Bacek

To get raw idea you can check T2A specs. Shouldn't be far, but this has fixed 4dB attenuation.

Ok, I found another example. This time on K33 (B?) actually. Previous movie looks more professional but treatment is similar.

Found some tutorial on JBL speaker. Probably that part was missed. So for K33 I too should use polyvinyl glue?

For a long time I had 2 square magnet K33 laying in boxes. One is fine. The other had strange measurements, was lacking low frequencies when mounted in La Scala. On closer examination it accrued that cone surround is "untreated", just clean fabrics that leaks air. To me looks like someone did recone but kind of wrong way. Cone part number seems to be same for both 451520-2, although one is R-451520-2 (R recone?). So question is if anyone knows if surround needs to be somehow treated/sealed on recone operation? Or maybe replacement cone should be "factory" treated and someone did something relay wrong with it? If possible I would like to fix that driver. First pic is faulty driver. Second one is working fine. You can clearly see treatment on second one. It glow slightly.

Not sure where you are buying it but current APT driver is not the same as originally used in Klipsch mods. In the meantime (few years ago) Eminence changed to some Chinese supplier and this is actually different driver even though it looks similar. Somewhere here there is Bob Crites thread with measurements of this new one, and it looks inferior.

One thing about T2A. In spec -3dBa setting is documented as "-3" and it's actually -3.38

Another thing I like about FIR filters that they don't change phase at crossover point. So signals from two drivers are always adding or subtracting (depending on a choice) and we avoid those strange wobbles near XO point where phase changes several times.

But in LaScala or KHorn, horn loading increases impedance. So even if nominal free air or infinitive baffle impedance is 4 Ohm when placed inside of a horn enclosure, impedance raises, it can be even doubled.

Tried to play little bit with FIRs and my crossover (Najda DSP). Unfortunately low frequency filtering has huge processing requirements. My XO allows only 1024 tapes per channel, mini dsp 2048. Good starting point would be 10k and more for sub. Anyway FIR's allow for very steep XO points. -90dBa is not a big deal.

Is this oil stained or lacquered?

Ok but while i remember correctly k55 impedance i k400 there is not more than 10% impedance variance in usable range. Does it this justify that large attenuation swing?

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This we actually know. Check PWK article on previous page. Although I never understood this measurement effect and if it's something general or rather it was artifact of that particular test circuit.

"eg build the original Heresy (or Klipschorn) according to its original specs" But what does it mean original specs? For Klipshorn exact set of drivers and horns from 1947? Not sure it's possible and it makes sense.

Does it mean that Klipsch does not produce Klipsch speakers anymore? Or they again use autoformerts? Anyway from Chief bonehead comments on other topic, if you put anything into a Klipsch speakers they are no longer Klipsch speakers (key word is you, not LPAD, and I get this point of view). But I have trouble following this thread. What was actual question that started this topic? I miss some context in here. Who advises L Pads and for what purposes and where and in contrast to what?