Diffraction Information & Graphs

Read the only Comprehensive Directory of DR. HENRY OLSEN Links

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Soundwave Length Chart Spherical Cabinet Volume Chart

Time domain models of edge diffraction

Diffraction problems with loudspeaker cabinets

On This Page: Exterior Diffraction Charts Caused By Loudspeaker Enclosures including the original Dr. Olsen charts from the late 1930's - early 1940's

The Following Charts Show the Exterior Diffraction Effects Caused By Loudspeaker Enclosures

These are complete original Dr. Olsen graphs and drawings of cabinet shape responses

The scans are of poor quality but the information is very observable.

This is the Entire Set of his observations produced in the late 1930's and early 1940's.

Compensation via electronics or Loudspeaker driver placement/aiming can only create a rough equivalent of the benefit of using curved loudspeaker enclosure shapes because the sound-spectrum bandwidth is far too wide for non-enclosure compensation.

These graphs do not describe the further benefits of internal diffraction reduction caused by focusing the internal sound waves into the center of the enclosure and also into the rings of Sound Diffraction found along the interior surface of the enclosure. Both effects cause far less time-delayed sound-bleed through the speaker cones-- which destroys sound-quality in the listening area outside the loudspeaker system. Using sound-absorbents can reduce reflections by 20db maximum. Proper curved internal wall design can reduce the internal reflections by close to 100%. These effects are not on these charts, which just show the benefits of external diffraction.

The Results, from Dr. Olsen in the late 1930's, show that any loudspeaker driver or driver array will benefit from a curved loudspeaker enclosure. This benefit will gain increased sales in the marketplace.

. $Diffraction Loss of a Sphere$

$Diffraction Loss of a Rectangular Enclosure$

$Diffraction Loss of a Cube$

$Diffraction Loss of a Cylinder$

Shape A- Sphere	Shape B- Sphere, squished	Shape C- Cylinder, center-mount	These graphs are from experiments performed in 1950 at RCA's research labs at Princeton University. The driver used a sealed-back cabinet using the shapes as drawn by Dr. Olsen. What this means is that the responses you see here are caused ONLY by *the Outer Shape of the Cabinet or Enclosure!*
			Notice how Shape C, the Cylinder, generates a strong "ringing" or resonance pattern. Shape A (Sphere) has by far the least distortion of all shapes on Olsen's charts. Nothing approaches the Sphere's lack of cabinet distortion. Properly curved cabinet designs approach the Sphere.
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Shape D- Cylinder, side-mount	Shape E- Cube, center-mount	Shape F- Cone, center-mount
			One would suspect these distortion patterns would appear, just from *interior shape reflections* back through the drivers cones-- given the cylindrical nature of ports, but it is interesting to see that the *exterior* effect apply as well as the data shows. Also review Shape E's responses, the Cube - same high-resonance pattern. Not a desirable cabinet to reduce cabinet distortion!
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Shape G- Dual cone	Shape H- Pyramid	Shape I- Dual Pyramid
			Here are more shapes with bad cabinet distortion- exterior effects are clearly in evidence based on Dr. Olsen's clean test methodology!
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Shape J- Tweaked cube	Shape K- Rectangular	Shape L- Tweaked rectangular
			Here are what most designers settle for, at best twiddling in the front baffle and driver placement. Helps a little but you can still see the bumps and dips compared to curved cabinets. Even computerized processing cannot approach the natural strong, smooth, response that our spherical, ovoid, or wing-shaped enclosures easily provide with a great never before seen loudspeaker look similar to a lamp, a piece of curved art, anything curved found in your home. .

Here is another form of exterior diffraction, the results graphed by Dr Olsen in the 1930's of sound bouncing off an object.

In this first case the shape is a Cylinder.

As suspected, the Cylinder shows the same strong resonance patterns shown above.

The acoustic reflections of a Cube. Bad as the cylinder, and naturally worse at some angles.

And here we have the sphere. Notice how it actually has a smoothing effect, in fact spheres have been hung in the Hollywood Bowl (see below) as acoustic correction devices. Talk about room treatment!

Curving The Loudspeaker Enclosure design Eliminates a large number of variables when designing mass-manufactured loudspeakers including the calculus involved with baffle-step diffraction.

Our ultimate enclosure shape-materials have the ability to eliminate baffle-step diffraction and thus literally lessen the work and cost involved with designing a proper loudspeaker system; it allows previous engineering efforts to be easily modified to create both Stellar - Sounding and Looking products- at a far lower percentage of your current Engineering, Manufacturing and Driver costs.

