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Sometimes after reading so many threads I get a hair and post a few humble opinions based upon decades of experience. Here I will give a few basic facts and describe my overall gain structure. It is what works with my system and is presented to give a little knowledge for inexperienced and those learning. BTW I am still learning.

Basics:

A typical amp whether RF or audio has a linear range from either side of mid gain. I have swept many amps and the standard was -3 DB on the low side to -3 DB on the high side. Before spectrum analyzers one had to inject freqs at intervals, record and graph. Another parameter is the signal should not vary over a certain amplitude  over the entire range. In the old tube amps this was critical to check.. With op amps and solid state amps now it is hardly considered.  A spectrum analyisis shows an immediate anayisis of an amp.

Each freq has harmonics For example if you feed a 1 K Hz into an amp and look at the spectrum the most apparent is a smaller node at half or 500 Hz. The other is double or 2 K Hz. Each sub harmonic puts out multiples which may or may not be visible depending on the gains  used and sensitivity of the equiptment. However in any typical natural sound they all add together and give the full rich natural sound. To reproduce or amplify all these harmonics the overall gain should be close to mid gain for all components. For those young ones still fortunate to be able to hear above 3 K Hz this makes a big difference on the high end.

This is my overall gain structure and while it is not to be taken as a standard it handles most situations. The mixer used is a Dfx-12 It has a clear led on the pre which can be used to indicate a proper input but sometimes with a 58 doesnt reach that level. Insering into a DBX 266 Xl I do try to get at least 1 red light blinking. The output gain on the 266 XL typically is at about +3 DB From there it is routed through a Lexicon 550 and reurned. Gains set so far results with the fader at about -3 DB . It is far from feedback unless under difficult circumstances. The faders on the music are typically about -6 to -8 DB The reason is I come out of the mixer and route through a Bbe #62 and an Aphex 104. I dont like to input procs with full unity just tickle them. It is then returned before the main isolation amp and faders which are used to set the overall voulume The eons depending upon the venue are usually at about 20 oclock or mid gain. Outdoors or in large venues they are opened almost to max. What works for me might not work for others.

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Amplfiers or powered speakers should always be run wide open.

The level that is heard can be adjusted by the main output of your mixer.

I disagree. If your speakers handle 500W program, and your amp puts out 700, I recommend backing off a few dB.


This I agree with.

You are operating near or in the non linear region of the amp plus you dont have any overhead. The finals on any amp has idle current and full current when run full blown  current is at the upper limit, generates heat and is taxing the power supply to the max. Any signal above unity will clip because the amp  is already drawing all the current it can from the power supply. If you need to run everything wide open then you need more power.

The keeping vocal above thread prompted this When you are running wide open your control of levels is limited and you run into level and feedback problems.

Outside I will run wide open but I keep a close watch on the system and feel the heatsinks every now and then.

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Really Not tryin to be a smart (@$%&#!)....But

are you really trying to teach....
or just impress everyone with your electrical vocab?

You totally lost me here.  Don't know much about this subject, and I still can't make heads or tails of it.

It is not ego related or trying to prove anything. It is a response to blanket statements made about gain structure. I thought I explained it in common sense terms but in a short post a lot of details are left out of the equation.  When an amp is operating in the upper or lower extremities or non linear range the result is distortion.

There was a recent thread about keeping the vocals on top of the mix. With the gain structure described above there is a 3 DB mic gain on the fader to start with if the vocal is buried. The music is not even at unity. It is better to decrease the mic level to balance rather than run it hot risking feedback trying to get it above the music. Make sense?  With all channels running hot or at unity your delicate control or setting levels is comprimised at best.

I dont know how many times I have read a post where somebody was saying a Bbe362 or other proc just screws up the audio. put a 0 DB or unity signal into it and you are over driving the $%% out of it. Nominal input is about -6 DB. Tickle it.. Good clean audio at any level can be amplified for the spl needed for that venue.

That's my story and I'm stickin' to it. This  is a few thoughts about gain structure. It is not meant to insult, create arguments or provoke anybody. You are welcome to disagree but at least give me some reasons why I am wrong.

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WOW! ... And that MACKIE-DFX doesn't even have Mid-Range adjustments on the Microphone Channels

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Edit

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More info and simple explanation on gain structure:

http://www.prosoundweb.com/studyhall/la ... _gain.html

I think karyoker is honestly trying to help but like most profesionals in a specific field he has gotten used to using jargon.  To most people on this board the amp is a box and the mixer is that thingy with all the knobs, the power supply is the wall socket etc.  Perhaps he could try it again but this time with subtitles?

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Okay, who took my pants?

I have to disagree with running amps full out.  We've had amps go down from thermal breakdown and I'm convinced they run hotter with levels set full out.  I now run everything 3/4 out and the amps run much cooler.  Carvin amps, although I've seen it happen with others.  If heat is not a concern then running full out is okay in my opinion.

As far as the post is concerned I found it good reading, but what is 20 oclock?

For us Navy guys, it's 8pm.

I refer to the thread on vocal over mix.... Gain structure is more than just pushing faders. It involves a complete processing of the audio.

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Ok, when running high end pro audio amplifers. In a Passive Sound system, that the speakers are properly matched to the amplifer one should run them wide open.

Due to the gain structure there is less chance of clipping the amplifer with it set wide open. Clipping will send DC voltage to you speaker causing the voicecoil to fry.