Earthquake SoundSLAPS-M8 8-inch Mass Tuned Passive Bass Radiator for Home and Mobile Audio Subwoofer Enclosures

Muy buen producto

I have an older JVC portable stereo (12 volts) that only has a moderate output (maybe 50 watts RMS), and I wired its high and low outputs through a terminal block mounted on the back. I also wired two low pass coils (around 10 mH) to the low outputs. Then I attached two small Polk outdoor speakers to it as satellites, which sound great on the sides for the highs and midrange. Now my design for the subwoofer was to use an old speaker box (1.7 cubic feet) with the speaker panel knocked off. Then I screwed and sealed a new inch thick panel to the front, with better insulation inside of all the other panels. I mounted a Goldwood Sound dual-coil 10 inch woofer and tuned it with a curved elbow of PVC conduit as long as possible to be 3” from the back panel and wide enough to keep down the port noise. I picked this woofer because of its good price and efficiency, but it does have a high total Q-factor for a ported system (about 0.6 at its 40 Hz resonance). As a result, I could hear that it wasn't reaching very deeply into the range below box resonance, with too much boom in the range above, so the system Q clearly wasn't getting flattened enough. Then about a month ago I decided to splurge on Earthquake Sound's 12 inch PR, which would be my first attempt with them in subwoofer designs. The selling point for me was its tunability by adding more fender washers behind the supplied weight. I used their chart to tune it at about 18 Hz, which required installing a slightly longer weight bolt. This second attempt definitely sounded better than the port, but the PR's additional rear suspension felt a bit too stiff for the moderate power I was running – like it wasn't open and loose enough. So with a rotary tool and a small sanding drum, I carefully carved out the original gaps into stretched out ovals, leaving ¾ inch bridges of rubber between eight much larger holes. And this was another big improvement – to the point where I can still feel the bass ten or fifteen feet away at fairly low volume levels. With this last result, I was happy and enjoyed comparing it with the good old ported dual-chamber Bose subwoofer I was using before. It's tuned fairly low for such a small box, but the difference is pretty striking. Of course, a slender Bose system has to use a smaller dual-coil with a tighter response curve, and I really noticed this after doing a side-by-side comparison of the same song. My new box isn't a whole lot bigger, yet because of the woofer/PR combo, its bass response is obviously much flatter than the Bose – especially on the low end of its spectrum. The sound is smooth from the Goldwood woofer in the 40 Hz plus range, while the PR is mainly adding to the octave below this with impressively deep and punchy sounds. And this is happening at a noticeably higher efficiency than my tightly banded Bose system! So the point of this long-winded description is: Which ever system or modifications you decide to go with, adding this well thought out passive radiator is definitely worth the extra expense and effort.

Mejora mucho las bajas frecuencias

I have never experienced passive radiators before so I had some expectations purely based on Youtube videos I’ve seen. I installed the 10” Slaps into about 14 litre 18mm thick plywood box with 8” GAS Alpha woofer and filled the box with acoustic wool. this thing is tiny, heavy and starts to rumble at around 21-22Hz and really hits hard 27Hz and up. no port noise and compact size compared to previous ported one. highly recommended.when installing, test for the soundwave phases before setting and forgetting.

Tl;dr - Throw these and some weight in a small box with a beefy high excursion subwoofer running lots of power, and you’ll get a super-clean sub that plays as low and loud as a very large ported enclosure. It’s basically the best of both worlds: clean bass like a sealed box with the extended output of a port.I’m running two of these in my car with a JL Audio 10TW3-d8 on 750 Watts in a small 0.55 cubic ft enclosure, and it gets down! Adding some weight compensated for the small box so I’m getting even inaudible ruble between 25hz and 20hz that visibly shakes my headliner on tones I barely hear. It’s crazy for a single 10in driver, but it’s because these help so much. They don’t do anything for higher bass notes, such as 50hz. The woofer will be on it’s own for that, but that’s fine because higher bass notes don’t need to move nearly as much air as low bass. For the lower bass notes, however, these things kick in to effectively act as three 10 in drivers (viz. one driver plus these two 10in passives).Keep in mind that you’ll want to find a high excursion sub to make these happy. They work when the driver moves. So, when the driver moves in, it creates air pressure in the box that pushes these out - like a balloon. And when the driver moves out, the air pressure sucks these in - like a vaccume. Sub drivers moves in and out the most on low bass notes, not on high bass notes, which is why these help most on the lower notes. I’m planning on pairing these next with a really beefy 10 in Sundown NS v.4 on a Rockford 2,500 w amp (T2500-bdcp), just to get as much excursion as possible for these radiators.Note that if you add a lot of weight to tune down a smaller box, you’ll naturally lose some efficiency. The extra weight will simply require more energy to flop around heavier radiators. My setup is like that, so I just threw extra power at it. Having extra power (i.e. amp headroom) is advisable anyway.The last thing I’ll mention is to model your box before building it, using software like WinISD or something. The lower rolloff of passive radiators is generally very steep, more so than sealed or ported boxes. That means your lowest tuning point will essentially be the lowest note you’ll get out of the box. Sealed and ported boxes are a little more forgiving in that they’ll still be able to play some notes below your lowest tuning point, and you’ll still be able to hear the note. The workaround for this, however, is easy. Just set your lowest tuning point as close to 20hz as possible. You can’t hear that low anyway, so the steep roll off becomes irrelevant. In other words, setting your lowest tuning point near or below 20hz makes the steep roll off purely theoretical: Basic physics allows no way to build a box that will cause you to hear things that your ears simply can’t detect. If your lowest tuning point is set near or below 20hz, you’ll be very hard pressed to find a better box type than a passive radiators setup (esp with these passives).