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Lbjefferies7 wrote:

Now, as for your drawing of the exaggerated port flaires, it is excessive.  A port is not a horn and, from an engineering standpoint, I treat them very differently.  A port is a resonator.

Oh, sure I understand it and drew it excessively solely for the sake of illustration. I have see a few companies did the exit of the horn in semi-horn profile, so that lead to a question of the entrance of the Helmholtz resonator might be benefited from the semi-horn shape.

Lbjefferies7 wrote:

Using ports as anti-compression devices is just plain bogus, in my estimation.  Above the port's tuning frequency (Fb), the enclosure acts just as a large sealed enclosure.  Below the Fb, it acts as a quasi-infinite baffle system.  When the driver reproduces the Fb, the port "opens up" at the Helmholtz frequency...where the air masses in the box and in the port reach a "balance" where the output of the port is 365 degrees out of phase with the driver.  The responces of each resonator combine and create a greater overall response.  By tuning the port, the port's output can extend the sealed response of the acoustic system.  This is how I understand it, at least.

Yes, it is a perfect explanation and it is how I understand it but read below…

Lbjefferies7 wrote:

Now, Petar is spot on when he says that the Fb must not be below the resonant frequency (Fs) of the driver.  If it is, you will certainly get a horribly disgusting cone-flapping sound and may just fry your drivers.  The vision of murder will be dancing in your head...like sugarplums on steroids!

Ok, this is exactly where I am a lost. As long we keep the port’s resonance below driver’s resonance then I agree that we are at more or less save ground. Even I - the person who never experimented with poet in my live- have written about it at in past. However, if we accept this premise then we defeat the entire purpose of using ports. Of cause we would like to have LF EQ on the enclosure in compare to a sealed solution. Of cause we would like to drive the port’s resonance below the driver/enclosure resonance to get more bass out of the situation, without use of ultra low Fs driver and increasing the size of the box. Or cause we would have a sever driver reactance when the resonances “meet”. Aren’t they all the ideas of port use and isn’t it how it works in all bass reflex loudspeakers. I was under presumption that by embracing the horn idea we are by default let the amplification, filtration and other thighs to deal with driver “comforting” during the cone-flapping… If we keep the Fb above the Fs then why do we need to a port to begin with?

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