Has anyone tinkered with adding to the port length on the EX to re-tune for dual-port Max Extension mode?

I was looking at another online sub retailer’s site, being that he is familiar with the EX design, and asked if it was possible to "turbo" my EX. His response was that I would need the exact length of port tube that is being used, then I could use both ports in Max Output mode and would be re-tuned as in max-extension single-port mode. The EX uses dual 3" x 12.25" ports.

Just thought it would be nice to have the additional DBs at the low bass levels. Granted since the sub’s ports are down firing, you would have to either run the sub on its side or add additional clearance using longer "feet" and a 90* bend coming out of the port (much like the other “turbo”). I haven’t tried this yet but thought it would be easy to test by purchasing some 3” pvc, just wasn’t sure how to couple a new piece of PVC to the existing port (especially with the flare at the end). Maybe some silicone tubing to couple the pieces together, like what is used for a car turbo?

Love my EX by the way…wife thinks it’s too loud so naturally I want another.

Look on the HSU site. They have a "turbo" version of their big sub. Exceedingly ugly but very functional. If you do the mod let us know how it turns out. Running the sub on its side might not be the best as there is filler material inside and I have had it spit out some in the past. I think it is due to me moving the sub around the room on its side.

Just changing the port lengths will move the resonant point of the sub around but it isn't going to create Max Output and Max Extension at the same time. You CAN move the tuning frequency around and maybe get a little more output at frequecies between 16 and 22 Hz but it will be a tradeoff between output and extension.

I was just going by what Dr. Hsu replied with when I asked how to "turbo" my LFM-1 EX.

"Regarding a 'turbo' for the Outlaw, what you need is to add an identical length port to what is inside the enclosure. That way the tuning stays the same but you can have both ports open for the max extension mode (making the EX-1 similar to a VTF-3 MK3 with one port open). Just make sure the external port has gentle bends. An abrupt bend in the port tube will lead to early onset of turbulence, negating any advantage of increasing the port area.

The hours of work needed coupled to the likelihood of it not working well makes me feel this is not a cost-effective approach to getting more LOW bass out of your current sub. However, if you just want to experiment and have fun doing it, that is just fine."

Ahh, I see. Shame on me for shooting from the hip on my first post.

I didn't realize there were actually some changes to the electronics when the sub was in one mode vs. the other.

So what is happening is that the tuning of the ports is being adjusted to a lower frequency but the mass of the air slug in the ports actually increases over the single port by a factor of 4 making it "safe" to drive the sub in the Max Output mode. Pretty cool.

Mating to the flared port will be tough. I don't really have any good ideas.

I was looking at the HSU turbo, and they have some sort of rubber or foam gasket around the turbo end of the PVC - HSU also uses flared ends on his 4" ports. That's why I was thinking the silicone tubing from automotive turbos. Weather stripping maybe? Ah heck, I will just ask Dr. Hsu what he used.

Dr. Hsu said "window sealing tape works well." Well, I guess I have my Home Depot list, some 3" (inside diameter) elbows both 45* and 90*, some 3" straight PVC and some foam (or rubber) window sealing tape. Now just need to figure out the feet extensions.

I would think that if the bass extension and the hi SPL were available without risk, Outlaw would have designed it in already. The manual cuations about running the EX in the max output mode with the ports in the max extension mode. Changing the ports could cause the EX to inadvertently violate this caution

There is some common sense and risk that goes with any mod right? I currently run my sub with the gain set at 3.5 position and a little hot on the receiver side. If I can get approximately 2+ more DBs with the port mod using the same settings, I think it would be worth it. Plus at those levels, I am well within the safe range for the sub running both ports open in max extension mode. I love my sub and would never want to hurt it, and fortunately know the limits of my equipment. Outlaw (and Dr. Hsu) can attest that the reason the ports weren't built like that in the first place is due to space. The cabinet would have needed to be even larger to house ports that are double in size. At some point in commercial sub building, there has to be a compromise between acceptable box size and output. Once size is out the door, you start talking about Mark Seaton and Danley stuff and then all bets are off. The good thing that this mod is not permanent in any way, if it ends up sounding like crap, it is a 2 min removal.

Let us know how it comes out. Could be an interesting experimental tweak. Not sure the WAF will meet the specs but what the heck.