EARTHQUAKESound SLAPS-M12v2 12-Inch Mass Tuned Passive Bass Radiator for Home and Mobile Audio Subwoofer Enclosures

I've been searching for a replacement for the passive subwoofer since my stock one finally cracked from 25+ years of abuse/enjoyment. I read a post online from a Sunfire enthusiast and he had replaced his Mark II with this Earthquake Passive Subwoofer and it was a complete success. Let me tell you, when I installed it in my Mark IV, all I can say is WOW! It performed even better than the original stock passive subwoofer. I experienced some massive excursion and deep deep base on this Earthquake. Highly recommended if you have the same problem with a Sunfire True Subwoofer Mark II or IV. The bolt pattern on the Earthquake is a complete match for the Mark IV enclosure. When you receive the Earthquake, I would be careful to drill out the holes on the Earthquake because it comes with the holes covered by the subwoofer rubber. But once you tap those holes, it is an exact fit. I love the Earthquake so much I will buy another one to replace my second Mark IV since I have a dual subwoofer setup.

I own four of these now. Even talked a few friends into purchasing them as well. Good quality product. Still confused on the version. 12 V3 or the added V3 on the end. I must be blind. I didn't see any difference between the point or version 2 versus version 3. Maybe it's marketing? Maybe it's the manufacturing material but they are quality but I don't agree with the price of them at this time. But the price of everything else has gone up too. But back to the review. These don't appear to make any type of flapping noise they handle. All of the pork pressure frequencies a port would use, but instead they stroke their suspension in and out to create the base wave from that port instead. Thus, they're silent. If you're looking to do a sealed enclosure and it's too small, you might put one of these in there. I've done experiments from using the old Sunfire subwoofer with these to a good high quality car audio f or home audio subwoofer with these as well. Don't think you'll go wrong. Give him a try. They are much better than using ports.

These bad boys really do slap next best thing to a ported box but can be placed into a smaller box...Days later it cracked I got another replacement and that also crack. I will look into a diffent brand.

I absolutely love the performance of this passive radiator. This is very likely the highest performance passive radiator on the market today.1. Tuning it though is made unnecessarily difficult though. The screw & nuts holding the tuning weights have some sort of thread lock glue on them that is quite permanent & very difficult for someone like me who is disabled & don't have a lot of power tools in order to get it off. It took me a couple hours of trying different ways to remove it without damaging the radiator.2. They don't provide any extra tuning weights. I had to go to the hardware store a couple of times in order to get weights. The first weights I bought were totally inadequate, but did use one as a large washer to help hold in the tuning weights that I eventually bought. This was necessary due to the large size of the hole in the weights that did work. Otherwise the bolt could have pulled through damaging the radiator. It would have been very nice if they had actually provided a set of tuning weighs for various tunings in the box.3rd, they need to provide a longer bolt.About the performance. You can gain a lot of performance & headroom using this passive radiator. I gained almost 10db at my tuning frequency of 16Hz & 5db at 25Hz. This represents a minimum of having at least 3 times more power without having to actually have a bigger amp. At 16hz that is almost equivolent to having an amp 10 times more powerful.Other than the issues listed above this appears to be a very well made passive radiator.People say it is cheaper to build a ported speaker. True, however if you make a mistake in your cabinet when utilizing the cabinet walls as part of your port it just became more expensive than a good passive radiator if you make a mistake in tuning as you will have to start from scratch again. With a passive radiator you can just add or remove weights to correct your tuning.A passive radiator won't be as loud as a port in a properly tune system but this one will get you close. It is truly super high performance. You also won't have unplanned resonances as you would with a port.Like the sound of your sealed system but need more output without a bigger amp or losing that nice tight sealed system bass. Look no further than this passive radiator. Make sure you get some DSP unit though so as to help balance the system. My sub amp has built in DSP but fortunately I didn't have to make any adjustments other than turning off my 5.5db bass boost @16Hz & adjusting the overall subwoofer volume down 5db.

I was given am old 12" MK powered sub, with a dead amp. After using it for a while , I really did not like the sound, is was not low enough. So I decide to retrofit the unit by removing the amp, closing the gap and slapping a 12" slap in its place. The result has been tremendous and strong clear bass, it has taken the sub to new levels. You can add weight to tune it to your liking by using washers and nuts. It has a very robust and strong thick rubber surround with a very respectable XMax. The unit is very nicely built, very robust and ready for low bass "abuse".

This was my first time adding a passive radiator to a sealed speaker. It's amazing how much additional volume this adds to such a small box. The sub digs deeper without unloading like it would with a port. It sure does shake the box around when it hits the resonance with that weight... the radiator is much heavier than the woofer coil. It's a good idea to install two radiators on opposite sides of a box, i might try that next. I would buy this again. I added 1 to a single Skar VXF 12 in 15 cubic inches.