g projects.

The primary purpose of paper tubes is to emit delayed, attenuated and coherent secondary waves with respect to the primary emission of the underside of the loudspeaker.
Further information on the operation: www.robinsrl.it/index.htm.
Section 3 implements the waveguide acoustic transformer.
Section 4 implements the waveguide acoustic diffractor.
The technologies are protected by a European patent but replicable for personal use.

Further information on the acoustics of 6XXg projects: www.robinsrl.it/installation_14.html.
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MDD Multi Delays Difraction 4 months 6 days ago #42164

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Hi everyone

in the new site: www.claudiogandolfi.it 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.

All measurements were taken with the UMIK-1 MiniDsp microphone.





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.

Claudio
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