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Questions on comparing motors and such.


xan326

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Okay so I've seen topics on this before but the answers I've seen have never been that clear. Based on rated specs, how would these compare?

One 12, 2400w, 4 inch coil, motor (magnet?) weight of 64 pounds, and 40mm of xmax. 43.74hz in 11.720 liters. Qms is 5.233, Qes is .364, Qts is .340.

OR

Four 10, 600w each - 2400w combined, 2.5 inch coils, magnet weight of 100oz, and 26.5mm of xmax. 37.01hz in 12.05 liters. Qms is 5.87, Qes is .623, Qts is .562.

That's the only comparable specs I have between the two. I know more surface area means more air is pushed, but I don't know how to compare motor force. I'm sure its not easy because of change in frequency, but at one frequency, how would they compare? Going by separate enclosures for the 10s, all being equal, would the 10s get louder than the 12? Would the 10s have more quality than the 12?

Is there a way to calculate combined motor force? Like would four 2.5 inch coils be equivalent to a 10 inch coil? I know xmax would stay the same, its common sense, I just know it wouldn't be reached as quickly. Does magnet size/weight have a huge effect on this?

Is there an easy way to tell if one would be better than the other?

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So coil size and magnet weight do not determine motor force. The motor force measurement is called BL. Also the volume measurement you are listing is Vas, it is a measurement of suspension compliance, not how big of a box the subs go into.

Four 10"s have a lot more cone area and will almost certainly get louder than one 12".

As far as which one will sound better, that's a lot more complex question.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

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The only parameter of BL calculation I don't have is Re, and I haven't seen Re specs on woofers before. But with the BL without Re, the 10"s have a much higher number, does this mean louder? I know based on just surface area, the 10"s would be louder, but does the BL being 4.72 times higher without Re being factored in, would that help or hinder the 10"s vs 12"?

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actually coil size does factor into motor force.

Coil area, thickness, depth in motor, gap size, motor material, motor shape, shorting rings.. anything to do with the physical characteristics of the coil or motor will directly affect the force produced and will change the BL curve.

4 2.5" coils will probably have more effective force than 1 4" coil, though.

Re is the impedance of the driver. 1 ohm, 2 ohms, 4 ohms, etc..

MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..."

Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through.

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Re is the impedance of the driver. 1 ohm, 2 ohms, 4 ohms, etc..

Yeah, my bad I just caught that. So would the 10"s end up being better than the single 12?

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Depends what "better" is.. low lows? crushing single note SPL? Endurance runs? massive clipping all day long?

Realistically i'd go with the 10's. Cone area is king for pretty much everything when you're just starting out and if you dont clip them all day every day they should last.

MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..."

Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through.

Hammerdown... 1%

no links to outside websites, business related FB/YT pages allowed.

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Knowing BL w/o knowing (or being able to determine) Re is pretty useless.

Another thing to keep in mind is BL alone does not allow you to determine efficiency, so if efficiency is what you are worried about, don't get too caught up on BL.

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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Smells like a vs. Thread.

I'm not trying to have a vs. thread. I have two options of what I can do, and I'm wanting to know which would actually do better. Plus I'm more curious about the motor side of it, since it's a topic I haven't seen much on.

Knowing BL w/o knowing (or being able to determine) Re is pretty useless.

Another thing to keep in mind is BL alone does not allow you to determine efficiency, so if efficiency is what you are worried about, don't get too caught up on BL.

Yeah I got the Re now, the impedance part kinda went over my head earlier. I'm not looking for efficiency, though it would be nice, but gotta sacrifice something when you're looking for power. Also how does BL increase effect db increase? Is it like double cone area and double power, where double BL = +3db?

Also I'm not looking for like super low lows, I want it low because it's woofers, its what they're made for, but I also want them loud.

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