|Rockford Fosgate Prime R250-1 Amplifier|
When I was a kid I used to read car magazines and dream of someday owning a legendary car like a Ferrari, Maserati, or Lamborghini. In the world of car audio amplifiers, one of the most legendary brands is Rockford Fosgate. But unlike in the domain of supercars, it’s possible to get the legendary performance of a Rockford Fosgate amplifier at a Hyundai price. In 2009, Rockford Fosgate introduced the “Prime” series of products, aimed specifically at the novice enthusiast or simply a buyer who demands top notch quality and value at a more modest price. In this review we’re going to take a look at one of the best sellers in the Prime family, the R250-1 monoblock amplifier.
The $149.99 (USD) Prime R250-1 is a single channel Class AB amplifier designed specifically to drive subwoofer loads down to 2 ohms. The chassis of the amplifier measures 11.6” long, 7.7” wide, and 2.4” tall. Very nicely finished in a brushed aluminum extruded heatsink with a black anodized finish, the cosmetics of the amp belie its low price. Power and speaker connections are made on one end of the amp, using standard nickel plated barrier strip terminals and Phillips screws. The Battery and Ground terminals are large enough to accept 4 gauge crimp terminals, and a set of dual, internally paralleled speaker connections provide convenient connection of multiple woofers. A 30A ATC fuse also resides on the business end of the amp. Spinning the amp 180 degrees presents you with the signal and control connections and adjustments.
For an amplifier at this price, I was impressed by the included control and adjustment features; gain, Punch Bass, a 40-130Hz variable crossover, a 0-180° phase switch, pass through RCA outputs, and even a wired remote level control! A blue LED indicates power on, and a red LED comes on if the internal protection circuits are activated. The only thing missing was a set of high level inputs so you could feed the subwoofer signals directly from your rear speaker wires if necessary.
Taking the bottom off the amp (which voids your warranty, so don’t do it!) reveals a typical Class AB amplifier layout, and at first I was a bit surprised to find large bipolar output devices instead of the usual MOSFET devices that have been found in every Rockford Fosgate amplifier since about 1990. However, none of those amps had this many features for 150 bucks!
The single sided PCB is populated with traditional through-hole parts, and the high mass components like the transformer, and current sense resistors are secured to the board with special adhesives to withstand abuse from temperatures and vibration, ensuring long term reliability. A pair of 2200µF caps provide current to the MOSFET power supply devices, and another pair of 2200µF caps supply energy to the two pairs of high current Epitaxial output transistors. The Prime R250-1 is well-made inside, and has some nice details you don’t expect at this price, like poly caps in the signal path, and a nice Pi filter at the power input to minimize engine noise problems. Plus, all Prime amplifiers feature Rockford’s exclusive POWER (Power Output Without Excessive Regulation) supply design to insure true rated output power.
Read on for Full Results
Powering a pair of four ohm subwoofers in my reference system, the R250-1 proved to be more than up to the task at all but extreme SPL levels. The small amplifier sounded larger than life, even on difficult tracks like the cannon blasts in Tchaikovsky’s 1812 Overture. Bass response was well controlled and the R250-1 had plenty of steam to drive my woofers to loud levels. As an added bonus, the amp has the excellent sonics of a Class AB amplifier, (which I still seem to prefer, even for my sub bass) to all but the very best Class D designs. I played with the controls and functions as I listened, and all worked just as expected. The gain control had plenty of adjustment range making the R250-1 compatible with virtually any source unit.
Moving from the listening room into the lab, I connected the Prime amplifier to my trusty Audio Precision and performed the usual battery of tests and checks. The R250-1 had no problem easily exceeding all of its published specifications, and in fact I measured more power than even the amplifiers serialized and dated “birth certificate” showed. Signal to noise performance measured outstanding as well. Efficiency was about average for a Class AB design but an amplifier this size is certainly not going to tax an electrical system anyway, but I did notice that the amp got warm fairly quickly. When all the measurements were complete, I deliberately tried to break it, but the various protection circuits (dead short, under and over voltage, and thermal) simply activated until I stopped being abusive, and prevented any damage.
The Rockford Fosgate Prime series of amplifiers really do represent a great performance value, and provide a very affordable way to incorporate Rockford Fosgate DNA into your system. You can be sure the Prime amps will deliver the advertised power, and a full 2-year warranty tells you Rockford Fosgate expects them to be virtually bulletproof. And because they’re available at over 800 retailers worldwide, finding one for your car shouldn’t be difficult.
For more information visit www.RockfordFosgate.com