Hello,
I am currently designing a TQWT for a friend, based on a Supravox 165LB. (I gave up the horn, way too big !!)
The previous enclosures I designed all used a frontal port, a solution that always gives satisfaction due to the synchronised driver and port waves.
My friend has a small room, and I'd like to take advantage of corner and floor loading in my design, involving rather a back or side port than a frontal port.
But I'm quite afraid to encounter phase problems and severe dips and peaks with a port that is not on the front of the enclosure.
I have also heard using a rear port could reduce the midrange output through the port, which is a very good thing.
I'm rather looking for a side port, because it doesn't involve leaving space behind the enclosure.
So I'm asking you, port experts,
what you think about this port stuff, and what you tried with success ! 
I am currently designing a TQWT for a friend, based on a Supravox 165LB. (I gave up the horn, way too big !!)
The previous enclosures I designed all used a frontal port, a solution that always gives satisfaction due to the synchronised driver and port waves.
My friend has a small room, and I'd like to take advantage of corner and floor loading in my design, involving rather a back or side port than a frontal port.
But I'm quite afraid to encounter phase problems and severe dips and peaks with a port that is not on the front of the enclosure.
I have also heard using a rear port could reduce the midrange output through the port, which is a very good thing.
I'm rather looking for a side port, because it doesn't involve leaving space behind the enclosure.
So I'm asking you, port experts,

The back wave is out of phase with the front, so there is absolutely no guarantee that putting the port on front will make the two outputs in phase. To the contrary, in fact.youyoung21147 said:The previous enclosures I designed all used a frontal port, a solution that always gives satisfaction due to the synchronised driver and port waves.
Rear-firing the port gives a little more boundary reinforcement for lows (expecially if near ground). It also attenuates some of the high freqs that aren't supposed to get through the port, but do.
Unless you plan on having the enclosure flush against the wall, I think rear-firing is the way to go.
OK I'll try the side port, so.
Length of the port won't be a problem, I find it even really short on my TQWT. TLs often have big and short ports.
Concerning the shape of the port, which is prefered ?
A tube, a slot, a vertical slot, several tubes ? (my port will not be at the end of the transmission line, but 8" above the the bottom.)
Length of the port won't be a problem, I find it even really short on my TQWT. TLs often have big and short ports.
Concerning the shape of the port, which is prefered ?
A tube, a slot, a vertical slot, several tubes ? (my port will not be at the end of the transmission line, but 8" above the the bottom.)
Round tube is easiest to predict, and I believe least likely to whistle. Flared ports are supposed to prevent turbulence at the ends, perhaps important for big vented subwoofer but probably not too important for full-range project.youyoung21147 said:Concerning the shape of the port, which is prefered?
Otherwise, do rear ports provide a well refined and fast bass, such as front ports ?
On the BR boxes I played around with, I didn't notice much difference between front and rear firing. If there is at least some space behind the speaker it shouldn't make much difference but I think if I had to make a choice, I would put a port at the rear!
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