I am trying to keep up with posts on this thread tonight but things are getting a little disjointed so bear with me if I miss something,.
I cannot photo the lines this week as we are re-decorating the lounge and making it more music friendly, however I have some photos of the line arrays I took at the old Cumbrian address that are on Photobucket at the following links :-
http://i700.photobucket.com/albums/w...Picture036.jpg
http://i700.photobucket.com/albums/w...Picture039.jpg
and the power amp :-
http://i700.photobucket.com/albums/w...lhynes/SE1.jpg
and the line preamp :-
http://i700.photobucket.com/albums/w...nes/VCCS1C.jpg
Anyone wishing to experiment and use these designs for their own personal system is welcome, but please do not use them commercially without arranging a license, as this is very disrespectful, and one of the main reasons people do not publish details of their design work nowadays.
Chris (technobear),
The efficiency gain is frequency dependant and gradual. Horn-loaded systems display this effect for different reasons.. The higher frequencies tend to beam and not reinforce, but the low frequencies couple and reinforce. With a bit of care with the selection of drive units, this can give a relatively flat response down to the low frequencies.
Another attribute of the line source is the wave front generated is essentially cylindrical in its expansion into the listening area. A floor to ceiling line source would show no ceiling or floor reflection removing a prime source of room interaction. Any reflection off the side walls sounds like venue reverb. In this instance as the line are open baffle there is a reflection from the rear wall, like planar speakers. If the line arrays are orientated correctly, the delay time is long enough not to interfere with leading edge information and the imaging remains intact with the reflection once again sounding like venue reverb. Venue reverb is normal and we tend to accept it accordingly.
I am aware of the phase plug options but I am not finding problems with beaming in reality. Once again this is a natural phenomenon and I think our brains may just ignore the effect as long as it is not exaggerated. When I get some time I will experiment with the recommended phase plugs to see how they affect behaviour with the line array.
Richard,
You are quite right about the commercial issues and domestic harmony. This is why I have not bothered to market the line arrays. However I think I am one of the lucky ones in that my lass and my daughter both love music and film, and art in general for that matter, so I can do what I want with the AV system even though it is in the main lounge. With this system I have not been working on a commercial solution, it is purely for myself and I will follow my wildest dreams to get the system where I want it to be. Speaking of dreams, I often dream up solutions to engineering problems while asleep. Does this happen with you too? It can save a lot of R&D time if the dream works in real time.
Ali,
The B200 is a good driver with the right parameters for use on open baffles. It is not perfect like every other driver, but it does have that musical magic that few modern drivers, that I have tried, seem to have. As you have some to listen to you will know what I mean. I did consider large diameter bass units in the early stage of my B200 experience but the benefits of the line array were drawing me like a siren. The reason the line arrays do not sum higher up the frequency bandwidth is due to the directional nature of the higher frequencies. The further up the bandwidth you go the more directional the beam becomes. This does increase combing effects. Even with a single source, as soon as the wave front hits an obstacle and is reflected back into the sound field, a combing effect will occur. For those mot familiar with this terminology, a combing effect occurs when two or more wave fronts collide and intermingle causing reinforcement, or cancellation, depending on the relative phase of the wave front. This is a natural phenomenon and the brain accepts it as normal.
The B200 line array is 2 metres tall.
You are lucky that your lass has the same love of music as you do.
John,
The line arrays are not as overpowering as you might think, as the baffles are quite slim. Tall maybe, but slim. Is the Ben Harper you refer to in your musical appreciation the son of Roy Harper?
Anthony,
Line arrays are used a lot in Pro Audio for good reason, so I am not surprise you are familiar with them. OK, they are relatively big in the domestic environment. If you want to have a go with them I will load the original drawings on Photobucket and post links on this thread. The concept will work with other drive units as long as they are happy working on an open baffle and have a reasonable bandwidth. I have tried some lower cost full range drivers but the results were less satisfactory. In fact I have just skipped a load of unsatisfactory drive units. Recycled properly of course.
Paul
