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Multi-Way Conventional loudspeakers with crossovers

Cloning a 00 Speaker for 0
Cloning a 00 Speaker for 0
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Old 2nd June 2010, 11:21 PM   #21
toptip is offline toptip  United States
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Originally Posted by Patrick Bateman View Post


The speaker is a Beolab3. It uses an unusual enclosure shape to reduce diffraction, and an acoustic lens and waveguide to shape the polar response of the tweeter.

I have a pair of these speakers. I originally bought them as a portable, "better" music source during vacations, etc. They fit neatly into a cardboard mailing tube which avoids damage at the bottom of a suitcase.

As to the sound... It is a bit of a disappointment, frankly. Despite the solid build, there is an unmissable "computer speaker" sound, like deep but underdamped bass being wrung out with a high Q tuning. Something artificial about the midrange too, like you get with excessive DSP or equalization. Curious what other members think? I have been unwilling to mess with a $3K toy so far but now (three years post-purchase) I am thinking of pulling out some leads from the output of the amps to run an external two-way speaker to see if the fault lies with the electronics or the mechanical tuning. Why use a class-D amp for the tweeter anyways? How much power can a 3/4" unit handle -- 3W?
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Old 3rd June 2010, 03:04 AM   #22
trusound is offline trusound  United States
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I had a few conversations many years ago with Manny Lacarrubba who is the inventor of the lens and it's applications for cars... and due to the non compete with B&O, it didn't go anywhere..

But after years of installing and listening... nothing has.. and I mean nothing has worked better then a traditional 2 or 3 way placed optimally, lessening tactile energy transfer... you really need to go to a MECA finals and listen to these cars before over complicating things
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Old 3rd June 2010, 06:27 AM   #23
navin is offline navin  India
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Quote:
Originally Posted by MaVo View Post
EDIT: just realized you want to use it in a car. i dont know how omni designs work in a car, but as the boundaries are even closer, i think you will listen to alot of very early reflections with omni speakers.
Some 6 months ago a friend of mine got a new German car. I dontknow if you guys get it in the US - it is called the Audi A8. At first I was looking for the speakers but up on the dash poped up a pair of wave guide tweeters that look very similar to what is being shown here. On top of the tweeter was written Bang and Olufsen.

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Originally Posted by cuibono View Post
I got two working systems, pretty cheap, and they look to be about the same idea. The thing is called the Spherex Xbox 5.1
When my sister was looking for a compact 5.1 system for her TV we auditioned the Mirage Nanosats. The sound did not impress and she finally settled for the KEF KHT3005. The Nanosat looked very simlar to these Spherex speakers.

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Originally Posted by trusound View Post
But after years of installing and listening... nothing has.. and I mean nothing has worked better then a traditional 2 or 3 way placed optimally
I agree, In larger cars a 8" 3 way can fit in the door in smaller cars a 6" 2 way in the front door works well to create a nice soundstage. If you are really getting into car audio do checkout what the guys on diymobileaudio are doing.
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Old 12th June 2010, 05:45 PM   #24
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by toptip View Post
I have a pair of these speakers. I originally bought them as a portable, "better" music source during vacations, etc. They fit neatly into a cardboard mailing tube which avoids damage at the bottom of a suitcase.

As to the sound... It is a bit of a disappointment, frankly. Despite the solid build, there is an unmissable "computer speaker" sound, like deep but underdamped bass being wrung out with a high Q tuning. Something artificial about the midrange too, like you get with excessive DSP or equalization. Curious what other members think? I have been unwilling to mess with a $3K toy so far but now (three years post-purchase) I am thinking of pulling out some leads from the output of the amps to run an external two-way speaker to see if the fault lies with the electronics or the mechanical tuning. Why use a class-D amp for the tweeter anyways? How much power can a 3/4" unit handle -- 3W?
That's unfortunate to hear. I listened to the top of the line from B&O in Portland a few years ago, and was impressed. It reminded me a bit of my Summas. The treble seems a bit "wonky" at first, because we're not accustomed to constant directivity. Once your ears adjust, it's difficult to go back.

OTOH, their top of the line speaker is much less compromised than the lower models, because it uses a larger waveguide and a larger enclosure.

And how do you have them installed in your room? I had a hell of a time coming up with a good location for my Summas, since constant directivity loudspeakers are sensitive to early reflections. (In a conventional loudspeaker the treble "beams" forward, so preventing reflections can be as simple as rotating the loudspeaker. In a CD loudspeaker, the off-axis response is quite similar to the on-axis response, so pulling the speakers away from the walls makes a noticeable improvement.)

