Understanding Danley Synergy ?
Looking at line-array-paper.pdf it states this
Furthermore, i can see how the horn dimensions would be fine for the Mid/Tops, but for the Bass it seems extremely foreshortened. How does it manage to achieve an f3 of 50Hz ?
Read the patent. Much more info there:
Time delay is achieved by the phase rotation caused by the low pass cross over. The bass has no horn loading, but is placed where it is to form a point source. The reflex port helps with extension and efficiency.
Hi, i read the patent, but you know what the're like for gobblygook talk :D in amongst the interesting details !
Thanks for the info :)
I'm surprised the SH-50 is only 100dB @ 2.83V @ 1M. Especially as it's rated @ 4 Ohms !
Hi Zero D
To understand how they work, start with subwoofers. If you take two identical subs and put them side by side, they are not twice as loud but 4 times as loud, 6dB. Take 4 and put them side by side and now they are +12dB or 16 times louder than one. You are putting in 4X more power but get 16X as much sound because they couple acoustically and act as a single larger and more efficient driver.
When drivers are about ¼ wavelength apart or less, they combine like this, into one more efficient source. If the spacing is larger than about 1/3 wavelength, the sources radiate as individual sources and the coupling and acoustic efficiency increase does not occur Two or more sources radiating the same signal from different locations, produces an interference pattern, a series of lobes and nulls as one moves around the loudspeakers radiation space.
The object of the Synergy horn is to combine multiple drivers, covering multiple frequency ranges into one single horn radiation, without any lobes and nulls and in most cases, to eliminate the phase shift the crossovers normally add. A loudspeaker like that SH-50 has constant directivity and you can walk up, even put your head into the horn and there is no trace of anything but one source floating in front of you.
It can reproduce a square wave over a broad band and by measure, by listening, by radiation pattern, it appears to have one crossover less driver.
We aren’t selling these for the home, an SH-50 works fine (I use them) but they are large and not pretty. As much as possible, my general objective is very large scale hifi sound.
The sensitivity is limited to about 100dB because the cabinet is constant directivity and has a wide pattern (50 by 50 degrees) all the way to the top. If the horn narrowed up high, the on axis sensitivity could be higher but then it wouldn’t be CD..
Prosound Network: Danley Sound Labs SH-50 Loudspeaker
If you have headphones, you can hear the difference this “single source” radiation makes in large scale sound where many large concert line arrays in sports stadiums have fallen to be replaced with a relative few Synergy horns.
Penn State Demo.MOV - YouTube
2 boxes replace 44 line cabs
Danley Sound Labs Jericho on Ledreborg 2012 - YouTube
Unlike most loudspeakers, the spectral balance doesn’t change with distance.
Newnan High School, Newnan Georgia - Latest Danley Jerico JH90 Stadium Speaker Technology by Performa Technologies, Inc. on Vimeo
the smallest of the J series synergy horns.
Danley Sound Labs - YouTube
same demo but at 500+ yards
Jericho Horn J3 Debut - YouTube
I have seen the 6dB figure explained as 3dB due to the increase in surface + acoustic coupling and 3dB due to the VC in parallel resulting in half the impedance, so double the amplifier power (3dB).
Also the OP was asking about the physical distance/offset between the drivers, high, mid, low and how they are maintained in phase, since the woofer (for example) is a good distance in front of the HF driver.
The OP's drawing is based on centers of voice coils, which sometimes works as a crude approximation of difference between acoustic centers, but doesn't indicate the actual acoustic centers even without a horn involved. It's a smart question even if the drawing is wrong, though.
Hey Tom, if I may be so bold, I suggest this is the question the OP needs answered:
Does the device...
1. Physically align the effective acoustic centers of the drivers into a point source right from the get-go? In that case, the crossover can keep them as such, or rotate 360° or whatever, and keep getting great results. The OP might appreciate an explanation of how their drawing should look to accurately reflect the acoustic centers. Or...
2. Physically align the acoustic centers such that while they are not actually equal in path length, it is easy for the crossover to bring them into good phase tracking on axis, and the horn is what manages to keep that working off-axis. In that case, it doesn't matter as much how the OP's drawing is off, only that they are close enough to make it work, which obviously they are. I realize #1 would also rely on the horn in a different extent, but ya know..
I've never really looked into it much to be honest. I just accepted it worked one way or the other, and both sound like a good trick to me, and I'm too lazy to try to figure it out right now but felt like posting anyway :D.
Group delay inherent with drivers and crossovers is significantly compensated for by the driver layout, resulting in speaker that does reproduce good approximation of square wave over portions of spectrum. Similar performance has been achieved with more conventional speakers with front baffles tilted back.
More important than the absolute phase performance is constraint of effective acoustic centers of drivers to approximately 1/4 wave separation distance through crossover points. This completely eliminates lobe behavior in both vertical and horizontal plane.
Driver separation on flat baffle with WTW or WMTMW layouts typically fail to get 1/4 wave distance of crossover point as separation of acoustic centers. Simple example: 6" driver and 1" dome tweeter. Discounting driver frames, acoustic centers on flat baffle can be no closer than 3.5"; this is 1/4 wave length for about 964Hz. Use of this as crossover point with typical 1" dome and typical crossover slopes isn't done because it leads to very poor power handling and IMD for tweeter. When 1" dome with magnet and face plate are accounted for, acoustic center spread increases.
Speakers such as Linkwitz Pluto overcome this too, but what Tom has with his design is suitable for PA, cinema, and for home use for those who have the space.
Yeah, but the distance between the mid and the compression driver in the Synergy is far more than 1/4 wave at the xover point of the compression driver - no doubt higher than "964Hz", therefore a smaller distance would be required.
The issue isn't so much a good phase relationship between any two drivers around the xover for flat response, as much as it is having them sum properly when looking at an impulse. If they can't do that then they can't "reproduce a square wave". I'm speculating that this may be the key to how the distances were figured out in practice. The xover's phase flip may also play a role in the spacing...
I'm guessing that Tom doesn't really want to comment on this point, since it may be something of a proprietary "secret".
The distance between the drivers isn't a big deal at any real distance. At 100' if the drivers are 4' apart then the path length difference would be sqrt(100**2 + 4**2)-100 or under 1 inch.
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