Car and Amp Ohm compatibilty

**nwigxp** · 07-23-2010

I understand the fact that Ohms are an important thing to consider with subs and amplifiers. I am a bit of a newb when it comes to these fancy numbers, so here's what i need help with.

Subs:

4-ohm total impedance
power handling: 500-1,000 watts RMS (2,000 watts peak power)

Amplifier:

mono subwoofer amplifier
500 watts RMS x 1 at 4 ohms (1,000 watts RMS x 1 at 2 ohms)

Now that's all of the information I could find for both on Crutchfield.com, the subs are Rockford Fosgate P3L-2X12 and the Amplifier is a Rockford Fosgate Prime R1000-1D. Just getting a second opinion on compatibility with both of those, making sure there's no possible chance of damaging subs/amp.
Any expertise would be greatly appreciated.

**CTKGP09** · 07-23-2010

ok here we go, those are dual voice coil (DVC) subs so its 4 ohms per sub and you are gettin two, each coil can handle 500 watts RMS or 1000 watts RMS per sub. the amp is 4 ohm stable and is good for 500 watts RMS or 2 ohm stable and good for 1000 watts RMS. SO if the coils on the subs are wired into series (8 ohm load per sub) and the subs wired to the amp in parallel, that would be a 4 ohm load to the amp. it wouldnt damage anything but you would be gettin only half the power out of your subs. i say get an amp that is good for 1000 watts at 1 ohm and that way you can wire the subs in parrallel (2 ohms per sub) and wire them to the amp parallel and you would get a 1 ohm load and get the full potention of your subs without damaging anything

**matt5112** · 07-23-2010

If you ran it on one coil i'm willing to bet you could still give it more than 500 W RMS based on the fact that they're right beside each other so the heat would transfer between the two....

But the rest you've got right.

summary: look for an amp that will put out 1000 watts RMS at 1 Ohm

**1LoudGrandPrix** · 07-23-2010

i'd say more than 1kw rms that way you can turn down the amp and also help with independence rise

**chickenfried** · 07-24-2010

Originally Posted by CTKGP09

ok here we go, those are dual voice coil (DVC) subs so its 4 ohms per sub and you are gettin two, each coil can handle 500 watts RMS or 1000 watts RMS per sub. the amp is 4 ohm stable and is good for 500 watts RMS or 2 ohm stable and good for 1000 watts RMS. SO if the coils on the subs are wired into series (8 ohm load per sub) and the subs wired to the amp in parallel, that would be a 4 ohm load to the amp. it wouldnt damage anything but you would be gettin only half the power out of your subs. i say get an amp that is good for 1000 watts at 1 ohm and that way you can wire the subs in parrallel (2 ohms per sub) and wire them to the amp parallel and you would get a 1 ohm load and get the full potention of your subs without damaging anything

and if you did quite catch that^... look at this diagram for wiring Subwoofer Wiring Diagrams, Two 4 ohm Dual Voice Coil (DVC) Speakers

**chickenfried** · 07-24-2010

Originally Posted by matt5112

If you ran it on one coil i'm willing to bet you could still give it more than 500 W RMS based on the fact that they're right beside each other so the heat would transfer between the two....

if in a sealed box wouldnt giving each sub a chamber help with this? i mean i know most sealed boxes are made in one chamber but its not that hards to add a peice of mdf in the middle. just curioius cuz i have never thought about it like the way you just said it.

**matt5112** · 07-24-2010

The only thing that would do is let you keep running one sub optimally if you blew the other.

**I800C0LLECT** · 07-24-2010

If you ran stereo subs it would allow for that too

**matt5112** · 07-24-2010

like you can have "stereo" subs in a car

**coreygnar** · 07-24-2010

Amazon.com: Brand New Cadence Tx-a1000d 1,000 Watt Rms @ 1 Ohm… there ya go

**nwigxp** · 07-25-2010

Originally Posted by CTKGP09

ok here we go, those are dual voice coil (DVC) subs so its 4 ohms per sub and you are gettin two, each coil can handle 500 watts RMS or 1000 watts RMS per sub. the amp is 4 ohm stable and is good for 500 watts RMS or 2 ohm stable and good for 1000 watts RMS. SO if the coils on the subs are wired into series (8 ohm load per sub) and the subs wired to the amp in parallel, that would be a 4 ohm load to the amp. it wouldnt damage anything but you would be gettin only half the power out of your subs. i say get an amp that is good for 1000 watts at 1 ohm and that way you can wire the subs in parrallel (2 ohms per sub) and wire them to the amp parallel and you would get a 1 ohm load and get the full potention of your subs without damaging anything

thanks for all that information. I appreciate it except, no offense most of it went in one ear and out then next, but ill remember this and I will look into it, any adive on how to wire subs parallel, is it the same as bridging?

**chickenfried** · 07-25-2010

Originally Posted by nwigxp

thanks for all that information. I appreciate it except, no offense most of it went in one ear and out then next, but ill remember this and I will look into it, any adive on how to wire subs parallel, is it the same as bridging?

cough posted a link about that exact question cough cough

**chickenfried** · 07-25-2010

Originally Posted by matt5112

The only thing that would do is let you keep running one sub optimally if you blew the other.

good to know

**I800C0LLECT** · 07-25-2010

Originally Posted by matt5112

like you can have "stereo" subs in a car

it's been done before. I would think install is crucial since cancellation could easily occur?

**matt5112** · 07-25-2010

How would that benefit you when most people end up with the subs in the trunk?

Most anything crossed over at 40 Hz or lower (where subs should be crossed over) is impossible to localize.

Again, get a proper mid-bass solution.

**I800C0LLECT** · 07-25-2010

Some people run subs as high as 200hz too...

As long as install is correct there shouldn't be any issues. When you get to very loud volumes a proper 3-way can help tremendously with power handling requirements. However...in a car environment, 3-way + sub is a b. Since the subs are so close, tuning and transparency are a must, but you could set up a two way + sub to make up the difference for the lack of a mid-bass.

The basic rule in 2-way is that you HAVE to sacrifice somewhere...either mid-range or bass. You can't have the best of both worlds.

**matt5112** · 07-25-2010

second order crossover for subs at 80 Hz still leaves too much sound coming from the sub at 150 Hz.

Sounds like its coming from behind you.

4 way is the only way to get loud in a car.

**I800C0LLECT** · 07-26-2010

Originally Posted by matt5112

second order crossover for subs at 80 Hz still leaves too much sound coming from the sub at 150 Hz.

Sounds like its coming from behind you.

4 way is the only way to get loud in a car.

I don't know what you do but my sub compliments nicely

I play with my sub between second order and 4th order as high as 160hz and as low as 80hz (trying to deal with a resonance issue in the doors). It always sounds like it's coming from in the front of my dash as if the mids are creating the bass. I keep the rear seats up too.

But we also have very different listening styles

Sometimes you can feel your hat moving tho

EDIT: The subs are also facing the rear seat so you can see them when folding down

This helped tremendously with mid-bass transparency. However, facing the rear would be fine if I stayed at 80hz or lower.