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Thread: Dual voice coil woofers

  1. #1
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    Dual voice coil woofers

    Not a JBL home audio system. But I know there's a lot of tech guys here. I'm needed help figuring out how to amp a signal coming from a stock car audio deck going to a stock subwoofer with dual voice coil. I'm trying to bypass the stock unit and use the signal to power an external sub with amp. I tried to see the two pair as a simple R/L audio signal and feed it into the amp as channel 1&2 but it didn't work well. It seems I need to wire them in series or parallel into 1 channel. I've watched videos on how to power a dual voice cool sub. But I'm needing to go reverse and use a dual vc signal to power an amp. How do I wire the pairs ing into one channel. Series or parallel? Thanks!

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    It depends on the speaker and how the coils are wound the position of the coils in relation to the magnet assembly. If one coil so to speak is pushing the cone and the other pulling the cone they will need to be wired electrically out of phase/opposite polarity.

    Also the impedance of the coils and the total impedance you need will determine if you wire the coils in series or parallel, some car audio woofers are only 1 or 2 ohms.

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    Senior Member HCSGuy's Avatar
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    So, just for clarification, you are trying to use the speaker level subwoofer output from an OEM/stock audio system to feed into an aftermarket amplifier and subwoofer, correct? I also assume that the subwoofer amp you are using does not have speaker level inputs - RCA only. If so, you will first need to get a speaker level to RCA converter - very common at car audio shops, Crutchfield, etc. Do a Google search and you’ll find them. Once you connect that, you can use an RCA Y adaptor backwards to sum the two signals to a single mono RCA, or your amp may have this capability built in. One warning - if you use the speaker to RCA adaptor and wire one of the speaker wires out of phase, then combine them to mono, the left and right speaker wire feeds will cancel each other and you’ll get nothing, so if you get nothing, try reversing the phase of one pair. Hope this helps
    That the internet contains a blog documenting your life does not constitute proof that your existence is valid. Sorry.

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    Now that I look at it again it seems like a two part question, amp input and speaker connection.

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    Senior Member grumpy's Avatar
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    ... warning #2, the speaker to RCA level converter mentioned is probably a resistive voltage divider, so wiring the two converter outputs in parallel (which is what would happen using a Y-adapter), will probably work fine, summing L+R safely.

    Doing so without the resistive elements is a no-no (e.g., L+R via Y-adapter directly from a line level or speaker output), as the output amplifiers would be actively fighting each other for control of output voltage and might not have protection for this. Normally, a Y-adapter is -only- used to send an output signal to two places. This is an odd exception.

    Also, a quick/dirty summation can work just wiring the L ch to one voice coil and the R ch to the other (probably what they did with the stock sub). A lot of deep bass is mono anyway.

    Is your new sub a single coil or dual coil? Your amp may be happier with dual coils in series, or -if low impedance capable-, may be happier/louder with them in parallel.

    The signal coming from the Y-adapter will be monophonic in any case.

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    Quote Originally Posted by Mike Caldwell View Post
    It depends on the speaker and how the coils are wound the position of the coils in relation to the magnet assembly. If one coil so to speak is pushing the cone and the other pulling the cone they will need to be wired electrically out of phase/opposite polarity.

    Also the impedance of the coils and the total impedance you need will determine if you wire the coils in series or parallel, some car audio woofers are only 1 or 2 ohms.
    Just to be clear the factory sub is dual voice coil. I'm trying to use those leads to the amp of an aftermarket unit.

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    Quote Originally Posted by HCSGuy View Post
    So, just for clarification, you are trying to use the speaker level subwoofer output from an OEM/stock audio system to feed into an aftermarket amplifier and subwoofer, correct? I also assume that the subwoofer amp you are using does not have speaker level inputs - RCA only. If so, you will first need to get a speaker level to RCA converter - very common at car audio shops, Crutchfield, etc. Do a Google search and you’ll find them. Once you connect that, you can use an RCA Y adaptor backwards to sum the two signals to a single mono RCA, or your amp may have this capability built in. One warning - if you use the speaker to RCA adaptor and wire one of the speaker wires out of phase, then combine them to mono, the left and right speaker wire feeds will cancel each other and you’ll get nothing, so if you get nothing, try reversing the phase of one pair. Hope this helps
    It has speaker level inputs and rca. I've tried both. Both not great. The output is not even at all levels. Not linear.

