Speaker Positioning: Bass or Imaging?

Hi Lee,

From my experience in my room with my rebuilt Dahlquist DQ-10 speakers I had to adjust the position of the speakers from the front and side walls for the best position. But, to fine tune the set-up for overall sound including highs, mids, bass, imaging, and soundstage I had to toe the speakers in till they were optimized. But, this is a single speaker per channel with no additional woofer. But, from the experience because these drivers are set up both left to right and up and down it affords some flexibility in their orientation.

I will have to wait for the Oswald's Mill Audio New Yorker Horn speakers to arrive in a few weeks to determine if they will require the same positioning and the toe in of the Dahlquist DQ-10 speaker cabinets.

Rich

Having Apogees the constant adjustment for the "sweet spot" is almost daunting. But when you hit it, the "wow factor" is worth all the work.
When things are right the imaging and bass come into line. No need to compromise between the two.

Thanks for starting the thread, Lee.

As you point out, the best position for imaging is almost never the best position for minimizing bass modes and I suspect a lot of folks are compromising flattest possible bass FR for perfect imaging. Best way I know of to avoid this conundrum is to crossover to one or more subs below 80-100Hz (below which frequency localization isn't a factor) and to place those subs in locations which best mitigate modes. Mains/sub transition is typically done with the use of an external crossover and some method for handling latency/phase issues. Ideally, one can also include some form of bass EQ to ensure flattest possible bass response.

In my case, I use a TacT digital preamp, which a) provides adjustable sub(s)/mains crossover, including selectable filter order, b) handles speaker latency issues by imposing appropriate delays, based on room measurements and c) provides DRC for any frequency band I choose, including full range if I so desire (and I do!). It's not a perfect solution as the DSP forces all processing into 24/96 i.e. any other input is converted. Whether one believes there's an audible consequence of that is another thread, entirely. In order to avoid redundant A/D conversions, it also "forces" me to put the input and DAC on opposite sides of the preamp, which can create other convenience issues.

Hi

Interesting thread I must say .. We audiophiles are very used to compromise and I believe strongly that for the most part we aim for aocmpromise between bass and imaging .. We can come pretty close to a good compromise but in my experience hittinh both targets is rarely if ever done.
It comes down to preference, some will sacrifice bass for imaging, some will do the contrary.

Physics tell us of the near impossibility of accomplishing such ... Fortunately there are solutions. Today more plentiful, common and their effect better know. Sub-woofers. Notice the plural. Best bass I've had in my system was through the use of 3 subwoofers... It is a rare occasion where theory meets reality.

In my personal experience, again.. Speakers with extended low bass work even better under these conditions than smaller bass-limited models. The way to achieve the best bass and the best imaging is to place your speakers wherever they image and reproduce the upper spectrum the best. Then supplement them with subwoofers to bring the bass ... Let the main do their things. Do not limit them in any way ... You may lose a few SPL in term of loudness but not in overall quality.

It takes a good amount of work to integrate subwoofers with any main. Quality subwoofers have no problem to integrate with any mains technology. Be it electrostatic , planar or cones.. The emphasis is on QUALITY. There has been a lot of progress on sub drivers this past decade and there are several good commercial subs on the market. Another route is DIY, where the results can be spectacular for much less than commercial. Often what we associate as "slow" sub is a lack of integration with main. mating a main of distinction with a sub in not plug and play. Not terribly difficult truly.. It does however require patience, a good amount of elbow grease and measurements ...

My personal experience has been that bass modes are less sensitive to speaker position than imaging, assuming you don't have the speakers buried in the corner. (In which case you probably haven't the room to tweak their position for much of anything anyway.) Another way of stating this is that I can tweak my speakers a little and significantly change the image, but it takes lot of change in position to impact the bass response. So, I position primarily for imaging and the bass has always been OK.

Subjectively OK or measured OK, as in flat response and good-excellent decay characteristics? Don, I also get good bass by simply using my F3@ 24Hz mains placed for best imaging (they do have some built-in filtering adjustments), but I can do much better by using an ideally placed, phase and FR-corrected sub.

Forgot to mention that the other benefit of crossing over the mains is that the bass drivers, freed from reproducing the lowest frequencies, suffer less distortion in the upper bass.

