Earlier this year I got my hands on a Dayton Audio Ultimax 15″ subwoofer and paired it with a Crown XLS 1002 amplifier. It completely changed music and movies for me. Having that much reserve power for peaks gave percussive instruments and action movie scenes a lifelike quality.
That being said, I was thrilled to try Rockville’s RPA12 rack amp and see what its boasted 1400W RMS power output (bridged) would be like.
I’ll share some of its core specs first, and then jump into my impressions.
Rockville RPA12 Specs:
- 500W x2 RMS at 8 ohm
- 700W x2 RMS at 4 ohm
- 1400W x1 RMS at 4 ohm, bridged output
- Class AB amplifier
- Optional adjustable crossover: 80hz or 160hz low pass filter
- Input sensitivity: 660mV – 1.5V
- THD + noise @ 1kHz full power: <0.03%
The Amp Itself, Size, and Weight
Simply put, this is a heavy amp. It’s wide and deep, and very dense with the internal heatsinks and fan. Class AB amps are said to have a cleaner sound than Class D, but generate a lot more heat. Especially at this wattage.
At 26 pounds, it’s 3 times heavier than the Crown XLS 1002 at 8.2 pounds.
It’s not a big deal if you’re going to situate it on shelves or a rack and not really move it after, but lugging it around is something you’ll feel. Just worth putting out there in case that’s a consideration for you.
Some power amps equipped with fans only engage them when the amp hits a certain temperature. The Rockville RPA12, however, runs the fan right from startup. I find this a little unfortunate, since during lower listening volumes you can hear the fan running.
By the time you’re listening at decent music or theatrical volumes you won’t notice it. I guess that’s a testament to a Class AB’s heat generation, since comparatively I’ve only heard the fans kick on once or twice with the Crown XLS 1002 even at pretty loud volumes.
(The input area allows for XLR inputs. In my case I used RCA->1/4″ TS adapters.)
The front panel features an amp temp readout, and even driving some high bass levels during movies and bassy music the readout never went above 96 degrees Fahrenheit. I’m not sure the max temp the amp can run at before going into protection mode and it doesn’t seem to be stated in any of the manuals, but I would assume it could handle quite a bit higher temps before you’d run into issues.
As you can see in the above picture, the front display also shows the level each channel is at. I found this a little misleading, though.
Audio enthusiasts are always quick to point out that a gain control is not a volume control. But the display’s dB rating going up as you turn the volume knob up is confusing, because increasing the gain is essentially decreasing the attenuation of the input signal. In other words, it means not diminishing the signal as much; it doesn’t mean adding to the signal.
(It’s the reason receivers’ volume controls are often displayed as levels like “-27dB” meaning it’s attenuating the reference level by 27dB, and why turning the amp up to -20dB is louder because it’s less attenuation.)
The way Rockville displays an increasing dB level as you increase the gain is kind of weird and it’s not clear to me what the relationship is between the two. In other words, what does the 10dB shown in the picture mean?
It’s a minor gripe, though. Ultimately for simplicity you can indeed see it as a volume control, set the knob to wherever blends well with the rest of your system (and doesn’t clip). Use the dB readout on the front as a reference point for different settings and you’re good to go.
Using The RPA12 With An Ultimax 15″ Subwoofer
It’s amazing to me the difference in input sensitivity between this amp and the Crown XLS 1002. Even set to 0.775V for home equipment (as opposed to 1.5V for pro gear) I had to turn the gain almost all the way up on the Crown to get good output. I mean, it was good output.
But with the RPA12 it’s plenty loud even with the gain turned up to 25% (also set for 0.775V on the back). I actually had to turn the gain down watching Inception at parts because it was rattling my house to distracting levels (at roughly gains a third of the way up). It’s always nice to have plenty of headroom.
The RPA12 certainly adds some extra thump to bassy music, and is helpful for certain older albums that were recorded with underrepresented bass. It can take some trial and error to set the gain just right with this much power, because what seems nice for some music ends up blowing up your living room with others to a greater degree than amps with less power.
Percussive hits are sharp and impactful, and variations of bass guitars and bass melodies alongside percussive hits are articulate and don’t sound slurred together. Not that the Ultimax ever struck me as a muddy subwoofer despite its large size, but it seems well controlled with the RPA12 given the power and cone movement involved.
I watched the recent movie The Outpost on Netflix thinking it’d be a good piece of the audition and it indeed made the combat scenes impressively immersive.
The Ultimax 15 has a peak power handling of 1600W, so this amp’s 1400W RMS is a great match. The woofer will take everything you throw at it, and this amp will throw a lot. Even more so than was the case when I was writing the Crown review, you’ve definitely bother the neighbors before you reached the end of what this amp could do. That’s some significant headroom.
