Hey everyone so I need some help with my aftermarket sub set up. I have an Rockford Fosgate P300-2 and I have it bridged. Now it says it 4-Ohms 300x1 (RMS) in the manual. My sub is an Alpine SWS-1234D. I have the jumpers set up so it according to the 2 Ohms set up in the manual. Is this okay to run on the amp or will it over power it. I check it after playing it for around 20 min and the amp did not seem to hot. ANYONE CAN TELL ME if this is bad for my amp?

 

you'll kill your amp over a not so long period of time

 

Are you stating that the sub is being fed off of the speaker level outputs of the main amp?

 

No the sub is being fed off the Rockford amp which gets it signal from the factory amp that i tapped on to. How do I set up the amp and sub to work together properly because according to the manual of my sub the only other set up is an 8 ohms set up. Does this mean I might have to buy a new sub?

 

Here's a simple answer from crutchfield...

Q: What do I need to know about impedance when wiring subs to an amplifier?

A: Impedance is the amount of resistance speakers provide to the current flowing from the amplifier. Every time you halve the speakers' impedance — switching from a 4-ohm to a 2-ohm sub, for instance — you effectively ask the amplifier to double its output. Some amps can handle this lower impedance, some cannot. The key thing to know about impedance, then, is how to match your speakers to the capabilities of your amp.

The typical car stereo amplifier is stable down to 4 ohms in mono (or bridged) mode or 2 ohms stereo. Some high performance amplifiers can operate safely with loads as low as 1/2-ohm in stereo (1-ohm mono). If you're designing a subwoofer system, ask yourself the following questions:

1.How many subs do I want? More subs = more cone surface area = more air moved = big bass! Balance this equation against the amount of room in your vehicle.
2.How much power do I want? If you're powering your vehicle's speakers with your receiver, you'll need less power for your subs. If you use a multi-channel outboard amp for your speakers, you'll need more power for your subs.
Check out suitable amps in your price range. Once you've found the right amplifier, look for subwoofers that complement your amp in terms of power rating and impedance. Most subs are rated at 4 ohms, but 2-ohm, 8-ohm, and dual voice coil subwoofers have become commonplace, so it's easy to find speakers that will bring out the best in the amp you've chosen.


Sounds like you need a diff setup. make sure to match up your amp/sub or you'll burn out/blow out one.

 

xxx

 

Yes this is bad for your amp. By running 2 Ohms bridged, you are running each individual channel at 1 Ohm. That amp is not 1 Ohm stable.

 

After doing a search on the setup and understanding what he has I believe you are correct. It also appears that the speaker is rated at 4 ohms.

 

As far as damaging the amp it depends on the design of the amp. One viewpoint is you have a mismatch in the upward direction which is safer for the amp than one in the downward direction. That is running a higher impedance speaker (4 ohms) is typically safer on a mismatched situation than if you had a 2 ohms speaker with a 4 ohm amp. What usually occurs however is that the sound quality will suffer at the minimum. If you run a lower impedance speaker 2 ohms the current flow will increase. This is typically harder on the amp.

Keep in mind that in the case of speakers impedance is not resistance in the way we normally think of it. It is resistance that changes based on frequency. From a resistance standpoint with a full range speaker at lets say 75 hz you could have a resistance of 30 ohms, at 125 hz you may have 4 ohms. Also in a speaker you have what occurs due to the mechanical movement of the speaker when the signal is released and the cone returns to rest.

In any case I would impedance match your setup again and if more power is what you want for the speaker then match another amp to it as the facts are with a mismatch in the upward direction you may not have gained anything by bridging in the way of power to the mismatched load.

 

After doing some research my self I came to realize that the amp I actually have is the P-300-1 and it is stable at 2ohms.
http://www.rockfordfosgate.com/produ...n_US&p_status=
My alpine sub is set up to be 2ohms currently.