Why even full range speakers need subwoofers!

Yeah, he pretty much nailed it.  

Nearly 3 years ago, I added a separate amp and active low pass crossover to drive my woofers and the high level inputs of my active subwoofer, and installed an inline high pass filter between the preamp and tube amps that drive the midbass/tweeters.  That move not only improved the quality of bass, extension, dynamics, and control, but it also notably improved the overall clarity and soundstage of everything above that high pass filter.  The main amps are just loafing along from the vocal range and up, with no low bass duties at all.  One the best enabling enhancements I’ve made to my system largely due to the reasons he states in the video. 

The "don't need subs with full range speakers" crowd who say this either never tried it or didn't do it properly.  One thing that surprised me going down this path was how much timing between the mains and subs mattered—not just level and crossover.  Actually doing this may require reexamining long-held positions.

Once I got that dialed in, the improvement wasn’t just bass—it affected image focus and overall coherence in a pretty obvious way.  This seems consistent with @knotscott .  I'm running full range mains and 2 subs.  

It made me rethink how much of what we call “good integration” is really about timing vs just blending levels.

Curious if others have played with timing, or if most people are just setting crossover, gain, placement and leaving it at that.

I always run a pair of subs in both of my systems.  I have stand mounts. Even if I had full range speakers,I probably would still integrate them.  However,my systems are built for my ears only.  Everyone else can build their systems for their ears. You like subs? Cool. You don’t like subs? Cool. 

I have my set up with a 50 Hz high pass for my mains. Works for my big ProAc monitors and my baby Maggie’s. In my set up having my single sub’s voice coil the same distance from the listening plane as the mains locked it in. No phase or time delay issues. 
 

Kills the system without a sub even though my monitors go pretty low on their own.

@klettermann It is amazing how the sub effects the entire system. So many comments are made how people think because they have 'full range' speakers they don't want any more bass. As you point out, the effects on imaging and the entire system are pretty obvious.

For years I ran a pair of subs each next to the main speakers. I too thought about the timing issue as well as the effect on stereo image. However, recently, I became interested in the REL stacking method. So I needed to hear for myself what benifits can be had by stacking both subs together.

I will confess I consulted with Chat GPT on how exactly it should be done. It gave excellent instruction and pointed out that when the speakers are close together the sound will "couple" together and produce bass with a +6db gain!! The advantage of doing this allows for both sub gain levels to be turned DOWN. This makes less excursion and reduces the stress on the amp, distortion reduced, making the bass cleaner and tighter. More well defined since it's not working as hard.

So the feet come off the top sub and a thin layer of drawer liner seals the two subs tightly together. I run them with High level inputs from both channels. They were placed off to the side about two feet from the corner. 

Wow!!! My gain setting went from 2:00 on the dial down to around 10:00. One sub is set at 40hz and the other sub is set slightly higher at 60hz. The effect is not subtle.

This not only produced more volume but the texture was greatly improved. Less stress. Tighter and cleaner. The overall image was improved with no localization of the offset position of the stack. No tilt or offset of stereo image.

Bass coupling (stacking) is the next level. I'll never go back. It is a HUGE leap forward in bass reproduction. REL is on to something. It's not just adding a Sub, it's adding a coupled stack where the real magic comes to life. It's Physics.

I can't recommend this enough!