Will low frequency extension be increased with multiple IHOPs?
Probably not-but directivity would be.
One common "misconception" in the "bass horn world"-is that the low freq extension gets lower with more cabinets.
While that is "technically true", it is not as much as most would like to think. You never hear any body quoting real numbers.
Yes it does go down-a little. But it "appears" to be lower with more cabinets. What is really happening is that a single typical bass horn has a jagged response down low-with a single cabinet. When you add multiple cabinets, the impedance coupling to the air becomes better, and the "valleys" start to fill in.
So while it may appear to be lower-what you are hearing is actually just a smoother response-with a little bit of extension.
For example on the Danley DBH218-basically a regular horn, when you go from 1 to 4 cabinets-the low freq (as measured by the 3dB down point as referenced to the average (whatever that is) sensitivity-goes down about 2 Hz.
So yes it is lower-but not WOW that is a lot lower. The bass just "fills in".
Think of it like this (and a game some manufacturers like to play). Take a bass cabinet and have a low pass at say 80Hz-and listen to it. Now simply lower the lowpass to say 60Hz.
It "appears" like the cabinet has a deeper response-yet the actual response is not any lower. There is just less highs to "get in the way". So with the "filled in notches", the ratio of lows to highs gets less-so it appears like there is more bass-which there is-but not really any deeper.
No I have not played around with a bunch of different horns-and my experience is a bit limited. HOWEVER I would love to see measurements of 1-2-4 of the same bass horns and see what happens with other designs.
If not far off topic-the whole idea of the Tapped horn was to have a smooth response down low (without the ripples) with a single cabinet. Multiples don't go any lower-but do gain directivity. The tradeoff is that the response up high (well out of the operating band) the response gets a bit ragged.
That is why Tapped horns make lousy bass guitar cabinets-the upper response is "out of whack".
Perception is not always reality. Hence the reason to MEASURE and CONFIRM.
