Running One VC on a DVC Sub

I am confused... wouldn't the amp have to work harder if it had "more" resistance? resulting in less output or maybe heat/ energy loss?

I use this site everyday for trouble shooting and this might be the best info i have ever seen. I have got a million ideas in my head now

This is so obsurd. When you short out one of the coils you create a elctromagnetic resistance (or brake) by doing so as you say. This is a bad idea.

Since a speaker is considered a motor, try this. Get two 6 volt DC motors. Connect their shafts with wire insulation. Supply 6 volts to one motor, wait a second and short the other motor. What happens? The RPM's of the motor system slows down. It also creates more heat as one moter is trying to overcome the resistance and the other motor is trying to keep from moving.

This is also what happens to the DVC with one coil shorted. It makes the overall movement of the cone have resistance to move and creates more heat. I think everybody can agree that more heat is a bad thing.

I also agree with another poster that only using half of a DVC will be able to only handle half the power. DVC were made with both coils, tested with both coils and should have both coils used.

If you need 4 ohm, just get a 4 ohm SVC. Period. Why risk it?

A.A.S. in Electronics/Industrial Electronics with 25 year as an electronics technician, Peavey MediaMatrix certified

I have 2 DVC 4 ohm subs.  They each handle 400 watts RMS total.

The only way I have ever seen this set-up is either in parallel or series/ parallell  I would end up with either a 1 ohm or 4 ohm load.  Even the12volt.com website says thats the two ways to hook them up. 

This forum is implying that I could hook up 1 4ohm VC from each sub into a 2 ohm load?  I would then only use 300 watts of power?  How would this give me the same SPL as hooking up all 4 coils with twice the power?  That would be like getting the same power out of a V8 by only running four of the cylinders.

Please explain.

Andy, Welcome to the forum!  I hope to see you around often to offer your vast knowledge.

As far as I know, nobody ever said you would get the same amount of output.  That isn't the point of this discussion.  The point is that you won't cause any damage by doing this as long as power limits are observed.  And it offers a way of electrically tweaking your Qtc.

Unfortunately the previous link explaining your concerns is broken.  Here's a new link that will explain: http://www.adireaudio.com/Files/RDOOperation.pdf  As you can see, the "resistance" (showing up as electrical dampening or QES as jkwylde mentioned) can be useful.

There isn't enough extra heat generated to cause concern.  Here's a quote from this tech paper explaining this http://www.adireaudio.com/Files/DualVoiceCoilDrivers.pdf:

"Take the "worst case" situation. You wire the two voice coils out of phase. At first, you think one coil is trying to push forward, the other backward, and suddenly the system tears itself apart, right? Nope. What happens is that one coil sets up a dynamic field. Let's say, for clarification, that coil 1 generates a signal to push the diaphragm forward. Since coil 2 is wired in opposite phase, it sets up a dynamic field to push the diaphragm backward. Net result is that the two magnetic fields CANCEL themselves out! That is, the dynamic field that's pushing on the static field from the magnets is ZERO. The field from coil 2 adds to the field of coil 1 in such a way that the net field is zero. Much like adding a two sine waves of the same frequency that are shifted by 180 degrees.

This is the SAME basic principle with shielded drivers that use bucking magnets. Use a field of the opposite polarity to cancel the original field out. If the driver's motor magnet has a given polarity, use the bucking magnet to introduce a field of opposite polarity, so that the two fields cancel themselves out. Net result is no field.

So, when we run two different signals to the voice coils, what we find is that the magnetic fields of the two combine to generate a net TOTAL field that interacts with the static field of the magnets. The two voice coils NEVER fight each other in a physical way; it's all in the magnetic field. 

Now, you might say, what about the increase in heat? After all, most subwoofers rely on the conversion of electrical power to acoustic power to lower the dissipation in the driver, right?

Again, wrong. Look at the parameters of a typical subwoofer. Look specifically at N0 (eta naught). This is the parameter that gives the electrical-to-acoustical power conversion efficiency of the driver.

This number, for most dynamic cone subwoofers, is less than 0.5%. In a FEW cases, it may be as high as 3%. But, for the most part, you'll see N0 well below 1%.

What N0 represents is the percentage of electrical power that's transformed into acoustical power. For example, let's take a driver with an N0 of 1%. Apply 100W to the driver. Of the 100W electrical power delivered, 1%, or 1W, is converted to acoustic power (1%). The other 99%, or 99W, is converted to heat.

Look at a typical dual voice coil sub, such as Shiva. It's N0 is ~0.4%. This number is VERY comparable to other 12" DIY high-end subs out there, and represents a driver with an 88 dB SPL rating.

Now, apply 300W electrical power. Wire the voice coils in parallel, in the same electrical phase. We'll get our acoustical output, or (300 * 0.004) 1.2 acoustical Watts of power out. The other 298.8W of electrical power is dissipated as heat.

 Now wire the two voice coils out of phase. What will happen? Well, we know from the above that the two magnetic fields from the voice coils cancel each other out, so there's no net cone motion. Thus our acoustic power output is zero (can't have any, if the cone doesn't move).

That means ALL the power is dissipated as heat within the driver. How much? 300W. Compare this to the situation where the two voice coils are connected in the same polarity: 298.8W. Net difference? 1.2W of dissipation. In essence, you will cause exactly 1.2W of extra power dissipation in the system by crosswiring the voice coils.

Now, is that 1.2W extra heat going to be a problem? Most likely, no. If a driver is rated to handle 300W, chances are it's not going to have a problem with 301.2W. 400W, sure, but a 0.4% increase in power dissipated? Well, the temperature of the voice coils may raise another 0.1 degree C, but that's about it.

Anyway, the net result is that the increase in heat from dissipation is essentially zero. The one area of consideration is that self-cooling of a driver is reduced when motion is reduced. So the driver can handle the out-of-phase situation for a little while, but because of the reduced cooling, heat will build up faster."