Hey whats up? i had a quick question for ported enclosures. When me and my buddy built my box...he said that the port doesnt need to have any depth to it. My port is 3"
8.75 (slot port) but I was wondering if he is correct..or does the port need to have some depth to it also?
Just thought id ask b4 i build my next one when i tune it for the highest SPL output
thanks
Jason CLAP
Replies (17)
uochronos on 07/20/2004 02:33:53
yes it needs depth the specific volume of the port is what tunes it to that frequency... a hole in the box i would think would be very harsh on the sub mechanicaly.... just for an example i'm building a ported box for my sub and the demnsions of the slot port are length 8inch, width 1inch, length 18inch... those specs arnt exact but are close thats what i'm going to port a ED 12" sub with... i think that was for 35hx tuning frequency. but the box well be differnt for every speaker... the company who makes your sub can give you some ideas usualy if you email them
P0werLifter on 07/20/2004 10:26:55
K thanks Chronos thats what i thought but my buddy the "master installer" swore up and down the port didnt need any depth to it...the specs from the factory for the port size in this case was only 2 dimensions 3x 8.75" for a slot port. (or am i mistaken)..anyways ill be building a new box myself in about a month..till then they still pound like heck and sound clean.
thanks
Jason
uochronos on 07/20/2004 12:06:40
what sub do you have? i would be very interested in looking up the specs on it to find out if he was right...
P0werLifter on 07/21/2004 04:32:03
Im running 2 Power Acoustik 12" MOFOs...the specs were 3x8.75 i believe. Powered by a Power Acoustik 3000db Amplifier run in series/parrallel to net 900rms per sub at 2 ohms..which the actual rms rating is 1200watts...i was going to run the subs in parallel and try to gross 2300watts total rms at 1 ohm but i believe that will put a .5ohm load on my amp..the subs are 2ohm DVC..and the amplifier runs 2300 watts rms at 1 ohm stable. The box we built for it its about 6cubes total for both the subs -3 cubes per sub
obviously.
Jason
swez on 07/21/2004 09:52:56
That spec you mentioned, sounds like a tube port with an inner dimension of 3" ID and 8.75" long. (not a slotted port dimension)
Your friend is greatly mistaken about the lack of need for anything more than a few open holes in a sub enclosure and calling it a port tuned enclosure. This is nothing more that a air vent to reduce back pressure on the subs. What the actual tuning freq would be here... anybody's guess. At high power, this approach could destroy your subs.
Try contacting PA about the recommended slot port tuning dimensions for this sub in that size box. They should be able to give you some accurate directions on the correct size of the ports, when slotted.
I think JL Audio has a section on slot port designs for their premim subs. Yep, page 4 of this .pdf file shows slot port designs for the JL 12W7 woofer.
http://www.jlaudio.com/subwoofers/pdfs/12W7_MAN.pdf
Swez
P0werLifter on 07/21/2004 14:31:16
K thats what i thought Swez...i didnt want to "bite the hand that feed me" so to speak since he was helping me a great deal and has tought me a bunch, but i didnt think he was right but went along with it anyway....ill start building a new enclosure soon and maybe just not tell him lol or maybe ill just tell him im going to tune it to a different frequency...dimensions will be the same, just build the port correctly...for now ill run it at lower power...it does sound good tho thats the wierd part lol and pounds at around 45Hz....is there a difference between tuning with a slot port vs a circle port?
and also..if i did run these subs in parallel would it net a .5 Ohm load on my amplifier? or a 1Ohm load? Both subs are DVC 2ohm and the amp is stable 2300watts rms at 1 ohm...1800 at 2 ohms which is what i have it run at right now with the subs wired in series/parallel
Materials so far for the box we built was about 120 but it will be cheaper now since ive got some of the stuff i need and easier..lol
thanks
Jason
uochronos on 07/21/2004 14:55:43
just a note about it soudning good i blew a sony sub once(didnt reaqlly care if it blew:) but anyway i had it in a box that had a hole in it for a port but no tube the sub eventualy blew but it sounded really loud and boomy till it did not good SQ but not garbled distortion eighter just alot of SPL and boom. eventualy it just blew though.
if you ran these subs in parrelel you would net .5 ohm load
honestly you wont hear alot of differnce between 1800 and 2300watts you only gain +3db of sound everytime you double the power so you would only gain around 1-1.5db of sound with 2300watts and at the levels we are talking thats really not noticable. i do understand trying to get every last drop of power out of it though:)
P0werLifter on 07/21/2004 15:05:16
Agreed Chronos,,,,lately ive just had my sub lvl around 8 for SQ puruposes and it sounds nice and clean...rather than at max sub output lol..ill go ahead and build a new sub enclosure stat cause i dont feel like blowing my subs after i spent all that time and money for a SPL setup (even tho im not near finished)..i get paid tomorrow once i get back from my trip ill buy tha materials i need and start over...yah id like to get the last drop of power but 900watts for each sub is still a crapload lol..eventually ill be doing a cuthrough with 8 Power Acoustiks in there or im thinking about switching and trying Adire Brahma 12's,..down the line lol
Jason
swez on 07/21/2004 18:23:32
The 0.5 ohm load will be tough on any amp that is not HC (high Current) in design. It would be safer to run the amp at 2 ohms and lose a tad of power. SPL drop is less than ~1.2 dB at 1800 VS 2300 RMS.
