Subwoofery: Smooth Operator?

Written by Jim Smith

Our last entry ended with this statement – “No matter how excellent the subs, no matter how much effort went into their placement, the results will never be satisfying if the following process (which has nothing to do with working with the subs) isn’t performed.

“The main speakers need to be voiced for the smoothest bass possible! Great subs will have little or no chance of blending with main speakers that have problems in the 25-250 Hz area. Please understand – I am NOT saying that the main speakers are problematic in the bass. Most likely they are performing well. It’s the room/listening position/speaker position that is the culprit. When attention to this vital detail has been properly applied (plus two more issues we will explore as well), only then can we begin to think about working with the subs.”

For our purposes in tuning our main speakers to our room, best bass is NOT the deepest, but the smoothest.  We want to minimize peaks (which mask the true difference in recorded dynamics) and bass suck-outs (which minimize the true difference in recorded dynamics).

To achieve this foundational aspect of our music, we will be working with the room, rather than fighting it.  Of course, various components have varying dynamic capabilities.  But this is not about evaluating components – it’s about transforming the musical effects of the components that you have now.

Rather than employing electronic adjustment at this point in voicing the system to the room, I tend to think of the process as organic, not electronic.  Therefore, we will not be introducing eq or speaker/room correction at this time.  Our concept is simply to be working with the room/system as it is.

The steps we will take are interrelated.  By far, the most foundational step is finding the best location for your listening seat in your room.  This is the anchor point for everything that follows.  Even if you cannot move your seat permanently due to decorative requirements, I’ve found that it’s nearly always possible to use a temporary location for tuning, and for listening those times when you really want to experience the full musical impact from what you purchased.  Especially once you hear and feel the difference this tuning will make.  I call it tuning, but it is really discovering how your speaker/room interface works and then working with it, rather than against it.

FWIW – I know that there are some so-called high-end audio rules – such as the “rule of thirds”.  But in actual practice, I’ve rarely voiced a system that ended up following these precepts or other “rules”, because – once items are introduced into the room – the math changes (as does the room volume and even the dimensions).

Basically, we will locate the best seating location, establish a grid for our room, and then listen to the musical presentation.  We will be making adjustments to speaker position, toe-in and separation, all the while using our grid to help us get back to and/or improve on our reference position musically.

More often than not, this process can be a bit lengthy.  But not to worry – once it’s done, the music will pour from your system in a much more engaging manner.  So the relatively small amount of time spent can pay dividends for many years of musically rewarding listening.

If you cannot change your seating position for tuning and serious listening, then you can skip ahead.  While the overall results may not be as powerful, they should still be very worthwhile.  However, you should at least read the following section on finding the “anchor” position in your room…

Part 1 – The anchor – establishing your listening position

The negative effects resulting from not addressing this critical issue simply cannot be overstated.  Even so, I am constantly amazed at how many audiophiles, dealers, reviewers and manufacturers miss this fundamental aspect of music reproduction.  When I see them worrying about speaker placement without having done the basic listening position evaluation first, I cringe.  Certainly better speaker placement (including distance away from the listener and from walls; speaker separation; toe-in; etc.) can make a real improvement, but it will not have been as powerful as it could have been had those steps been built on the foundation of finding the best listening position.

Basically, we are concerned about the effects of room resonances in the bass (from 25-250 Hz).  The resonances are related to the room dimensions, and to some extent, the shape of the room, the contents of the room, and even the entryways into the room.  Sometimes referred to as the boundary dependent region (25-250 HZ), resonances in this region may appear as peaks in the response (phase reinforcement) or they may appear as dips (phase cancellation).

Essentially, these peaks & dips in the 25-250 Hz region are part of the sonic signature of the room.  I have never encountered a room, no matter how much money was spent on designing and building it, that didn’t still have sonic irregularities in the boundary dependent region. It behooves the listener to locate a listening area where the room is most neutral in this region.  The ultimate result of ignoring this aspect is reduced musical dynamics (and reduced musical engagement) as I mentioned earlier.

By most neutral listening area, I mean the area in the room where the bass is smoothest, not necessarily the deepest. In other words, resonant peaks are diminished and resonant suck-outs are less deep.

Can equalization help?  Can room correction help?  Maybe.  Can bass traps help?  Probably.  But first, we will look at the organic process, one that you can do without spending money on additional items.

After we complete our examination of the best set-up for our main speakers, we’ll look at the issues that usually contribute to a less than satisfactory sub integration with “Full-range” speakers.

Teaser Hint – here are a few Subwoofery issues that we will cover in upcoming issues, which – IMO – are rarely addressed sufficiently or properly (if at all) by most audiophiles, many dealers, more than a few manufacturers, and all too often – a lot of reviewers:

1 & 2 – Subwoofer location and direction.  Hey, isn’t bass omnidirectional? Why would location and direction matter?

3 – Subwoofer crossover frequency. Frequency & level adjustments can make or break seamless sub/main speaker integration.  And it’s not what you think.

4 – Subwoofer level.  Same as above.

5 – Subwoofer polarity.  What is the effect of this adjustment?  When do you make it?  How do you recognize when it is right?

The above five issues (in bold type) will dramatically effect the performance of any sub-woofered system. That’s because they are completely interrelated. IMO, if only one of these is ignored or inadequately addressed, there is little chance that you will get optimum results. In fact, this is one of the areas where reports of “slow” woofers and/or “poor blending” occur, thereby assigning blame for the less-than-satisfying results on the innocent subwoofer…

Uh-oh, that reminds me that I should have introduced another topic earlier in this series. 🙁

For now, I’ll just mention it:  I would far rather have no subwoofer than have to use one subwoofer. Or, to put another way, if you can’t have stereo subs, wait until you can.  Don’t compromise your system with just one.

See you next time!

You can read Jim’s work at his website. 

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