Useful Computer Programs:

Sitting Duck's Listening Room

Acoustic-X* 1.0 (acoustic design software, 416-868-0809, www.pilchner-schoustal.com)

Useful Web Sites:

www.sysdevgrp.com System Development Group: This site provides product information, acoustic principles, a calculator for determining small-room reverb times, room modes, bass traps, and a list of acoustic and audio links.

Useful Pamphlets:

"High Fidelity's Hidden Variables," Tips and Tweaks by John Vicario. Available from Affordable Audio, 9605 Venice Blvd., Culver City, CA 90232, 310-558-0716.

- APPENDIX B -

STATIC AND DYNAMIC NEUTRALITY

Conventional science and engineering have established test methods which have been developed for audio or have been accepted by the audio community as being applicable. These tests methods have been well subscribed to by designers and manufacturers for at least the last few decades. There has been no real advancement in making these tests correlate with good sounding audio components. Some components that should sound bad because of poor test specifications actually sound quite good when part of the right system. The converse is equally true: some components that test exceptionally well can sound quite awful when used in the wrong system.

It has been this lack of correlation between a product's bench specifications and its sound that has caused so much dissension in the audio community as a whole. Tests that make sense don't always make for good sound. But we now have removed the sole responsibility for sonic excellence from the shoulders of these older testing methodologies.

An important aspect of all audio components (resonance response) which has only recently come into its own makes it possible to separate and validate old and new test methods (and some of the new test methods haven't been invented yet).

Static Neutrality

The test methods/specifications which have been in use for many years, can be said to lead to high levels of Static Neutrality (which, when combined with high levels of Dynamic Neutrality, can only result in superior products).

These tests include:

1) %THD & Noise

2) frequency response

3) input and output impedance

4) phase shift

5) power bandwidth

6) other distortion mechanisms: TID,IM

7) polar plots and other dispersion characteristics of speakers

8) cumulative spectral decay

9) jitter

Dynamic Neutrality

At this time, the human ear is the only test instrument available for this test. However, a part (resistor, switch, connector, etc.) or component that has a high degree of Static Neutrality (tests well) can have its resonance response modified, if need be, to impart a high degree of Dynamic Neutrality. However, this high degree of DN will only be in context of the larger system of which it is a part. Because a product's resonance response is not at this time bench testable, universal compatibility is not possible.

The duality of a product's sonic neutrality is for now a useful tool in understanding and describing current situations. Some day in the future, the resonance response of a product will be an accepted and common design tool, and there will be no need for separate concepts of neutrality.

- APPENDIX C -

BACKGROUND INFORMATION ON EQUIPMENT FEET

There are two general types of feet on the market. There are soft energy-absorbing types and hard energy-transmitting types. Those that absorb energy are said to "decouple"; those that transmit energy are said to "couple."

Pointy feet are explained by analogy; they don't really suck-out the "bad" energy. They and other coupling type feet keep the energy from building up in the first place. This means that there is no energy to drain away when soft feet are replaced with hard feet.

Proponents of the "it's draining away 'bad' energy" concept build their concept upon the fact that energy is entering the component through the feet and causing problems. A lessening of overly "fat" sounding bass energy and increased high frequency definition usually occurs when cones are placed beneath components. This is often a sonic plus. The sonic differences are not the problem. The problem is the accepted concept which supposedly explains how this is accomplished. How can a pointed object both block energy and drain energy? If the 'bad' energy can't enter, where is it coming from? If it's not there, how can it be drained away? What is actually happening?

The central theme of the accepted explanation is that cones allow energy to pass through them in one direction only because of their shape. However, this idea can be negated through simple observation. Speaker stands are spiked, top and bottom, to "drain away" "bad" energy. The same kinds of sonic benefits occur when speakers are spiked in this manner as when a component is put on cones: overly fat sounding bass is removed and high frequency detail is increased. Take a close look at the top spikes: they are pointing UP! How can the result be the same unless the direction of the spike doesn't matter? If a cone doesn't block energy from entering a component, then energy is free to pass freely in BOTH directions. It CAN'T drain energy AWAY from that component! Obviously, the direction of the point is NOT the primary mechanism for the sonic benefits that DO occur.

