I keep seeing references to setting gains @3/4 volume on the head unit
Some will say to leave head room ect

Are those of you setting your target gain of the amp to 3/4 of max when doing this?
Just curious

 

If you don't know when your HU sends a distorted signal, 3/4 is a safe place to set it at.

 

So do you set the gains at Full volume but dont go over the 3/4 rule

 

You set the HU at 3/4 volume and adjust gains to the point of distortion, then back them down a bit.

 

What happens if the HU goes over 3/4 Volume. setting the system up that way

 

Nothing good. as Sbates said use 3/4 for max head unit then st gains then back gains down this also leaves some room . I cant speak for the rest of the guys but i use 4 bars short on 6.5 maxx volume set gains but with 1000 test -10 and can tell you none of my three amps are running maxx Vac due to sound preference/eq or blending/balancing.

 

Hope I'm not side tracking the OP's original question but this topic brings up a question I've had in my mind since day one that's kind of related... I use the JL Audio Fix86 between my Boom 6.5 HU and my amps (I have 3 on my bike). When you calibrate the fix86 it drops the output of the HU significantly while also flatting the HU's EQ. I usually calibrate the Fix86 four bars short of max volume as instructed then adjust my amps accordingly, however, as an "experiment" I've done the Fix86 calibration process at full volume on the Boom 6.5 HU and I've never heard any distortion. Does having a DSP like the Fix86 change the rules as far as setting 3/4 volume on the head unit. I'm not sure I understand the whole "head room" theory. And why is 3/4 volume a general rule? Aren't all HU's different as far as when they begin to distort?

Maybe I should have started a new thread with this question.

 

Hearing the distortion and having an instrument pick up the distortion are two different things.

I can tell you while i had my full stock Rushmore audio setup i could not hear the distortion at full volume. Now that i have some tuning instruments i have found that my Rushmore stock head unit distorts at 15/17 on the volume. With as much as i have invested into my setup i can tell you that i have setup my amps gains with the head unit volume at 14/17.

I also had the JL FiX86 and i still used 14/17 on the volume for calibration and for setting the gains in my amps.

I also learned the hard way that distortion is harder to hear at higher frequencies and i ended up frying 4 sets of speaker tweeters.

So if you want to heed the advice from the guys that have learned from their mistakes to help us regular guys go ahead and set gains at full volume, see how long your setup lasts.

 

Very well said Matt
I myself went thru the same thing of losing tweeters.If they don't want to listen and learn from the mistakes and misfortunes of others letting the magic smoke out let them learn the hard way
Only thing I can say is either listen to those that have learn the hard way or don't bitch when you let the magic smoke out.

Just a little FYI been there done that blew the **** up because I thought I knew more than I did. We are here to help and learn so take the advice with a grain of salt.

 

it is sooo much cheaper to learn from others mistakes than to make them yourself...hey Rob...im guessin those werent $20 tweeters that fried???