Port Interference?

[okiepolkie]

I have a question concerning the possibility of port "interference" on the LSi's.

Each speaker has an offset tweeter/port on the front. Polk's recommendation is for the tweeter to be placed towards the center of your listening position. My assumption is that the air produced by the port "interferes" with the dispersion of the tweeter to a small extent. Therefore, having the tweeter towards the center would minimize this for the listener.

On the LSiC, the ports are below the tweeter when the speaker is upright. So, if the center channel is placed above a television, will the ports interfere with the tweeter's dispersion? If this is the case, should the speaker be turned upside down so the ports are closer to the ceiling?

[newsman]

hmm, good question. I also noticed that the opening of PowerPort on LSi15 is not completely smooth. I would think it would contribute to additional port noise noise on the lower notes.

[gmorris]

Port wind interfering with the tweeter dispersion? Holy cow, you are really thinking too hard about this one.

If the air exiting the port had any affect on the dispersion of the tweeter, (I'll assume, in theory, that this is possible, it does seem reasonable) it would be soooo minor that it would make no difference what so ever.

The placement of the tweeter to the inside has to do more with phase & time alingment than anything.

[okiepolkie]

The phase and time alignment makes more sense to me in the LSi's case.

However, this might actually be a problem if you have a large driver/port combination next to the tweeter. Therefore, the larger volume of air might make more of a difference since the wavelengths of high frequencies are more easily interfered with.

[gmorris]

First off, I'm not a speaker designer, so I'm just guessing here.

I totally understand what your theory is stating. It makes sense that, since the tweeter is vibrating air to produce sound, if there is a port right next to it creating a disturbing air flow, that the tweeters dispersion could be affected. It is a very clever idea, although, I doubt that it actually happens.

The sound coming off the tweeter is travelling at the speed of sound, obviously. The air coming out of the port is traveling no where near that spead, so I'm guessing that the air from the port really has no affect on the sound.

Then again, I could be totally wrong. I don't know. It just seems a little far fetched to me. I wouldn't worry about it. Polk does there homework when they design speakers. If you use them the way they are intended to be used, all is well.

[PolkThug]

Nothing pvc and an elbow joint can't fix!

[VR3]

I believe Sean...

Plugged all the ports in his LSi15 and found good results (could be wrong though)...

One thing is for sure, Polks speakers are ported all over...lmao

[scottnbnj]

Originally posted by PolkThug
Nothing pvc and an elbow joint can't fix!

heh heh,.. the wave radio mod.

)