If it's not a cone's shape that causes better bass and high frequency definition, what is it?

An analogy can be drawn between a component with "excess" energy and a pond formed when water enters a depression and doesn't have a way out. The pond is the storage mechanism for this excess energy. Cones are thought to "block" energy transmission into a component and to also "drain away" energy that has entered that component. This would be like keeping the water from getting into the pond, and, at the same time, draining the water out of the pond. We've seen that cones do not block energy, and so won't interfere with the movement of the "water." What else is left? The pond!!!! Get rid of the depression and suddenly there IS no problem. It's the storage mechanism (pond) that is at fault here, NOT the water (vibrations).

Rubber and other soft feet act like a spring. The weight of the electronics, together with the spring-like rubber feet, form an ENERGY STORAGE MECHANISM (a "pond"). The resulting resonant frequency is most often in the mid or upper bass, not where a lot of listening rooms need an overabundance of energy. By coupling the weight of the electronics to the shelf (using hard feet between the component and the shelf), we eliminate a system resonance which can contribute to a fat, muddy bass. An important point to note is that for coupled electronics, the weight is now sprung by the compliance of the shelf; its resonant frequency will be much lower in both amplitude and frequency. (This is quite often, but not always, a plus.)

Decoupling-type feet can help a system's sound by partially isolating a component from shelf-borne vibrations, "partially" because this decoupling action is frequency dependent. Usually the effectiveness of the decoupling effect goes up with frequency. Some decoupling devices will still manage to have resonances in the higher frequencies. This decreases the effectiveness of the decoupling action at those frequencies.

Regardless, it is still a good idea to have two or three sets of aftermarket decoupling feet in your arsenal. At least, know where you can borrow some. No one single concept can be the answer for all possible problems. An open-ended 7/16" wrench may have been a life-saver at one point in time, but that doesn't mean you should toss away the rest of your toolbox. In one situation you will need to couple a component; in another you will need to decouple it.

Both coupling and decoupling feet also dampen the bottom panel's vibrations. This may or may not be good. Just as antibiotics kill the good bacteria as well as the bad, rubber and other decoupling-type feet kill the vibrations that can help the sound of the system, as well as those that may harm it.

- APPENDIX D -

WHY POWER CORDS AND POWER CONDITIONERS HAVE A SOUND

There is a common misconception about the nature of the power going through a power cord. Many people, including engineers, think power is just 60 Hz/120VAC. One frequency: plain old power. To "think" is not to "know." Measurements do have their place, and the results of some meaningful measurements are to be found in the VansEvers publication, "Why Do Power Cords And Power Conditioners Have A 'Sound'?"

To sum up the measurements, the power going through a power cord has much the same bandwidth and frequency content as does the power going through your speaker cables. Is it really any wonder that power cords affect the tonal balance of an audio system?

- APPENDIX E -

MORE THOUGHTS ON POWER FROM THE WALL AND ITS SOUND

The water used in making coffee isn't important. The taste is all in the beans. Right? No, not right. Water has a taste, just as your wall power and its path to your equipment have a sound.

-Some Questions Answered So That You Don't Have To Ask Them-

Q#1. How can the power affect the sound of our electronics?

A#1. Take for example, a power amp. It has one input and one output per channel, right? Not really. A power amp cannot create a bigger, more powerful output signal from the input signal without a source of power to use as its raw material. The source of power is, in effect, a second input. Here is another case in point where the resonances in the power supply, power cord, and the wall outlet (etc.) will definitely affect the sound of your equipment.

It helps to think of the wall outlet as an AC battery. The "AC" part of the designation indicates that the wall voltage changes direction 120 times a second. Because of this, the direction of current flow changes at the same rate. The "battery" part emphasizes the point that the wall is supplying current. This may not be obvious, but it is the important part: the frequency content of the current drawn from the wall varies with the music. As the music changes, the raw materials needed by each piece of analog electronic equipment also changes. If the music goes from bass-shy to bass-heavy, then more bass energy from the wall is needed. If the music goes from treble-light to treble-bright, the wall is asked to provide more treble energy. This isn't theory; it is measurable.

