Port sealed double 15" subs

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
hi, like from the title, I want to port my sealed doublé MTX RT15 sub.

here comes the reason:

my car, is a sedane (alfa 159) and the only conntection between trunk and cockpit, is the gap of the rear armholder.

so my idea was, to drill a port at the rear of the box, that matches at the high of the gap to the cockpit.

I know, the encosure does not matches the litres for the 2 MTX to be ported, but with a Little bit of good work, it could sound better.

My first question is, should I go with 1 port tube or 2????

later on, I'll give you the measures of the box, to calculate the ports

thanks!!!

 

germanyt

CarAudio.com Elite
Nov 15, 2005
1,756
0
Ponchatoula, La
If the subs are facing to the rear and your port forward it'll have serious cancellation. Also, itll need double the volume of a sealed enclosure. I'd suggest you scrap the box and build a new one.

 

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
If the subs are facing to the rear and your port forward it'll have serious cancellation. Also, itll need double the volume of a sealed enclosure. I'd suggest you scrap the box and build a new one.
here's a picture of the trunk.

the speakers are firing out of the car, and as you see, the enclosure fits almost perfect to the trunk. the port should be on the other side, firing into the cockpit.

I can't build a bigger enclosure because of many factors, I have to find the best solution with what I have.

 

Popwarhomie

Team Lethal Pressure
Jan 22, 2010
6,092
248
Florida
Bad idea. Sell the 15s, buy some 10s and build a 4th order for two 10s with the port through the ski hole.

 

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
Bad idea. Sell the 15s, buy some 10s and build a 4th order for two 10s with the port through the ski hole.
no, i'll keep the 15", at worse case scenario, I'll stuff the port, and keep it sealed. you think i'll have much cancellation??? I've seen many home theatre subs with the port behind the cone and they do well. most of subs out there actually have the port opposite to the woofer. only caraudio has the port on the front for obvious reason, because on the back, you would seal the port with the back seats. in my case, the port woud match exactly to the hole that connects to the cockpit.

Another question I have, I've seen most of ported doublé woofer have divided enclosures, with a Wall beween woofers. is there any difference to play both woofers in the same enclosure??

thanks!!

 
Last edited by a moderator:

Jeffdachef

Gunz That Turn on Nunz
Feb 5, 2013
17,261
252
South Coast Metro, CA
no, i'll keep the 15", at worse case scenario, I'll stuff the port, and keep it sealed. you think i'll have much cancellation??? I've seen many home theatre subs with the port behind the cone and they do well. most of subs out there have the port opposite to the woofer. only caraudio has the port on the front for obvious reason, because on the back, you would seal the port with the back seats. in my case, the port woud match exactly to the hole that connects to the cockpit.Another question I have, I've seen most of ported doublé woofer have divided enclosures, with a Wall beween woofers. is there any difference to play both woofers in the same enclosure??

thanks!!
Get any kind of home theater logic out of car audio completely and never ever link the two together again.

Home audio you dont deal with cancellation and rear waves anywhere as close to what happens in a car environment. Home theater is literally EZ sound for dummies vs Car audio which has a lot more acoustical challenges going on in it. Whatever you think is good is basically complete garbage in actual real world results purely due to cancellation aka ZERO bass.

The only way any of this would even work would be to go down to two 10s and do a 4th order blow through. Your first idea of porting 15s with already a tiny sealed box is already beyond stupid because ported literally needs a box 2-3 times the size of your sealed to even properly perform. I'd highly recommend reading up on ALLLL the basics of car audio enclosures before screwing up your system even more. A proper ported box for two 15s would be around 7 cubic feet to 9 cubic feet NET meaning subtracting all the space the wood, bracing, subwoofer and port takes up. thats pure 7-9 cubic feet of airspace alone just for the sub to properly function and breathe. Your port needs to be big enough as well. for two 15s, you need at least a 6-8 inch aeroport. So yeah man, just leave sh*t as is. Or actually sell everything and do things right because all you are doing is shoving things that dont work in a small space like a big noob.

We already told you this months ago from your other thread but you didnt listen at all.

 

Buck

Premium Member
May 19, 2008
19,442
178
FL
Dude that is way too much woofer cone area for the size of your trunk

 

---------- Post added at 10:59 AM ---------- Previous post was at 10:59 AM ----------

 

You are not fitting a ported box for both of those in that trunk that will sound remotely good fyi

 

LosIsATool

CarAudio.com Veteran
Apr 7, 2011
18,504
68
Pensacola, Florida
I didn’t read everything but having a port in the back of the box isn’t a big deal. But the box is 2-3 times to small to port. Leave it sealed or sell and start over.

 

Jeffdachef

Gunz That Turn on Nunz
Feb 5, 2013
17,261
252
South Coast Metro, CA
I didn’t read everything but having a port in the back of the box isn’t a big deal. But the box is 2-3 times to small to port. Leave it sealed or sell and start over.
you are literally losing all sense of spl lately dude. That orientation only works in crxs doing a huge cone area burp setup.

 

XxAndreaxX

Member
Mar 18, 2016
169
-2
spain
guys, I managed to fit my sundown X8 in a 10L (minus the sub) round box, and port it.

The port was a total experiment, something like a 50cm long tuve, but guys, it souded not only much louder, but the port, was at the exact frequency I wanted.

So what I'm about to do is only an experiment, I was lucky with my sundown, so maybe i'm still lucky with this. and if it sounds crap, I'll seal it and problem over. 2 15", will sound strong even sealed.

 

Buck

Premium Member
May 19, 2008
19,442
178
FL
If you fire the port into the cab and fire the woofers into the trunk, you're gonna have a bad time

 

Jeffdachef

Gunz That Turn on Nunz
Feb 5, 2013
17,261
252
South Coast Metro, CA
It’s worked in trunks also.
I wouldn’t call a pair of 12s huge cone area.
Uhm try a pair of 15s or 18s in a CRX. i dont remember saying 12s.

Cancellation and interaction between front and incident waves in a trunk with lower frequencies is way more chaotic than in a hatch at a higher frequency.

 

Buck

Premium Member
May 19, 2008
19,442
178
FL
Anytime the port isn’t on the same plain as the driver it isn’t ideal.
No, the port needs to be in the same airspace as the woofer on both ends, unless it's intentionally designed that way. The port can fire in the opposite directions of the subs and be completely fine. A lot of SPL dudes fire the subs forward and the ports backwards in small cars, like CRX's. As long as the port is phasing the wave properly, it doesn't really matter what plane it's on, unless you are chasing tenths, in which you go with whatever is loudest.

 

LosIsATool

CarAudio.com Veteran
Apr 7, 2011
18,504
68
Pensacola, Florida
No, the port needs to be in the same airspace as the woofer on both ends, unless it's intentionally designed that way. The port can fire in the opposite directions of the subs and be completely fine. A lot of SPL dudes fire the subs forward and the ports backwards in small cars, like CRX's. As long as the port is phasing the wave properly, it doesn't really matter what plane it's on, unless you are chasing tenths, in which you go with whatever is loudest.
I was speaking of phase. Which is already off anyway.

 

Buck

Premium Member
May 19, 2008
19,442
178
FL
Yeah, if that port is in the cab and those subs are in the trunk- yes

 

---------- Post added at 11:53 AM ---------- Previous post was at 11:53 AM ----------

 

It would be very difficult to design that properly.