New Heathkit AS101 owner - First post.

[voice of the theater]

But I can't quite get my brain around why the horn itself would have such limitations. I gather the curve of the horn structure is tuned to maximize a certain frequency range, but what would happen if you put a 500Hz signal into an 811b horn, assuming the driver itself could handle it? Of course a sound would come out, but what would be happening to it to make it undesirable? Inquiring minds want to know.

I think part of the reason that you never got an answer to your question (above) is that it was "buried" at the very end of your post. Now, due to inactivity, your thread is buried under many active threads. This post will bring it back to the "top of the deck".

I'm not sure of the specifics and I know there are people on our forum who would have a much more precise/accurate answer (I've been waiting to reply, hoping that one of these people would chime in with an answer for you). My best attempt at an answer (partly an educated guess) is that it's not just the curve of the horn structure (as you suggested) that determines it's frequency response characteristics, it's also the size. For example, your 811b horn is considerably smaller than Altec's 511b horn which I've owned in the past (which has a rated frequency response down to 500 hz). On the other hand, the smaller Mantaray horn in my Model 14's isn't considered usable below 1200 hz. I think even in the absence of all the scientific data, you will have trouble "picturing" a 500 hz signal coming out of a tiny three or four inch horn (to use an extreme example to illustrate my point). As far as the other part of your question, if I were to venture an educated guess, I would say that if you use a 500 hz crossover through an 811b horn, you will not get a flat response down to 500 hz and there will most likely be a "hole" in your sound (weaker/less output as you approach 500 hz). I don't (and Altec doesn't) recommend going below an 800 hz crossover point with this horn. Not sure what else the 811b horn will "do to" the sound below 800 hz, but I'm (fairly) certain that using a 500 hz crossover with an 811b horn will (hopefully) not blast a hole in the fabric of the space/time continuum.....

Anyone else with more knowledge on this question care to chime in?