Looking to upgrade to horns

AngrySailor

AngrySailor

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---not quite right
#201
You might want to research this more. It’s not something I considered so didn’t look into it much but you want the energy from the port to be in phase with the energy from the speaker to gain the summing effect which is theoretically 3dB at resonance. Firing he port backwards at the same tuning would seem to mechanically invert that phase 180* whichbwould be a cancellation of 3dB? Maybe not but I’d look into it.
 
J!m

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I think placement would become more critical with distance from the back wall.

It would be (roughly) 180 out rear firing and then reflect off the back wall (180 out) to summ but at a time delay... I could see being too far from the wall, or too close, getting muddy.

I think we need a slide trombone port. Right out the top. Once you are placed you slide it to accentuate the desired frequency. Then the “periscope” top could be aimed for best advantage.
 
roccus

roccus

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#203
J!m said:
I think placement would become more critical with distance from the back wall.

It would be (roughly) 180 out rear firing and then reflect off the back wall (180 out) to summ but at a time delay... I could see being too far from the wall, or too close, getting muddy.

I think we need a slide trombone port. Right out the top. Once you are placed you slide it to accentuate the desired frequency. Then the “periscope” top could be aimed for best advantage.
Click to expand...
'I think we need a slide trombone port. Right out the top. Once you are placed you slide it to accentuate the desired frequency. Then the “periscope” top could be aimed for best advantage. " lol
 
roccus

roccus

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#204
I think I want to try down firing, I will put them forward in the cab next to the woofer... maybe forward corner. I wonder if I mount the port inside the cab instead of pushing it in from outside, and maybe flare the hole in the 3/4 mdf? That would be like adding a flare to the end of the port, I wonder if that would make it a little more forgiving and help my clearance between the opening of the port and the floor?

I ordered the MDF from Home Depot last monday I decided to just pay and have them deliver. When I placed orderand paid online it said they would contact me within 48 hours to schedule the delivery then agin 30 minutes before they actual deliver.... well it is thursday night and they still not have contacted me to set up a delivery time and day so I guess if I don't hear anything by tomorrow afternoon I will try to find a way to contact them and see what is up.
 
J!m

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#205
I like the flare idea. Maybe a 1/2” radius with the router...

But that expansion will essentially be an imperfect horn, so you might need to adjust the length of the port with the flare on the end.

I also think it will reduce “chuffing” for you, which would not be ideal against the floor.

You flare a rocket nozzle to equalize the internal and external pressure at the exit. If it’s ideal, you get no visible shock diamonds in the gas stream. It’s only ever ideal at one specific external pressure (altitude). Not easy to see with plain old air... and the sound is probably traveling at the speed of sound, not beyond it.
 
roccus

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I fund this... looks like the ticket and better than spending $40 ea. at PE for these..... a 2' X 6" piece of pvc id all that is needed
 
roccus

roccus

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Oh and wifey wont mind if I take one of her bowels out to the shop to melt pvc on! lol
 
VSAT88

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Too bad you need to cut holes for ports to find out what way is best. Thought about using a port less cabinet ? Many prefer them. No port position to worry about and smaller enclosures. I have heard plenty that would knock your socks off...in car stereo systems mind you, way in the past...
 
roccus

roccus

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VSAT88 said:
Too bad you need to cut holes for ports to find out what way is best. Thought about using a port less cabinet ? Many prefer them. No port position to worry about and smaller enclosures. I have heard plenty that would knock your socks off...in car stereo systems mind you, way in the past...
Click to expand...
I think big difference in a car sub is they are is small confined spaces like trunks I think the small space almost becomes part of the sub. There has to be a reason you never see sealed subs in pro use or in bigger venues... Also I would think a sealed sub would not be as efficient which is probably why in cars they run 10,000 watt amps at 1 ohm
 
mlucitt

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#216
The information about ports on the front or the back is funny. It matters not where the port exits from the enclosure, the pressure wave comes from the back of the speaker regardless. Phase is electrical, cone excursion timing between drivers or between enclosures is another matter (see BOSE). Port tuning for cross-section size is critical near the resonant frequency, and port tuning for length is critical for bandwidth around that resonant frequency. And, the criticality matters very little in the performance of a subwoofer. Send a rigid cone, large diameter (15"), compliant and powerful speaker lots of power through a properly designed low pass filter, in a proper 'sealed' enclosure (~1.5 cu.ft.) and there you go. Add a port if you want more excursion (lower frequency response), but increase the enclosure size because now you have a 'ported' enclosure. This is a handy site for car audio, but works for home audio too:
http://www.bcae1.com/spboxnew2.htm
 
WOPL Sniffer

WOPL Sniffer

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#217
Put your ports on top.... Then you can sit your cowboy hat over the port and if it flys up more than a foot, you know you are loaded and better turn it down before the law gets there... :)
 
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