Try a sub a third in the back

I’ll share something I stumbled upon in the off chance it transforms your listening experience as it did mine. I purchased a rel s/510 while they were on sale to replace a lesser sub. First, the sub is remarkable. I thought it would just add bass extension. I had no idea it would improve the sound stage so much. But now I had 3 subs with absolutely no space in the front of the room to place the third. I planned to sell it. If you like to tinker like me with your system, you probably would have had the same thought I finally did: connect the third sub for the hell of it. In part, the idea was inspired by the long and very good article someone on here linked to about subs: that talks about putting a sub at the back of the room for HT. The lower the frequency, the more non directional the sound. So, having a sub behind me should be okay in a two-speaker setup. The worst that might happen, I thought was that I might shake my house off it’s foundation. But what happened was absolutely unexpected. The sound in the room became amazingly three dimensional. This is not hyperbole. I have a good system and especially with the new Rel sub, there was good width, height, and depth to the sound. But the effect of adding the third sub was to double or triple the depth into the room. I didn’t believe it so I turned the rear sub on and off, repeating the songs. I’ve done this for a week because sometimes new experiences don’t hold up over time—a product of wishful thinking. This one has lasted. I will describe the change this way. Without the rear sub, the vocals were centered, other instruments were placed around the front of the room—some further away than others. Adding the rear sub stretched the centered voice in front of me from 2d to 3D, like someone was in the room, or better, I was in the vocalist’s room. Imagine taking a photo of the singer and stretching it into a 3-dimensional figure in front of you. It’s like that. Although my previous system had good depth before, with the third sub it sounded like I was swimming in the music. there was an exceptional separation of the instruments around and over me not just in front of me. I won’t go on because results will vary. But if you like to tinker and you have a third sub in the house, give it a go. I hope it turns out as holographically for you as it did for me. (Details: I connected the Rel using the line in from my power amp and two RCA outs on my Dac (it also has XLR outs that I use) to connect the other subs.)


I believe that a minimum of three subs works best in many HT systems, especially if there is an open floor-plan in the mix. MY main HT system is in the living room, with a 5-foot opening at the right-side rear into the dining area/kitchen. An L-shaped hallway branches off of the front right-side of the room and no two opposing walls are the same dimension as a result. I think all of that actually works to my benefit, making it easier to tune the subs for the best (even) bass response. There are two 15-inch subs at the front and two 12s at the rear, with the rears slightly offset from each other on opposing walls. The plane-crash scene from Cast Away is a gut wrenching thing to experience and is a good test to see how your system can handle that cacophony of mixed sounds.

Earl Geddes and Floyd Toole both contend that three asymmetrically located subs will provide the best bass response.

Glad to hear you've agreed.



Just want to thank you for posting about your discovery.  I sure appreciate it.  

I use three RELs in my 2 channel setup to great effect. Ears and RTA show very even bass throughout the room (and house, for that matter).

I have a REL Carbon Special in the front right corner playing both channels and two REL S/5s on either side of the listening position playing the right and left channel bass frequencies.

All are crossed over very low ( my main speakers go fairly low) and set at relatively low volumes in order to have them stay in a linear range.  They are completely aurally invisible, but provide outstanding bass weight.

I love this setup...



Glad to hear they liked 3 subs. I have 4 and could not be happier.

I believe the secret is asymetricality (is that is even a word?).

A lot of us audiophiles suffer from OCD and the urge is to place the subs in a balanced formation, similar to our main speakers. Typically, two subs in front placed behind the main speakers and two in the rear corners.

This is a less than ideal configuration, as it only exacerbates any bass issues by doubling up the reflection points.