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Is the Infinity Subwoofer info correct? It says selectable 2-ohm or 4-ohm impedance.
A DVC-2-ohm sub would be 1-ohm or 4-ohms and a DVC-4-ohm sub would be 2-ohm or 8-ohms.
I'm curious how Infinity pulled this off, since even triple or quad DVC subs can't accomplish both settings.
2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs
The info is correct, but I'm not sure at this point how they have pulled this off - We don't have any in-stock right now - so I don't have one I can get to for inspection.
I have a couple of people trying to track down the info on this.
I'll update as soon as I know more.
So here is the skinny on this one (super cool stuff):
has a patent on the first ever woofer with 3 voice coils. Using the switch in one position the voice coils are wired to provide a 2.1 ohm load, and in the other position it is a 4.3 ohm load.
I don't have the details at this point on the individual voice coil impedance - however, this is not really that much of a concern, as there is only a single input on the subwoofer - so the 2-ohm and 4-ohm figures are really the ones that matter.
This provides a whole new level of flexibility to building a system.
I am not seeing how they work this.
The math is simple enough, in series, the impedance sums,
so if 4.3 is the series impedance:
but in parallel, that results in a 0.47-ohm load.
if 2.1 is the series impedance
but in parallel, that results in a 0.23 ohm load.
I made the assumption that all voice coils were the same impedance and power handling, you could do something with series-parallel wiring and one voice coil handling more power than the other two and maybe come up with something that works, but that doesn't seem extremely practical.
Actually, this would be easy to do with a dummy VC, and that COULD be what they are doing -
I think this would work:
Of course this is possible with any DVC subwoofer, but usually brings up the issues highlighted by Scott Neill here, but perhaps Infinity has found ways to work around this, or perhaps they have decided a more marketable solution was worth the drawbacks.
Just supposition on my part, though ....
Thinking more about this ....
Either way - it's nice to have a sub that is the same power handling at 4-ohms or 2-ohms to make up for all the times people bought a sub and amp only to find they weren't compatible at the required impedance.
Still digging, but here is a bit more of the story:
It has a simple switch/jumper which uses either all three in parallel to offer a
2ohm load, or 2 in series then parallel to offer a 4.3 ohm load.
Hopefully we will have more info on exactly how this works in the next week or two -
That ALMOST works but not quite (one of the electronics theory guys correct me if I am wrong).
I think you mean two in parallel, then series ....
For the parallel, I just guessed at numbers off the parallel site.
Turns out three 6-ohm VC's give you a 2-ohm load.
Two 6-ohm VC's in series gives you a 12-ohm load, and 12-ohms in parallel with 6-ohms gives you a 4-ohm load.
Sounds great so far ....
Here's the problem ....
Let's say I have a 300W regulated amp.
At 2-ohms, the load splits evenly between the VC's so we see 100W on each voice coil.
At 4-ohms, in parallel, more current goes to the lower impedance, so the single VC sees 200W and the dual VC's split 100W total or each gets 50W - not good.
Lets look at it the other way, though:
Two 6-ohm voice coils in parallel are 3-ohms and in series with the remaining one are 9-ohms, so that idea doesn't work either.
Again, I am assuming that all of the VC's are the same impedance and power handling, and that might well not be the case ...
It's interesting, though!!!
Okay, I played with the numbers and I figured out another
way it could work, but I ran into the same obstacle:
If we try:
The first config gives us that each VC is 1.333 ohms, so 300
W @ 4-ohms splits evenly at 100W per VC.
The second config …
Two 1.3333 VC’s in parallel is half the impedance or
0.6666-ohms. Add the remaining VC in
series and you are at 2.0 ohms.
However, in a series circuit, the most power goes to the
higher resistance, so again, the single 1.333-ohm VC sees 200W and the 1.333’s
in parallel see 100W total or 50W each.
The other options I thought of didn’t even come close to
3 VC’s in parallel for 4-ohms makes each VC 12-ohms,
3-series gives you 36-ohms
3VC’s in series for 2-ohms gives you each VC=0.6666, but
3 VC’s in parallel = 0.22 ohms
It also occurred to me that if we don't assume non-identical voice coils, what Infinity could be doing is simply "under-rating" the sub.
For example - let's assume the sub is wired per the previous post (which makes the most sense).
For 350W subs, each VC should see 117W.
But in the 4-ohm config, one VC will see 233W.
Let's assume instead of each VC being 117W, all of them are 233W (or even that one of them is 233 and the others are 117W, that would work also).
I am not enough of a subwoofer engineer to know what the downside of sending half of rated power to a voice coil, but assuming it doesn't matter there are only two "drawbacks" to this:
If that is truly what is happening, it's not necessarily a bad engineering idea, but it is a bit deceptive on the marketing (although so is Kicker selling you a 900W amp when it is claimed to do 750W), but that kinda fits the bill as well - Not to totally bring up the dead horse again, but this is the company that did the following:
I've been very patient for the specifications for these subs to show up on infinity's website, but so far nothing. I couldn't speculate any further about how they did it, but selectable impedance would be a desirable feature if it works. If they also incorporated the variable Q feature, i'd be buying them in bulk tomorrow!
I just hope the subs don't end up with wildly variable theille-smalle parameters that make them unpredictable. If the voice-coils indeed have different impedances, it would likely skew the characteristics enough that a box it works great in at 4 ohms is suddenly all wrong at 2 ohms.
Anyone notice the photos for the 10 and the 12 is identical?
Hi....,Great post....Thanks for sharing this update...this is very useful and helpful...i appreciate you!!!A very useful thread that will be referenced
long into the future...Nice sharing.
Glad you liked it!
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