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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Installed Sound/Contracting => Topic started by: Tony Smith on March 18, 2011, 05:52:02 PM
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Scenario and Question - If you have Subs rated at 900 watts@4 and an amp rated 500@4 - amp gain set below half and you are achieving the level and sound desired, you should be good right? As long as you remain within those parameters you should be safe? Yes or NO.
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Scenario and Question - If you have Subs rated at 900 watts@4 and an amp rated 500@4 - amp gain set below half and you are achieving the level and sound desired, you should be good right?
By "amp gain" do you mean the level controls? They are really two different things.
As long as you remain within those parameters you should be safe? Yes or NO.
There is no guarantee but with the caveats that the overall system gain structure is good, that there is no clipping earlier in the signal chain and that no one tries to run the system louder such that it causes clipping, you should be fine.
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Scenario and Question - If you have Subs rated at 900 watts@4 and an amp rated 500@4 - amp gain set below half and you are achieving the level and sound desired, you should be good right? As long as you remain within those parameters you should be safe? Yes or NO.
As Brad was hinting at-the level controls are just that-NOT power controls as many people "think" they are. Even with the controls turned down the amp can still put out full power-if you hit the input with enough signal.
And you are correct, if you are getting the levels you need-without anything clipping-then you are fine and nothing to worry about. The loudspeakers should live a long healthy life.
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As Brad was hinting at-the level controls are just that-NOT power controls as many people "think" they are. Even with the controls turned down the amp can still put out full power-if you hit the input with enough signal.
Would it be correct, that turning down the input gain on an Amp will cause a "Lower" input signal to produce Maximum output?
Regards, John
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Would it be correct, that turning down the input gain on an Amp will cause a "Lower" input signal to produce Maximum output?
Regards, John
Other way around.
Lower the gain knob, and more input level is needed to reach full power output.
In most cases, it is called a "Gain Attenuator", as in Turn it up, and there is less attenuation to the input signal.
Chris.
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Other way around.
Lower the gain knob, and more input level is needed to reach full power output.
In most cases, it is called a "Gain Attenuator", as in Turn it up, and there is less attenuation to the input signal.
Chris.
Thanks Chris,
It sounded counter intuitive when someone who should know informed me (During Sound Check) to try it this way.
His "advice" (unsolicited) was to "Lower the setting of the Amp Input to compensate for the board gain settings.
I thanked him and said when we have time we will try that. (We never have more then 10 minutes, Usually we set things
up during the first act, on the fly for sound levels.
Regards, John
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His "advice" (unsolicited) was to "Lower the setting of the Amp Input to compensate for the board gain settings.
And he could have been correct. A typical mixer may have a +24dBu or so maximum output level with 0 on the master output meters representing a +4dBu signal level. The input sensitivity of an amplifier, which is the input signal level that creates the full rated output, is often around that same +4dBu level, maybe 20dB below the maximum output of the mixer. So if the board outputs directly feed the amplifier then to allow good gain structure in the mixer it would not be uncommon to want a minimum of somewhere around 20dB or so of attenuation at the amplifier input. If you were running the mixer at lower than optimal levels for it then what he may have been suggesting was that it would be better to run the board at more optimal levels and turn down (attenuate) the amplifier inputs.
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It sounded counter intuitive when someone who should know informed me (During Sound Check) to try it this way.
His "advice" (unsolicited) was to "Lower the setting of the Amp Input to compensate for the board gain settings.
It depends on how you look at what "lower" means. Does it mean to turn something down? or to turn something up?
If you lower the input requirements (for full power) on the amplifier-you are actually INCREASING the gain. ie going from 1V to .5V for full power.
If you are lowering the level control, then you are DECREASING the gain.
Yes it can get confusing-depending on how you look at it.
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It depends on how you look at what "lower" means. Does it mean to turn something down? or to turn something up?
If you lower the input requirements (for full power) on the amplifier-you are actually INCREASING the gain. ie going from 1V to .5V for full power.
If you are lowering the level control, then you are DECREASING the gain.
Yes it can get confusing-depending on how you look at it.
Hi All,
Thanks for the input.
I will try to be more clear.
I believe What he was suggesting to me was that, If I were to turn the Gain Input Knob on the front of the Amp Counter Clockwise, That would cause a Lower (Weaker) signal from the Mixer to be able to cause the Amp to reach Maximum Output sooner.
In other words, Turning the input gain down (Counter Clockwise) would allow a weaker signal to produce more Amp output.
The main issue I deal with is Weak Vocals, The person using the Mic is not loud enough (we have no control over that).
So we are already having issues prior to the signal reaching the Mic Pre Amp Gain.
I think he was suggesting this to try to raise some of the Vocals.
Regards, John
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I believe What he was suggesting to me was that, If I were to turn the Gain Input Knob on the front of the Amp Counter Clockwise, That would cause a Lower (Weaker) signal from the Mixer to be able to cause the Amp to reach Maximum Output sooner.
In other words, Turning the input gain down (Counter Clockwise) would allow a weaker signal to produce more Amp output.
If that is what he was suggesting, he is just plain wrong.
Mac
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i'll try to explain it , remember i'm from south missippi ! if the mixer has a tone generator connected to input 1 and the mixer is putting .5 volt signal to the amp and the gain on the amp is at max then the amp will be sending that .5 volts through the input stage. if you turn the gain on the amp to the "half gain" mark then the sound level at the speakers will be reduced. if you increase the output voltage at the mixer to 1 volt and leave the amp at half gain the sound level at the speaker will increse. if you also turn the gain on tha amp back to max the sound level at the speaker will increase even more. i hope ya'll understand watt i just posted.