Ok, I've been reading this thread for the better part of a week and there seems to be a handful of questions being asked over and over. I have recently hooked up a couple sets of shakers in my theater and will post some tools, info and things I've noticed.
Pro vs non-Pros
It seems from other's experiences and my phone calls to aura that there is no difference between the pro and standard bass shaker aside from the housing. The pros have fins to dissipate heat, the standards do not. These units were originally designed for car audio. This means operating in tiny spaces surrounded by lots of insulation. It also means that its probably going to be driven by some audio thats bass heavy which results in them being active more often than not. This is also why aura recommends them to be set at 100hz low pass. In a car there wont be any Darth Vader voices or door slams that break the realism, just music. I realize that people do watch movies in their cars and other things that result in situations other than described but these weren't intended for those exceptions.
In home audio, in situations where you have more ventilation, you could easily drive the standards with the same power as the pros. The LFE channel isn't nearly as active as it would be in a car unless you're watching something with insane bass. I've been watching Transformers, Iron-man, Jurassic park etc and had absolutely no issues with mine. Mine are mounted to the underside and rear of chairs and they're mostly open, though out of view. I measured them with an IR thermometer during some of the heavy LFE scenes of Jurassic Park and they were only 5 degrees above room temp. If you have them stuffed in a couch or some place that doesn't have a reasonable amount of thermal capacity, you may want to honor the posted wattages.
Parallel vs Serial installations
Lots of people have questions as to the correct method of installation. I found this
link earlier in the thread and used it to build the following excel spreadsheet.
The spreadsheet will calculate all the important information simply by putting the specs of your speaker, amp and method of connection. (parallel, series or both) Its calculations are based on 1 channel which means if you plan to hook 3 shakers to your left channel and 4 to your right channel you'll have to fill out the spreadsheet twice. The user fills out the blue section and the red section is calculated.
The info I have displayed is for my current setup. I have 4 standard shakers, 4 ohms each and an amp that is rated at 150 watts at 4 ohms. You could say the amp is a 75 watt amp at 8 ohms and just know that its safe to run it at 4 ohms, the spreadsheet will account for that. As you can see, I could connect all 4 in series and be at 16 ohms for the channel. Almost any amp will handle that. The problem is my current amp will only deliver 9.3 watts per shaker. If I hook 2 of them up in parallel not only does the power skyrocket to 150 watts per shaker but the ohms for the channel drops to 2. My amp is only good down to 4 so that method is out. If I connect each pair in series and then connect the pairs in parallel I get rather good results. The channel is loaded at 4 ohms and all 4 shakers receive a max of 37.5 watts each. (almost like I planned it that way.
) 37.5 watts gives me the ability to drive them up to their RMS yet is still under their peak, should I turn the amp all the way up.
My setup has 2 shakers in series in each chair, and both series circuits go to the amp in parallel. I have RCA connections between the shakers in the second chair and the amp. This way if I need to move chair 2 away from the chair with the amp in it I can simply unplug the RCA cables between the two. My original chair is left with 2 shakers in series which gives me the exact same output
as when there were 4 connected.
The load rises to 8 ohms on the channel and the per shaker output is still 37.5. Its invisible to whoever's sitting in the prime chair.If you'd like a copy of the spreadsheet send me a PM with your email address.
If JL or someone else equally as knowledgeable would like to check my math I'll extend the parallel and series+parallel out to more than 2 and 4 drivers respectively.
It seems that most people want to use an old receiver to drive their shakers which is easily feasible should you know the specific properties of each channel. If its more than 2 channel or if it has an LFE output theres a good chance that any LFE signal routed to it could get cut out or unevenly distributed. To keep things easy I'll describe some of the serious gains from using a sub plate amp.
First of all, theres only 1 channel so its very easy to use the above spreadsheet to calculate which way works best for you. Most of them seem to support 4 ohm loads which makes it even easier in many cases to drive your shakers the most efficient way. Almost all have volume control thats easily adjustable. A good portion of them have an adjustable crossover which makes experimenting with performance very easy without the hassle of buying different FMODs or having to swap them in-line. I mounted my plate amp in the bottom of my chair, facing down, so I can simply reach down and modify the volume or crossover while sitting in the chair. Movies like Jurassic Park and Transformers have very good LFE and turning it down near 50hz gives a great effect. Iron-man on the other hand didn't seem to have as much LFE info and I have to turn up the crossover to near 100hz to get what I expect as acceptable feedback. You also don't need long runs of amplified signal since its only a few feet to the furthest shaker from the amp, which means you don't need to calculate the loss to the cable/change in channel ohms. Its easy to run line level feeds to the amp as well.
I also find it easy to do things if you buy your shakers in powers of 2. So 2 shakers is easy to do the math for, so is 4, 8 and 16. Id rather have 8 shakers being run efficiently with equal power distribution than 6 with odd power distribution.