Paul's Posts — 17 October 2011
By Paul McGowan
Oops. Sorry about yesterday’s surprise post. Aaron Berger, a contributing writer to PS Tracks, posted right after I did and the mail system grabbed his article instead of mine. It was a good article, but quite a surprise! Here’s today’s post.
Ever wonder how moving a loudspeaker a mere matter of inches can make a big difference in imaging?
Here’s an experiment for you to play with so you can see. Try toeing in your left and right speakers 1 inch and you’ll discover the center image and the soundstage will change dramatically. Now, put them back to where they were and move one of the speakers backwards by 2 inches, relative to the other. What happens? The imaging shifts. Why?
Because millimeters matter at high frequencies and meters matter on bass notes.
For example, a 20Hz bass frequency is 56 feet in length, but a 10kHz treble note is a mere 1.3 inch long (53mm).
So if you move your speakers backwards or forwards by a matter of inches, the bass will be unaffected but the high frequencies will be seriously changed.
This is just one of the reasons why I have always been a proponent of separate subwoofers . You need to make tiny changes to affect imaging, but extremely large changes to affect bass.
The main speakers are all about imaging and the separate woofers are all about bass: both have to be moved independently.
That is, if you want the best sound. And who doesn’t?
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audiofilodigital.com
Very interesting article, Paul, as usual.
In fact, some professionals think like you, ‘thoug… from the “sweet-spot” point of view ( sorry for invoking so many senses !): that could be one of the reasons why, some audiophiles can notice/hear/listen to some differences sometimes, while they can’t be noticed/heard/listened to in other occasions: http://www.ethanwiner.com/believe.html. Not everything depends on listener’s mood. But, again, thank God, it can be clearly measured (sorry for gathering God & measures).
BR
Paul McGowan
Thanks!
o2audio
Super Post Paul…
Bravo!
I think it would be good to note that making multiple changes in one’s system is never a good idea. Just what you are suggesting alone is wonderful – but don’t change (say) power cords at the same time.
Excellent stuff,
With thanks!
Paul McGowan
Indeed! One of my earlier posts addressed that http://www.pstracks.com/pauls-posts/one-at-a-time/2195/
Thanks for commenting.
Hiro
I agree. Millimeters matter! I believe you are correct about the 56′ bass frequency. I don’t know the physics behind this, nor why it works this way, but I strongly disagree about needing large movements to affect the bass. No disrepspect, you are infinitly more knowledgable than I.
I know, for a fact, that you get huge changes in bass when making adjustments in the millimeter range.
I position speakers to get optimal imaging AND deep, linear bass, without compromise. I strive to eliminate spitty, shouty, nasally vocals, and congestion at the same time. This isn’t easy, but you CAN have it all (to the best of the equipment’s abilities). Plumbing and proper (and equal) rake, also do wonders for quieting and smoothing the sound.
Speakers are rarely identical distances from the back wall. One must be fudged forward or backward to get the bass, and the image, to fire from the center. If not, it will pulse from one side to the other.
I feel, as you do, subwoofers are essential. The other day I positioned my subwoofer with my girlfriend’s help. She was sitting in the hot spot. I started by bringing the subwoofer from the wall out into the room. We listened for optimum bass. Once there, I began to swivel the forward firing subwoofer on its axis. I was creeping it around very slowly. I’d moved the subwoofer an 1/8″ when she said, “Whoa! Right there!”
The bass locked in, and worked as one with my speakers. She has zero experience with audio, and could tell instantly.
That’s my 3 cents….