The changing power requirements of an amp playing different frequencies are illustrated in the VansEvers literature, "Why Do Power Cords And Power Conditioners Have A 'Sound'?"

Q#2. What affects the ability of your wall outlet to supply the needed current?

A#2. Its impedance.

Q#3. What affects a wall outlet's impedance?

A#3. Every power supply and transformer in your stereo, room, house, and at least, your neighborhood. If an electric/electronic something is connected to a wall outlet or power line in your neighborhood, it affects the impedance of YOUR wall outlet.

Q#4. Why is this?

A#4. Transformers store energy. If the voltage across the transformer primary drops, the magnetic field of the transformer collapses and puts energy back into the circuit, thus buoying up the voltage. The electrical and mechanical resonances of that transformer/power supply determine its "sound." If there are more resonances (energy storage) in the lower midrange than other areas, then the sonic contribution of that transformer/power supply will be tilted towards the lower midrange. Why would anyone assume that this scenario would or could be possible? The answer is simple: experience. For example, I found that turning off the fluorescent lighting in the VansEvers Company's listening room lightens the lower midrange of our reference system. (A member of the Florida Orchestra was at this listening session and also heard this effect.)

Think of the power company as a large warehouse on the other side of town. Think of the transformer/power supply of every piece of 120VAC equipment in your neighborhood as convenience stores.

Your active electronics are not discriminating shoppers. They are going to get their raw materials (power) from whatever source is most convenient.

For some people, if candy is easier to get than something good for them, the percentage of candy in their diet will be higher than it should be. The same is true with power. If there are more transformers/power supplies attached to your local power grid that have excess mid-treble resonances than not, then the sound of your power will be more forward in the mid-treble.

Q#5. Why does the sound of my system change during the evening?

A#5. As people leave work they turn things off. As people progress through the evening hours they also turn things off. This means that the level of noise and RF garbage injected into the power grid goes down over the course of the evening. The resonance response of the power grid is then also less cluttered by non-audiophile approved transformers and power supplies.

Q#6. Why does changing the power cord on my CD transport change the sound of my system?

A#6. The analog portions of your music system pull power from the wall, as needed. If the music suddenly has more bass (treble, etc.) content, then more of that frequency's energy is pulled from the wall outlet in response.

Digital equipment draws the same amount of power all the time, more or less. It is different from analog equipment in that the power drawn from the wall doesn't fluctuate with the music. Because of this, its power supply can then supply energy by transformer action back into the wall. The actual tonality (resonance response) of its contribution to the impedance of your wall outlet is influenced by its power cord.

- APPENDIX F -

MANUFACTURERS OF TUNING PRODUCTS

Disclaimers, etc:

No claim is made as to the completeness of this list.

These products are all of high quality and are worthwhile additions to your tweaker's tool box. (No guarantee is implied as to the effectiveness of any specific tweak in solving any specific problem.)

The intended primary function of some of these products may not be resonance modification. However, if the intended placement is upon the top of equipment chassis or around system cabling, the audible effect of the resonance modification will be a significant portion of the overall effect.

Andy Bartha Audio, Ph.: 954-583-7866 (Whatchamacallits: mass dampening and/or feet; Reveal CD cleaner)

AudioPrism, 1420 NW Gilman Blvd., Ste. 2593, Issaquah, WA 98027, Ph.:206-641-7439, FAX.: 206-644-5485 (IsoBearing*)

Black Diamond Racing, 2625 South Greely St., Milwaukee, Wisconsin 53207, Ph.: 414-747-8733, FAX.: 414-747-8734 (The Pyramid Cones, The Shelf)

Bright Star Audio, 2363 Teller Road, #115, Newberry Park, CA 91320, Ph.: 805-375-2629, FAX.: 805-375-2630 (Big Rock, Little Rock)

Combak Harmonix, U.S. distributor= Fanfare Int'l, 500 E. 77th St, #1123, New York, NY 10162, Ph.: 212-734-1041, FAX.: 212-734-7735 (CD Foils, Tuning Bases, Tuning Cable Rings, Tuning Insulators)

