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Author Topic: Gain Structure  (Read 5593 times)

Johnny Diaz

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Gain Structure
« 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?
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Johnny Diaz

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Re: Gain Structure
« Reply #1 on: April 10, 2011, 07:00:39 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?

Any help will be greatly appreciated.
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Ian Stuart

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Re: Gain Structure
« Reply #2 on: April 10, 2011, 08:00:16 pm »

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.
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Brad Weber

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Re: Gain Structure
« Reply #3 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.
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Ian Stuart

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Re: Gain Structure
« Reply #4 on: April 11, 2011, 08:05:24 pm »

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.

What was wrong?
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John Roberts {JR}

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Re: Gain Structure
« Reply #5 on: April 11, 2011, 08:17:24 pm »

For one, the under powering myth has been debunked here many times.

Speakers can not be damaged by too little power, they are damaged by too much power either short term peak power causing over excursion, or longer term average power causing voice coil overheating.

When an amplifier is driven past clipping there is nothing mysterious that happens to the waveform other than the average power, and ability to overheat the voice simply continues to increase as you keep turning it up, even past clipping.

Several things you said were accurate or adequately so.

JR
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Brad Weber

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Re: Gain Structure
« Reply #6 on: April 11, 2011, 10:31:44 pm »

What was wrong?
JR already touched on a couple of points, I would add that while unity gain is an option for system gain structure, I am fairly sure that setting gain structure based on maximum or clipping levels is probably much more common.
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Bennett Prescott

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Re: Gain Structure
« Reply #7 on: April 12, 2011, 01:40:28 am »

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? Oh God, dude. Why are you giving advice?
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luis Markson

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Re: Gain Structure
« Reply #8 on: April 14, 2011, 08:43:54 am »

For one, the under powering myth has been debunked here many times.

Speakers can not be damaged by too little power, they are damaged by too much power either short term peak power causing over excursion, or longer term average power causing voice coil overheating.

When an amplifier is driven past clipping there is nothing mysterious that happens to the waveform other than the average power, and ability to overheat the voice simply continues to increase as you keep turning it up, even past clipping.

Several things you said were accurate or adequately so.

JR

Is there anything at all about a clipped signal that can contribute to driver failure?
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Charlie Zureki

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Re: Gain Structure
« Reply #9 on: April 14, 2011, 10:25:37 am »

What was wrong?
JR already touched on a couple of points, I would add that while unity gain is an option for system gain structure, I am fairly sure that setting gain structure based on maximum or clipping levels is probably much more common.

  Hello,

   And.....Speakers do not "blow up".   ;D

  Hammer
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Re: Gain Structure
« Reply #9 on: April 14, 2011, 10:25:37 am »


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