Hi guys. So I've looked all over the internets on this one and I haven't been able to turn up much. Here's the situation. I have an old junky Sherwood sub that sounds pretty bad. I also have an orphan RBH bookshelf speaker that sounds pretty good. It turns out the RBH was a prototype speaker that I'll never be able to find again, so no hope in completing the pair (I live in Utah, near RBH factory, found the speaker thrifting, emailed the company, etc.) So I had the idea to replace the junky driver in the Sherwood with the nice driver from the RBH. Same size driver, fits the Sherwood perfectly (the magnet is about ten times heavier though). So here's where I'm sort of stuck. The sub is wired for dual voice coil, but of course the RBH driver is not. So I wired the RBH with one set, and then just taped up the other set and mounted the speaker. I tested it out and it works, sounds better than it did, but I was just wondering if I wired this thing in the optimal (or only) possible way. Is there another way to wire this? If not, what is the result of leaving one set of wires unused? I'm really just looking for an explanation of what the heck is going in there given this particular set up. (Note: I know that at bottom, the fundamental point here is: there's no good reason to do this anyway, so who cares? But think of it like we're in the laboratory, and I don't care if we make a mistake for the sake of learning something new.)
How to wire a single voice coil driver to a dual voice coil sub...
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Each voice coil has an impedance. If you wire up a single voice coil, you get that exact impedance. If you wire both coils in parallel, you get half the single coil's impedance. If you put the coils in series, you get twice the impedance.
Example: You have a dual vice coil sub, each coil is 4 ohms. You can run a single coil as 4 ohms, put them in parallel for 2 ohms, series is 8 ohms. If this is car audio, I'd run it as low as possible for most current.
Example: You have a dual vice coil sub, each coil is 4 ohms. You can run a single coil as 4 ohms, put them in parallel for 2 ohms, series is 8 ohms. If this is car audio, I'd run it as low as possible for most current.
Hi, thanks for the reply! So I've been doing quite a bit of reading on this question/issue throughout the day, and I think I understand exactly what you're saying here. But just to be clear, I am not talking about using only one voice coil on a DVC driver. I am talking about replacing the DVC woofer in powered sub with a woofer from a high-end bookshelf speaker. So there are two sets of wires coming from the internal amplifier. The original woofer has two coils, so both sets of wires can be used. The replacement woofer is SVC, so one set of wires has no where to go. So I guess what I'm wondering is, will the replacement woofer receive the entire 50W of power through that one set of wires? Or does each set carry a 25W load? In which case, could I just connect the second set of wires to the same terminals as the first? The RBH woofer is almost certainly rated higher than the amp in the sub, so 50W wouldn't blow it. But I just don't know how the power is being delivered here. As I said, I hooked one set of wires to the single set of terminals on the new woofer, and it works and sounds fine, but I was just trying to figure out if hooking up the other set of wires (observing correct polarity obviously) to the same terminals would have any effect. I know that each coil in a DVC receives half the total W, but why? Is it because the coils split the total wattage between them? Or is it because each set of wires carry half the total W? If the former is true, then I've hooked it up optimally. If the latter is true, then my RBH woofer is only running on 25W instead of 50W, and if it's feasible, I should solder the other set of wires onto the terminals in order to get the 50W the internal amp is putting out. Sorry for the long post, but I want to make sure I'm presenting the issue correctly. Thanks in advance for thinking this through with me.
stillspin'n
Well-Known Member
Depends on if its a mono amp with both sets of wires running to the same place on the circuit board or if there are two amp channels each one running a different voice coil on the original subwoofer. If its a mono amp using only one set of wires shouldn't make a difference, if it has two amp channels, then don't hook them together as this may damage one or both amps.
elnaldo
Lunatic Member
You need to follow the traces on the amplifier board to see how the connectors to the VCs are connected.
If they are in parallel, there is nothing wrong in using just one VC. If they come from different circuits, you need to do some reverse engineering to see which wiring to use. Perhaps there is some inverted phase, or some difference in the crossover going to each VC.
Do you know the impedances of the original VC?
If they are in parallel, there is nothing wrong in using just one VC. If they come from different circuits, you need to do some reverse engineering to see which wiring to use. Perhaps there is some inverted phase, or some difference in the crossover going to each VC.
Do you know the impedances of the original VC?
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Does this replacement speaker have the excursion capability to be used in a sub, and do it's specs work out with the volume/port configuration of the sub box? If not you could be going to a whole lot of effort for not a lot of gain.
This is the answer I think I've been looking for. Thanks mate! It's connected to the RCA output on a DAC, which connects to my flat screen by optical cable. So it's not interfacing with any amplifier other than it's own. I'm going to open her back up and see what I can see following those wires back to the circuit board.