I run my X-2's full range and then use my Gothams to reinforce the bottom end crossing them at 43 Hz

RUR said:

Thanks for starting the thread, Lee.

As you point out, the best position for imaging is almost never the best position for minimizing bass modes and I suspect a lot of folks are compromising flattest possible bass FR for perfect imaging. Best way I know of to avoid this conundrum is to crossover to one or more subs below 80-100Hz (below which frequency localization isn't a factor) and to place those subs in locations which best mitigate modes. Mains/sub transition is typically done with the use of an external crossover and some method for handling latency/phase issues. Ideally, one can also include some form of bass EQ to ensure flattest possible bass response.

In my case, I use a TacT digital preamp, which a) provides adjustable sub(s)/mains crossover, including selectable filter order, b) handles speaker latency issues by imposing appropriate delays, based on room measurements and c) provides DRC for any frequency band I choose, including full range if I so desire (and I do!). It's not a perfect solution as the DSP forces all processing into 24/96 i.e. any other input is converted. Whether one believes there's an audible consequence of that is another thread, entirely. In order to avoid redundant A/D conversions, it also "forces" me to put the input and DAC on opposite sides of the preamp, which can create other convenience issues.

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+1

Steve, the Gothams, like my much smaller f112, do have the benefit of JL Audio's ARS i.e. they will flatten the single worst peak, and that's a big help. Phase is adjusted to synch with the mains. You're doubling-up frequencies between the X2's bottom end and 43Hz, which could theoretically be a problem, depending upon how it all measures out. Since Marty has measured your response to be near the B&K curve and that curve pleases you, it's apparently not a problem and you're done. All that ASC bass-trapping serves you well! Unfortunately, most folks have nowhere near the level of bass absorbtion you possess.

OTOH, you might find that other crossover points and/or bass-region DRC sounds even better. A future experiment when I bring my TacT up to your place.

looking forward to it Ken

As I have said many times however I am not prepared to give up some of that midbass and upper end magic from the tubes

Steve Williams said:

looking forward to it Ken

As I have said many times however I am not prepared to give up some of that midbass and upper end magic from the tubes

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Steve, as an erstwhile tube lover, I know exactly what you mean and I wish I could figure out how to effectively re-inject some of that tube magic into my system.

All we can do is to conduct the experiment and see what works best for you!

Hey! Wha's up? You coming back to the Bay Area?

My experience has been that separating bass reproduction from soundstaging allows the most flexibility and highest sound quality reproduction potential. Maybe in some rooms you might get lucky and find a good imaging and good bass position. In others you might not be so lucky.

The challenge is that it does take some experience to place and optimize subs, and this is difficult to do without access to acoustic measurement equipment. Plus in two channel land we would need to introduce a crossover between the mains and the subs which a lot of us audiophiles are averse to because of a belief that it degrades sound quality.

Nyal

Any reason why you cant run what I call "full range plus subs"

Here's a tweakers delight, a good friend in NY owns a pair and he loved it enough to finally get off a two decade loudspeaker merry-go-round. It's form suggests it is a solution for folks that have to choose between imaging and smooth bass response. It even comes with an external crossover. I have no connection with Proclaim whatsoever.

After 40 some odd years of experimentation, I reached the conclusion that having woofers aligned with the upper frequency drivers, all firing in the same direction was the most accurate representation of percussive sound. In the old days, with anemic electro-magnet speakers like my McMurdo Silvers (18" cone, 1-1/2" voice coil, DC powered electromagnet), I had to place them in corners to get the deeper bass, as having them in the middle of the room with the rest of the speakers would leave the sound lacking in deep bass. However, the bass was always blurred and percussion didn't have a clear impact.
Today, I line up all speakers in a row, to form one unified field with no "power alley" effect (Google that term for details) and rely on brute force to get low bass without corner reinforcement. It sounds so much better with percussion and is free of the coloration that corner-placed woofers seem to suffer from. Corner placement is okay if you listen to organ music and nothing else. But if content has percussion, you'll prefer the sound of woofers that are unobstructed by early reflections and are front-firing. Bass may be non-directional to your ears, but your body can tell which direction the energy is coming from.

