Hello All,
Don't know if this is the proper description of this type of ESL; where the diaphragm size gradually gets larger from top to bottom. Something akin to a Sound Lab speaker.
As with most flat panel ESL's, my previous ones were very restrictive in listening position; I needed a tennis ball strategically hanging from the ceiling where my nose should be for optimum imaging. An inch side to side was noticeable and could become very tiring.
From reading several post at DIY on dispersion it seems I had three choices to broaden the 'sweet spot': 1-angled or curved panels, 2-segmented wire stators using resistors to vary the frequency, or 3-decrease the size of the radiating area.
I knew curved was out of the question for my abilities, while angled panels might have future possibilities. Segmented stators showed promise, but for my limited knowledge of electronics seemed a little too complicated, especially for the type of wire stator I'm familiar with building. That left smaller 'cell' panels which I thought would be the easiest to build, but at the cost of diminished output and bass response.
A review on a Sound Lab speaker made me think that gradually increasing the size of the diaphragm possibly could help with the two issues of smaller diaphragms. I am sure I've read posts here at DIY that question the effectiveness of this design, but figured it might be fun to give a try. It was never the intention to build a complete system initially, just a few experimental panels to start out. However after making the jigs and templates, I found myself in full production mode. Having a blast. Just like a kid building a giant model kit.
Had no idea of proper sizing, specs, formulas, etc.. Just dove into it. From a little research, a 3 inch width sounded like it should work well. The Sound Lab reviewer seemed to think that the length started out at 2 1/2 inches so thats where I began. I just randomly chose a 1/2 inch increase for each diaphragm. Since I wanted to reuse my existing Magnepan wood moulding and base, the 1/2 increases took me down to a final diaphragm length of 6 1/2 inches. I later added a two cell panel of 7 inches horizontally(still not sure if that was a mistake).
For ease of construction(although much more time consuming!), smaller plastic panel frames were used. All are 5 inches wide and average around 17 inches in length. I figured this way if I ever wanted to add on I could build more, or eventually have two rows facing forward and one row on each side slightly angled for even better dispersion.
I'm a slow typer and getting a little tired so will give some detailed impressions later. I will say this, though, the sound output is diminished, but not by much. The bass response is lower than the older panels but inconsistent. The dispersion is greatly improved! I can now swing the tennis ball a foot side to side. More importantly I can wake up from a stupor in my listening chair with my head nodded to one side and still be hearing a good image.
Below are a few pictures. Wished they were more clear, but the camera didn't always like focusing on the stators. Will post more if there's interest. Any comments or suggestions are greatly appreciated.
Bondsan
Don't know if this is the proper description of this type of ESL; where the diaphragm size gradually gets larger from top to bottom. Something akin to a Sound Lab speaker.
As with most flat panel ESL's, my previous ones were very restrictive in listening position; I needed a tennis ball strategically hanging from the ceiling where my nose should be for optimum imaging. An inch side to side was noticeable and could become very tiring.
From reading several post at DIY on dispersion it seems I had three choices to broaden the 'sweet spot': 1-angled or curved panels, 2-segmented wire stators using resistors to vary the frequency, or 3-decrease the size of the radiating area.
I knew curved was out of the question for my abilities, while angled panels might have future possibilities. Segmented stators showed promise, but for my limited knowledge of electronics seemed a little too complicated, especially for the type of wire stator I'm familiar with building. That left smaller 'cell' panels which I thought would be the easiest to build, but at the cost of diminished output and bass response.
A review on a Sound Lab speaker made me think that gradually increasing the size of the diaphragm possibly could help with the two issues of smaller diaphragms. I am sure I've read posts here at DIY that question the effectiveness of this design, but figured it might be fun to give a try. It was never the intention to build a complete system initially, just a few experimental panels to start out. However after making the jigs and templates, I found myself in full production mode. Having a blast. Just like a kid building a giant model kit.
Had no idea of proper sizing, specs, formulas, etc.. Just dove into it. From a little research, a 3 inch width sounded like it should work well. The Sound Lab reviewer seemed to think that the length started out at 2 1/2 inches so thats where I began. I just randomly chose a 1/2 inch increase for each diaphragm. Since I wanted to reuse my existing Magnepan wood moulding and base, the 1/2 increases took me down to a final diaphragm length of 6 1/2 inches. I later added a two cell panel of 7 inches horizontally(still not sure if that was a mistake).
For ease of construction(although much more time consuming!), smaller plastic panel frames were used. All are 5 inches wide and average around 17 inches in length. I figured this way if I ever wanted to add on I could build more, or eventually have two rows facing forward and one row on each side slightly angled for even better dispersion.
I'm a slow typer and getting a little tired so will give some detailed impressions later. I will say this, though, the sound output is diminished, but not by much. The bass response is lower than the older panels but inconsistent. The dispersion is greatly improved! I can now swing the tennis ball a foot side to side. More importantly I can wake up from a stupor in my listening chair with my head nodded to one side and still be hearing a good image.
Below are a few pictures. Wished they were more clear, but the camera didn't always like focusing on the stators. Will post more if there's interest. Any comments or suggestions are greatly appreciated.
Bondsan