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Dual Voice coil subs and amp options
So I am planning to built a sun box for my car. One for each of the front seats. The question is whether is to buy the Rockford Fosgate P3SD2-8 or Rockford Fosgate P3SD4-8. The difference is that one is a 2 ohms and one is a 4 ohms. Also I want to stick with one amp instead of having two amps. The option for that is JL Audio XD600/6 or JL Audio HD Series HD900/5. For 4 of the channels of the amp it would be for speakers and other channel will be for the sub. How should I wire them and which one should I pick. I been reading about it but still kind of confused. I know if I got the dual voice coils sub I have more option when it comes to wiring them.
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Rockford Fosgate P3SD4-8HTML Code:
JL Audio XD600/6 |
The subs impedance need to match what the amp can handle. Being that u are looking for a single amp setup and the subs u are considering come in different configurations I would say choose your amp first with the intent of enough power for the 2 8" subs. Then depending on what ohm load the amp can handle you can choose the subs. I know that doesn't exactly answer ur question specifically. But should help. You can pm me and I'll give u my number if u wanna text any questions you have. Or I can answer them on here. Just bring on my phone right now doesn't allow for elaborated replies.
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Originally Posted by pj1800
(Post 4113136)
The subs impedance need to match what the amp can handle. Being that u are looking for a single amp setup and the subs u are considering come in different configurations I would say choose your amp first with the intent of enough power for the 2 8" subs. Then depending on what ohm load the amp can handle you can choose the subs. I know that doesn't exactly answer ur question specifically. But should help. You can pm me and I'll give u my number if u wanna text any questions you have. Or I can answer them on here. Just bring on my phone right now doesn't allow for elaborated replies.
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So I talked to other people and with my Infinity Kappa 60.9cs and my plan to get the Rockford Fosgate P3SD2-8, I should get the JL Audio XD700/5. The set up will look like this.
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Infinity Kappa 60.9cs |
Sub system
3 Attachment(s)
If you use the dual 2 ohm Fosgates, run each speaker's voice coils in series (to get 4 ohms), then the speakers in parallel (to get a final load of 2 ohms). Be very careful in your wiring, otherwise you'll could end up with 1/2 ohm load for the amp!
The box volume for the Fosgate's range from .2 cu.ft. (345 cu in) to .7 cu ft (out of the question for underseat). My own underseat boxes have a raw volume of about 430 cu. in. each, but the left and right boxes have different dimensions, but identical volumes. I used Trimble SketchUp to design the boxes. I decided not to use MDF, as I wanted as much internal volume as possible to get a good bass curve of about .707. This meant I had to use 1/2" material, which I didn't trust to not split with air driven staples. Instead, I used 1/2" Baltic Birch plywood, using rabbet joints glued and staples. Screws can also be used, but use a countersinking pilot bit to make the holes and mark the hole locations by ruler and not by eye. The boxes were then stuffed with polyfill and sprayed with truck bed liner. Speaker connections were cup and post. I also mounted the amp over the spare, taking out the foam accessories bin. |
Originally Posted by KaneoheKoa
(Post 4113527)
If you use the dual 2 ohm Fosgates, run each speaker's voice coils in series (to get 4 ohms), then the speakers in parallel (to get a final load of 2 ohms). Be very careful in your wiring, otherwise you'll could end up with 1/2 ohm load for the amp!
The box volume for the Fosgate's range from .2 cu.ft. (345 cu in) to .7 cu ft (out of the question for underseat). My own underseat boxes have a raw volume of about 430 cu. in. each, but the left and right boxes have different dimensions, but identical volumes. I used Trimble SketchUp to design the boxes. I decided not to use MDF, as I wanted as much internal volume as possible to get a good bass curve of about .707. This meant I had to use 1/2" material, which I didn't trust to not split with air driven staples. Instead, I used 1/2" Baltic Birch plywood, using rabbet joints glued and staples. Screws can also be used, but use a countersinking pilot bit to make the holes and mark the hole locations by ruler and not by eye. The boxes were then stuffed with polyfill and sprayed with truck bed liner. Speaker connections were cup and post. I also mounted the amp over the spare, taking out the foam accessories bin. |
I'll look it up in my notes and post them.
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CWong, here are the dimensions for the boxes
LEFT: 15.5" x 9.25" x 5" RIGHT: 18.25" x 8.5" x 4.75" Note on R box: you may want to add "wings" onto the sides of the box where the speaker's trim ring may overhand. I used 3/4" MDF (it was around) 1.5" x 5". It was for purely cosmetic reasons. 1/2" Baltic Birch, air stapled (but you can use #7 drywall screws, just remember to draw a guide line and pilot drill and countersink). Sprayed with truck bed liner and held down with 1" web straps. I didn't need anything more secure, as you'll have to take out the seat to remove the boxes. Remember to spray undercoat where the mounting screws penetrate the metal above and under the car. Baltic birch is a kind of specialized plywood, normally used for drawers. You can find them at the better wood suppliers (not Home Depot or Lowes). They're 5' x5' sheets, so you'll need to borrow a truck, unless you have roof racks like my Box. You will need to cut some of the carpet away from the front area (the formed sheet metal where the front seat bolts attach) so the box will sit flush. Also, the blower vents under the seat will need to be cut back. Good building and have fun! |
Originally Posted by KaneoheKoa
(Post 4115290)
CWong, here are the dimensions for the boxes
LEFT: 15.5" x 9.25" x 5" RIGHT: 18.25" x 8.5" x 4.75" Note on R box: you may want to add "wings" onto the sides of the box where the speaker's trim ring may overhand. I used 3/4" MDF (it was around) 1.5" x 5". It was for purely cosmetic reasons. 1/2" Baltic Birch, air stapled (but you can use #7 drywall screws, just remember to draw a guide line and pilot drill and countersink). Sprayed with truck bed liner and held down with 1" web straps. I didn't need anything more secure, as you'll have to take out the seat to remove the boxes. Remember to spray undercoat where the mounting screws penetrate the metal above and under the car. Baltic birch is a kind of specialized plywood, normally used for drawers. You can find them at the better wood suppliers (not Home Depot or Lowes). They're 5' x5' sheets, so you'll need to borrow a truck, unless you have roof racks like my Box. You will need to cut some of the carpet away from the front area (the formed sheet metal where the front seat bolts attach) so the box will sit flush. Also, the blower vents under the seat will need to be cut back. Good building and have fun! |
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