Quote Originally Posted by Earl K View Post
Your original question is ambiguous enough that I'm unsure if you know the following ( your most recent post suggests otherwise ) , so ;

> A horn similar in size to the displayed pic will give a rolled-off HF starting at say 3 or 5Kz ( though it'll still go up to 15K which is the HF limit of the 399 /just rolled-off at around 6db per octave) .

> The size, Q & type of horn will dictate relative response levels of the HF to MF .

> The "real"top-end performance ( extension ) will barely change ( barring obstructions ) when you play around with the various horn parameters. What does change is the relative level of mid to HF ( bigger horn reinforces lower & lower in frequency ) .
> "Real" HF performance is measured at a constant distance to the diaphragm ( not to the lip of horn ) .

> One way or another , you'll need to measure what you construct before you can confidently add in a tweeter ( with appropriate nerwork ) and achieve a flat response from 500hz to 20Khz.

Sorry if my question was ambiguous, but as you can see, this is a bit above my technical knowledge.

I see what you are saying though, in that the driver will still perform out to it's limit, but will be rolled off at 6db/octave. That type of technical info is what I was looking for, so thanks.