See Loudspeaker Cabinet Diffraction In-Action... http://www.silcom.com/~aludwig/images/diffdem.gif

                                 Sound Diffraction at Rear-Corner of box- shaped speaker

Curving your OEM enclosures also allows you to differentiate your products from the competition while offering a Class-A finish, at a manufacturing cost lower than any wood, metal or plastic curved loudspeaker enclosure on the market, produced in any country. And properly-designed curved loudspeaker enclosures are Wife-Friendly as the home is filled with curved objects

                                                              Port Soundwave Vortex

                                                                              creates Standing Waves

Our SHAPES reduce exterior diffraction and also reduce the additional smeared sound-quality even the highest costing loudspeakers have which are caused by internal reflections which travel through the loudspeaker cone... up to dozens of milliseconds after the sound was originally reproduced by the drivers... both distorting the cone motion and also propagating unwanted reflective sound even with near field monitors. No electronics can hide the internal effects nor can any stuffing reduce internal sound even 30 db let alone the 140 db found inside loudspeaker enclosures. Our shapes and our materials together are literally The most technologically advanced Loudspeaker Enclosures available. They simply improve loudspeaker sound quality in a way no electronics can at a cost lower than your existing loudspeaker enclosure costs and with higher visual quality. Our product materials create a true breakthrough in loudspeaker technology.

Defeatable Internal Diffraction in a curved loudspeaker cabinet.

US Enclosure’s Technology can add tremendous value to a given OEM loudspeaker system. This is accomplished by Smoothing and Widening the response.

Loudspeaker Definition is Enhanced...

SMOOTHING-- Lower exterior wall diffraction smoothes and sweetens the response. Even the best existing electronics can only crudely simulate this effect. Less diffraction from exterior walls also lowers the delays created from sharp enclosure corners. Our loudspeaker enclosure shapes also create far less diffraction from the enclosure's interior walls. The benefit is far less sound-pressure induced loudspeaker cone bleed-through of time delayed time-delayed sound from the loudspeaker into the listening area.

WIDENING-- Lower exterior cabinet surface diffraction from the causes soundstage widening.

Diffraction. All waves diffract no matter their frequency. As an example, review diffraction using light waves. When a yellow light wave diffracts, it slows and turns orange. The exact same thing occurs when a sound wave slows after encountering a loudspeaker box corner... corners found either on the inside of the box or on the outside of the box-shape loudspeaker enclosure. The sound changes from it's original quality.

Currently with standard box-shapes, both internal and external diffraction occur, both negatively effecting

And this is unacceptable now that curved loudspeaker enclosures can be manufactured that look as good or better than existing box-shaped loudspeaker enclosures and with the same manufacturing costs than box-shaped loudspeaker enclosures.

The mix of "yellow" & "orange" sound causes loudspeaker enclosures to negatively "color" it's sound.

OUR BENEFIT: Your drivers will sound more expensive when this coloration is ( in practical-terms ) "eliminated" from the product's sound field. And we can provide these benefits to your company at the same or lower cost than you currently are paying for box-shaped cabinets. Our Design Division has a long-term proven success record when your design engineers request additional assistance.

Manufacturers using either electronic or other diffraction-compensation systems still have the reality that their compensation system has to properly handle a 20- 60 hz to 8 - 10 khz wide bandwidth in real-time and the compensated sound then still travels past both external and INTERNAL corners-- causing time-delayed bleed through the driver cones from internal diffraction & phase-shifts from exterior cabinet corners as external diffraction.

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http://www.livesoundint.com/archives/2003/aug/three/three.php

http://stereophile.com/reference/704cutting

BUILD YOUR OWN CURVED   LOUDSPEAKER CABINETS...
"How-To DVD" for crafting your own curved or spherical loudspeaker cabinets--

PREVIEW

The clip is a very small slice, taken from the middle of the entire video
* Use a composite material you make that is as dense as MDF--
and denser than 13 ply Baltic Birch 3/4"

* The size you need--
up to 36" diameter, almost 13 cubic feet

* with details on how to port these cabinets

COST: $10.50 INCLUDING SHIPPING (IN USA)
checks only
Contact us for additional information
From the Instruction Booklet in the DVD...
MAKING SPHERICAL COMPOSITE ENCLOSURES

Kris Metaverso, Engineer at US Enclosure Company

Hello and Welcome to the world of post-MDF enclosures.

We have been making spherical and other shapes from a wide variety of composite and plastic materials for 15 years now. Using the techniques and resources in this booklet and DVD, you will make spherical composite enclosures from 6 inches in diameter all the way up to 30 inches in diameter and more. No special tooling or equipment other than what you have in your garage or can easily get from Home Depot, Lowe's, Ace, or any home improvement or hardware store is required...

Topics Include:

WHAT'S WRONG WITH WOOD OR MDF?    WHY USE SPHERES OR ROUNDED SHAPES?             WHAT'S WRONG WITH BOXES?

      GETTING STARTED:       TOOLS AND EQUIPMENT          SUPPLIES         OVERALL DESIGNS

      THE 9 STEPS TO PRODUCE A FINISHED CURVED LOUDSPEAKER CABINET IN YOUR WORKSHOP

    STEP BY STEP, THE DVD SHOWS A CURVED LOUDSPEAKER CABINET BUILT WITH ALL THE NEEDED MATERIALS AND TECHNIQUES

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