Ever wonder how much power you can get from a little 2 channel class "ab" Rockford Fosgate amp? Stay tuned, as we do a few not so typical mods under the hood to explore the possibilites. First things first... we will need to restore the amp to a working order to get some usable measurments before mods!
Head over to our facebook page to catch some video of the initial rebuild process. We are planning to do another live video for the remainder of the repair and intial output power tests!
Currently waiting on a parts order to come in... ended up needing a few parts that were not in my stocked parts. Good news is we should be able to rebuild its twin that is also sitting on the shelf ready to be brought back to life.
DC offset of a fully rebuilt channel vs a channel that only got a new set of output mosfets.... 6.95mV on the completely new channel and 18.17mV on the old channel... I'll be posting a video clamping this little amp to see what kinda power it makes once some hardware arrives to get it properly mounted back in the heatsink.
The amp tested out on the bench making a decent 240 watts into a 4 ohm bridged load with a battery voltage around 12.5V. Not bad considering Rockford's manual stating a rating of 250 is meausred at 14.4 volts. In the factory condition the protection circuit limited output into a 2 Ohm bridged load to a poor 134 watts. However, swaping out the source resistors for some 17 awg jumpers altered the voltage drop that the protection circuit monitors for an overload condition making the amp run pretty decent into a 2 Ohm bridged load. Again, testing the amp at 12.5 volts it produced a decent 334 watts rms for several minutes before ultimately destroying the power supply mosfets.
See the short video clip above for the exciting part of the stress test. A full length clip can be seen on our facebook page.Full Length Feature.
Next step is upgrading to a set of power supply mosfets that have better ability to transfer heat into the amps heatsink. Also, a power transformer rebuild to keep it from working outside of its designed current limits and hopefully running a bit cooler! Next clamp tests will be at 12.5 volts and maybe step it up to around 13.8-14 to see what kinda RMS wattage this little amp can do.