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Justi
Dodge Dakota
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4/07/2004
21:19:50
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 Subject: 4ohm DVC Single Sub Question..
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I've looked over the board and can't find the exact answer to this question, at least clearly...
I have a single 8" Dual 4ohm Voice Coil subwoofer that I'm installing behind the seat in my quad cab. I have a Rockford Fosgate 301S amp that I am going to bridge that can handle 4ohms.. The question is how do I wire the voice coils to the bridged amplifier to create a 4ohm load.
If you can speak to me like I'm an idiot (quite possibly fittingly). Please tell me where to run the positive and negative from the amp and what to do with the other two terminals on the sub (total of 4 since it's DVC).
Thanks A LOT I really do appreciate your help guys!
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timmi
Dodge Dakota
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4/07/2004
21:32:44
| RE: 4ohm DVC Single Sub Question..
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i am a guest here, so i will not reply back...
that sub is not capable of a 4 ohm load. you have a dual 4 ohm sub, so you can wire the coils in series (red to black) and make it a 8 ohm sub, or wire them in parallel (red to red and black to black) and make it a 2 ohm sub.
your best bet is to wire it at 8 ohms with that amp. you wont get the full power of the amp, but it will work and it will be safe. if you wire it at 2 ohms, you risk overheating/blowing the amp. and running only one coil of the sub is not an answer.
or...
buy another sub, wire the subs to 4 ohms, and be happy.
or...
buy another amp and run one amp per coil (at 4 ohms each amp)
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Justi
Dodge Dakota
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4/07/2004
21:50:11
| RE: 4ohm DVC Single Sub Question..
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That's exactly what I was suspecting but am greatful to you for confirming. This may actually work for me. The sub is 300w RMS x1 when bridged and 4ohm capable. But the single 8" I'm going to run really can't handle that much power so I was going to have to be careful. Hopefully running it in 8ohm mode (DVC in series) will drop the amps bridged power down enough to not be overkill. Does this sound right?
And does anyone know what power the RF 301S will push out when bridged to an 8 ohm load?
Thanks again...
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Jim Z
GenI
4/07/2004
21:51:15
| RE: 4ohm DVC Single Sub Question..
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that sub is not capable of a 4 ohm load.
Please explain how a sub with two 4 ohm coils is not capable of
presenting a 4 ohm load to the amp. (Hint: you don't
have to use both coils.)
If you can speak to me like I'm an idiot (quite possibly
fittingly). Please tell me where to run the positive and negative
from the amp and what to do with the other two terminals on
the sub (total of 4 since it's DVC).
well, I'd advise against bridging the amp into that speaker. Why?
three reasons:
1) to get 300W, you have to bridge into 4 ohms, which means
using only one coil. It's unlikely that your speaker can handle
300 watts into one coil.
2) wiring the coils in parallel will give you a 2 ohm load, and
bridging into that is likely to overstress the amp's power supply.
3) wiring them in series will give you an 8 ohm load, which is
safe to bridge into. But you'll only get 150 watts.
So, what I'd quite honestly do is forget about bridging. Your
amp has two channels, run one channel to one coil, and the
other channel to the other one. You'll get 75 watts per coil, 150
total.
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timmi
Dodge Dakota
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4/07/2004
22:02:47
| RE: 4ohm DVC Single Sub Question..
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Good advice... but one comment..
Bridging an amp at 8 ohms is almost identical to using both channels at 4 ohms. you are using and producing the exact same power, the only difference is the output when bridged is a single combined channel, which is ideal for a DVC sub. running two channels at 4 ohms each on a DVC sub is not the best idea, reason being is the two channels will most likely be in stereo, and each DVC coil will be recieving a slightly different signal. this is not ideal, but it will work, and you may not even notice the difference... but the option to do bridged at 8ohms is just as easy and is really a better setup for your system.
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Justi
Dodge Dakota
JOIN HERE
4/07/2004
22:49:40
| RE: 4ohm DVC Single Sub Question..
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Jim Z and Timmi, thanks a lot for the breakdown. I think I will wired both in series bridged which leaves me with the 8 Ohms but like Timmi said, leaves it as a mono channel so I don't have differnet signals working against each other.
I'm running an MTX T6000 8" woofer, which isn't what I wanted but my dumb ass can't hold off bidding on a good eBay deal! I'll probably eventually go with an L7 Kicker Solobaric which will solve all of my problems, but we'll see how this T6000 sounds first. I'm just adding the sub to compliment the Infinity speaker system already in there. I'm not disappointed with the mids or highs from the infinitys, just looking for some low end fill and a little punch, which the 8 "should" do nicely. We'll see. Thanks again for the help guys...
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Jim Z
GenI
4/08/2004
00:09:04
| RE: 4ohm DVC Single Sub Question..
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the only difference is the output when bridged is a single
combined channel, which is ideal for a DVC sub. running two
channels at 4 ohms each on a DVC sub is not the best idea,
reason being is the two channels will most likely be in stereo,
and each coil will be recieving a slightly different signal
Low-frequency information in most recordings is monaural.
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Jim Z
GenI
4/08/2004
00:30:51
| RE: 4ohm DVC Single Sub Question..
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the only difference is the output when bridged is a single
combined channel,
Er, no it isn't. The amp isn't "combining" anything. The second
channel is inverted; meaning that on channel 2, the signal is on
the (-) side with (+) tied to ground, while channel 1 outputs
signal on the (+) side with (-) tied to ground. Connecting the
speaker to channel 1's (+) and channel 2's (-) will give the
speaker a differential signal, doubling the voltage swing across
it. However, the amp is still for all intents and purposes a stereo
amp, so if there were any differences in the left and right signal
they would affect the output of the speaker just as if you
connected each channel to a separate coil.
Wiring the coils in series has an added disadvantage in that the
impedances of the coils can never be perfectly matched.
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