gain controls

JL Man · Post by **JL Man** » Mon Apr 17, 2006 1:13 am

on my amp i have "input sensitivity", thats gain right? so if that is all the way down is the amp still giving rms power? or do you have to turn it up all the way to get rms power?

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 1:36 am

All head units are not created equal, for that, they put a gain control on amplifiers. All the gain is for is to match the input stage of the amp to the output voltage fo the head unit. If your head unit puts out 200 milivolts, you're going to need to crank up your gains. If you have a head unit that puts out 2 volts, you can probably turn your gain all the way down. If you have high output from your head unit and you crank your gain up what you're doing is limiting the headroom of the amplifier.

Look at the voltages marked on the amp or in the owners manual for the gain of the amp and adjust it according to the output voltage of the deck.

JL Man · Post by **JL Man** » Mon Apr 17, 2006 2:03 am

my head unit has 8 volt pre-outs, so i should keep my gain down . . would that also reduce stress on the amp?

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 2:13 am

depending on your amp, too much voltage into your inputs can burn out that stage of your amp. But otherwise, the only real stress on your amp is the load you put on it on the output. And whether or not it's being properly cooled and all that. Assuming you don't have it hanging upside down under your rear deck or something like that, you should be fine.

JL Man · Post by **JL Man** » Mon Apr 17, 2006 2:18 am

lol, nah its not hanging upside down. but it is a jl 300/4 running my comps and my subs, its mounted to the back of my seat, and i keep my seats folded down.

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 2:21 am

You should be good. What are you running again, one pair of components and two subs? Are the subs single or dual voice coils? How do you have them wired? Bridged, the amp can only go from 3 to 8 ohms.

JL Man · Post by **JL Man** » Mon Apr 17, 2006 2:31 am

yeah i'm running boston comps up front and 2 10w3v2s, dual 4 ohm, bridged . . as for how they are wired i don't know because when i got my jl 500 checked out he wired the subs, umm . . positive and negatives are connected on each sub, then the other set of positive and negatives are ran to the terminals, out side of the box both positives and both negatives are twisted together and put in the bridged outputs on the amp.

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 2:38 am

if they're wired how it sounds, you're running 2 ohms to the amp. If you're having overheating problems, that might be it. You have everything paralleled. You need to series either the voice coils of each sub or the subs themselves. Like this ... http://www.usspeaker.com/speaker%20wiring-1.htm

The last one on the page.

JL Man · Post by **JL Man** » Mon Apr 17, 2006 2:42 am

the last one looks just like what im pretty sure is the way they are wired in the box . . i still have the manual for the subs and in there it tells you how to wire them 4 ohm, i should do that huh?

Robert Wollenberg · Post by **Robert Wollenberg** » Mon Apr 17, 2006 2:47 am

when all said and done, if you put a mulimeter to the terminals on the outside of the box, it should read 4 ohms. You have one set of terminals on the outside of the box, right?