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Gain Structure

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Johnny Diaz:
How do you guys set gain structure?  How do you prevent your speakers from blowing up?  How do you know how much power to feed the speaker safely but get the most performance safely?

Johnny Diaz:

--- Quote from: Johnny Diaz on April 10, 2011, 01:21:34 pm ---How do you guys set gain structure?  How do you prevent your speakers from blowing up?  How do you know how much power to feed the speaker safely but get the most performance safely?

--- End quote ---

Any help will be greatly appreciated.

Ian Stuart:
Generally speaking, speakers "Blowing up" is usually due to under-powering them. It might seem surprising but this is due to the operator driving the amps too hard to supply the correct voltage to the loudspeakers.

What sometimes happens is the amp gives up on it's task and starts to send a voltage similar to your wall power right to the terminal of the loudspeaker. Back in the old days, the driver could catch on fire and could subsequently burn the entire cabinet and possibly the stage too.
This doesn't happen a whole lot with modern drivers though, they are a lot better designed.

To keep your loudspeakers healthy, choose an amp rated higher than your speaker. 100% - 200% range is fairly common (that is 100-200% amp RMS rating to speaker RMS rating). Ensure limiters are put in place and, most importantly, engage hi/lo pass filters throughout the systems crossover. This is the most important step to ensuring that your loudspeakers have a healthy life. Failure from pushing incorrect frequencies into the drivers is the most common symptom for failed loudspeakers. As a general rule of thumb, it's acceptable to roll-off your hi/lo pass filters at higher frequencies than specified by manufacturer, but NEVER lower than specified. for example, if I'm setting a hi-pass on my tweeters, I can start at the specified 3k, but nothing should break by placing my crossover point at 3.5-4k.

There are many ways to set limiters, some people like to use a voltmeter across the terminals and set the threshold that way, others call the manufacturer and talk to their engineers, others just use an ongoing process of trial and error. this depends on the style of the systems guy.

Everything else in your gain structure should be unity. unity in, unity out. You can't go wrong if you keep your gain structure uniform.

Good Luck! Let me know if you have any other questions.

Brad Weber:
I suggest starting here, http://www.prosoundweb.com/studyhall/tag/audio+basics, and also searching in these forums and in the old forums (http://srforums.prosoundweb.com/) for topics such as setting limiters, gain structure, selecting amplifiers and so on as these topics have all been discussed many times before.  And Ian may actually want to do the same.

Ian Stuart:

--- Quote from: Brad Weber on April 11, 2011, 08:30:39 am ---I suggest starting here, http://www.prosoundweb.com/studyhall/tag/audio+basics, and also searching in these forums and in the old forums (http://srforums.prosoundweb.com/) for topics such as setting limiters, gain structure, selecting amplifiers and so on as these topics have all been discussed many times before.  And Ian may actually want to do the same.

--- End quote ---

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