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Discussion Starter · #1 ·
I have a DVC sub (ID12v3) that can be wired for 8 or 2ohms. I have an amp I'd ideally like to drive into 4ohms. Can I throw an inductance coil (like those used for passive low-pass sub filters) in line with this thing with the VC's wired in parallel to raise the impedance from 2 to 4ohms?
 

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you will just be wasting power and turning it into heat, pointless really....not even sure about the safety of doing something like that

either pick up a new subwoofer, new amp, or live with a final 8ohm load or 2ohm load if you amp can handle it
 

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I tired that exactly one time, with the other coil shorted, for a customer who refused to change equipment.

Long story short, I ended up just running the coils in series after all.
Well then that sub was already screwed. Using just one coil should not do any damage to a DVC woofer.
 

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Discussion Starter · #10 ·
wow, for a bunch of DIY'ers you guys seem averse to the ugly hack I've suggested.

1. SVC config: ID says don't do it. besides, this would halve the power handling and defeat my purpose.
2. BTA: *sigh*
3. azngotskills: if I quarter the impedance by wiring the 2 VC's in parallel, and then increase the impedance 2X by adding an inductor, how exactly am I wasting energy? If the net effect is to bring the circuit to an impedance of 4ohms, and the 2 VC's see all the current the amp is capable of, then mission accomplished.

look, this was not meant to be a well thought-out install. I'm doing the best I can with what I got. I was hoping this could be an electrical problem to which someone might have an adequate solution. I know it'll probably take a hack, but I can live with one that works.
 

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wow, for a bunch of DIY'ers you guys seem averse to the ugly hack I've suggested.

1. SVC config: ID says don't do it. besides, this would halve the power handling and defeat my purpose.
2. BTA: *sigh*
3. azngotskills: if I quarter the impedance by wiring the 2 VC's in parallel, and then increase the impedance 2X by adding an inductor, how exactly am I wasting energy? If the net effect is to bring the circuit to an impedance of 4ohms, and the 2 VC's see all the current the amp is capable of, then mission accomplished.

look, this was not meant to be a well thought-out install. I'm doing the best I can with what I got. I was hoping this could be an electrical problem to which someone might have an adequate solution. I know it'll probably take a hack, but I can live with one that works.
I think azn was replying to 89's suggestion to only wire one coil.
 

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wow, for a bunch of DIY'ers you guys seem averse to the ugly hack I've suggested.

1. SVC config: ID says don't do it. besides, this would halve the power handling and defeat my purpose.
2. BTA: *sigh*
3. azngotskills: if I quarter the impedance by wiring the 2 VC's in parallel, and then increase the impedance 2X by adding an inductor, how exactly am I wasting energy? If the net effect is to bring the circuit to an impedance of 4ohms, and the 2 VC's see all the current the amp is capable of, then mission accomplished.

look, this was not meant to be a well thought-out install. I'm doing the best I can with what I got. I was hoping this could be an electrical problem to which someone might have an adequate solution. I know it'll probably take a hack, but I can live with one that works.
Post #9 is a pretty good hack. ;)
 

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wow, for a bunch of DIY'ers you guys seem averse to the ugly hack I've suggested.

1. SVC config: ID says don't do it. besides, this would halve the power handling and defeat my purpose. How would it halve the power? Its what you want. A four ohm load. it does decrease efficiency and it changes the T/S specs.
2. BTA: *sigh*
3. azngotskills: if I quarter the impedance by wiring the 2 VC's in parallel, and then increase the impedance 2X by adding an inductor, how exactly am I wasting energy? If the net effect is to bring the circuit to an impedance of 4ohms, and the 2 VC's see all the current the amp is capable of, then mission accomplished. Yes and no. The Inductor is still seeing an electrical signal which is now taking half your amplifiers power. I would run the sub parallel to be a two ohm load. With impedance rise you will be over 4 ohms. Just watch the heat of the amp. Go easy on the gains until you get a feel for how your amp will take it.

look, this was not meant to be a well thought-out install. I'm doing the best I can with what I got. I was hoping this could be an electrical problem to which someone might have an adequate solution. I know it'll probably take a hack, but I can live with one that works.
What amplifier?
 

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The only real solution is to utilize an impedance matching transformer which:

a) costs a **** ton of money
b) will likely be lossy
c) is hard as hell to find

Save yourself the time and money and just use the thing at 8 ohms or buy another amp or speaker.
 

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Discussion Starter · #15 ·

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Discussion Starter · #16 ·
The only real solution is to utilize an impedance matching transformer which:

a) costs a **** ton of money
b) will likely be lossy
c) is hard as hell to find

Save yourself the time and money and just use the thing at 8 ohms or buy another amp or speaker.
really? why not just use an inductor with the same impedance as the VC? I'm not saying I have the answer here, I just would like to understand why my first thought wouldn't work.

I think another solution would be a high-current resistor. Couldn't I run a 2ohm resisitor in series and obtain the same effect?
 

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You're really talking about a 1-2db difference on a pretty low power setup. You could probably gain more than that difference building a different enclosure than you would worrying about impedance. Either way you look at it, your sub is gonna see 150 rated watts. Being that it's Zed-built, I would say it makes more power than that.
 

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Discussion Starter · #18 ·
You're really talking about a 1-2db difference on a pretty low power setup. You could probably gain more than that difference building a different enclosure than you would worrying about impedance. Either way you look at it, your sub is gonna see 150 rated watts. Being that it's Zed-built, I would say it makes more power than that.
Ok, now I hadn't thought about that. Just so we're on the same page:
right now I've got 150W into 8ohms. I'd like to be able to drive a 4ohm load for 300W. Are you suggesting that doubling the power would only result in a 1-3db increase in sound output from the sub?

I also don't plan on actually running the thing that hot. I was hoping to keep the amp below it's rated output which is easier to do if it's wired for 300w rather than 150.

It's also more than just a practical solution, I'm curious how the electronics work here. My rudimentary understanding is that one can increase the impedance of an AC circuit by adding an inductor *or* a resistor.
 

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Ok, now I hadn't thought about that. Just so we're on the same page:
right now I've got 150W into 8ohms. I'd like to be able to drive a 4ohm load for 300W. Are you suggesting that doubling the power would only result in a 1-3db increase in sound output from the sub? Somewhere in there, yes.

I also don't plan on actually running the thing that hot. I was hoping to keep the amp below it's rated output which is easier to do if it's wired for 300w rather than 150.

It's also more than just a practical solution, I'm curious how the electronics work here. My rudimentary understanding is that one can increase the impedance of an AC circuit by adding an inductor *or* a resistor.


Someone with more technical knowledge should probably explain the reasoning behind why that won't work, but I would think it has something to do with that resistor being able to absorb 150w without bursting into flames. ;)

Another thing to consider is that halving/doubling impedance does not always have the exact opposite effect on the wattage being produced. My Fosgate T1500-1bd measures [email protected] ohm, but still does [email protected] ohms, as opposed to ~900. To the point- your Zed amp more than likely makes more than half the power at 8 ohms that it does at 4.
 

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Discussion Starter · #20 ·
Someone with more technical knowledge should probably explain the reasoning behind why that won't work, but I would think it has something to do with that resistor being able to absorb 150w without bursting into flames. ;)

Another thing to consider is that halving/doubling impedance does not always have the exact opposite effect on the wattage being produced. My Fosgate T1500-1bd measures [email protected] ohm, but still does [email protected] ohms, as opposed to ~900. To the point- your Zed amp more than likely makes more than half the power at 8 ohms that it does at 4.
Good point on the flames. It would have to disipate as much as 150w. I hadn't thought of it that way. Thanks.
 
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