    I stumbled upon a terrible solution I'm not happy with where I have 3 of the 4 pairs of wires connected to the amp. One pair in channel 1. One lead only in channel 2. Sounds great but can't be right electrically.

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    Quote Originally Posted by grumpy View Post
    ... warning #2, the speaker to RCA level converter mentioned is probably a resistive voltage divider, so wiring the two converter outputs in parallel (which is what would happen using a Y-adapter), will probably work fine, summing L+R safely.

    Doing so without the resistive elements is a no-no (e.g., L+R via Y-adapter directly from a line level or speaker output), as the output amplifiers would be actively fighting each other for control of output voltage and might not have protection for this. Normally, a Y-adapter is -only- used to send an output signal to two places. This is an odd exception.

    Also, a quick/dirty summation can work just wiring the L ch to one voice coil and the R ch to the other (probably what they did with the stock sub). A lot of deep bass is mono anyway.

    Is your new sub a single coil or dual coil? Your amp may be happier with dual coils in series, or -if low impedance capable-, may be happier/louder with them in parallel.

    The signal coming from the Y-adapter will be monophonic in any case.
    But are those leads just a L/R output?. I'm trying to follow along. I know they need to be combined into one channel but how.

    It's a dual VC also. The amps not handling the signal properly because it's not wired correctly in the front of the amp.

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    Quote Originally Posted by Mike Caldwell View Post
    Now that I look at it again it seems like a two part question, amp input and speaker connection.

    Yes, The stock unit is a deck and a dual VC sub. I thought those leads were just a L/R channel and wired it to an external amp. It didn't work well. High output at low volume, diminished output at high volume. I can't be sure if the leads are actually just one channel further up the system, split into two signals for the dual vc sub, or if they inverted one pair.

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    Thanks for all the replies. As a recap, the stock unit has a dual VC sub with two pair of leads going to it. I thought they were just a L/R signal. But it didn't sound good.
    1. I'm now not sure what these leads are, or if the factory split one channel into two, or if they inverted a pair. That's one problem.

    2.I watched some video's on wiring up a dual VC sub https://www.youtube.com/watch?v=jryFmICR4qA&t=301s I think I need to reverse the process to the amp and wire the 2 pair back to a single pair.

    3. I tried a speaker to rca converter, and it was the same as speaker level inputs. Same results (treating the leads as L/R channels).

    4.While making connections I found that if I wired channel 2 up with only one lead, sound and power increase dramatically I'm not sure why that's working, but expect smoke any time now!;<img src="images/smilies/eek.gif" border="0" alt="" title="EEK!" smilieid="10" class="inlineimg"><br><br>

    5.The new sub is also dual VC. But that part was already working, I'm just trying to figure out how to feed the amp.

    I tried to reply as best I could by phone. If I missed something, please remind me. Thanks again!

  11. #11
    Senior Member grumpy's Avatar
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    maybe just pick one pair and run it to both amp inputs... sounds like it might have been mono to the sub (maybe two inverted, bridged outputs, to get the max out of a 12v head).

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    Quote Originally Posted by grumpy View Post
    maybe just pick one pair and run it to both amp inputs... sounds like it might have been mono to the sub (maybe two inverted, bridged outputs, to get the max out of a 12v head).
    Thanks! I did. If I run just one pair into one channel, there's not much output. If I run both pair into two channels, there's more output, but it's not great, it's loud at low volume, and diminishes at higher volume. And it doesn't sound that great at any volume. Gain had to be all the way up. I considered it was out of phase so swapped the positive and negative, but that wasn't the issue.

    I stumbled upon a channel and a half when playing around with it. Power went through the roof and it was shaking loose change in the car door. I now have the gain all the way down (speaker level inputs). But how can it work on a channel and a half? That's why I believe both channels must be re-combined into one. Just trying to figure out how to wire the leads together properly without frying the deck. Is there a danger wiring these leads together, or more specifically, getting it wrong?

    The unknown variable is how the manufacturer powered the two pair. The simple solution is an aftermarket deck with dedicated sub out. This is just a bit of intrigue.

    Edit: Ah, I see what your saying. but shouldn't we know which leads of the two pair are actually the real channel for that to work?

  13. #13
    Senior Member grumpy's Avatar
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    The speaker level input to your amp is probably high enough resistance to not worry about it.

    Without access to specific model information, we’re flying a bit blind.

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    Quote Originally Posted by grumpy View Post
    The speaker level input to your amp is probably high enough resistance to not worry about it.

    Without access to specific model information, we’re flying a bit blind.
    Yes we are.

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