Originally posted by brickie
I wired 2 in parallel , then 1 in series. Iv'e got 3 shakers on each channel..I had a minimum rating of 4 ohms per channel for the Onkyo i'm using.I should be running 6 ohms if i'm correct.
Although your expertise with popcorn is legendary, and your knowledge of Ohm's law sounds pretty decent, I'm not sure about your knowledge of Kirchoff's law.
The way you described your wiring of your bass shakers does indeed result in 6 ohms load to your receiver... However, the distribution of power to the shakers is anything but equal.
The 1 shaker in series (representing 4 ohms in your combination) will have two-thirds of the total available voltage from your amplifier across it.
The two shakers in parallel (representing a total parallel value of 2 ohms) will have one third of the voltage from your amplifier across them.
Let's assume your amplifier puts out 12 volts AC. If that is the case, 8 volts are delivered to the single shaker, and 4 volts to the two in parallel.
8 volts / 4 ohms (the resistance of the single shaker) = 2 amps current.
4 volts / 4 ohms = 1 amp current (through each of the two parallel shakers) for a total of 2 amps current. Note that this same 2 amps is exactly the same 2 that is flowing through the single shaker. (That is basically Kirchoff's law, the sum of the electrons flowing into a node in a circuit are equal to the sum of the electrons flowing out of a node)
now... if you follow me so far, 2 amps (through the single shaker) * 8 volts (across the single shaker) = 16 watts power that is being dissipated by the single shaker you have wired in series.
and 1 amps (through one of the parallel pair of shakers) * 4 volts (across the parallel pair) = 4 watts being dissipated by each of the two shakers you have wired in parallel. (for a total of 8 watts)
So the power is divided up like this
Shaker #1 = 16 watts
Shaker #2 = 4 watts
Shaker #3 = 4 watts
Did you intend that two thirds of the shaking power be delivered by one of your shakers and that one sixth of the shaking be delivered by each of the others? Or did you want equal power (and equal shaking) be done by each of the three? I addition to uneven shaking, you run a higher risk of burning out the one shaker dissipating the higher power when you turn the volume up on your receiver.
I only know three ways to get equal power to 6 shakers.
1. All in series (three on each channel of your receiver). This would result in a load of 12 ohms on each channel of your receiver. It would be an easy load on your amplifier and if it still provided enough shaking, is probably the simplest solution. (The amp will deliver roughly half of the power to 12 ohms than it can to to 6 ohms, but if it is strong enough shaking, who cares)
2 All in parallel. This would be just over 1 ohm resistance and probably way too low a resistance for most amplifiers...not a good choice for your Onkyo.
3. Put two shakers in series, parallel that set with another set of two in series... hook that to one channel of your amplifier. It will be a load of 4 ohms. (Two in series are 8 ohms, two parallel sets of two in series = 4 ohms)
On the other channel of your amplifier, put the remaining two shakers wired in series. It will be an 8 ohm load.
Then, adjust your left/right balance control on the Onkyo receiver for equal shaking of the two vs. the four shakers. Yes, the one channel of the amplifier will be delivering more power than the other, but the Onkyo will be operating within its ratings and all the shakers will be shaking the same amount .... and that is what matters.
Now... do I smell fresh popcorn???