Setting gains
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=79611
Printed Date: April 29, 2024 at 11:13 AM
Topic: Setting gains
Posted By: punkbastard
Subject: Setting gains
Date Posted: June 25, 2006 at 3:40 PM
I am sorry to post a new topic that has already been exhausted. But I figured maybe somebody could answer this and then we could sticky it. I have been installing for about a decade and I would say that I have accumulated my fair share of knowledge in that time. However, I have this sneaking suspicion that I dont know how to set amplifier gains properly (ie. why does min gain on the amp produce max output?) My thought is that it is because the gain setting is more of a sensitivity thing. Like if your HU puts out 2 volts then you want the gain of the amp to be at 2 volts or lower right? Or if your HU puts out 4 volts than the 2 volt gain setting would not be high ( or low as it appears) enough. As you can see I have all kinds of mixed up info in my head about this. Can somebody who really knows their stuff please just lay it all out for me? I think I will be a much better installer once I am rock solid about this. Thanks.
Replies:
Posted By: DYohn
Date Posted: June 25, 2006 at 3:44 PM
You are correct. "Amplifier gain" is the same thing as its "input sensitivity." The idea is that the sensitivity of the amplifier can be matched to the output voltage level of the head unit. The only reason car audio amplifiers have this control is because there is no set standard for pre-amp (head unit) voltage levels. ------------- Support the12volt.com
Posted By: punkbastard
Date Posted: June 26, 2006 at 12:06 AM
So if a HU has an output of 2 volts then the gain needs to be set at 2 volts exactly or just somewhere around there? I figured if I need to know the exact output voltage of say a Factory HU than I can just meter the speaker lead in ac volts and get a reading, but on an aftermarket with rca's is the middle pin positive and the outside negative? Would it still be ac? I would assume so because its audio signal. Finally, when you are hooking up an amp to a factory deck and you use an LOC, and say the output voltage of the deck is 2 volts then would you set the gain on the LOC to 2 volts as well (not that you can tell), or would you just turn it up until clipping and then back off a bit?
Posted By: zhalverson
Date Posted: June 26, 2006 at 12:06 AM
DYohn] wrote:
he only reason car audio amplifiers have this control is because there is no set standard for pre-amp (head unit) voltage levels.
Oh, if there was just a standard... How many headaches, blown speakers, fried amps etc. would have been saved? Anyways, there are all those great stickies up there and one of the biggest issues of setting your gains has not been addressed. So get with it guys!! Just kidding. But seriously I think if someone went through the correct way(s) of doing it and left it up there for good it might be the most useful topic yet.
Posted By: punkbastard
Date Posted: June 26, 2006 at 1:10 AM
Thats why I started this topic, not only to help me but to help others as well. So, the gain setting basicly tells the amp what kind of input voltage it is gonna get right? I assume if it actually gets the voltage it is expecting, determined by the setting, then it puts out the rated amount of power right? But what if you tell it that it is going to get more than it actually gets? It will work harder to try to compensate for what its not getting? Resulting, I assume, in more power but at a higher cost of heat and inneficiency? So what if you tell it that it is going to get less than it actually gets? It really seems as though gain setting is some kind of ancient secret or something. Some people think its a volume knob, some swear to their death its not. Some people "pre-tune" every amp they install to a certain setting, some bust out o-scopes and measure voltage. C'mon, all you guys out there with the little icons under your names that mean you are all that is man, step up and set it straight for us.
Posted By: stevdart
Date Posted: June 26, 2006 at 5:36 AM
.come on now, I know your just kidding but....addressing a topic like this can be done by someone wanting to earn some extra recognition, and there are plenty of experienced members like you who could do it. Setting gain shouldn't need to seem so complicated as you have it presented here. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: DYohn
Date Posted: June 26, 2006 at 8:10 AM
It is an ancient secret that only a select few installers learn at the feet of the Master, high in the mountains near Kathmandu (or is it Denver?) You MUST take your system to one of the shops listed on our installers network and pay them at least 10 hours labor to get it done properly. If you are nice (and slip the installer and extra $20) we'll even teach you the secret handshake. 
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Posted By: punkbastard
Date Posted: June 26, 2006 at 12:58 PM
Okay, lesson learned, sarcasm is not welcome here. I know its not an ancient secret, duh. There are just a lot of different ideas and opinions floating around about it and I just wanted to make sure I'm doing it right. Nobody wants to help? That's fine. Or maybe its just that you guys aren't so sure you're doing it right either.
Posted By: quiksilver
Date Posted: June 26, 2006 at 1:30 PM
ahah. personally i think this topic can be extremely useful. so if anyone really knows what their talking about, a few simple explanations would be key.
Posted By: DYohn
Date Posted: June 26, 2006 at 2:05 PM
People, there have been hundreds of threads on "how to" set your gains on this forum. A little use of the SEARCH function at the top of each page will get your answer quickly without having to rehash it again. If someone wants to write a tutorial on this topic, I will be happy to review it. ------------- Support the12volt.com
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