February 1, 2010
Tweaks . . . That Work!
What with all the
ranting Ive been doing about tweaks this last little while, it was heartening to
read the SoundStage!
Networks coverage of the 2010 Consumer Electronics Show and learn that real
engineering still rules the new-product roost. Take Stellos cool new Ai500
integrated amplifier, which at $3500 might represent the biggest bang for todays
audio buck; or the refined design of Parasounds JC3 phono preamp, with its short
signal paths isolated inside subenclosures that are themselves shielded from the power
supply by a metal barrier. But enough of that -- I promised you some tweaks . . . that
I havent tried every isolation cone/pod/blob out
there, but I do have an assortment of Black Diamond Racing cones, JA Mitchell aluminum
pucks, Nordost Pulsar Points, and some ebony triangles kicking around the listening room.
I even played with a Gutwire Notepad (v.1) before it evaporated on me. None of them holds
a candle to the best isolation device Ive tried, which also happens to be the
cheapest: the humble Vibrapod Isolator.
It took me some time to figure out that an
annoying resonance emanating from my home-theater rack was being produced by my always-on
TiVo. This presented me with a terrific opportunity to objectively experiment with various
isolation doodads: theyd either subdue the vibration or they wouldnt. To make
a long experiment short, not one of the so-called isolators did anything more than slightly
damp the vibration -- except the Vibrapods. With them in place, the vibration was
completely contained within the TiVo. I never heard it again. And Vibrapod Isolators are
cheap: from $25 for a set of 4.
The architecture of the average Gothic cathedral might be
inspired by Heaven, but its acoustics come straight from Hell. Naming a company Cathedral
Sound thus throws down something of a gauntlet, or at least a strong implication that the
product can work wonders with problem rooms. Cathedral Sound's Room Dampening Panel (model RDP150C) is claimed to
offer the damping performance of a large bass trap, but a size small enough (16"W x
11"H x 2"D) to be easily hung on a wall. The key to their performance is said to
be their exploitation of the Venturi effect, a physical phenomenon in which, when the
pressure exerted by a fluid decreases its velocity increases, and vice versa. The
fluids velocity can be increased by passing it through a tapered tube, called a
Venturi, that lowers the pressure exerted by the fluid.
How does this apply to acoustics? Air is a fluid. When the
Venturi-loaded Cathedral Sound panels are placed near room corners, they take in the air,
which in those spots can be excessively bass-loaded due to the meeting of room boundaries,
cram it through their Venturis, and thereby decrease air pressure while increasing air
velocity. The trading of pressure for speed seems to reduce the sound-pressure level of
the air passing through the panels, thereby attenuating excess bass energy. I can only
surmise that the size of the panels dictates how much air can be pushed through them at a
given moment, which in turn likely accounts for the panels ability to remove just
enough bass energy from the room.
Thats some fine theory, but the great thing about the
Cathedral Sound Room Dampening Panels is that they work. Theyre most effective when
hung on a wall (6" to 8" down and 3" out from the nearest meeting room
boundaries), but also do very well when just sitting on the floor in the rooms
corners. The effect of the panels was instant and easily noticeable in my room, with
marked decreases in boom and bass bloat. This was accompanied by a clearer, more focused
midrange that had been masked by the overloaded room. Overall, the Cathedral Sound
products were just the ticket for reforming my spacious listening room. The facts that
theyre cheap ($90 each, with discounts available for multiple units), and of almost
microscopic size compared to traditional bass traps, make them worth a close look. They
actually deliver as promised: a tweak that . . . works!
Were not done tweaking yet, dear friends. Next time
Ill talk about electrical and magnetic tweaks.
. . . Colin Smith