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Signal Flow and Isolation of Sound

By November 21, 2013March 20th, 2016Audio

Here comes thanksgiving !!!! I hope your Turkeys are in a row, or at least one is.

This months sound Blog is about Signal Flow and Isolation of sound. This can used for live or the studio.  The reason I am putting Signal flow and Isolation into this one blog, is because they relate to one another very closely.  If you are setting up a sound system, or trouble shooting the system, you need to use both in either case or will at some time.  This will be general and brief in many ways, as in I will not go into how a microphone, nor a speaker, nor other components work inside them selves. That would take chapters of a book.

Here we go;
The sound starts at one end of the sound system, the microphone or D.I. box,  and comes out at another end, into the speaker. There are many components and paths the “Signal ” goes through along the way.  This can be very complicated or some what simple depending on the sound system.  This can be very intimidating as well.  Let’s take a very simple sound system with a few components in the path and put them in order from beginning to end. The following example will be a simple analog sound system.

First, a sound source hits the microphone or Direct Box, it comes down a mic cable, it then goes into a stage snake, then into a mixing board, then into an Equalizer for the main system, then into processors for the main system, then to amplifiers, then to speakers. This is a very basic example of “Signal flow”. You need to know the main components in YOUR sound system and how the signal flows from beginning to end. Far to often I have come across band members in charge of the sound system, or even sound guy’s / gals,  that are not certain of the signal flow in regards to the system they are working with.  Unless there is a system tech for the sound system, this can be dangerous.

Now let’s talk a bit about Isolation.  This is mainly used in trouble shooting, however when setting up a system, this can be very useful as well.  When using isolation techniques, you can make sure the signal path is hooked up and working before going to far with the set up.  Example, looking for signal lights on a mixer before turning on amps.  Once your system is set up all the way, there can be lots cables going to lots of destinations.  At times it is better to check as you go along.  Always keep your cables organized for trouble shooting later if needed.

In trouble shooting, isolation is key in finding where a problem is or where it is not. You must Isolate, Isolate, Isolate in order to find the problem.   Did I say Isolate?   Be it a buzz, a hum, or no audio at all, it will take some form of Isolation to find it.  Perhaps it just does not sound right.  The last one is a tough one and very objectionable in many cases. What helps with that is this, knowing how your sound system normally sounds and one good known working mic, and how that sounds.  Also knowing what does not sound right is great to know as well.  Make “Brain files” of these sounds.  I wrote about “Brain Files” in Blog #4.

You must become very factual, like a forensic investigator.  You would say to your self “I have it here, but not there.”  Use your “Signal” indicators on the equipment looking for “input” and “output” signal.  That is part of there job and what they are designed to do. This will  help you to see where signal is present, not just hear were signal is present and where it is not.  Visual as well hearing will find your problem.

Remember to protect your hearing during trouble shooting !!!! NEVER EVER put your ear close to a speaker. Watch out for others being close to the speakers as well or even in the field they can impact.

Have a great Thanksgiving…. gobble….gobble…


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