To those who have expressed interest in, and have even asked Brian to offer, a subwoofer with an 18" driver, may I ask what it is you think an 18 will provide that a 15 doesn't? Yes, all else being equal, an 18 sets into motion more air molecules than does a 15 (due to it's larger radiating surface). But two 15's move more air than does a single 18, right? Why not just get an F25 (which has two 15's), or two F15's? But okay, let's go with the 18; What if the 18 is less sensitive/efficient than the 15 (which it most definitely WILL be)? It will then give up some output to the 15 if using the same amplifier---no gain! Brian would need to design, build, and install a larger amplifier in an 18" sub, therefore increasing it's price of course, perhaps to the equal of two F15's. I, personally, would rather have two F15's than a single F18. And that is assuming that all WILL be equal (see above). Will a Rythmik 18 driver have the sound QUALITY of the 15? It's cone's mass will be definitely be greater, and it will most likely be not as stiff as the 15. Will the increased output (with the extra power required to do so) be worth a loss (if any) in SQ?
There is the hardcore DIY segment of the subwoofer market that has embraced 18" models. Enthusiasts looking for the highest output at the lowest frequencies are putting the TC Sounds LMS Ultra 5400 woofer ($750 retail) into homemade 4cu.ft. and larger enclosures, and powering it with a pro audio 2,000-4,000 watt amp. There is also the required cross-over and filters, etc., that add to the cost. For those who don't know, the DIY crowd holds subwoofer shootouts, at which a group of subs are driven as loud as they will play, with movie sound effects and certain kinds of music (often the kind with double-kick drumsets and highly distorted electric guitar---what we used to call Speed Metal) as sound sources. The subs are played loud enough that participants must insert earplugs to protect their hearing. The participants then judge the subs with the plugs in their ears! Do you find that as funny as I do? Is everyone aware that out hearing mechanism, in an attempt to protect itself, have a means of "shutting itself down" after a certain length of high SPL is experienced? And that our response curve/sensitivity is then different than it was before the "shut down"? These shootouts are hours long, at extremely high SPL. Ear fatigue is real. The "monster" subs with TC Sounds driver and 4,000w amp have, of course, been found to provide the highest SPL at the lowest frequencies, and are, therefore, considered by this crowd to be the reigning Kings of subwoofers. The high-powered amp is required, by the way, because the LMS Ultra 5400 is an extremely insensitive/inefficient driver, so the power is not so much responsible for the sub's output, it is just required by the driver's electrical characteristics. The high output levels are actually possible because the Ultra 5400 has extremely long travel. These subs are what I call "brute force" designs: extremely inefficient, therefore extremely high-powered, with extreme output. Which raises the question: Just how much output do you need from a sub? Those of you wanting an 18" Rythmik: Why? Do the Rythmiks you have now not play loud enough, or low enough? Or are you just like a teenage boy, wanting the biggest, uh, car engine, at your High School? I'm just askin'!
But what of sound QUALITY? That's very subjective, isn't it? Everyone has his own idea of what low frequencies should sound like. From the sources used at these shootouts, and the terms used by the participants to describe what they hear, I have no idea what these monster subs would sound like in my system, with my music (my Rythmiks are in a music-only system). I have my sound sources, very different from theirs, and I use terminology to describe sound very different than do they. Rythmik subs have been present at some of these events, and I found it telling what were said about them. The output levels reached have been found to be respectable (amazing, considering what they're up against), but the listeners often don't quite know what to make of the Rythmik "sound". They are often described as being different than all the other subs, with less of a hearable, on their own, character, less "calling to attention" to themselves. These enthusiasts don't consider the ability of a sub to "disappear" to be an attribute, but a shortcoming! They listen for low-frequencies as a separate entity from the rest of the sound spectrum, and typically boost them way above "flat" response. Bass heads, as they say.
So, to those of you desiring an 18" sub, I wonder, are you sure you are really a Rythmik customer? I dislike the old phrase "Pearls before swine" (also the name of a late-60's Group on Reprise Records), finding it elitist, pompous, and condescending. But Rythmik's can be seen as being for those who require more than just lotsa bass from a sub. Like some refinement; the ability to distinguish between the low registers of a Steinway and a Bosendorfer piano, between a 300-year old upright hardwood bass and a modern plywood one, and between a bass drum with calfskin heads and plastic ones. Any ol' sub will pound out Metallica, if that's all you require.
Last edited by BDP24; 09-04-2015 at 10:40 PM.