RUR said:

Subjectively OK or measured OK, as in flat response and good-excellent decay characteristics? Don, I also get good bass by simply using my F3@ 24Hz mains placed for best imaging (they do have some built-in filtering adjustments), but I can do much better by using an ideally placed, phase and FR-corrected sub.

Forgot to mention that the other benefit of crossing over the mains is that the bass drivers, freed from reproducing the lowest frequencies, suffer less distortion in the upper bass.

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1. Both. I use RPLusD and a measurement mic (Earthworks M30) for my personal measurements; I grab equipment from work when I need to go further (rarely, now). My AVR and sub do have (independent) phase compensation, a topic I touched on elsewhere and agree is critical to matching sub and mains. When I have tried different sub positions, I have been able to get essentially the same FR after all the calibration and compensation is done no matter where I stuck the subs. I am less familiar with waterfall plots and have not yet used them extensively (yet -- stay tuned); my initial trials to date show similar results with waterfall plots as just basic FR plots, i.e. I can make them look decent no matter where I stick the subs. After some tweak time, mind you, with lots of measurements and listening.

2. My mains are Magnepan MG-IIIa's and, while old, are quite clean in the bass region, though certainly do not play as loudly as my subs. I am crossing over to the subs (a pair of Rythmik F12's) at around 40 Hz, just a little above the Maggies stated -3 dB point (but closer to where I measured the 3 dB in-room). The speakers I had before, a pair of Infinity Alphas, sounded better with the sub offloading more of the bass, and the system just before that was a sub/sat system (Mirage OMD5/Nanosat/10" Mirage sub, forgot the model). In general, I agree with your statement, just thinl 'most everything has exceptions...

In my case, remembering I am coming back into audio after a long layoff (and pretty new to HT, and least in a quality sort of way), my past life experiences led me to believe in having stereo subs in close proximity to the mains for the best image and cleanest overall sound. I feel the music is best served when everything is lined up at the source, the source being the speakers in this case. The times I have moved things around (i.e. tried the subs in different positions) I have not liked the overall sound as well even though frequency response was fine. Impulse response (measured) was somewhat trashed because it's hard to really line up the wavefronts with the sub and mains when they are physically separated, imo. So, even though I may or may not "feel" the waves in snch, I prefer to set up my system that way.

I participated in all sorts of tests (sighted, blind, double-blind, ABX) in my youth through a series of luck and being a pushy young kid. One the tests was an attempt to see where people localized subs. I don't recall everything, or even most, but what I do recall is that at 50 Hz virtually nobody could tell where it was; at 120 Hz everybody could; and, between 50 and 100 Hz or so was a continuum, with different people successfully (statistically) being able to localize the subs at different frequencies in that octave'ish. With THX movie the sub crossover to 80 Hz (about where I could localize it) and taking the range up to 160 Hz max, I felt it better to use a stereo full-range pair with the subs right there with the mains.

My final comment is one I should have placed earlier: I am not using the sub output of my AVR (Pioneer SC-27), but rather running the subs in parallel with the mains to create what I (and I think Steve and others) have called a "full-range-plus-sub" configuration. This is the way I last ran them, but then I biamped (active crossover) the Maggies plus used a pair of (custom, with a servo loop controller of my own creation) subs. I did not try the "normal" way and so cannot say if my way is better or not; it's the way I have done things for ages, and am too old/lazy/weak (take your pick) to keep moving things around and changing the hookups (HDMI has only slightly alleviated the rat's nest behind my console, and I get tired of having to undo and re-dress all those wires every time I try something new).

Sorry to be so long-winded, but now you know where I'm coming from, for better or worse. I certainly cannot claim my way is better or worse than anybody else's, but it works for me.

Or so I tell myself - Don

Don

Wouldnt you agree that if one can, with eyes closed, localize the postion of a sub in the room it is due to it being crossed over too high thus adding some mid range. IOW IMO a well placed and set up sub should be essentially invisible in the room if crossed over correctly

No reason why you can't but then the best way to do it is to choose sub crossover and slope to match the low frequency extension and roll off of the main speakers. That way you don't them playing over each other. I have done just this for a client who didn't want to introduce a line level XO, and it seems that you may be doing this with your setup as well.

If you have pretty full range mains and then you are just running a sub over them then it is unlikely you will get good outcome