Bridging a Dual Voice Coil

[davidwhit]

Okay, I have a dual voice coil sub. Both coils are at 4 Ohm. When put in a series it makes 8 Ohm. When I bridge my amp I should get 250W @ 8 Ohm. But isn't that 250W total for left and right? Since my sub, once put in a series, only has a (+) and (-), can't I only connect one side to the sub? Then is only 125W going to the sub? Can I combine the left and right (+) and (-) wires coming from the amp, or is that really bad? I just want to know what will give me the most power. I can't just connect the right and left coming from the bridged amp to the dual voice coil cause the amp says it only supports 8 ohm while bridged. any suggestions would be greatly appreciated. David

[DonoMan]

-What sub, what amp?
-Yes, you can connect just one voice coil, as long as you're not overloading it (it should be at least a 500W sub, so 250W per coil in your case) or the amp
-Do not put the amp channels in parallel without a 0.22 to 0.47 ohm 10+W resistor between each (IE channel -> resistor -> wire (both channels meet here) -> sub) - note: this is not bridging and it only is necessary for low impedance loads (you can use it for 1/2 output power, giving the gain control more resolution, but also dissipating more power because you need the resistors, so I wouldn't)
-Do not put one voice coil on each channel of the amp

suggestion: bridge the amp, use the voice coils in series

[timtimes]

[QUOTE=davidwhit]Okay, I have a dual voice coil sub. Both coils are at 4 Ohm. When put in a series it makes 8 Ohm. When I bridge my amp I should get 250W @ 8 Ohm. But isn't that 250W total for left and right? Since my sub, once put in a series, only has a (+) and (-), can't I only connect one side to the sub? Then is only 125W going to the sub? Can I combine the left and right (+) and (-) wires coming from the amp, or is that really bad? I just want to know what will give me the most power. I can't just connect the right and left coming from the bridged amp to the dual voice coil cause the amp says it only supports 8 ohm while bridged. any suggestions would be greatly appreciated. David[/QUOTE]


On every bridgable amp I'm aware of you don't combine the left and right speaker outputs from the amp IN ANY FASHION. I'm working from memory here (at work) but on my Kenwood THX home amp, I believe that the only thing necessary for me to 'bridge' it to a MONO amp with twice the power is to use both the PLUS leads on the left and right speaker outs. THAT IS ONE TWO CONDUCTOR WIRE that gets run to the the TWO CONDUCTORS you have after tying the dual voice coils together in series (in your case to get to 8 ohms)

That's the way most of the amps work. I'm sure others will verify.

Enjoy.

[davdev]

Any reason to ask the same question on two forums:

http://www.avsforum.com/avs-vb/showthread.php?t=559496

[davdev]

actually make that three forums

http://www.avsforum.com/avs-vb/showthread.php?t=559501

[cwb4tx]

the forum police strike again!!!

[davidwhit]

http://support.radioshack.com/support_audio/doc61/61477.pdf
This is the way I was shown how to bridge the amp, from the manual. Also, I was running the DVC in a series to the bridged amp. I don't believe I am confused. I posted in three forums because different people read different threads giving me different answers. I need all the help I can get. But I won't do it again. Thanks.

[Allan Jayne]

[QUOTE=DonoMan]--Do not put one voice coil on each channel of the am[/QUOTE]
Just curious, why is it bad to connect one unbridged amp channel to one of the two voice coils and another unbridged amp channel to the other? Isn't a double voice coil specifically intended for this kind of connection?

[timtimes]

[QUOTE=Allan Jayne]Just curious, why is it bad to connect one unbridged amp channel to one of the two voice coils and another unbridged amp channel to the other? Isn't a double voice coil specifically intended for this kind of connection?[/QUOTE]


That shouldn't be a problem except that if the amps aren't run in mono mode the voice coils will be getting different info and 'fighting' amongst themselves.

I looked at the Radio Shack PDF for bridging mono. Very weird. They're 'bridging' from FOUR speakers to TWO? My bridgeable power amp only has ONE PAIR of speaker outputs and when you bridge, you bridge to the TWO POSITIVE leads. ON the Radio Shack amp there are FOUR positive leads because it is apparantly set up for TWO PAIR of speakers. So if you were to use the RS amp 'bridged' to one speaker, it WOULD HAVE TO HAVE DUAL VOICE COILS and it would be ok to use both sets of speaker outs to the separate voice coils.

Enjoy.

[TonyBDA]

So if you were to use the RS amp 'bridged' to one speaker, it WOULD HAVE TO HAVE DUAL VOICE COILS and it would be ok to use both sets of speaker outs to the separate voice coils.

You need to look at that PDF again.
The amp has A and B speaker outputs, there is no reason you have to use both of them. The DVC sub should have it's coiles in series, presenting an 8 Ohm load to the bridged amp.

[davidwhit]

The only problem with that is that my DVC has both the coils at 4 ohm. I can't bridge the amp and then run both channels to my amp because it won't support anything but 8 ohm bridged. Right now I just have the sub in a series (which makes it an 8 ohm speaker), then I have the amp bridged, but only using the A set of speakers. I have heard that this is the best way to hook it up. Thank you for your post.

[timtimes]

[QUOTE=davidwhit]The only problem with that is that my DVC has both the coils at 4 ohm. I can't bridge the amp and then run both channels to my amp because it won't support anything but 8 ohm bridged. Right now I just have the sub in a series (which makes it an 8 ohm speaker), then I have the amp bridged, but only using the A set of speakers. I have heard that this is the best way to hook it up. Thank you for your post.[/QUOTE]

I think you've got it hooked up correctly given the circumstances of that RS power amp. I think you're better off running it the way you are. Given the choice to do it the way you're doing it with ONE speaker with dual 4 ohm VC's or TWO speakers with dual 8 ohm VC's, you're better off running more power to the SINGLE speaker than TWO anyway.

Enjoy.