When it comes to manufacturing loudspeakers for automobiles, RVs and boats, Rockford Fosgate is one of the most reliable names on the market. Its Prime series features high-performance midrange speakers with many sizes and purposes. The speakers are also marine-rated for boats and other outdoor vehicles. The RM1652 is the best 6.5-inch marine speaker in the series. It's fully certified for marine use and promises high-quality audio performance. The biggest downside is the extremely low speaker efficiency and average power handling, which limit its ability to play loudly over the open water.
In my audio performance test, I recorded the RM1652 playing a 20Hz to 20kHz sine wave on a loop for five minutes. Using a frequency analyzing plugin, I created a frequency signature based on the average recording. Then I graded the low, midrange and high frequencies by comparing the average frequency signature with the original sine wave's frequency signature.
Overall, the RM1652 received a C+ for the overall audio performance. This was the lowest grade I gave to any speaker. Even though it received the lowest grade, I would characterize the audio performance as being average, as I was testing the best marine speakers on the market. In other words, it's still an upgrade over most factory-installed speakers. It just didn't provide the same accuracy and balance as high-ranking boat speakers such as the Fusion FR6022 and the Clarion CMQ1622RL.
The low and midrange received B+, but the highs received a C. This was largely due to fatiguing. If high frequencies are too emphasized in a mix, your ears will fatigue quickly and long-term exposure can lead to headaches. This is exactly what happened during testing. In fact, the highs made me wince and gave me an intense headache. It's fine if you're listening to music at low volumes, but becomes too much as it gets loud.
The sensitivity rating for the RM1652 is only 89 dB, which makes it one of the least efficient marine speakers that I've reviewed. This was confirmed in my comparative loudness test, which showed the RM16522 as tied with two other speakers for the sixth-loudest speaker. In the test, I measured the volume produced by each speaker when connected to the same stereo. With some speakers having sensitivity ratings as high as 93-dB, such as the Polk MM1, a C+ grade is about what you should expect from the RM1652. That said, some speakers with similar sensitivity ratings, such as the Clarion CMQ1622RL and the JL Audio MX650, were among the loudest in the test.
The continuous power handling is only 75 RMS watts. While this isn't the lowest rating I've seen, it is below average, which means it can’t handle as much power as most marine speakers. The same issue exists with the peak power handling, which is 150 watts. This is half the power that the best boat speakers are capable of handling.
One of the areas where the RM1652 excels is marine-grade durability. Not only has it received ASTM certification for salt, fog and UV exposure, but it also has an integrated concealed crossover network that's completely sealed inside the basket, protected from water exposure. The tweeter is made of aluminum alloy, and the grille is made of noncorrosive plastic. The input terminals are gold-plated for optimal signal transfer. Few marine speakers can match its durability out on the ocean or lake.
The Rockford Fosgate Prime RM1652 failed to impress in our audio performance tests. And while it has comprehensive marine-grade certification for salt, fog and UV exposure, the power-handling specifications are below average.