ESS HEIL membranes

[automojo]

Room acoustics also play a part, as well as crossover points.
Same goes for bass output, as all manufactored driver response graphs below 200hz are only a estimate, as room acoustics play fairly large here.
Your best bet is to have a woofer in the low to mid 90's.
It's usually a tradeoff between slightly higher bass distortion and extension-depening on how deep you want to go. Some woofers like going up a few hz higher then fs, some right around it. Also excursion limits are something to look at if you plan to play them loud.
The latest woofers I'm looking at sound very clean but are close to x-max 7 hz or sobelow the tuning frequency (fs as well)-granted this is at 250 watts-so I'm not too worried.
You also should provide some padding for the Heil-all ESS speakers had a way on managing the Heil output.
The set of network resistors on the AMT3 works perfect if you don't like l-pads-but regardless I would use some sort of adjustable padding.
Things change withn equipments/rooms etc, and I wouldn't want to be stuck with having to redo the crossover.
Regardless of what the specs are for the "New" Heils-they still have respectable output.
They are what they are, as well as the company-the glass is have empty, or half full depending on your perspective, just like anything in life.

 

[el seven]

The sensitivity baseline would account for approx. 3db, if I remember right.(apples to apples) ... the diaphragm differences I'd have no idea (lacking both examples).

What I do know is that my experiences with the heil sort of mimics what djnagle has found. My woofer is around 92db eff. My AXO has input level meters and it's able to adjust db levels to match output signal. It takes 3-4db of boost to align the output of the woofer to the heils. (this is taking the human ear out of the equation).

While 100db is not a real level, considering the 8-4ohm factoring ... it is definitely hovering around 94-95db IME here (with the newer versions of diaphragm).

As an aside, I've seen Nelson Pass mention that the heil actually performs as a 6ohm driver.**(load presented to the amplifier) So, perhaps a straight 3db reduction in the sensitivity figures is not appropriate either.

We need to take into account the load every single time we test. While changing input parameters is what some say is an apples to apples argument i don't agree. If apple a) is 1w and apple b) is 2w then i see that as one apple having twice the flavor of another.

So back onto the load stipulation, each membrane swap is akin to pulling the voice coil out of a motor and replacing it with another voice coil. And even more so the "cone" of a said conventional driver is being swapped. Mr Pass was conveying the very early 6ohm diaphragms which were then-folded and today we're talking about a now-folded 4ohm unit. As the information here presents itself, the 6ohm unit is not applicable for comparison since that data isn't currently presented. I will agree that those early membranes prove fairly well in test.

The newer versions as it were, have never tested 94-95db 1m/1m with the current membrane under scrutiny, which always plays a major role. The polyamide tested in Frankfurt ranks well due to a) 2.83v @ 4ohms and b) the inherent integrity of that given substrate. If we run a mylar substrate, we will achieve vastly different results. Like changing out the entire cone and motor, let's not forget.

Tests i've seen on the 4ohm mylar membrane hover between 90.8 and the topside of 91 with load placed in an anechoic room. While we don't know the environment of the polyamide tests we do know, that 2.83v @ 1m into a 4ohm load was presented to us, in an unknown environment. Could've been all software and no acoustical amplitude / attenuate semantics portrayed but, again we don't have this information. Knowing Herman i would say he did whatever he could to augment the results. Polyamide does perform better than mylar, this i can confirm.