Marigo Audio Lab, 4926 W. Howard St., Skokie, IL 60077, Ph.: 847-674-1265, FAX.: 847-674-1266 (Bear feet, VTS Tuning Dots, CD Disc Mat, CD/Laserdisc edge treatment and optical fluid)

Original Cable Jacket (The), Inc., 618 Grand Avenue, Oakland, CA 90291, Ph.: 510-893-8403, FAX.: 510-893-3818 (The Original Cable Jacket)

Shakti Audio Innovations, S.A.I. 2405 Cloy Ave., Venice, CA. 90291 Ph.: 310-305-1857, FAX.: 310-827-8373 (Electromagnetic Stabilizer)

Shun Mook Audio, 618 Grand Avenue, Oakland, CA 94610, Ph.: 510-581-6372, FAX.: 510-839-008 (Mpingo Discs)

Sounds of Silence, 7 Blueberry Lane, Nashua, NH 03062, Ph.: 603-883-0065, FAX.: 603-625-4712 (Vibraplane Isolation Platforms)

Ultra Resolution Technologies, 5140-C Commerce Ave., Moorpark, CA 93021, Ph.: 805-523-3005, 531-1001, FAX.: 805-531-0004 (Cornerstone, Keystone, Ultra Coupling Foot, Ultra Suspension Foot, and more)

T.G. Audio Lab, 5000 Redstart, Houston, TX 77035, Ph.: 713-721-4756 (Pointy Things)

Ultra Systems, 1 Walter's Lane, Box 570, Point Pleasant, PA 18950, Ph.: 800-724-3305, 215-297-0227, FAX.: 215-297-8661 (Audio Points)

The VansEvers Co., Inc., 1250 E. Hillsborough Ave., Tampa, FL 33604, Ph.: 813-239-0700, FAX.: 813-239-0805 (Tuning Blocks, Cable Multi-Resonators)

Versalab, Ph.: 606-224-2650, FAX.: 606-224-8290 (Wood Blocks, and Red Rollers)

V.P.I. Industries, 77 Cliffwood AVe. #3B Cliffwood, NJ 07721, Ph.: 908-946-8606, FAX.: 908-946-8578 (V.P.I. Brick)

Yamamura Systems, P.O. Box 1598, Novato, CA 94948, Ph.: 415-898-8067, FAX.: 415-382-0572. (graphite blocks, shark oil)

- APPENDIX G -

MANUFACTURERS OF ROOM TREATMENT PRODUCTS

No claim is made as to the completeness of this list.

Acoustic Innovations, 6780 East Rogers Circle, Boca Raton, FL 33487,Ph.: 800-983-6233, 407-995-0090, FAX.: 407-995-0290 (absorbitive room treatments)

ASC Tube Traps, mfg. by Acoustic Sciences Corp., PO Box 1189, Eugene, OR 97440, Ph.: 503-343-9727. (absorbitive/reflective room treatments)

Echo Busters, 2 Vauxhall Ct., Melville, NY 11747. Ph.: 516-643-6895, FAX.: 516-253-0298. (absorbitive/reflective room treatments)

Kinetic Noise Control, 6300 Irelan Place, Dublin, OH 43017. Ph.: 614-889-0480, FAX.: 614-889-0540. (absorbitive room treatments)

Markertek, 4 High Street, Saugerties, NY 12477, Ph.: 800-522-2025 (absorbitive room treatments)

RoomTunes by Michael Green Designs, Ph.: 888-Room-Tun(e) (absorbitive room treatments)

RPG Diffusor Systems, Inc., 651-C Commerce Drive, Upper Marlboro, MD 20772, Ph.: 301-249-0044, FAX.: 301-249-3912 (absorbitive and reflective room treatments)

Sonex, mfg. by Illbruck, 3800 Washington Ave. North, MN 55412-2197, Ph.: 800-662-0032 (absorbitive room treatments)

Systems Development Group, 5744 Industry Lane, Suite J, Fredrick, MA 21701, Ph.: 800-321-8975, FAX.: 301-698-4683 (absorbitive and reflective room treatments)

* Trademarked by their respective companies