Originally Posted by oman321
You seem to be the current authority on how to wire these shakers up, so let me ask. I will have 7 HT seats in my setup when completed. I am looking to get a shaker for each seat. I have already run 2 seperate wires, one for the rear row of 4 and one for the front row of 3 from my equipment closet.
Do you recommend a 2 channel amplifier one for each row, or single channel amp and wire accordingly which I can do in the closet? Also would I be better off, for wiring purposes on getting 8 shakers vs 7 and simply install 2 in the center seat of the front row?
I tried looking for diagrams through this and the other shaker thread which I found through google, but there is simply to many pages. I did get some useful info but I wanna be certain. We need an index or a sticky for diagrams only. Thanks for any help you can offer.
First, as you probably already know, there is no way with a single channel amplifier to power 7 shakers and have them all shake the same amount... You can add a 4 ohm resistor in place of an 8th shaker, or as you are considering, an 8th shaker to get then to all shake the same amount...
Unfortunately to get even shaking, a series/parallel combination of 8 shakers can be wired as an 8 ohm load (series/parallel), or as a .5 ohm load (all in parallel) The .5 is too low for almost any amplifier, that leaves the 8 ohm wiring. Most of the subwoofer amplifiers only out out about 150 watts or so into 8 ohms, so each shaker would get about 1/8th of that. Depending on how much shaking you desire, it would probably be enough. My own theater is wired exactly that way with 8 shakers.
You can use a two channel amplifier, with the set of three in series on one channel, and two paralleled sets of two-in-series on the front. The three shakers set would be a 12 ohm load, and the 4 shaker set a 4 ohm load. You could then feed both channels with a "Y" splitter from the subwoofer out of your receiver, and then turn the balance control off-center to equalize the shaking between the back row and the front. This is probably what I would do in your situation. You would need a pretty good amplifier though... probably something around 100 watts per channel, or more.
If you can deal with uneven shaking, you can wire three shakers in series in the front row, and four in series in the rear row, and then parallel those two sets to a single amplifier.
The total resistance is then
1/ (1/(4+4+4+4)) + (1/(4+4+4)) ) or
1/ ((1/16) + (1/12)) or
1/ (.0625 + .08333) or
1/ .145833 or 6.8 ohms. ( a good load for am amplifier)
Using my same 30 volts output from a typical amplifier, it would result in 10 volts across each shaker in the front row, and 7.5 volts across each in the rear row.
Power = (voltage squared / resistance) so
(10 * 10 ) / 4 = 25 watts per shaker in the row of three
(7.5 * 7.5) / 4 = 14 watts per shaker in the rear row of four shakers.