- Full Range Drivers For Open Baffle Design Ideas
- Full Range Open Baffle
- Shooting Range Baffles
- Best Open Baffle Speaker Design
- Baffle Range Hood
- Open Baffle Full Range Speaker
B - High-End Audio design at CES 2003
C - CES 2004 - Does it get any better?
D - Sort of a summary - August 2005
E - Commercial dynamic dipole loudspeakers
F - CES 2006
G - August 2006 - ORION and PLUTO+
H - AES Convention, San Francisco, 2006
I - AES Convention, Rocky Mountain Audio Fest, Burning Amp Festival, October 2008
J - Burning Amp Festival, October 2009
A - Some general observations
B - High-End Audio design at CES 2003
C - CES 2004. Does it get any better?
A full-range speaker needs to be at least 3-way. The typical 2-way speaker can be easily equalized for flat response down to 20 Hz, but it cannot produce sufficient low distortion acoustic output in the frequency range where the ear has low sensitivity. A 4-way speaker should have no such problem, but the design complexity increases dramatically for optimum performance in other parts of its frequency range. The ORION is 3-way.
Then there is the cabinet. Should it be a closed box, vented box, open baffle, or a combination of those? If the low frequencies are reproduced from some form of a box, then the polar response will be uniform or omni-directional up to several hundred Hz. This uniformity in polar response needs to be carried up in frequency and leads to speakers such as those from MBL or the new Beolab 5. In contrast, the vast majority of loudspeakers today are boxes and exhibit increasing forward directivity with increasing frequency. Their power response rolls off at least 10 dB with frequency. Box speakers suffer from strong excitation of listening room resonances in the frequency range below 200 Hz and uneven bass response unless absorptive room treatment is applied. What streaming services let you download to macbook pro?. The Beolab 5 uses a clever woofer equalization scheme which seems to work well. It had, for example, no problem reproducing the very low frequency drum note at the beginning of the 'Temple Caves' track from the Planet Drum CD, when several over $40,000 speaker setups had failed the test.
The open baffle, or dipole, loudspeaker is the least room resonance sensitive platform, though in planar form it suffers from insufficient output at low frequencies. At higher frequencies the planar radiator becomes acoustically too large in size with consequently irregular polar pattern. The ORION, instead, employs acoustically small cone drivers with large excursion capability in an open baffle arrangement and is capable of high volume bass output down to very low frequencies and wide dispersion at high frequencies.
The drivers ultimately limit the accuracy of reproduced sound, ignoring for a moment the recording side of the signal chain. Some of the cone drivers - for lower frequencies - and some of the dome drivers - for higher frequencies - are now the lowest distortion, most reliable and rugged forms of electro-acoustic transducers available. Ribbons are fragile and acoustically too large for a uniform polar response. Horns have linear distortion in the form of resonances, or stored energy, and narrow polar response. The frequency response of any driver can be equalized, but non-linear distortion and stored energy cannot be removed. When I wander around CES I pay great attention to the sound quality of the drivers used by different manufacturers. The cone and dome drivers used in the ORION are as accurate as I have been able to find by listening and by test.
The right drivers can only make for a great speaker when used with a cabinet of proper acoustic and vibration behavior, and with electronics that tailor the frequency response of each driver to obtain minimum distortion and desired overall polar response. In addition, the drivers need adequate power and this is most effectively accomplished by assigning an individual power amplifier to each unit, rather than to use a single, very large wattage amplifier for all of them. This avoids power losses in passive crossover components and gives maximum control over the motion of each driver. It also makes it easier to find amplifiers where the most important 'first watt delivered' is very clean. The ORION uses four power amplifiers per speaker. They are driven from a 3-way fully active electronic crossover/equalizer. All electronic elements are matched to each other for optimum performance.
The driver and baffle dimensions, and their shape, strongly affect the frequency response on-axis and off-axis. From all my experience, I would argue for a near constant directivity that extends from the lowest frequencies up to around 5 kHz. An ideal dipole has 4.8 dB directivity, its frequency response is 3 dB down at +/-45 degrees off-axis, and -6dB at +/-60 degrees. Audi q5 mmi update. This is a good target. An omni-directional speaker would have low frequency and possibly high frequency room interaction that requires treatment. A speaker like the Beolab 5 was designed for wide dispersion in a horizontal plane using a particular layout of drivers and baffles, though this limits the vertical dispersion. On listening, the soundstage seemed to have a slight balcony perspective, which is common with many speakers. The ORION presents a soundstage that is also tall.
A form of linear distortion that is not corrected in the vast majority of loudspeakers is due to acoustic phase shift, if it increases non-linearly with frequency. I have heard speakers from Thiel and Dunlavy, which claim linear phase shift, but cannot say that this feature was noticeable. I have not heard speakers with DSP linearized phase shift, but would not expect anything significant in this regard. My own experiments, and corroborative investigations of others, have convinced me that the 24 dB/octave acoustic crossovers used in the ORION at 120 Hz and 1400 Hz have no noticeable detrimental effect, though they change the shape of the signal waveform.