If you can remove the front baffle panel, (panel subs are mounted to) where you can just replace that panel and reuse the present box or... if there is a 3/4-1.0" recess of the front panel, then you can glue and screw a new panel right over the one you have now, recut your sub holes and add ports as noted. A 1.5" baffle panel is not a bad idea on a heavy pair of subs mentioned.
What do you think?
Swez
P0werLifter on 07/21/2004 18:35:50
Yah I agree ill still run the subs at 2ohm stable 1800watts vs 2300...now as far as just removing the front baffle panel...that might be tricky with the design we have...its hard to explain but i have pictures..whats your e mail? ill send the pictures of the enclosure i have rather than type an essay of the actual design lol
Jason
swez on 07/21/2004 19:29:32
swezdp@juno.com
Swez
P0werLifter on 07/21/2004 19:29:34
Heres the design of the sub enclosure we built....3Cubic Feet for each sub...Each side is 18hx18wx18d,The subs face eachother with a back, top, and front,12" spacing between both subs with the ports 2" above the subwoofer...the front of the box has an giant Oval where all the sound and pressure escapes.
I uploaded some pictures to http://briefcase.yahoo.com/flex4success
although im not sure if their working
Jason
P0werLifter on 07/21/2004 19:39:41
K i sent you some pictures Swez
swez on 07/21/2004 19:58:01
Got em.. very interesting design here... well made cabinate... you guys did a very good job on the mechanical side of the box construction. CLAP
This looks more like a bandpass hybrid with an isobaric twist. The hole in the front panel is your port??? Each sub is in own sealed chambers. Hummmm, never saw a design quite like this before... but can see why it was designed this way. Three cf/sub... about the only way you can install the subs are this way or upward firing.
Uhmmm, how deep is this box from front to back? If at least 14", I would consider mounting the subs up firing and cut out the air hole panel and seal up the current sub holes. Then install ports as noted in ealier posts.
As for the open hole panel, can either seal it up tight with a fresh panel or leave open and install amps inside the box???
Comments?
Swez
Again, nice carpentry work here!
swez on 07/21/2004 20:00:28
Care to meet me in the chat room to discuss options?
Swez
P0werLifter on 07/21/2004 20:05:44
yah sure...whats the link again?
P0werLifter on 07/22/2004 03:33:40
Scratch those last 2 posts...i got it all to work...thanks for the help Swez
8.75 (slot port) but I was wondering if he is correct..or does the port need to have some depth to it also?
Just thought id ask b4 i build my next one when i tune it for the highest SPL output
thanks
Jason CLAP
Replies (17)
uochronos on 07/20/2004 02:33:53
yes it needs depth the specific volume of the port is what tunes it to that frequency... a hole in the box i would think would be very harsh on the sub mechanicaly.... just for an example i'm building a ported box for my sub and the demnsions of the slot port are length 8inch, width 1inch, length 18inch... those specs arnt exact but are close thats what i'm going to port a ED 12" sub with... i think that was for 35hx tuning frequency. but the box well be differnt for every speaker... the company who makes your sub can give you some ideas usualy if you email them
P0werLifter on 07/20/2004 10:26:55
K thanks Chronos thats what i thought but my buddy the "master installer" swore up and down the port didnt need any depth to it...the specs from the factory for the port size in this case was only 2 dimensions 3x 8.75" for a slot port. (or am i mistaken)..anyways ill be building a new box myself in about a month..till then they still pound like heck and sound clean.
thanks
Jason
uochronos on 07/20/2004 12:06:40
what sub do you have? i would be very interested in looking up the specs on it to find out if he was right...
P0werLifter on 07/21/2004 04:32:03
Im running 2 Power Acoustik 12" MOFOs...the specs were 3x8.75 i believe. Powered by a Power Acoustik 3000db Amplifier run in series/parrallel to net 900rms per sub at 2 ohms..which the actual rms rating is 1200watts...i was going to run the subs in parallel and try to gross 2300watts total rms at 1 ohm but i believe that will put a .5ohm load on my amp..the subs are 2ohm DVC..and the amplifier runs 2300 watts rms at 1 ohm stable. The box we built for it its about 6cubes total for both the subs -3 cubes per sub
obviously.
Jason
swez on 07/21/2004 09:52:56
That spec you mentioned, sounds like a tube port with an inner dimension of 3" ID and 8.75" long. (not a slotted port dimension)
Your friend is greatly mistaken about the lack of need for anything more than a few open holes in a sub enclosure and calling it a port tuned enclosure. This is nothing more that a air vent to reduce back pressure on the subs. What the actual tuning freq would be here... anybody's guess. At high power, this approach could destroy your subs.
Try contacting PA about the recommended slot port tuning dimensions for this sub in that size box. They should be able to give you some accurate directions on the correct size of the ports, when slotted.
