Why spacer strips and not dots?

[Penguin87]

I see a lot of ESL's using long vertical and/or horizontal spacer strips. Given that the area to be supported between the diaphragm and the stator only needs to be 70-100 times the d/s distance, wouldn't it be more efficient to use say 1/4" or 1/2" dots spaced out from each other at the appropriate distance between the d/s? More of the diaphragm would be able to radiate and fewer stator holes would be covered.

I'm not talking about staggering the dots, just replacing the lines with dots every few inches (determined by the 70*diaphragm stator distance).

I suppose there is a reason, but I haven't found any discussions on it. Maybe it's so obvious I missed it, so I thought I'd ask.

[alexberg]

BECAUSE you have to know where to put those things. Calvin claims he knows... but would not tell. Membrane has too many modes it resonates at.

[SM7UYJ]

In my designs I have used strips mainly to gain mechanical stability!

I have tried using "dots" but with the thin sheet metal I use, the d/s distance tended to be uneven -> used strips again.

/R

[bolserst]

Originally Posted by Penguin87

I see a lot of ESL's using long vertical and/or horizontal spacer strips. Given that the area to be supported between the diaphragm and the stator only needs to be 70-100 times the d/s distance, wouldn't it be more efficient to use say 1/4" or 1/2" dots spaced out from each other at the appropriate distance between the d/s? More of the diaphragm would be able to radiate and fewer stator holes would be covered.

I'm not talking about staggering the dots, just replacing the lines with dots every few inches (determined by the 70*diaphragm stator distance).

I suppose there is a reason, but I haven't found any discussions on it. Maybe it's so obvious I missed it, so I thought I'd ask.

Obviously both dots and strips can be used to improve diaphragm stability and define/modify the diaphragm fundamental resonant frequency.

I think what your are asking is why would somebody decide to divide an ESL panel into sections with strips rather than using dots every few inches along the same lines that the strips were to be placed. Your thinking being that using dots instead of strips would free up a bit more radiating area.

Two main reasons I moved from using dots to strips:
1) For me it is much easier and less time consuming to build with strips rather than adding dots.
2) I found it much easier to consistently build ESL panels that don't exhibit any buzzes or rattles when building with strips rather than dots.

Fortunately, for typical ESL panel sizes (5ft - 6ft) tall x (7" - 10") wide) the loss in sensitivity when going from dots to strips is pretty much lost in the noise. I saw < 1dB difference.

[Penguin87]

Thanks for the repsonses. Wouldn't you know it, my connection went out after I posted.

I can definitely see, from a practical stand point, that if you use the spacers as part of the structural support to hold up the stators, strips are better.

All of your explanations help explain the the common choice of strips.

Looking to start an ESL build this fall--what? Fall is here?

[CharlieM]

I'm with Bolserts on this one. I use strips mainly because I have yet to purchase any perf steel that's truly flat and straight. I straighten it as best I can but there are always anomalies and I figure I need the extra glue area the strips provide with about 75 x d/s spacing for stability and to keep the diaphragm centered between the stators-- notice I didn't say the strips make the stators flat & true; rather, they bring the diaphragm parallel to the stators and approximately centered between them. I'm sure glued plastic strips would last indefinitely but I use 1/16 thick 3-M foam tape because it greatly simplifies the construction.