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This upcoming week, with some holiday time off, I'll be installing some goodies in my car. Started this thread, which ended up pointing out that I need more education with this subject. So after a couple of weeks of using up a whack of free time, I have more questions that I can't find answers too or don't know how to search for. The whole idea of 6db of headroom didn't make any sense to me. Reading through countless threads here, as well as some articles like Why Do Tweeters Blow When Amplifiers Distort? and Smart Q I'm left wondering what the best settings for my drivers with the amps I have are. For now, I'm going to use my old TMA T10S4P (specs here)in the .65 cf enclosure that I've got with my Alpine MRP-M500. With the nonadjustable high pass at 15hz, and nondefeatable lowpass about 80hz at 24db/octave this sub hits it's excursion limit with about 125 watts of power. So using a 50hz 0db test tone, If I set my gain with my dmm using V=sqrt(P*R), at 22.36 VAC I have no excursion headroom. Since music seems to be put out on CDs or in digital form with varying levels, some of it will be clipped, and some of it will be sending my sub past it's excursion limit. Is there a reasonable point below this excursion limit for all of my drivers to set my gains at? What kind of excursion headroom is reasonable, not too much under powering a driver, not too little leading to clipping and distortion? And how about these damn JL C2s that I have, with MSmith not being able to, or not willing to provide TS parameters for them how do I find this point? I'm starting school in a week, and I'm not going to be in a position to replace them for a couple of months. So I'm going to be pigheaded and use them with my ONX4.80 bridged. Leaving me with plenty of headroom there as well. JL advertises 60 watts RMS max constant, and as I've come to understand, that's in a specific environment. I want what I have to sound as good as is possible. No clipping, no distortion from over excursion. And being me I've over analyzed this. I understand that small amounts of this will be inaudible to me, but with an hour a day in my car - I intend to make the most of it.

Long winded, sorry. Any help with this would be appreciated. And happy holidays for those that partake!
 

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when initially setting your I like to use the highest bit rate and loudest song that I have so that I don't have to worry about excursion after the amp is set. if you are really trying to accurately set your amps gain you need an oscilloscope; its the only instrument that can actually tell you when your amp/head unit is clipping. What does your modeling say about excursion and power handling as a function of frequency?
 

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How's this!

I understand that an oscilloscope can be an accurate way of setting gains, and I understand the different reasoning behind the different methods and arguments as to how to set gains. Read that one to death, understand it. Not interested in anyone arguing one way or another. What I want to know is what kind of excursion headroom is appropriate.
 
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