Explain to me how a gain works?
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Bronze Member Username: Ishkabobble55Post Number: 70 Registered: Jul-05 | what does it do? why did it make my sub so much quiter when i turned it to 5v? whats the difference from 5v to the lower settings? thanks alot |
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Gold Member Username: Basshead86Ocala, FL USA Post Number: 1071 Registered: Aug-05 | it matches the input sensitivity from your HU. ir your HU has 4 volt preouts, then your gain should be set to 4volts input sensitivity. the higher the gain(the more sensitive the input signal is and will drive the amp into clipping if oyour not careful. whe you turn it down. aahhhhh i'm tired of typing. here read this page: http://www.bcae1.com/gaincon2.htm |
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Gold Member Username: Basshead86Ocala, FL USA Post Number: 1073 Registered: Aug-05 | to answer your question a little quicker, your sub got quieter b/c your HU probably has 2v preouts, and when you turned the gain down to 5v(which is down, b/c it is making the gain less sensitive) it weakened the signal input causing your amp not to put as much power to the sub at the same volume level on your HU, i think that's how you say it. |
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Bronze Member Username: Ishkabobble55Post Number: 72 Registered: Jul-05 | no my hu has 5v preouts |
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Gold Member Username: Basshead86Ocala, FL USA Post Number: 1074 Registered: Aug-05 | then, your gain might have been too high in the first place |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 10126 Registered: Dec-03 | ok "gain" is really a misnomer. it's an input sensitivity adjustment, to be accurate. what it does is add impedance to the input signal to attenuate it so the input voltage matches what the input stage of the amplifier requires for an ideal line signal voltage. say your amp has a range of 2V to 5V on the "gain." when set to 5V, it is "least sensitive" meaning the input voltage is the strongest, so the input signal has to be attenuated to match the input stage. (may appear that the music gets quieter as you go toward the 5V setting) If you set the gain to 2V, this tells the amplifier that the input voltage from your head unit is weak, so little or no voltage attenuation is required to get a matched signal. music may seem to get louder as you go toward the 2V position on the amp, due to the decrease in attenuation. if you set the gain improperly, and have it set too "low" (toward the 5V position) in regards to the head unit's voltage you'll be trying to amplify an inherantly weak line signal, so your amp will be amplifying more noise in comparison to the actual signal, and the output will be decreased. If you set the gain too high (toward 2V) you'll overdrive the input stage of the amplifier, and cause the amp to clip, since the power supply can't produce enough power to keep a clean AC output waveform at that input signal level.. so you get distortion, and worse yet, clipping which sends DC voltage to the speakers, in turn frying the speaker coils. www.bcae1.com and www.jlaudio.com both have good tutorials on proper gain setting (although you already know you have a 5V setting on the amp and 5V preouts so just set at 5V) and bcae1.com explains clipping etc if you want to learn more. often, people buy an amplifier that's too weak for what they want, and try to compensate for the lack of power/volume by turning the gain up too high. while they get a little more volume, they also cause the amp to clip and end up cooking their speakers in the process. never use gain settings to compensate for a lack of power.. just get a bigger amp. |
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Bronze Member Username: Ishkabobble55Post Number: 73 Registered: Jul-05 | hey thanks alot you guys!! |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 10135 Registered: Dec-03 | you bet |
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Silver Member Username: JbaileyIndianapolis, Indiana Post Number: 164 Registered: Mar-05 | Hey Glass, isn't it true that many HUs don't actually put out the preamp voltage they claim during music playback? I think I remember reading a couple articles that stated many HUs that claim up to 4 or 5 volts for the preamp outputs actually only send a 2-3 volt signal during usage. This kind of makes sense considering some currently produced amps still only have a 2.5 to 4 volt input rating. If you tried using these amps with the 4-5 volt HUs or a higher quality HU like an Eclipse (8v preouts), wouldn't you be more likely to overdrive the signal to those amps and inevitably have issues with clipping? Basically, what I'm trying to ask is whether you should just match up your amp gain setting to your HU signal output level (number to number), or should you take a little time to actually "adjust" the gain settings until just before clipping and not worry about whether the gain level on the amp is set to say 2.5 volts when connected to a 5 volt preout HU (since actual HU voltage may not be as high as what the specs indicate)? Thanks. |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 10141 Registered: Dec-03 | a 4 volt head unit puts out 4 volts at full volume with a -0dBA reference tone. as you decrease volume and reference point (since music is dynamic) the voltage will decrease. yes. at normal volumes, the voltage is below 4 volts, but that doesn't mean the head unit can't put out a 4 volt signal. It's a lot like a speaker saying it's 4 ohms. that's a nominal impedance, and that impedance varies with the frequency being produced.. that's why the nominal impedance is never the same as the DCR of the speaker. |
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Silver Member Username: JbaileyIndianapolis, Indiana Post Number: 167 Registered: Mar-05 | Okay, so do you think it is uncommon/unnecessary to have a gain setting on an amp that is set higher (more sensitive) than the rated preout strength of the HU? Is that why setting the gain level properly entails setting HU volume to 3/4 and then adjusting the gain on the amp, since the HU voltage probably won't be at its max rated strength at the 3/4 volume level (meaning amp gain will be set a bit higher)? Thanks again. |
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Platinum Member Username: GlasswolfWisteria, Lane USA Post Number: 10168 Registered: Dec-03 | setting the gain higher than optimal just opens you up to clipping the amp which damages speakers. you use 3/4 volume because above that most head units (except some high end models) start to produce measureable distortion. below that point, it's a clean signal. |
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Silver Member Username: JbaileyIndianapolis, Indiana Post Number: 168 Registered: Mar-05 | Okay, thanks buddy. |
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