Now live - Do subs do more than just improve bass?

[Boomzilla]

hometheaterhifi.com/editorial/oped/do-subwoofers-contribute-more-to-the-sound-than-just-improving-the-bass/

[thezone]

My set up has always been (setting my Large speakers to "Small" to induce Bass management in the XMC-1) but with internal crossover for all speakers set to 120Hz. Then I connect a single mono sub out from the XMC-1 to an active 3 way cross over and feed three different size subs from there as follows large sub 0-60Hz, middle sub 60-90hz small sub 90 - 120Hz.

I find this exhibits the best bass control, low and huge for movies or classical music, tight and punchy for commercial music, with no theoretical frequency overlaps or phase cancellation issues. There maybe timing issues present but I don't notice them maybe I have just winged it or may be their presence is beyond my abilities to discern.

I also find I can crank the volume without it sounding excessively loud as everything appears to be more 'balanced'.

[Boomzilla]

Hi thezone - One can't argue with success! Enjoy.

Boom

[mfeust]

I have been running a 2.2ch system for 10 yrs now since buying a very capable pair of stereo speakers, Chario Sovruns. I have always run this system full range to speakers and blending the 2 subs into the speakers with very good success. I am using the XSP-1 g2 with the high pass to the subs at approximantly 60hz, hard to tell for sure on the XSP-1 and full range to speakers. I have done frequency sweeps with just the speakers and with speakers and subs. The 2 sweeps are almost identical, but definitely prefer the sound of my system with the subs active. In my room system is flat to 25hz, down 9db at 20hz. I am very happy with my system.

Mark

[ttocs]

It's very timely that you pose this question concurrent with my experimentation with subs this week. But, I am not able to support your conclusion in the first sentence of your article - that one must split the split the low freqs to send them to subwoofers.

My Mains have dual self-powered woofers which use built-in Anthem ARC calibration. There is just the one crossover at 300Hz between the woofers and the stat panel. Further, as far as I'm able to figure out, the built-in amps are both after the crossover - each woofer connects directly to its own amp.

The calibration works very well to my untrained eyes looking at the calibration curves before/after. The Left woofers are pretty flat from 300Hz down to about 30Hz, then -2dB down to 22Hz.  The Right woofers are pretty flat from 300Hz down to 24Hz, then -2dB at 22Hz. After 22Hz-L/20Hz-R they both fall down the abyss. The pre-calibration curves for the Left was pretty flat down to 70Hz, for the Right it was good down to 50Hz.

That being said, the speaker by themselves sound great. I've never been happier with a stereo setup!

Because I've got the "audio plague", I MUST tinker with things. I am definitely not opposed to attempting to achieve lower and slightly more voluminous bass. To those ends I began this week to tinker with my subs. Nothing super special or super expensive. When I bought them I had smaller Martin Logans which needed subs, and they were setup using the bass management in the XMC-1. Things were good, maybe really good, but as was said by Richard Pryor in Brewster's Millions - it's not "a room I could die in", or in this case, it wasn't the speaker setup I could die with. But things changed when I got my current speakers, then my tube amps. Since they were married together I haven't had a single urge to upgrade any further . . . . . . . but I'm not opposed to more bass.

In the past I've tried using the High Level inputs on the subs, Left Speaker with Left Sub, Right with Right, but wasn't pleased.
I tried bass management with the XMC-1, not pleased. I figured, why would I want to not use the great bass these speakers already possess?

I want to keep the bass I have, and augment in the very low end of it.

So this week I connected the Left Speaker to the Right Sub using High Level Speakon connection, and the Right Speaker to the Left Sub. I figure this is the same concept of using multiple subs in various locations in a room. The subs' crossovers are set at their minimum of 30Hz, and after playing with the Level controls beginning with too low, then raising till the bass was too much, I ended up with the Levels being set low at about 1-1/2 out of a 10 scale and using just one of the Hot wires connected to each speaker out of each amp going to each sub. I am liking very much what I'm hearing!

I'm actually hearing lower bass, as well as feeling lower bass. The bass now has a greater level of impact I wasn't expecting. But I'm hearing other things as well, but don't have enough hours with this new experience to be able to decipher what is going on. There is one song by Sade (Keep Looking) which has a "tiny" sound and can be destroyed by bad phase and cancellations. My current speakers in their current positions have no problem exhibiting this tiny sound, but it's even better with the subs connected the way they currently are. This tiny sound is not a low frequency sound, it's a sort of medium scale flute sound, probably a synth, dunno, but it's not a sound you would think has much bass in it. All I know is that this tiny sound is better now with the subs.

This is probably the placebo effect, but I'm noticing other tiny little non-bass sounds in music I'm very familiar with that I either never noticed before or never heard as well. It's kinda like the phasing is better.

Here is a pretty accurate layout of my speaker setup. And yes, the ML's are "that" toed-in. I sit slightly nearfield, and this arrangement augments the sweet spot as well as negates the effect of the front wall on the backwave of the stat panels. And yes, there's absorption on the front wall behind the Right speaker to catch said backwave, but I'm able to get away with nothing on the windows, lucky me. Normal ML toe-in means I need absorption at first reflection on the window wall which I used to have there - but hated it! Glad it's gone.


So the bottom line for me is, yes, subwoofers do more than just improving the bass. I figure it's got something to do with harmonics, but that's just a guess.

[Boomzilla]

Hi ttocs -

There are exceptions to just about every statement in audio. Yours is a perfect example. But I'd still say that in MOST cases, using bass management is better than not.

So what makes your setup the exception? Right off the bat, your tube amps are NOT driving the bass of your speakers. Your speakers have their own bass cabinet with its own internal crossover and amplifier. So any further bass management (splitting the bass frequencies, so to speak) won't do a darned thing to help your tube power amp. If your built-in bass amplifier needed help, then yes, directing the lowest frequencies just to the subs would "unload" your speakers' built in bass amplifier. But your built-in bass amp doesn't need help - it was designed properly for the woofer that it's already driving. So in your case, doing exactly what you have (letting the "main speakers" run full range and then blending in the subs below) works great.

Why, then, do you hear more detail in the upper frequencies when the subs are active? I'd contend that that particular phenomenon IS a psychoacoustic one. This does NOT mean that you're not hearing what you say. It does mean that with a wider bandwidth on the entire system (now like 19 Hz to whatever with the subs working), the overall "balance" of the system sounds more like "real music" to you.

Note that the "average" listener does not have a self-powered woofer as part of their speaker system. That means that their power amplifier is driving their speakers FULL RANGE. And most of the amplifier's current is being used to move the woofer(s). In this situation, having active bass management DOES relieve the power amp from having to play full range. It also helps the speakers in that their woofers don't have to travel as far to produce the same SPL (they've unloaded the deepest bass to the subwoofers). This reduces distortion and increases the potential for greater resolution at all higher frequencies. So I still stand by my statement concerning bass management for most folks.

Boom