Help! I'm overwhelmed! (And I'm a newb!)

[audioholic 5,000+ posts]

Follow those JL guidelines and set the gains. Now, hook up your o-scope and look at the graph...see any clipping? You will...lots of it. JL's regulated amps can "hide" clipping very well as that's what make a good amp a good amp.
Gas the amp the old fashioned way using an o-scope and you'll wonder where all the volume went. The amp will still be maxing out, however, your average power has gone down. That's the "volume" people often think of when they think a system is loud. Personally, I like a lot of headroom. I want a whisper to sound like a whisper and a kettle drum to sound like a bomb just went off. Setting the input sensitivity to compensated for a desired volume makes everything sound compressed...to me at least.

It's also important to keep in mind that some amplifiers are very tightly regulated and can be set up w/a volt meter. Other amps cannot be set up this way, the output channels need to see a load and output can vary based on the vehicle's voltage. At rest, idle, and the RPM in which the alternator is at maximum charge will yield 3 different voltage readings on an unregulated amp.

JL is a good company with many bright minds & great product. But their 'way' of doing things, such as the links you've provided, should only be applied to certain products and looked at as a 'general' guide. It's a way of doing something that'll work for most people most of the time. In that regard, setting your radio at 3/4 volume and listening for the woofers to clip also works for most people most of the time.

Just b/c it works for most people most of the time does not mean it's the correct way...to me at least.

Im not trying to single you out and pick on you, I swear Im not. lol Maybe its jsut Im not use to how you word things, but you made another statement in this reply that strikes me as odd at best, and incorrect at worst. Im 100% with you in agreement on headroom, but you lost me when you said this: "Setting the input sensitivity to compensated for a desired volume makes everything sound compressed...to me at least."

Im confused because you start off saying you like headroom, but then say you disagree with gaining an amplifier's output down to reach a desired volume level... which is how you correctly set up an overly large amp with lots of headroom. I dont see how else you would suggest obtaining/using this headroom (remember, headroom is power that is only used for momentary peaks in current demand, think of it like an 'emergency reserve' of power), unless you mean to suggest simply leaving the volume knob on your h/u lower, which results in the exact same output from the amp (including dynamic range, what you seem to be describing as it sounding compressed), but the weaker signal from the h/u means the system is more susceptible to induced noise in the signal chain, and the amplifier's gain will simply need to be adjusted higher to compensate for the lower signal strength.

Lets take a step back and discuss how to properly tune a system when its new. In the most basic terms, what you do is set the gains of each amp/output at or near their peak non-clipped level (be it via your ear, a DMM, or an o-scope). You then determine what are the quietest components in your system (front mids, front tweets, subs, midbass drivers in doors perhaps). Those speakers that are the quietest, are now your reference point. You gain the outputs down on all the other spealers' amplifiers until they level-match the quietest speakers in the system. You now have a system with no audible signal distortion (theoretically), and the power you gained down from the amplifiers is now 'headroom' for those peak demand situations that would have otherwise driven the amplifier into clipping.

 

[audioholic 5,000+ posts]

Ahh. I see what you mean. Miscommunication.
If we were BSing over a beer or two this conversation/discussion would probably go a bit better. A great orator I am not. If I can think of a better way to explain myself, I'll PM you.

I admit your replies have had me scratching my head a few times. Your wording sometimes does tend to... over complicate your point. I have the same tendency. I many times will write a reply, and then go back and make a conscious effort to condense it before I hit the reply button.

 

[hispls 5,000+ posts]

OP should consider adding a short piece of #4 wire from his battery - to the frame (close as possible, sanded clean, put some vaseline over it when you're done). The factory groud is the path that EVERY electrical device in your car has to get it's electrons from and is typically woefully inadequate. IMHO it helps just with running the normal regiment of power windows/lights/fans/etc. etc. that you use every day.

 

[audioholic 5,000+ posts]

But instead of using vaseline, a car audio DIY'er really should have a small tube of dialectric grease handy. Most auto parts stores sell it.

 

[BnGRacing 10+ year member]

Im not trying to single you out and pick on you, I swear Im not. lol Maybe its jsut Im not use to how you word things, but you made another statement in this reply that strikes me as odd at best, and incorrect at worst. Im 100% with you in agreement on headroom, but you lost me when you said this: "Setting the input sensitivity to compensated for a desired volume makes everything sound compressed...to me at least."

What I meant to say is most people choose clipping over headroom. They turn the gains up to the point it's clipping pretty bad, and to me, that will make any system sound compressed. The quiet things in the music are too loud and the things that are supposed to be loud are clipped...

If the interior speakers are not loud enough, most people turn up gains instead of turning down the subwoofer to match levels. Like EQing, it's a lot easier to turn something down than up. Often, greater/better sound levels can be reached by swapping to more efficient speakers or just plain more speakers. This is the better route than adjusting gains to meet specific volume demands at the expense of increased distortion.

Have you ever installed professionally? If so, have you ever had to hot glue the gain knobs on an amp for a specific customer(s)? Have you ever wanted to?

There's a lot of damage a man can do with a screwdriver whether it's home remodeling, adjusting a Holley, or gain setting. A lot of people set their gains and say "wow, that's loud" and someone with experience will say "wow, that sounds like crap".

That was the point I was trying, albeit poorly, to make.

 

[BnGRacing 10+ year member]

I admit your replies have had me scratching my head a few times. Your wording sometimes does tend to... over complicate your point. I have the same tendency. I many times will write a reply, and then go back and make a conscious effort to condense it before I hit the reply button.

Are you suggesting I switch to decaf?

Those would be fighting words...

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[audioholic 5,000+ posts]

What I meant to say is most people choose clipping over headroom. They turn the gains up to the point it's clipping pretty bad, and to me, that will make any system sound compressed. The quiet things in the music are too loud and the things that are supposed to be loud are clipped...
If the interior speakers are not loud enough, most people turn up gains instead of turning down the subwoofer to match levels. Like EQing, it's a lot easier to turn something down than up. Often, greater/better sound levels can be reached by swapping to more efficient speakers or just plain more speakers. This is the better route than adjusting gains to meet specific volume demands at the expense of increased distortion.

Have you ever installed professionally? If so, have you ever had to hot glue the gain knobs on an amp for a specific customer(s)? Have you ever wanted to?

There's a lot of damage a man can do with a screwdriver whether it's home remodeling, adjusting a Holley, or gain setting. A lot of people set their gains and say "wow, that's loud" and someone with experience will say "wow, that sounds like crap".

That was the point I was trying, albeit poorly, to make.

Ah, you meant setting the gain artificially high, not low. In that case, I agree with you.

Yes, output levels should always be adjusted down for blending purposes. I think I said earlier in this thread that this is the proper way to blend/level match a system... set gains by ear/o-scope/DMM, then gain all other amps/speakers down to match the quietest ones in the system. EQ's are the same, if you want to boost a freq range, you dont 'boost' it, you adjust everything else lower. I tell people to 'always cut, never boost' with an EQ. Truth be told that is not *always* true, if you have the headroom available you can boost some. But people smart enough/experienced enough to understand that aren't requiring my advice either.

Nope, never installed professionally. Have had that urge with friends' cars tho. I look at it as all I can do is educate them as best as possible, and then they are on their own to take my advice or not. But with friends, you dont have that whole warranty/'the customer is always right' cloud hanging over your head like you do in a business setting.

 

[audioholic 5,000+ posts]

Are you suggesting I switch to decaf?
Those would be fighting words...

//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Nope, you keep doing whatever you are comfortable with. We'll muddle through it. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif