Whats going on Guys!


Ive searched around but found very little info. I recently purchased Rockford Fosgate 750x four channel amp which specs are :

# 90 watts RMS x 4 at 4 ohms
# 187.5 watts RMS x 4 at 2 ohms
# 375 RMS watts x 2 at 4 ohms in bridged mode
# 2-, 3-, or 4-channel output


to push a single Kicker Comp CVT10 Sub:


Size (IN.,CM) 10, 25
Impedance (OHMS) 2 or 4
Max Rec Amplifier Power (WATTS PEAK/RMS)* 800/400
Frequency Response (Hz) 25-350
Mounting Depth (IN.,CM) 4-3/16, 10.7
Mounting Cutout (IN.,CM) 9-1/8, 23.2
Min Rec Sealed Box Volume (CU. FT., Liters) .8, 22.7
Max Rec Sealed Box Volume (CU. FT., Liters) 3.0, 85
Min Rec Vented Box Volume (CU. Ft., Liters)** 1.25, 35.4
Max Rec Vented Box Volume (CU. Ft., Liters)** 1.75, 49.6

If someone could help me understand if the 375 rms watts x 2 at 4 ohms in bridged mode would be a close match the 400 rms recommend for the Kicker 10? Im pretty new to the car audio scene and hoping someone could explain in more detail what exactly this means .

Thanks!


Jay

 

According to the info, the 750x has 4 channels but can be configured to operate in 2, 3 or 4 channel mode depending on bridging.

Bridging is a method of operating multiple channels as a single channel. It allows you to combine their output power.

In 2 channel mode, two pairs of channels are bridged. In this mode the amp would typically have two inputs and two outputs.

In 3 channel mode, only 1 pair of channels is bridged; the remaining 2 channels operate independently. In this configuration the amp would have 3 inputs and 3 outputs.

In 4 channel mode there is no bridging. All 4 channels operate independently. The amp would have 4 inputs and 4 outputs.

If you elect to bridge one pair of channels, the combination can deliver up to 375 watts to a single component. Since the Kicker 10's stated RMS maximum capacity is 400 watts, that is a good match in my opinion.

This leaves the question of how the other two channels could be used. Does the CVT10 have more than one voice coil? If it did you could bridge the other channel pair to power the 2nd coil. For a sub that can only handle up to 400 watts rms, though, that might be overkill.

Do you have other components that could use the remaining two channels? If not, you might rethink the CVT10. By itself it does not seem to be a good match for the 750x. Possibly look for a sub with dual voice coils and a total RMS capacity around 750 watts.

 

I wouldn't recommend biamping separate voice coils as Dierk suggests. Dual voice coils should be run in series or in parallel off the same amplifier input - not separately biamped. Even a small difference in power/audio signal and the voice coils can/will work against each other - causing your subwoofer to self-destruct.

The amplifier you have is fine for powering the sub you have. If you want, you can use the front 2 channels to power a set of door speakers and bridge the rear two channels to power your subwoofer (a 3-channel setup).

 

Appreciate all the help guys! After speaking with Crutchfield today they recommended running two 2ohm Kicker CompVR 10's to get the most out of the amp. The CVT are apparently single voice coil where as the the VR are dual. They said this would be close to the best match for the amp. They also said the older Rockford amps are underrated, that the amp is close to 950 watts dont know how true this is or not.

Now only question i have is best way to build the box. Should the subs be sitting flush into the floorboard facing up or remove the spare tire and have them facing the rear of the car like most cars.

 

are your front speakers currently amp'ed?
how much bass do you actually want?
yes, two subs may get the most out of the amp, but if you don't
need 750 watts worth of subwoofer, seems like a waste, and if
you're running just headunit power to the fronts (which is probably
10-20 watts RMS depending on the headunit), your system may
sound a little unbalanced.

 

You're better off not listening to Crutchfield (who wants to sell you another amp, btw) and running a 3-way system off that amp unless you already have an amp for your door speakers.

They were right about needing a sub with either dual 2ohm voice coils, or a single 4ohm voice coil.