Axiom Home Page Forums General Discussion Technical Questions Speaker Resistance (Ohm) Wiring Question

A basic discussion of voltage dividers is shown here . The voltage drop across each of the fixed resistors is proportional to its relationship to the total resistance in the circuit. Likewise, the voltage drop across the speaker voice coil is proportional to its resistance relative to the total resistance including the fixed resistor. At frequencies where the impedance is higher, the voltage drop across the speaker voice coil is higher and results in a relative increase in loudness at that frequency.

Here is a partial copy/paste of what I posted over at AVS and haven't gotten a response back on yet...
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The bass shakers I have are the non-pro version (4 ohms and 25 watts each). I know that "ideally" I would have 200 watts total, but my previous experience with these shakers is that they are most effective in adding to the experience (without being just a stupid level of shaking) that they don't require that much power. I mean, they won't be run at max anyway.

So, I can wire up each row with a combination of series/parallel and get either 4 ohms or 16 ohms per set of four shakers.

So far so good.

So if I go with that, I would need something with 2 channels that can handle 4 ohms or 16 ohms per channel and output up to about 100 watts (any more is overkill).

OR

I can tie both rows together and get a single 8 ohm connection at about 200 watts.

So can I assume that any of the option options would work?
#1) Dayton Audio SPA250 - 156 Watt at 8 ohms plate amp (connect both rows together)
#2) Dayton Audio APA150 - 2x75 watts in 4 ohm mode, 150 watts in bridged 8 ohm mode
#3) Dayton Audio SA70 - 70 watts at 4 ohms - Buy 2 of them, one for each row.

#1 is priced between the others, and would just require a simple box to house it in.
#2 is the most expensive, but still within reason, it is a finished product not needing a box to be constructed.
#3 is the cheapest, requires a box to house both amps, but adds control for both rows independently.

First up, is my math correct on the Ohms?
Second, opinions/options for powering this setup? While I would have loved something like a receiver with remote capabilities to dial in the level of shake from my seat, I can deal without. Otherwise I would need a 2 channel receiver that could handle 4 ohms at 100 watts per channel...

Thanks!

This all seems unnecessarily complicated. Why not just wire them in series? (Rcv+ to spkr1+, spkr1- to spkr2+, spkr2- to rcvr-; keep extending until you've added as many speakers as you want.) You'll wind up with a 16 ohm resistance with 4, but that won't hurt any receiver, just makes in a little less loud.

So if I picked up the originally named Sherwood receiver which has 100 watts at 8 ohms per channel, what could I expect if I had each row of 4 shakers (16 ohms each 'load') for wattage? Half of the rated 100? If it would work from the ohms perspective, I could have the advantage of each row being separate and have remote control....

Nick, although I've commented on the interesting(to me, at least)technical aspects of drivers connected in series, I should also reply to your basic question. I tend to agree with Cork, and you may be over-thinking this shaker setup. Wiring four in series for each row and using that Sherwood receiver(theoretically about 50 watts per channel into 16 ohms, which is also just a theoretical number)would be relatively simple and should be plenty to get the folks all shook up.

Any concerns about frequency fluctuations would be minimal with identical drivers with identical impedance graphs. Also, any possible irregularities caused by series connection would be less bothersome in shaking as compared to listening, although ardent "audiophiles" might claim that their butts were just as golden as their ears.

Wasn't it Mark that had an avatar years ago with a picture of himself with giant golden ears? I don't think that I want to see his picture of his golden butt...

Almighty, so if memory serves me correctly from the last time I had shakers booked up, I don't even think that I came close to 50% power, so maybe I will just go the route of the Sherwood and be done with it.

Yes, it was me.

The Golden Butt photos aren't free.

But I've found that they do hold their value.