D - Sort of a summary - August 2005
Here is a 2-way satellite and subwoofer system that was published 1978 in Wireless World. I was aiming for a small box size to obtain wide dispersion. The woofer is flush-mounted to radiate into half-space. The satellites hang from strings and away from reflecting surfaces. The satellites transition from full-space, omni-directional radiation to increasingly forward radiation above 500 Hz, though with a broadening again as the tweeter takes over. Equalized for flat on-axis response, this system is an early attempt at reducing the off-axis frequency response variation which is typically summarized by the 'power response' of a loudspeaker. |
1) A small 2-way closed-box speaker with 8' and 1' drivers crossed over at 3 kHz. 2) The KEF 107 as a 3-way speaker that was typical for good speakers of the time. 3) The L-07 was 3-way dipole speaker with front and rear firing tweeter and a wall mounted closed-box subwoofer. |
Its W-M-T/T-M-W arrangement of drivers narrows the vertical dispersion somewhat and reduces total power output further. The increasing beaming of the front tweeter with higher frequencies and shorter wavelengths is compensated power-wise by a rear tweeter. The surface mounted subwoofer has 3 dB lower total power output than in free-space for the same on-axis SPL. The above power response estimate for the L-07 is an improvement over the 2-way satellite/subwoofer system. This was clearly audible as a smoother and more open sound. |
The Quad ESL-63 electrostatic loudspeaker has been a strong inspiration to me. I loved the neutrality and realism of its sound the first time I heard it. Peter Walker designed it to act as a dipole point source by breaking up the large radiating surface into circular rings which were then driven from a tapped delay line. Besides having exceptionally low non-linear distortion, this is a speakers which has a minimum phase response. This should be of particular interest to audiophiles who consider 'transient perfect response' - as much as that is physically possible in a band-pass system - to be of importance for their music enjoyment. The ESL-63 has two prime weaknesses: Its tweeter disc is acoustically large which leads to beaming and a tight sweet spot. It has limited low frequency output volume and overall dynamic range. I like to listen at near realistic sound levels and so my goal was to design a speaker that preserves the admirable characteristics of this one and some other planar speakers, but without their shortcomings. |
This goal set me on a journey from which the L-07 is an early example. This design became simplified, and was described as a 'compact dipole speaker' in one of my AES papers, using M-T-M main-panels and separate dipole woofers. From this I developed a line of Audio Artistry loudspeakers, the Dvorak, Vivaldi and Beethoven. The PHOENIX project belongs to that family. With the availability of improved drivers it became possible to build an even more compact open baffle speaker, to improve the uniformity of the polar response, to extend low frequency response and volume while maintaining a very large dynamic range. This is the ORION. |
The total SPL capability of the ORION can be further increased by adding two closed box, monopole THOR subwoofers. This might be needed for home theater applications or where extremely high volume levels of music can be tolerated in a domestic environment. This turns ORION into a 4-way system with added crossover at 40 Hz. Now the tweeter becomes the system component that ultimately limits the maximum SPL. |
Similarly, it is the tweeter that ultimately limits the maximum sound output capability of the Audio Artistry Beethoven-Grand. This open baffle speaker, though, was designed for much larger rooms. The symmetrical driver arrangement on the physically very tall main panel maintains a more constant acoustical size of the source and gives increased vertical directivity. Thus the speaker reaches deeper into the room for greater listening distances. The large number of drivers keeps non-linear distortion very low.The dipole woofers employ eight 12' drivers each. |
A loudspeaker of completely different size, cost and shape is PLUTO. It approximates an acoustic point source, an almost perfect monopole. Being omni-directional it has a power response that is essentially flat from 60 Hz to about 3 kHz where it begins to roll off as the speaker becomes increasingly forward aiming due to the increasing acoustic size of the tweeter with increasing frequency. PLUTO illuminates the room very uniformly and thus the response from an acoustically neutral room adds no coloration to the direct sound. Tonality and openness are almost indistinguishable from the ORION when set up corresponding to their reverberation distance. Imaging is superb. The small drivers limit, of course, the maximum low frequency SPL. THOR subwoofers could be added, but that would defeat the speaker's small size and easy portability for optimum placement in small rooms. |
With PLUTO I will put the dot on the i. It's time to relax and enjoy the music!
Full Range Drivers For Open Baffle Design Ideas
2 - The Sound of Audio, Proceedings of the AES 8th International Conference, 1990
3 - Audio, Acoustics & Small Spaces, Proceedings of the AES 15th International Conference, 1998
4 - Auditory Scene Analysis by Albert S. Bregman, 1990. I have the feeling that this subject is worth studying for its possible application to loudspeakers and to sound reproduction in rooms.
