- 2014-12-16 1:52 pm
If such an area is increased three times more, then the bass will still be "caressing".To be clear, I am not talking about increasing sensitivity(SPL out for voltage in) but rather increasing maximum SPL output capability. For mid-HF range, the on-axis sensitivity of two panels will be essentially the same whether they are side-by-side, or stacked one behind the other.(again with the caveat that you need to keep spacing between the diaphragms to a minimum. For mid-HF you can adjust transformer design and gap to get most any sensitivity you are after. But, the max SPL is fixed by the area of the panels used since the available driving force per unit area is a fixed quantity for ESLs. Also, efficiency is kind of irrelevant with ESLs since it is so high that essentially all the power dissipated by the driving amplifier is due to the transformer and any crossover parts. In my experience, it is becomes difficult to get max SPL > 100dB unless you start narrowing the dispersion. Even segmenting the panel and using RC or LC transmission lines, you are still left with conflicting requirements resulting in compromises between max SPL and polar response. The Quad ESL63 is a case in point with a central disk of about 14cm diameter to reach 105dB.
I agree that(if domestically acceptable) the best path for woofing with dipole ESLs is increase the area as much as possible. But you may still reach the limit of your room size before target SPL. See example SoundLab ESLs with extra woofer panels. Even those used double diaphragms.
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This is because the ESL motor is very weak.
This construction will not give a real energy of the drum a priori.
Only an isobaric will give the desired effect. And then an isobaric with multiple membranes, but not two or three. I went through all this in practice, and not theoretically.