The Ultimate Church Sound Operator’s Handbook
By Bill Gibson


Comments by Ray A. Rayburn

Updated 9 October 2012

I have been told that many of the issues I raise below have been corrected in a new edition, but that other issues in other parts of the book have not. I have not seen the new edition. The comments below are from 2007.

I sent these comments to Amazon.com, but they never posted them. Amazon has repeatedly deleted comments critical of this book, while keeping comments that were positive.

The comments below are not in any particular order, and which portions of this book I have chosen to comment on should not be taken as being of particular significance. They are merely the points I have read that seemed to indicate significant misunderstandings by the author of the issues discussed, and were issues I felt like addressing. I will probably add more comments in the future.

Chapter 9 covers Interconnect Basics.

I reviewed this chapter because when scanning the book this was the first chapter I came to where there were both significant misunderstandings by the author of the issues discussed, and were issues I felt like addressing. I will probably have comments on other portions of this book in the future.

My qualifications to comment on the topics in this chapter include 37 years of full time experience as an audio system designer, engineer, and consultant, and the fact that I am the Chair of the Audio Engineering Society’s Standards Subcommittee on Interconnections.

Under the Speaker Cables section it says “Ask a salesperson which wire gauge and type is best for your situation.” Unfortunately it is the rare salesperson who is better informed than someone reading this chapter will be.

It continues “Let him or her know how long a run it is from your power amp to your speakers, what kind of connectors your amp and speakers have, and the brand of your amp and its power rating. If the salesperson gives you a glazed look when you recite all of these specifications, this indicates that he or she doesn’t understand your situation. I suggest you get a second opinion.” I completely agree with the comment on salespersons and the possible need for second opinions. However I am more concerned about the factors the reader is told are important in selecting a speaker cable.

Wire length is a very important factor in determining the needed wire gauge, or thickness of the copper in the cable.

The types of connectors needed at each end are important to enable the reader to buy a cable that will connect correctly, but are unimportant in determining the needed wire gauge.

The brand of amplifier has no relevance to selecting the correct wire gauge.

The power rating of the amplifier likewise is unimportant when determining the correct wire gauge.

What is important but is not mentioned is the nominal impedance of the speaker or speakers at the end of the cable, the number of speakers if more than one, and the type of application the speakers will be used for. By application I mean are you connecting speakers used for sound reinforcement, or speakers in a recording studio or other critical listening environment. You will in general wish to use heavier gauge wire in a recording studio, than it makes sense to use in general sound reinforcement.

I have a spreadsheet that takes all the factors into consideration and allows selection of the proper wire gauge. It can be downloaded from here:

http://www.soundfirst.com/LZ_DF_calculator.zip

The book says “As a rule of thumb, a good quality 18-gauge speaker wire works well in most cases.” If by “works well” it is meant that you will get sound out the other end, this is certainly correct. If, however, “works well” is taken to mean the performance is a good compromise with cost for the application in question, then this rule of thumb will often be in error.

In the section titled “Some Cable Theory” it is implied that electrical voltage is the same as electrical current. This is a gross confusion. Voltage is electrical pressure, while current is the flow of electricity. Just as with a garden hose you can have water pressure with no flow of water if the nozzle at the end of the hose is closed, but can also have water flow through the hose, which is driven by the water pressure when the nozzle is open. The same is true of electrical pressure (voltage) and flow (current).

The rest of this section veers even further from reality and gets downright mystical. It ends with the statement “Two main considerations must be addressed in cable design: balance of amplitude across the full audio bandwidth and the time delays as different frequencies transmit throughout the cable length.” This is as fine an example of audio bovine fertilizer as I have read in a long time. It is expanded on in the following two sections “Balance of Amplitude” and “Timing Considerations”. It would appear that the author has been taken in by the marketing serpent lubrication of a certain cable manufacturer, and has based this part of the book on the false claims of that manufacturer.

Just for the record, when talking about audio cable, there is no need or advantage to make a cable out of “multiple types and sizes of wire” and that doing so will not ensure “each frequency is carried in an optimized way.” It is further false to claim “High frequencies travel at a higher rate than low frequencies throughout the length of a conductor (wire).”

There is a highlighted section on “Speaker Wire Gauges” that relates speaker cable length to required size, and ignores the other important factors in determining speaker wire gauge. This section is also notable for confusing “phase” for polarity. It shows a picture of lamp cord, but never discusses the disadvantages of the use of this sort of wire construction as speaker cable.