I think JL Audio has a section on slot port designs for their premim subs. Yep, page 4 of this .pdf file shows slot port designs for the JL 12W7 woofer.
http://www.jlaudio.com/subwoofers/pdfs/12W7_MAN.pdf
Swez
P0werLifter on 07/21/2004 14:31:16
K thats what i thought Swez...i didnt want to "bite the hand that feed me" so to speak since he was helping me a great deal and has tought me a bunch, but i didnt think he was right but went along with it anyway....ill start building a new enclosure soon and maybe just not tell him lol or maybe ill just tell him im going to tune it to a different frequency...dimensions will be the same, just build the port correctly...for now ill run it at lower power...it does sound good tho thats the wierd part lol and pounds at around 45Hz....is there a difference between tuning with a slot port vs a circle port?
and also..if i did run these subs in parallel would it net a .5 Ohm load on my amplifier? or a 1Ohm load? Both subs are DVC 2ohm and the amp is stable 2300watts rms at 1 ohm...1800 at 2 ohms which is what i have it run at right now with the subs wired in series/parallel
Materials so far for the box we built was about 120 but it will be cheaper now since ive got some of the stuff i need and easier..lol
thanks
Jason
uochronos on 07/21/2004 14:55:43
just a note about it soudning good i blew a sony sub once(didnt reaqlly care if it blew:) but anyway i had it in a box that had a hole in it for a port but no tube the sub eventualy blew but it sounded really loud and boomy till it did not good SQ but not garbled distortion eighter just alot of SPL and boom. eventualy it just blew though.
if you ran these subs in parrelel you would net .5 ohm load
honestly you wont hear alot of differnce between 1800 and 2300watts you only gain +3db of sound everytime you double the power so you would only gain around 1-1.5db of sound with 2300watts and at the levels we are talking thats really not noticable. i do understand trying to get every last drop of power out of it though:)
P0werLifter on 07/21/2004 15:05:16
Agreed Chronos,,,,lately ive just had my sub lvl around 8 for SQ puruposes and it sounds nice and clean...rather than at max sub output lol..ill go ahead and build a new sub enclosure stat cause i dont feel like blowing my subs after i spent all that time and money for a SPL setup (even tho im not near finished)..i get paid tomorrow once i get back from my trip ill buy tha materials i need and start over...yah id like to get the last drop of power but 900watts for each sub is still a crapload lol..eventually ill be doing a cuthrough with 8 Power Acoustiks in there or im thinking about switching and trying Adire Brahma 12's,..down the line lol
Jason
swez on 07/21/2004 18:23:32
The 0.5 ohm load will be tough on any amp that is not HC (high Current) in design. It would be safer to run the amp at 2 ohms and lose a tad of power. SPL drop is less than ~1.2 dB at 1800 VS 2300 RMS.
If you can remove the front baffle panel, (panel subs are mounted to) where you can just replace that panel and reuse the present box or... if there is a 3/4-1.0" recess of the front panel, then you can glue and screw a new panel right over the one you have now, recut your sub holes and add ports as noted. A 1.5" baffle panel is not a bad idea on a heavy pair of subs mentioned.
What do you think?
Swez
P0werLifter on 07/21/2004 18:35:50
Yah I agree ill still run the subs at 2ohm stable 1800watts vs 2300...now as far as just removing the front baffle panel...that might be tricky with the design we have...its hard to explain but i have pictures..whats your e mail? ill send the pictures of the enclosure i have rather than type an essay of the actual design lol
Jason
swez on 07/21/2004 19:29:32
swezdp@juno.com
Swez
P0werLifter on 07/21/2004 19:29:34
Heres the design of the sub enclosure we built....3Cubic Feet for each sub...Each side is 18hx18wx18d,The subs face eachother with a back, top, and front,12" spacing between both subs with the ports 2" above the subwoofer...the front of the box has an giant Oval where all the sound and pressure escapes.
I uploaded some pictures to http://briefcase.yahoo.com/flex4success
although im not sure if their working
Jason
P0werLifter on 07/21/2004 19:39:41
K i sent you some pictures Swez
swez on 07/21/2004 19:58:01
Got em.. very interesting design here... well made cabinate... you guys did a very good job on the mechanical side of the box construction. CLAP
This looks more like a bandpass hybrid with an isobaric twist. The hole in the front panel is your port??? Each sub is in own sealed chambers. Hummmm, never saw a design quite like this before... but can see why it was designed this way. Three cf/sub... about the only way you can install the subs are this way or upward firing.
Uhmmm, how deep is this box from front to back? If at least 14", I would consider mounting the subs up firing and cut out the air hole panel and seal up the current sub holes. Then install ports as noted in ealier posts.
As for the open hole panel, can either seal it up tight with a fresh panel or leave open and install amps inside the box???
Comments?
Swez
Again, nice carpentry work here!
swez on 07/21/2004 20:00:28
Care to meet me in the chat room to discuss options?
Swez
P0werLifter on 07/21/2004 20:05:44
yah sure...whats the link again?
P0werLifter on 07/22/2004 03:33:40
Scratch those last 2 posts...i got it all to work...thanks for the help Swez
Copyright ClubKnowledge 2009 * All Rights Reserved
