Is it possible to wire two 4-ohm DVC subs into a 2 ohm load? - AVS Forum
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post #1 of 10 Old 04-07-2013, 06:04 PM - Thread Starter
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I've heard both yes and no.

Wouldn't it work if I just used one voice coil to wire it instead of two?

I have a monoblock amp. (Hifonics ZRX1500.1D)

My subs are Rockford Fosgate P3's (12")
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post #2 of 10 Old 04-11-2013, 03:27 AM
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no but you can get to 4 ohm.....not great...a little low on power at 4 ohm....or go to 1 ohm, just make sure you have plenty of ventilation.

Tim
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post #3 of 10 Old 04-11-2013, 10:05 AM
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What are you trying to do?
2 of those 4ohm subs wired in parallel will present a 2 ohm load to that amp, or in series will present an 8ohm load to the amp.
That amp specifies it's power output for a given load so if you present a 2ohm load it states 1kw.
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post #4 of 10 Old 04-11-2013, 08:10 PM
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Quote:
Originally Posted by RCbridge View Post

What are you trying to do?
2 of those 4ohm subs wired in parallel will present a 2 ohm load to that amp, or in series will present an 8ohm load to the amp.
That amp specifies it's power output for a given load so if you present a 2ohm load it states 1kw.

They are 4 ohm dual voice coil subs, so wiring each VC in parallel and then each sub in parallel will present a 1 ohm load.

wiring each VC in parallel and then each sub in series will be a 4 ohm load.

and then series and series again will be 16 ohm.

Tim
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post #5 of 10 Old 04-18-2013, 10:25 AM
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You only need to use one coil on each sub, then run them in parallel and you will have a 2 ohm load. The second voice coil has two purposes; to allow flexibility in the impedance that you present to the amp, and to be able bridge a non-bridgeable amp to sum a stereo signal into mono. Using only a single coil will not affect any spec of the sub other than how much power you could put to it if the coils were in series. In parallel, they have the same power handling. Efficiency may also be affected, so you might want to do some testing of using both coils and running the subs in series, but I would wager that you will hear an improvement by using only one coil and creating a 2 ohm load.
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post #6 of 10 Old 04-22-2013, 08:21 AM
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Quote:
Originally Posted by Warren_G View Post

You only need to use one coil on each sub, then run them in parallel and you will have a 2 ohm load. The second voice coil has two purposes; to allow flexibility in the impedance that you present to the amp, and to be able bridge a non-bridgeable amp to sum a stereo signal into mono. Using only a single coil will not affect any spec of the sub other than how much power you could put to it if the coils were in series. In parallel, they have the same power handling. Efficiency may also be affected, so you might want to do some testing of using both coils and running the subs in series, but I would wager that you will hear an improvement by using only one coil and creating a 2 ohm load.

What about the T/S parameters being affected? Which in turn will cause the enclosure requirements to change. Actual thermal power handling should be very close to the same as there is the same amount of copper/aluminum that will heat up.

I suggest that if you are going to only power a single coil of a dual coil woofer you short the non used coil. This helps keep the unused coil from "influencing" the performance of the woofer.

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post #7 of 10 Old 04-22-2013, 10:29 AM
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The Thiel Small parameters are mostly influenced by physical characteristics of the sub, so should not be affected much by only using one coil. As well, shorting the terminals of the unused coil WILL have a mechanical impact on the sub, as the electrical energy created by cone movement would be damped, and that would affect T/S and reduce efficiency. Leaving them open would be electrically the same as not having the second set coil present on the sub at all.

I can recall a long time back where some company that made closed-loop servo subs had a demo box that allowed switching between 3 settings, an open sub, shorted coils, and active servo damping, and it was used to show the control exerted on the cone by the damping circuit, and the demo was to simply press on the sub cone and move it by hand. The setting that shorted the coils showed that it would offer more mechanical resistance to movement due to the smaller amount of damping offered by the subs own electrical feedback. A sub moves from the electrical energy put across the coils, and in the same way that a motor and a generator appear to be generally the same, if you manually move a speaker cone electrical eneryg is created and would be measurable across the terminals.
Anyone with a spare sub laying around can try this themselves. Move the cone in and out by hand, then short the terminals and try it again, it will feel that the suspension is stiffer.
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post #8 of 10 Old 04-22-2013, 02:28 PM
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T/S are the ELECTRO mechanical parameters. While the mass, Xmax, CMS, SD and other physical attributes won't change, the very very important electrical ones will.


Depending on how the T/S specs were taken (series wired or parallel, have never seen a per coil spec given except maybe adire) it will affect the Qe and Qt. Most everything I have ever read has suggested connecting the unused coils positive and negative together as there will be inducted current that can cause unexpected results. Heck some woofer manny's even recommended just running a single coil while attaching a resistor or pot across the unused coils for variable Q/ some rudimentary signal shaping.

Again, I am agreeing that it can be done. Just the box requirements may change as well as power handling will be slightly reduced but should not be much.

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post #9 of 10 Old 04-23-2013, 04:42 PM
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This is why i try never to suggest running only one VC in a DVC sub. Sure it can physically be done, and it wont damage the driver. But getting people to agree on what goes on when you do it is always a complicated mess.smile.gif

Tim
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post #10 of 10 Old 05-26-2013, 11:11 AM
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Not possible with a monoblock amp, but with a 2-channel amp it is possible.
Here is a pic to show you how to wire them:
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