REL Subwoofer Input Options

The benefits of high level, RCA and XLR connections

Customers, especially ones new to high performance audio, can get confused by the several methods of connection available to hook up their new subwoofer. We’re here to help you sort these things out.

There are essentially three ways to connect your subwoofer, two involve variations of low level connection and the third uses a High Level connection wherein one or more channels of your receiver or amplifier’s speaker connections are connected to the input of the subwoofer using a special cable.

RCA-RCA Low Level

This simple tried-and-true method connects using a low level signal and is used on the vast majority of more modestly configured systems. It takes a very small signal from the .1/LFE subwoofer output on the rear of your receiver and outputs, typically, a theatre-centric signal to your new subwoofer.

It uses the ubiquitous RCA cable and plugs in similar to how tuners or CD players have done so for decades. It’s easy and works fine for relatively short runs of, say, 25’ or so. So why would anyone use anything else? Quality of sound and quietness, or the ability to keep the signal robust and the noise down to a minimum are the reasons to move up from this basic standard.

Balanced XLA-XLR Connection

This connection is also a low level signal (meaning a small voltage signal operating below 2 volts).  Balanced XLR connections have been the standard method of connection in the music making industry for years. 

First, the mechanical connector itself is a far more secure locking connector. Second, the method of sending the signal is more robust: Instead of one very low level positive signal being sent out to the sub, and the return energy of this signal simply dumping to ground (think of a garden hose in the desert trickling water onto the sand), this balanced circuit actually uses two much stronger signals, one sending energy out, the second returning out of phase. This signal is more like a fire hose sending out a much stronger signal that rejects noise and hum better, then adding a second identical but reverse phase signal that cancels any noise that can get on the line. 

This is a better connection from .1/LFE because it’s an inherently stronger signal, plus it rejects noise and hum better. So, a nice step up. Many of the better receivers on the market and virtually all high end AV processors offer this connection on the rear panel.

High Level Connection

This connection method has been used by REL Acoustics for over thirty years and offers several performance benefits. Many of the most experienced listeners strongly prefer the performance gains available from this type of design. But it does require paying a little more attention because the receiver you are using has its own amp and depending upon what type of amplifier class it uses, you’ll want to connect it one of a few different ways. We’ll explore this further in just a moment, but first: Why do the worlds most careful listeners insist on using only this method?

Experience has taught us that when we connect to a REL using our High Level Connection, the sound takes on all the sonic qualities of your main system. This means that all the musical qualities present in your main system feed forward into the sound of your REL. And what that means as a benefit to you is that, all of a sudden, a subwoofer actually fuses with and becomes one with the rest of the system.

And why is this experience remarkable?

Because the most difficult thing for a sub to do is to blend perfectly with the main speakers. So connecting in a way that allows ALL the elements of your existing system to be fed forward into your REL means that in contrast to the normal speaker/sub system, in which the sound acts a little like a marching band moving past, with the bass instruments and drums lagging at the rear of the band, you are suddenly able to hear the entire ensemble playing at once, in correct timing, rhythm and tempo and suddenly music makes wonderful toe-tapping sense.

But wait, I really only bought a subwoofer so I could have big bass for all the cool special effects for movies.

We have that covered too. RELs that offer a High Level Connection (our mostly-for-theatre HT range only offer conventional low level/.1) also offer a complete, dedicated .1/LFE input for theatre sub bass including its own volume control so you can set it for the perfect level and still use our High Level.

I thought you said the High Level was all about music

This is true when music is the preferred art form you’re taking in. BUT and it’s a big but, when movies are being played, the High Level does this wonderful trick of improving every single sound in the movie, not just the special effects but the music and the dialog, creating a richer and more full theater experience . 

So movies need both High Level and .1/LFE?

Ideally yes. You see all sounds in nature (including the altered reality of movies taking place in the future) feature sounds we’re used to hearing in nature and every one of those sounds is full range, meaning that they all benefit from a high quality subwoofer. This means that the High Level Connection will perform a kind of sonic restoration of movie soundtracks, restoring all the rich natural sounds. So voices sound natural and don’t suffer from that bright hard shallowness that makes many movies difficult to get through after the first hour. Music scores convey the full emotion of the moment. The bottom line is spatial qualities are conveyed by a full range sound, and hearing this full range properly rendered in movies makes them so much more enjoyable ––just like in a movie theater (remember those?).

Quick refresher that covers the basics (and then some) of proper connection. 

  1. For a simple theatre-only system the basic, trustworthy RCA interconnect works well. 
  2. If you’re running longer runs for a big engineered theatre, then stepping up to XLR connections makes sense
  3. If you want it all, then by all means, step up to a REL with both High Level and either RCA low level or, for our more expensive models, XLR connections for the .1/LFE connection. And don’t worry that going for the gusto means having to spend huge sums of money, there are RELs with the dual connection facility of offering both High Level AND .1/LFE starting below $500/£350.

Finally, enjoy the pursuit of perfect sound and if you every need support, we’re standing by to help. 

August 31, 2020 - Posted in: Principles of Sound