“Paul, you need a kick-ass speaker,” an audiophile friend of mine told me a while ago. This fellow isn’t a headbanger, rather a serious listener and a producer of many recordings of classical music distinguished for both their musical and sonic qualities. Nor was he talking about loudness, as he is aware that my Quad ESL-2805s play plenty loud enough, even on orchestral music, in my room. He was talking about bass—big bass, deep bass, fearsome bass. Despite my arguments—made many times over in this publication—that the bass from Quads goes pretty deep (-6dB at 35Hz) and does not sound thin—I have to grant my friend his point: Quad bass is beautifully defined, extremely low in distortion, and high in resolution, but it doesn’t plumb the deepest depths, it’s rarely powerful, and it’s never physically powerful. Though I’ve used subwoofers with great success in the past, I don’t on a regular basis. But from time to time my buddy’s injunction comes back to haunt me, so when Sumiko asked if I’d like to review REL’s new Serie R528SE subwoofer, I quickly accepted. It’s been well over a decade since I’ve had a go at subwoofers in TAS, and the last time I had a very good experience with an early REL.

No sooner had the new model arrived than I set it up, not even bothering to read the instructions. I just put it behind one of my Quads, set the crossover at the midposition, cranked the volume, slipped Also Sprach Zarathustra into the tray, and let her rip. Wow. The opening organ pedal point made the whole room shudder— it was awesomely, goosepimplingly spectacular. In another part of the house my wife found it quite unsettling because we live in Los Angeles, which is earthquake country after all, and the whole house came alive with that note. It wasn’t just that the note was loud; rather it was one of the rare occasions when I’ve been aware of the true fundamental of a 32-foot stop reproduced on a stereo system—that is, the 16–17Hz wavelength which the pipe is actually producing. I felt almost giddy.

I also felt a little ridiculous because I was playing it so much louder in relative terms than you’d ever hear in a concert hall or a church. I know this from experience, because the First Congregational Church in Los Angeles has the largest church pipe organ in the world, which I’ve heard on several occasions. (All local audiophiles and any who visit our city should not pass up the opportunity to hear it, an experience you’ll not soon forget.) But I’m glad I started this way because it taught me three things about the 528SE real fast: its loudest outer limits I would not begin to approach in normal (or abnormal) listening, even with the most demanding material, in my 2600 cubic-foot listening room; its output is ultra-clean and unbelievably low in distortion; and its cabinet appears to be bomb-proof. Despite the insane levels, there was nary a thump, rattle, or rumble from the enclosure itself and no hint of doubling.

The Design

REL’s Serie R subwoofers, of which the R-528SE, at $2799, is the flagship, are designed both for bass support in a conventional stereo system and for the LFE (low-frequency effects) channel in a multichannel setup, such as home theater. My evaluation is only on the stereo music system application. The front-facing main driver is the same heavy-duty carbon-fiber twelve-inch woofer with aluminum chassis used in REL’s far more expensive Gibraltar G-1, and is reinforced by a twelve-inch carbon-fiber downward-facing passive radiator. Electronics, including crossover and Class D amplifier of 500 watts, are housed with the drivers in a cube slightly larger than seventeen inches per side—a beefed-up version of the standard R528 cabinet with large, nickel-plated feet and a black lacquer piano finish. The styling is handsomely, albeit severely contemporary, and I would personally wish for options in light or dark wood finishes. On the back panel are level, variable crossover, and phase controls. As with all REL subwoofers, a supplied cable (34 feet long) terminates in a Neutrik plug that connects the 528 to the main system by taking the signal off the speaker outputs of the amplifier—an arrangement, claims REL, that allows the integrity of the total signal to be carried forward to the subwoofer.

RELs are designed to be used in augmentation mode, which means there is no external crossover that divides the signal into low frequencies for the subwoofer while sending everything higher to the main speakers. This has an advantage and a disadvantage. The advantage is no additional electronics or cables in the signal path, which eliminates the possibility of consequent distortion and phase anomalies. The disadvantage is that the main speakers are still required to reproduce bass, which in the case of most small speakers can extract a toll in terms of a certain constriction when the going gets tough. Freeing the mains from handling bass typically has the effect of liberating the reproduction, increasing dynamic range, and reducing distortion.

But REL subwoofers are not necessarily designed for speakers that are challenged with respect to dynamic range and bass response. As the company points out in its literature, its “products are not traditional subwoofers, but true Sub-Bass Systems...designed to augment the performance of ‘full range’ speaker systems in order to provide linear response down to below 12Hz [!].” If I’m reading this correctly, most mini-monitors and other subcompact and even some compact loudspeakers need not apply. From the description, I am inferring that REL’s designers presuppose that their sub-bass systems—now that the explanation is out of the way, I shall continue to refer to them as subwoofers—will be paired with speakers of at least adequately flat response down into the upper end of the bass range (i.e., 70–80Hz). Although the crossover range is from 32 to 120Hz, I’d not be inclined to use the 528SE with any speaker with a -3dB point in its frequency response much higher than 50–60Hz. In other words, the 528 isn’t designed to make a speaker that is seriously thin in the upper bass and baritone region sound full.