I’ve spent 18 months with the REL Carbon Special subwoofers, and while I wanted to love them, I find myself more frustrated than impressed. For a subwoofer at this price point (MSRP: $4,499 each), there are design flaws that make setup and fine-tuning unnecessarily difficult—flaws that shouldn’t exist in a product marketed as a high-end audiophile subwoofer.

REL has a strong reputation, and their subs do some things well. But when you actually live with them, small issues become big frustrations, and at this level, I expect better.

Let me back up a bit. I reviewed the REL Carbon Specials here, back in September 2023. I’d owned them a few months at that point but what I hadn’t done was schlep them around different rooms, using different speakers and different amps. So the review back then was a bit lukewarm, but slanted toward the positive. I touched on some of the issues in that review, and I’m going to expand upon them here. Around the same time, I published a YouTube video aimed at helping people set a pair of REL subs, and that video is here: REL Carbon Special – Setting up a Pair of Subs

Here I pulled them out of the corners so I could get behind the subs..

Let me cut to the chase:

The Main Issue: Impossibly Frustrating Adjustments for Gain and Crossover

The biggest flaw of the REL Carbon Special isn’t its sound—it’s the terrible user experience when setting them up.

At this price, I shouldn’t have to fight with poorly designed potentiometer dials every time I want to make an adjustment.

1. Gain and Crossover Dials Are Too Sensitive

The volume (gain) and crossover dials are absurdly sensitive. Turning them even a single degree results in large jumps in output—there’s little room for precise fine-tuning.

With most subs, you can gradually adjust output to match the system. With the Carbon Special, it’s a nightmare. You either have too much bass or too little, and finding the sweet spot is pure frustration.

2. No Tactile Notches, No Point of Reference

There are no tactile notches on the dials. So when making adjustments, there’s no way to track or repeat your settings—you just have to guess.

This wouldn’t be a huge issue if you could see the dials clearly, but…

3. Controls Are Inaccessible

REL recommends placing the subs close to a wall, which is fine—except the controls are on the back, and since there are no tactile notches, you can’t feel your way through adjustments.

The result? You’re blindly reaching behind the sub, trying to turn a hyper-sensitive dial in half degree increments, hoping you don’t overshoot your target. It’s beyond frustrating. Half the time I don’t even know if I’ve made an adjustment or not. I think maybe I moved the dial a fraction, but I then get back to my seat and repeat the test-tone or track, only to find that the output is the same.

Now, multiply that frustration if you’re using two subs, as REL recommends.

4. Matching Settings Between Two Subs Is Nearly Impossible

Since there’s no detent system and no clear markings, trying to replicate settings from one sub to the other is a complete guessing game.

With most subs, you can match levels easily using clicks, digital readouts, or even just better-calibrated scales. Not here. You just have to eyeball the dials and hope for the best. Except you can’t see the dials because they’re on the back of the subs and there’s no room to get back there!

For a product aimed at precision audiophile integration, this is a fundamental failure in design.

It looks like there’s space here, but I’m a fat old sod and I can’t get behind the subs without breaking something.

Where’s the Remote? Where’s the DSP?

At $4,499 per sub, I expect some form of remote control or digital interface.

No Remote, No Presets, No EQ

Most modern subs—including those at far lower price points—have some form of remote adjustment, DSP, or at least a basic preset system.

• Switching between music and home theater? Prepare to spend an hour recalibrating the subs manually.
• Want to slightly adjust bass for a vinyl record vs. a digital source? Good luck getting back to where you started.
• Need more bass for a movie? You’ll have to crawl behind the sub, guess your adjustments, and hope you don’t ruin your 2-channel setup in the process.

Other brands—like Martin Logan, JL Audio, SVS, and even some Velodyne models—have self-calibrating DSP, parametric EQ, and app-based remote control. REL? Nothing. 

Phase Adjustment Is Crude

Another oversight: the lack of a variable phase control.

At this price, I expect a rotary phase adjustment for fine-tuning from 0 to 180 degrees, not just a basic two-position phase switch (0 or 180).

Why does this matter? Because integrating a sub seamlessly into a system requires precise phase alignment, and the REL’s simplistic approach makes it much harder than it should be. You have to physically move the subwoofer to get accurate time alignment and integration with the mains, it’s just plain silly.

The Hi-Level Input Workaround Isn’t Enough

REL markets their Neutrik hi-level input as a way to match the sub’s character to the main speakers, but even if you follow their recommendations, the gain issue persists.

• REL suggests using only the red and black leads (leaving the yellow unconnected) to lower gain, but it barely helps.
• Running from the pre-out on your linestage doesn’t help either, you still have the same issues with integration.
• I’ve tested the subs with multiple power amps—tube and solid-state—and the gain range is always too sensitive to make reliable adjustments.

Maserati interiors look stunning… but then you realize they use parts from a Chrysler. Is that what REL are doing? Maybe they bought out the old Radioshack inventory a few years back.

Other Subs Do It Better

I’ve owned several high-end subs over the years—some integrated seamlessly in minutes. Aerial Acoustics SW-12 were old-school but far easier to integrate than the REL. The REL Carbon Special feels archaic and unnecessarily difficult. In fact, I’ve owned older RELs in the past that were easier to integrate than the Carbon Specials.

Compare This to Other High-End Subs:

✅ JL Audio Fathom – Has full DSP, parametric EQ, and remote calibration.
✅ Martin Logan Dynamo – Comes with an app for remote control and adjustment.
✅ Velodyne Digital Drive Plus – Features automated room correction and detailed user controls.

Even the built-in subs on Martin Logan ESL 11A electrostats come with software integration to help with setup.

The REL? No remote. No DSP. No software. No easy adjustments. No shit.

Final Verdict: Not Worth the Hassle?

The REL Carbon Special sounds good—but so do plenty of other subs that are easier to integrate, adjust, and live with.

At this price point, I shouldn’t have to fight with hyper-sensitive dials, inaccessible controls, or an outdated phase switch. And I shouldn’t be manually tweaking levels every time I switch from music to movies. (which I never do, but what if?)

For REL to call this an “audiophile” sub, while ignoring basic usability features, is a major letdown. Their whole mantra about their subs being ‘fast and musical’ – come set them up for me and I”m sure I would be thrilled with their speed and musicality.

If you’re willing to put up with these quirks, you can make them work—but for someone who changes out gear quite a bit, they’re a pain in the rear.

Should You Buy the REL Carbon Special?

🔴 No—if you want ease of use, remote control, or digital integration.
🟡 Maybe—if you’re willing to fight with poor controls for good sound.
🟢 Yes—if you love the REL house sound and don’t mind outdated design choices.

At $4,499 per sub, I expected more. Much more.

Rant over – Your move, REL.

CAH March 2025

CAH Owner/Editor

Owner, Editor, designer, and writer of articles and papers on such diverse topics as audiophile industry products, law and legal, natural health industry, and executive recruitment.

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