(Users with home theaters in their basements will definitely benefit in that regard.)
While the Crown amp could really drive the Ultimax as well, the gain headroom of the Rockville is nice if you’re after a nice warm sound at lower overall volume levels. In other words, you don’t have to rely on turning your stereo up as loud to get the bass kicking.
There were a few points where I thought having a more adjustable low pass filter (like the Crown) would’ve been nice. Throwing all that power at a subwoofer that totally outpaces the main speakers makes sense for most bass, but every now and again the upper bass sounds a little bloated even crossed over at 80hz, and I suspect crossing at 70-75hz would clean it up.
In this case the switch on the back only allows switching between no low pass filter, 120hz, or 80hz. Not a big deal, but a minor point worth noting.
The RPA12 With An Infinity Kappa 12″ Subwoofer In A Custom-Built Ported Box
At 8 ohms bridged the RPA12 can put out ~1000W, which seems in line with the Kappa’s stated 1350W peak power handling.
The input sensitivity I mentioned earlier really helps for using the amp with a computer (with lower output levels than other sources). I demoed it alongside my desktop speakers via a cable splitter, also sending signal into the RPA12 for the Kappa to play alongside. A gain level of ~40% was perfectly adequate where once again the Crown XLS 1002’s gain required being set all the way up.
(As a quick aside, it’s surprising the degree to which good-sounding bass will improve the perception of the overall sound, even when you’re still using the same little desk speakers alongside it.)
The Kappa has always been a subwoofer that, to me, sounds great but requires a lot of power. Versus other 12″ subwoofers I’ve auditioned it against, it can sound flat and unimpressive with less than 500W where other subs could still make it work with less. Because of this, the Kappa really shines with the amount of power available here.
With the 28hz-tuned port in the box I have the Kappa in, it responds clearly down to the deepest notes of electronic music, pop, and rap. And that deep rumble really enhances gaming as I made it a part of a Fallout 4 gaming session day 1 of the amp.
Between moving the Kappa to the custom-built box it’s in now and throwing this kind of power at it, it’s a totally different subwoofer than my earliest impressions of it.
I’m impressed. Rockville has provided a very affordable alternative to other frequently-referenced power amps in the audio forums such as Crown and Behringer. Both of those are invoked all the time for those looking for DIY home theater solutions to power subwoofers, but both can be pricey.
For comparison, the Rockville RPA12 goes for $249.99 while the Crown XLS 1002 I have retails for $329 and is capable of 300 less watts bridged.
The Crown is a great amp, and I wasn’t sure at first what to expect with a brand like Rockville that doesn’t have the long legacy reputation of making quality gear. But I have to say that the Rockville provides a lot of value at the price.
Whether you’re into subwoofers marketing for DIY like the Ultimax or you’re interested in using some car subs in your house and building an appropriate box (car boxes are too small to sound good in your home), an amp like this one will drive basically anything you’ve got.
You can get some pretty respectable subs for a few hundred bucks or less in a lot of cases. If you’re willing to build your own box, you could end up having a whole sub system for roughly $500 (give or take) that will smoke anything you’d buy at a big box store in the same price range.
And just because this amp can put out 1400W doesn’t mean it has to. The nice thing about adjustable gain controls is you can dampen the signal to match lower powered speakers — but acquiring an amp like this for your setup is a super way to future proof.
For me, it’s nice to know that there will never be a peak in the signal where I run out of amp trying to reproduce it.
Ideally the amp wouldn’t be as big and heavy as it is, and it’d be nice if the fan didn’t come on until temps got high enough where it was warranted, but these feel like minor nitpicks on an otherwise very capable amplifier.
Considering the affordable ~$250 price tag and the sheer amount of power you get with this amp, it’s a solid purchase for anyone building a better home theater system.
- A LOT of power for the price. If you’re using it for subs, it will power basically anything with plenty of headroom.
- Good use flexibility between the input range (home or pro gear) and selectable crossovers. Not all power amps have low pass filters built in, and it’s super useful for those of us who aren’t using a big theater receiver with that handled there.
- Also decent flexibility in terms of ohm loads it will accept.
- Output is solid for hours of use at a time at high volumes, and the temp readout on the front helps you make sure you’re not overdriving it (I think that’d be hard to do).
- It’s larger than other power amps in its class, and heavy.
- Class AB amps will draw more power from the wall to produce their stated RMS output than Class D, if that’s a consideration for you. (In other words, less energy efficient.)
- Fan runs all the time and can’t be turned off or set to only engage when needed. This also means if the fan dies out after a couple years of use you’ll have to open up the amp to swap it out, something that could be avoided if it didn’t run constantly. For listening in a quiet environment, you’ll hear the fan on.