Sunday, February 19, 2012

Your Stereo's Missing Component

So you've swapped this for that, tweaked here and there, compared A to B, and after listening to live music up close, your rig is - well you're still not happy with it. There is something wrong and nothing seems to help. No amount of money gets your system to sound like the real thing.

Yet, going to a friend's home, you hear the speakers literally disappear, transformed as if by the audiophile gods into producing a sound stage so three-dimensional that you can close your eyes and visualize performers walking up to microphones, hear sheet music turning on a stand, and almost make out the shape of the small recording studio in which the musician was playing. What's up with that? What does this system have that yours does not?

All high-end loudspeaker manufacturers use computer aided programs to minimize resonances within the cabinets carefully calculating dimensions and placing speaker drivers in such a way as to minimize reflections and resulting interactions. Incredible pains are taken to recess driver frames and smooth surfaces so that the first reflections - the closest surface capable of producing an echo that could reflect back to the source - are reduced to the point where their effects are controlled if not completely eliminated. But yet these manufacturers are unable to control the other speaker box that has identical and complicated resonances and another whole set of first reflections: your listening room.

Yes, my friend, the room in which you place your speakers is literally another speaker box, one in which the other must operate. The constraints you place on your speakers is predefined by the shape, size, and contents of the room. Take for example theaters and music halls. Here, acoustical engineers take the time to minimize these nasty acoustic interference patterns so that the audience can appreciate what the singers and musicians are trying to produce. The greatest concert halls in the world are rectangular in shape with the stage along the short wall of the room. Why do you think this is and what can you learn from their experience?

Avery Fisher Hall, Home of the New York Philharmonic

See the panels at the back of the stage in the above photo of Avery Fisher Hall? Why do you think they are there? What about the strange shapes on the left and right walls, what are they doing? And then the ceiling has these weird contours and symmetrical patters so they too must be part of the plan, right? Right indeed.

Nothing in a truly great concert hall is done by accident. Every square inch of its design is conceived, reviewed, tested, and adjusted based on listening tests and adjusted accordingly. The best ears in the world come to hear performances from the finest musicians and voices at such places and such people are far less forgiving for mediocrity.

Of course you can always hire a similar engineer to come out and treat your listening room, and you may need to after trying these next three tips. But there are a few things you can do to help improve the sound of your room so that the sound of your system is enhanced.

Tip Number 1: tame the first reflection. All audiophile listening rooms have a "sweet spot," a point where the sound is best heard. At this position, moving just a little in any direction, left/right, front/back, up/down, drastically changes the sound and therefore its appreciation. From this place, have a friend move a flat mirror along the left wall until you see the left speaker and then until you see the right. Mark these two places with painter's tape. Do the same on the right wall, ceiling, and floor. Now you have identified where you must place sound absorbing materials so that the reflected sound does not interfere with the direct sound. Hang tapestries, rugs, or acoustic panels at these points.

Wall Rug Absorbing First Reflection

Tip Number 2: use the Live End/Dead End room concept. This approach in listening room treatment encourages reflections from the non-speaker half of the room and discourages reflections in the speaker half of the room. Here all walls, floors, and ceiling are somehow treated so that all reflections are reduced or eliminated. Much like the acoustic panels at the back of the Avery Fisher stage, absorbing all reflections along this wall helps to improve the sound coming from your speakers. Treat whatever you can while still maintaining reasonable aesthetics (that nasty compromise).

Wall Tapestry Adding to Dead End Concept

Tip Number 3: deaden the rear of the speaker.If you do not own dipole speakers (those intended to radiate from the front and rear of the design), you can tape a small amount of sound absorbing material to the back of the speaker. This reduces the first reflections caused by the sound wrapping around the speaker cabinet and reflecting off of the speaker wires, terminals, and whatever hides behind.

Sound Pad on Rear of Speaker

Try these three tips and see if the sound of your system improves. Remember that the shape of the room is already fixed so unless you move your system to another room, you have little other choice than to try to make this room compliment the sound produced by the speakers.

Yours for higher fidelity,
Philip Rastocny

I do not use ads in this blog to help support my efforts. If you like what you are reading, please remember to reciprocate, My newest title is called Where, oh Where did the Star of Bethlehem Go? It’s an astronomer’s look at what this celestial object may have been, who the "Wise Men" were, and where they came from. Written in an investigative journalism style, it targets one star that has never been considered before and builds a solid case for its candidacy.

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