The next section is titled “Do Cables Really Sound Different?” The answer is yes, in at least some cases there are audible differences between cables. To claim “The difference between the sound of a poorly designed and a brilliantly designed cable is extreme in many cases.” is hyperbole. While there are important factors that will determine how well a given cable will work in an application, they are not mentioned or discussed in this section. Instead this section and the following are devoted to touting one particular manufacturer of expensive audio cable’s products.

The next section is about “Digital-Interconnect Cables”. It starts out with the claim “Digital-interconnect cables also have an effect on sound quality.” This is hokum. The only time properly made digital interconnect cables will have an effect on sound quality is if the equipment on at least one end of the cable is defective.

The section on “Impedance” seems confused and confusing. It is not even particularly self consistent. The attempt to illustrate impedance with pipe sizes is inaccurate and confusing. However, the summary paragraph at the end of page 101 is correct. If the reader ignores the rest of this 2 ˝ page section and just reads that paragraph they will have a better understanding of this subject than if they tried to understand the whole section.

The section on “Balanced versus Unbalanced” gets across in very basic terms some of the practical differences, but completely confuses the reason balanced interconnects have an advantage. This section also repeats the error of confusing phase for polarity.

The section on “Connectors” is mostly right, and in the part about Dual Banana Connectors even uses polarity correctly. The major error I spotted in this section is the claim “The Speakon connectors can also be plugged in upside down for occasions in which reversed polarity is desired or necessary.” Speakon connectors can’t be “plugged in upside down”.

The section on “Plugging In” talks about Electrical Power and encourages the use of power strips containing surge protection. It does not mention the differences between these inexpensive surge protectors and better products, nor does it explain why in some cases the use of inexpensive surge protectors can cause more harm than good for the equipment you are trying to protect.

This section has excellent advice on the proper way to power up and power down a system.

In the section on “Ground Hum” it is stated that “Sixty-cycle hum is the result of a grounding problem …” which implies that hum is always due to some sort of grounding issue. This is untrue. Hum _may_ be caused by grounding issues, but they are far from the only cause.

The section on “Grounding” correctly states “The purpose of grounding is safety.” Or to be more precise, the purpose for the third prong or safety ground conductor in an electrical outlet is safety. This section however incorrectly claims that the critical thing about the safety ground conductor is that it provides a path to earth. The important thing is that the safety ground conductor provides a path to the Neutral bond point at the electrical service entrance to the building. That bond point is also connected to earth, but the earth connection plays no part in safety inside the building. The earth connection is there to protect from faults and lightning external to the building.

Under “Ground Loops” the discussion confuses ground potential differences with ground loops, and indicates loops are the result of power safety ground connections. There can be loops even without any connection to power mains. For example you can have ground loops in the audio wiring of battery powered equipment. Mention is not made that ground loops do not have to cause problems in a properly designed system.

The section called “Connect All Equipment to the Same Outlet” it is correctly pointed out this can be of benefit when the power draw of the system is low enough to allow this approach.

Under “Hire a Pro” it is suggested to have a “qualified electrician” rewire the power at your church. While a licensed electrician should be able to wire the church in a safe way, few electricians have the specialized knowledge to properly design a technical power system for audio / video / computer equipment. It is suggested the electrical outlets should be connected “to the exact same perfect ground.” Aside from the fact that there is no such thing as a “perfect ground”, attempting to get such a thing often leads to not properly connecting all the safety ground conductors to the neutral ground bond point at the electrical service entrance. Failure to provide such a connection is a serious safety hazard.

The section titled “Lifting the Ground” suggests a very dangerous practice that can result in someone getting killed. IT IS NEVER SAFE OR REQUIRED TO DISCONNECT THE ELECTRICAL SAFETY GROUND CONDUCTOR!!! (Yes I am shouting.) Putting such a suggestion in print is the height of irresponsibility.

This section also contains the myth of a “true ground”, and implies it is superior to the electrical system safety ground conductor. This is false.

The next page has a box on “AC Plug into Ground Lifter”. The devices pictured are _not_ intended to ever be used as “ground lifters”. Just read the warnings printed on every such device or on a tag attached to every such device. The claim is made “This tab can be attached to the center screw of a wall plate to re-complete the ground, or it can be bent back to lift the ground.” I hope no one follows the advice of this book and is killed.

The chapter concludes with a section titled “Danger, Danger” which cautions about the potential dangers of electricity. It does not mention, however that the highlighted advice on that same page is the sort of danger you should be aware of.

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Last Edited 10/9/2012

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