[bensl]

i have a tempest x driver powered by an oaudio 500w amp in a ~200l sealed box.

i have had it running for a while now and i guess i am a little disapointed with how it sounds. im not sure what i was expecting but it doesnt seem to give the shaking bass that some people suggested it would. at the moment i have the driver pulled out (see other thread - i broke one of the braids off the cone ) so i was wondering if it would be a good idea to add an port (or 2)? is it possible to add a port to an alreadt built sub? how many and what size would be best? what sort improvements would be had?

this is my first DIY project so most of the tech talk goes waaaay over my head.

at the moment im close to canning the DIY idea and going the easy (but expensive) manufacturer route.

thanks guys

 

[Mike P.]

Which hi pass setting were you using on the O-Audio amp?

 

[bensl]

do you mean the subsonic filter setting? i think i had it on 16 (or even 12). stupid i know now but as i said this is my first attemp at DIY and i guess im learning from my mistakes. i had no idea of the settings to use when i first turned it on so i just put everything on 1/2.

 

[Ricci]

What are your enclosure dimensions and is this the original model Tempest X?

 

[bensl]

enclosure dimensions 1200 x 450 x 450mm. and yes it the orig tempest but as per the other topic, i may replace it with the gen II.

 

[Mike P.]

Yellow is with the HPF at 16 hz which also has about 6 db of boost.
Green is with the HPF at 12 hz which has about 8 db of boost
This would explain the broken braid.

Porting the 200 liter cabinet tuned to 18 hz with a 6" diameter port 29" long would result in the green line below. Both the sealed and ported models shown is with the HPF at 20 hz with about 4 db of boost. This is the best you can do with this box size and amp. If this doesn't give you the "shaking bass" you're looking for then you need to rethink the box size and amplifier.

 

[bensl]

so what would be the best way to do this? can i simply drill a 6' hole up the top of the box somewhere and add the tube? if its 29' long i guess it needs to be angled down from the top (or up from the bottom to the top)?

thanks for your help.

 

[Mike P.]

Cut a hole in the top of the sub at least 5 inches away from the side walls and install the tube.

 

[bensl]

ok thanks. next question.. what to use? i have been looking at parts express, would something like this be ok for the top and just add the extra length http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-401

i think something like this would be better but i cant seem to see it in 6" http://www.parts-express.com/pe/showdetl.cfm?Partnumber=268-330

can you just add regular pvc pipe for the extra lenght? is a flare required on the inside end?

thanks again

 

[Mike P.]

The air speed is low enough of this setup that you can use a 6" diameter sonotube for a port.

 

[bensl]

is there any special way of fixing the tube to the box? would construction adheseve be suitable to glue it in?

do you know of anywhere i could get a 6" Outside Flare with Mounting Holes? it seems this would be the easiest way.

 

[bensl]

i forgot to mention i may be replacing my driver with the tempest x2. will that have any affect on the port size required?

 

[Mike P.]

I think Precision Ports sell a separate 6" flare, check their website. The Gen II sub won't have any effect on port size.

 

[bensl]

ok, i just checked my sub box and i think a 29" port will extend very very close to the driver. there is about 25" from the top of the box to where the driver cutout starts so at 29" the end of the port will nearly touch the magnet. can i reduce the lenght a little or would it be better to have to port portrude from the outside of the box a bit? how close can the port get too the driver???

 

[Mike P.]

You can use a 25" long vent for a 19 hz tune or use a 22.5" long vent for a 20 hz tuning.

 

[bensl]

ok, one more question... i having all sort of difficutly finding a 6" port & flare here (in australia) no one here has sonotube and none of the US retailers will ship their ports & flares here with a reasonable rate. i can get 6" pvc pipe from a plumbing supplies shop but flares for the ends are proving the problem.

can i build a rectangular port out of mdf and achieve the same results? ive been playing around with winisd but i can seem to duplicate the results you posted earlier.

thanks again for all the help.

 

[evilskillit]

This web page is made buy a guy who lives in Australia and makes all sorts of subs, he has several different methods for making large flared ports if you're handy at all.

http://www.subwoofer-builder.com/

If nothing else you could always just not flare the port tho that is less than ideal.

 

[bensl]

yeah i have a prinout of his guide to making donuts in front of me now! its a fair bit of extra work plus i have to find someone with the right tools.

 

[evilskillit]

You can actually buy large flared pipes, flared ends and donuts from him, if you have the cash. If not and you have a friend with a router you can try to make your own. Tho if he doesn't have a giant round over bit that alone will probably cost more than buying large flares or donuts would.

 

[Mike P.]

You can actually buy large flared pipes, flared ends and donuts from him, if you have the cash. If not and you have a friend with a router you can try to make your own. Tho if he doesn't have a giant round over bit that alone will probably cost more than buying large flares or donuts would.

Bill is no longer making the 6" flared port. The PSP 6" port can be found here:

http://www.audiomarketplace.com.au/...d,0/option,com_virtuemart/Itemid,49/vmcchk,1/