E - Commercial dynamic dipole loudspeakers
Over the years I have had stimulating email exchanges with its designer, Kolja Willimzik. |
F - CES 2006
I did see the Jamo R 909 open-baffle speaker and liked its appearance, but could not listen to it on the Convention Center floor. Using passive crossovers to cater to the prejudices of the high-end audio market place, Henrik Green Mortensen had to make design trade-offs in order to approximate the necessary dipole equalization of the woofers. But even so, the advantages over a box speaker design should be clearly audible.
![Full Range Drivers For Open Baffle Design Full Range Drivers For Open Baffle Design](/uploads/1/2/9/4/129447535/696925431.jpg)
G - August 2006 - ORION and PLUTO+
The other problem with boxes is their shape and the panel area to which drivers are mounted. These cause the speaker to be omni-directional at low frequencies or long wavelengths, and to become forward directional at high frequencies. Thus their off-axis response rolls down from low to high frequencies by over 10 dB, the room is illuminated unevenly, and the replicas of the direct sound lack high frequencies causing a dull rather than open sound. PLUTO fires upwards, downwards, and uniformly around over most of its frequency range. In terms of the absence of secondary radiation through the cone, the enclosure walls, and edge diffraction, PLUTO behaves like a box-less speaker.
Finally, most box speakers use vented enclosures which means stored energy to increase otherwise insufficient or distorted bass output. PLUTO+ is sealed with a Q = 0.5 roll-off at the low end of its frequency range for optimum highpass transient response.
H - AES Convention, San Francisco, 2006
I - AES Convention, Rocky Mountain Audio Fest, Burning Amp Festival, October 2008
'Where is the acoustic center for a driver in a baffle? Joerg Panzer, Stan Lipshitz, Jim Hayward, Laurie Fincham, SL | Wolfgang Klippel and John Vanderkooy |
I had interesting discussions with a number of audio engineers about how the brain seems to deal with phantom sources and under what conditions they are located outside the head. They were further motivation to present papers at the next AES Convention in Munich, jointly with Don Barringer, who is experimenting with recording techniques.
Don Naples, Wood Artistry, demonstrates his ORION creation in Bubinga wood with Ebony trim. | . as people listen and Janet Naples looks on |
J - Burning Amp Festival, October 2009Just like last year this was a fun event and a great opportunity to meet interesting people, to talk audio stuff - some of it far out for me - to see unfamiliar products and to do some listening. All this in a relaxed, slightly chaotic happening, but free flowing and with a welcomed absence of 'audiophile neurotics' and in a good spirit. My interest is, of course, loudspeakers and so I looked forward to hearing two exotic full-range drivers that would be mounted in Nelson Pass's large open baffle loudspeakers right on location. The first was a new Feastrex pair, the only one in existence and build with paper cones by a Japanese master craftsman using centuries old techniques for making archival papers. The drivers had very large diameter field coils. So did the Lowther pair, except these were in long cylinders. Both needed magnet supports since the baskets obviously could not hold the weight. The large 15' woofers had their own amplification and there was no shortage of bass output. The full-range drivers were straining and rather colored, though the Lowthers sounded more neutral. It was like viewing a slightly abstract painting when I wanted to see a photograph of the landscape. I did not hear anything that would have given me an incentive to investigate such drivers or to re-evaluate what I am doing. I was quite surprised to learn the retail prices of around $48,000 for the Feastrex pair and $4,400 for the Lowther pair. Nelson showed and used a clever power amplifier with a single depletion mode MOSFET device that he had designed and built the day before the Festival. With a slight amount of FET linearization and about 5W output capability and it was used for the Lowther pair. It all seemed to me an invitation to experiment with audio and to have fun with it. http://www.diyaudio.com/forums/clubs-events/ |
The Burning Amp Festival - 2008 in nearby Sausalito, California, gave me the opportunity to talk about my current preoccupation with phantom images in 2-channel audio playback and how they relate to how our brain has been wired to function for survival over millions of years. This has definite implications upon loudspeakers, rooms and recording techniques. The professional and DIY exhibitors for this one day festival came from a rich variety of backgrounds in amplifier, loudspeaker, turntable and electronic design. Their audience were dedicated audiophiles and each other. This was an opportunity for enthusiasts to meet as they pursue their passion. I briefly demonstrated Pluto-2, driven from an Oppo DV-980H, which generated a welcomed surprise and comments of musicality, imaging and warmth of sound. I had a good time at the event and returned home tired but satisfied from talking with many attendants. |
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A journey through no-brand loudspeaker land - Part I
Four, simple DIY projects
[Italian version]Published: February, 2015
Project 1 - unknown drivers in simple transmission line cabinets
Full Range Open Baffle
Shooting Range Baffles
Project 2 - vintage full-range on an open baffle
Plessey 8' full range drivers