In other words, do you have your speakers set up as far from the walls as is practical?

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Old 22nd June 2010, 11:06 PM   #25
toptip is offline toptip  United States
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I do not think positioning will change my particular complaint (the speaker has switches in the back for wall-corner-free space positioning, BTW). It just seems to me when the size of a speaker gets reduced this much and yet the designer is still trying to get a reasonable amount of bass out of it, something nasty happens. Maybe a variety of middle frequencies reverberate inside or some bass bump is introduced which muddies the midrange (all guesses, no real idea what it is...).

I recently bought a pair of Beolab 4000s, which are slightly larger and there is none of this problem.

It is interesting: perhaps because these speakers are laughably expensive ($3-4K/pair), there are almost no reviews on the internet.
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Old 7th October 2010, 12:35 AM   #26
Antonyhu is offline Antonyhu  Australia
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Any more progress with creating these lenses for the car patrick?

Ant
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Old 7th October 2010, 11:09 AM   #27
whgeiger is offline whgeiger  United States
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Default Acoustic Lens

An AES paper [1] is available that discloses details of the "lens" design used in the Beolab3. While it exhibits the behavior of a divergent acoustic lens, it reflects acoustic energy, it does not refract it. When signal wavelength becomes comparable to, or larger than its dimensions, the device loses its divergent properties; i.e., it becomes "transparent" to a low frequency signal.

Regards,
WHG

Ref.: [1]
File: AESP-2392
Title: 360 Degree Dispersion Frequency Invariant Acoustic Transduction System
Author(1): Ferralli, Michael W.
Author(2): Moulton, David
Affiliation: Phase Coherent Audio, Inc.,Girard, PA
Publication: AES-P No. 2392, Cnv. 81 (Nov-1986)
URL: AES E-Library: 360 Degree Dispersion Frequency Invariant Acoustic Transduction System
Abstract1): An acoustic transduction system has been designed which couples the sound field of two transducers in phase and produces a resultant acoustic radiation pattern which has a full 360 degree horizontal by 90+ degree vertical frequency invariant beam-width. The system incorporates an acoustic lens, rather than a phased array or electronic technique, to couple the sound fields and produce the wide dispersion.
Abstract2): The system is used in a loudspeaker to achieve a 360 degree sound field which is devoid of high frequency beam collapse, and combing.
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Old 7th October 2010, 11:51 AM   #28
whgeiger is offline whgeiger  United States
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Default "Lens" Ref. Correct

Sorry! Related, but wrong reference given. Here is the correct one:

File: AESP-5648
Title: Driver Directivity Control by Sound Redistribution
Author(1): Pedersen, Jan Abildgaard
Author(2): Munch, Gert
Affiliation: Acoustics Research, Bang & Olufsen, Struer, Denmark
Publication: AES-P No. 5648, Cnv. 113 (Oct-2002)
URL: AES E-Library: Driver Directivity Control by Sound Redistribution
Abstract1): The directivity of a single loudspeaker driver is controlled by adding an acoustic reflector to an ordinary driver. The driver radiates upwards and the sound is redistributed by being reflected off the acoustic reflector. The shape of the acoustic reflector is non-trivial and yields an interesting and useful directivity both in the vertical and horizontal plane. 2D FEM simulations and 3D BEM simulations are compared to free field measurements performed on a loudspeaker using the acoustic reflector.
Abstract2): The resulting directivity is related to results of previously reported psychoacoustic experiments.
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Old 7th October 2010, 05:11 PM   #29
glasswolf is offline glasswolf  United States
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waveguides (HLCDs) are outstanding in a car, but the trick to using them is that for them to sound right, you have to use 1/3 octave EQs on each horn, and tune them with an RTA. Otherwise they are far too difficult to control, particularly in such an adverse environment. I've worked with horns in cars before, and it's quite a bit of work.
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Old 8th October 2010, 05:05 AM   #30
TerryO is offline TerryO  United States
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Quote:
Originally Posted by glasswolf View Post
waveguides (HLCDs) are outstanding in a car, but the trick to using them is that for them to sound right, you have to use 1/3 octave EQs on each horn, and tune them with an RTA. Otherwise they are far too difficult to control, particularly in such an adverse environment. I've worked with horns in cars before, and it's quite a bit of work.
I know that Paterick has been doing the SOTA car audio horn thing for quite a few years and, in my opinion, has had some of the best car audo I've ever heard. His mini-unity horns that I heard a year ago in his Honda were stunning!

Best Regards,
TerryO
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