Down firing vs side firing?

[richie00boy]

If the sub is not far enough off the floor and the exit mouth is not enough area, ported or not the response will be changed. If done right it's ok to port.

[rabbitz]

Originally posted by Amit_112dB
sorry to intrupt this enclosure conversation
But i think down fired port is no good idea
floor will choke the port, flow of air into port will be distruped, this means effective port dimensions will change... means bad i guess

now if any 1 thinks down fired acts as a horn and can give u extra db spl, for 50hz horn length is almost 3.5 meters long so dont think there is any horn helping u down there

i am not pro audio geek but can any 1 explain me if my concepts are all false or true

Nothing to do with pseudo horn loading. Here's some clues.
Better room coupling
Hiding leaking mids
No boundary dimension effects due to the small distance to floor
Smoother as only boundary effect is due to close wall
etc etc

Have a look at vented subs from B&W, Proac etc and you'll find some downward ports. I think you will find the majority of commercial subs these days has some coupling with floor by driver or port or PR.

There's plenty of info out there on the subject.

[troystg]

Page 91 of the July Stereophile is a pretty good picture / drawing of a popular speaker downward ported.

[Amit_112dB]

thanks u all
i think i'll go for down fired port in my comming up exlosure

MAIN REASON- i can have only limited port length if my sub is front fired..... top and Down fired offer an advantage of effective space utilization (as height is normaly kept more than width and depth) and thus i can have bigger port.

The only issue of down firing i suspect now is that it wont be suitable for outdoors use(my roof top beer parties)....for outdoor only front fired is suitable coz u can direct all the energy in single direction...

troystg: i did'nt get you, where can i find down fired drawings ??

[troystg]

Page 91 of the July Stereophile "magazine". Common publication in the US. Sorry, I wasn't thinking globally and I should be.

[troystg]

I saw Tee-Bruce's sub enclosure today. Very well constructed and although not perfect it is still light years ahead of the original factory enclosure.

He should be getting some pictures soon. Thing to note is the dampening "wool" that was rubber cemented to all the internal walls. He will be using poly-fill but he had a really neat 3/4 - 1 inch padding that starts out very dense and gradually thins out. I think he used a "rubbery" type of glue so it stays compliant.

He bought 2 of the flared ports from Parts Express so we can experiment with one then when we have it "right" set up the other permanently.

[speedie]

I was thinking along the lines that have been discussed in these posts
Was wanting to use peerless 830500 and matching passive radiator along with a 600 watt “d” class plate amp so am not sure if the discussion was conclusive re port or drone in downward firing position
Have been tinkering with bass box and can only achieve f3 of approximately 28 Hz in a cube shape having 55 litres, would like to be around the 20 Hz mark am I doing something wrong with my calculations
I want to use veneered 32 mm MDF board and have no internal bracing would this be ok with respect to cabinet vibrations, I would fabricate feet to elevate the enclosure of the floor to allow for cone movement but am not sure how high it should be.
I have searched the posts and there is a similar design but in a tower configuration it uses the same components but achieves 19 Hz (both are forward firing)
Some more discussion would be appreciated
Cheers speedie