The sub is 8 ohms, I'm assuming 8 ohms going into each coil on the original DVC woofer?
Oh it goes without saying that this is a fool's errand. I don't think there'a any sense in which this RBH woofer belongs in that sub. Having said that, it's given me an excuse to extend my understanding of how these things work. It's the only way that works for me. I need to solve a problem in order to take another step (even if I have to invent one)
elnaldo
Lunatic Member
We can't assume, you need to measure at least the DC resistance of each coil in the original woofer. Some dual VC woofers have a 2 ohm coil.
Regarding the amplifier, if you don't feel confident to open the unit and trace the connections, just leave it as it is now, or try connecting your replacement woofer to the other 2 terminals to see if you hear a difference.
Don't connect both original connections to one single VC. Choose a pair of wires and use just one. If they come from a single amp, no need to connect both. And if they come from different circuits, you can damage things. So nothing to win but risking the amp.
Regarding your question about "watts", Watt is a unit of power. It's Volt * Ampere.
Your amplifier gives Volts to the woofer, not Watts. The Watts come from those volts divided the VC ohms. The Watt rating of an amp means how many Ampere it can deliver without damage to the amp. It's usually calculated by the manufacturer, so at the voltage it can deliver, on a suggested minimum load, the watt generated can be hold and heat dissipated by the heat sinks. The Watt rating of the speaker means how many Ampere can flow through the VC without damaging it.
Imagine at certain position of the volume knob, the signal at the output is 10 Volt. On a 10 ohm VC that's 1A (10V/10ohm), V*A=W , so 10 Watt.
Same 10 Volt on a 5 ohm VC is 2A, V*A=W , so 20 Watt.
That's how car audio amps can deliver 1500 Watt, using very low impedance loads (I think some car audio amps can handle 0.2ohm loads). Same 10 Volt on a 0.5 ohm load is 200 watt.
whoaru99
Epic Member
Yes, car amps often do take advantage of low impedance to reduce voltage requirements. That said, many (maybe most) car amps these days also use DC-DC switching power supplies to raise the (nominal) 12V to a higher value for the amp rails so that higher power is available at more normal (typ.) 2 - 4 ohms.
Most dual voice coil subs have dual 4 ohm coils. They can also be 2 ohm, or 8 ohm, but those are rare.
As said above DO NOT CONNECT BOTH PAIRS OF WIRES TO THE SINGLE COIL! If it's a 2 channel amp, you'll blow it, if it's a single channel, it would do nothing.
An easy way to tell would be to turn the balance to each side, and if the sub stops working, it's a stereo amp. I couldn't see them using a dual voice coil sub unless it was stereo.
If it is stereo, to do this right, you'd have to mix both channels together, then invert the phase on one side. Then you'd connect the voice coil to the positives on the amp. This would bridge it, but it would probably be cheaper and easier to order a new subwoofer amp from parts express designed to drive a single sub.
As said above DO NOT CONNECT BOTH PAIRS OF WIRES TO THE SINGLE COIL! If it's a 2 channel amp, you'll blow it, if it's a single channel, it would do nothing.
An easy way to tell would be to turn the balance to each side, and if the sub stops working, it's a stereo amp. I couldn't see them using a dual voice coil sub unless it was stereo.
If it is stereo, to do this right, you'd have to mix both channels together, then invert the phase on one side. Then you'd connect the voice coil to the positives on the amp. This would bridge it, but it would probably be cheaper and easier to order a new subwoofer amp from parts express designed to drive a single sub.
elnaldo
Lunatic Member
( OUT OF TOPIC:
I see !! 440Volt DC from your car battery !!!
100,000 Watt -yes, 100K Watt output power- at 0.25 ohm
No afiliation: http://www.somsc.com.br/produto/mod...ower-100k-evolution-hi-volt-alta-tensao-71609
Output Power: 100,000w
Minimum Voltage: 70V DC
Maximum Voltage: 440V DC
Minimum Impedance: 0.25 ohms
Channels: 01 )
soundmotor
super modified
I would determine if the sub amp actually has (2) independent amp channels or only (1) channel with (2) sets of woofer leads. You can determine that visually but you will likely need to pull the amp out so you can see it more clearly. One clue would be each pair of wires with the same polarity (+/+ & -/-) are soldered close together (or together) on the circuit board. You need to verify that where they are soldered actually touches either by a big solder blob on both leads or copper trace connecting them. If they do, it's a mono amplifier and you only need to use (1) set of wires on the new woofer. If however it is a 2-channel amp, you need to replace woofer you have with another DVC one.