libert69

iTrader: (7)

I really dont want to spend lots of money on an upgraded system on this car but i just want to add some bass. i have 2 rockford 15" hx2 dvc subs in seperate sealed boxs. they are about four years old, but have not been used in about 2 years. they are in good condition and the box is fine as well.

i would to use only one 15" sub with a rockford p5002 amp bridged. heres the amp link....quick specs...can i have opinions on the amp please or better recomendations. thanks

Rated Power
125W x 2 @ 4-Ohms RMS
250W x 2 @ 2-Ohms RMS
500W x 1 @ 4-Ohms bridged RMS

http://www.rockfordfosgate.com/produ...n_US&p_status=

im not sure if i should keep the stock sub in place, or just unplug and use the sub lead for the new subs? i think thats the way to go..or are u supposed to tap into the stock amp by the passenger side footwell?

adding a sub is all i would like to do. i just bought a optima red top 34/78 battery. would a need a capacitor with just one sub or will the battery be enough? thanks in advance....all opinions welcome

Crook

Bridging the amp and wiring up only one 4ohm voice coil is probably the best way to go with your setup. The 15" sub is more than enough to supplement the stock system so you'll probably end up lowering the gain setting on the amp to balance it with the rest of your system. I recommend setting the gain on the amp to where yours system sounds good with the radio's "Bass" setting is around -3 or -4. You'll still get a usable bass signal from the stock sub wire and you won't overwork or "clip" your sub when you turn up the volume way up. This also prevents early distortion with the door and rear deck speakers.

You can leave the stock sub connected to run your stock system in case you need the remove the Rockford box for more trunk space. You can tap into the sub speaker wire right at the stock sub's magnet/terminal. Just drop the felt trunk liner in the trunk below the sub and you'll be able to find the wires. There's not much room to work with or slack in the wire but you can get it to work.

I can't tell you if you need to install a Cap but it may help in your situation if you intend to listen to your music with bass at high volumes. (Especially with a bridged amp) At night, see if your lights dim when the bass hits. If there's a significant difference with your dash and headlights then you might need to cap it.

libert69

iTrader: (7)

thanks for the response. im not going to do the install, im having a shop do it b.c i have no idea how to install it. what do u mean by only wiring only ONE voice coil? i really dont understand bridging amps, 2/4 ohm loads, mono etc... could u explain please?

this is what i thought. the sub is rated at 600watts rms, 300 per voice coil (not sure what that means). stable 2 or 4 ohm loads. specs of the amp say 500 x 1 RMS @ 4 ohms.

500 x1 means its bridged to reach that level correct? if only one voice coil was used, then it would only be getting half the power the sub can handle correct? then a different amp setting would have to be used im guessing.

please school me in this if u can. thanks

also, is this a good/correct/compatible amp to be using?

libert69

iTrader: (7)

another question about the amp kit. not sure what to buy...

CP4PIS
4 AWG Power & signal installation kit
http://www.rockfordfosgate.com/produ...status=current

CP4CKDS
4 AWG Deluxe complete installation kit
http://www.rockfordfosgate.com/produ...status=current

i cant see the difference...man im so confused

libert69

iTrader: (7)

^

Crook

I'll try to make this simple.

Your amplifier is a two channel amp which means it was designed to power two separate speakers with it. You can also "bridge" the amp which lets it behave as a single (one) channel amplifier designed to supply power to one speaker. Each speaker has a (voice coil) which is spun wire coiled around a magnet but not touching it. In your case your speaker has dual voice coils. Energize the coil with current (speaker signal from amp) and the coil with shift (attract or repel) along side the magnet. This voice coil is attached to your speaker cone which ultimately vibrates creating base waves in the air for you to hear and feel.

Your subwoofer has two voice coils instead of one which means that there are two separate voice coils wrapped around a single magnet. This give you more options and versatility with your install since you have a two channel amp. The dual voice coil sub can be wired up like it is two separate speakers sharing one cone surface to vibrate.

Each voice coil in a speaker has resistance usually measured in ohms. The lower the number, the less the resistance. Four ohm speakers are common in car audio applications and eight ohms speakers are usually found in home audio speakers. If you lower the resistance in a speaker setup, more current can flow through the voice coil(s). Basically your speaker is more efficient. In turn your amplifier is going to work harder sending all of that extra power and it will run hotter.

Here's an analogy: A garden hose will have a lot of resistance if you use it on a fire hydrant. You'll have plenty of pressure (resistance) but the actual amount of water flow (speaker signal from amp) will be low. Let's lower the resistance by attaching a real fire hose to the hydrant. Hardly any resistance and the (power) can flow. If you extend the fire hose with a second hose, you'll increase the resistance. The same thing will happen if you extend a voice coil with a second voice coil(wiring in series). Two 4ohm voice coils wired in series would result in am 8ohm load(resistance). Your speaker will not sound as efficient at 8ohms than it would at 4ohms.

Parallel wiring of a speaker decreases resistance because several voice coils share the same speaker signal. Like tapping into the first fire hose with two other fire hoses. (lowering resistance) The first hose won't be able to keep up with the demand of multiple hoses. An amplifier will have to work hard to keep up the demand from several speakers. The amp will run hot and the electrical system in your car may not be able to keep u the electrical current drawn by the amp. That's why some people get "caps" installed. A capacitor is basically a temporary reserve power storage component that supplies a burst of power during high current draw from your system. It supplies extra power to your amp so your car's battery doesn't have to thus preventing your flickering lights when your music is turned up.

Earlier I suggested bridging your amp and only hooking up one of your speaker's voice coils. Remember that bridging the amp will usually make it run hotter because of the increased output. It will also increase the THD(Total harmonic distortion) but you probably need to have a bionic ear to hear that from a sub in the trunk. I recommended using a single voice coil on your sub because I didn't know if your amp could handle the demand of being bridged and handling a 2ohm load.
The other option is to run your amp in two channel mode and wiring up both voice coils. The amp will run cooler and it will probably sound just as good especially if you are only supplementing the stock system. It looks like your amp has plenty of power so youl will have to decide on your install options based on your setup and location of the components. Just make sure you have adequate ventilation to cool your amp.