Clipping - What is it and how do I stop it

[CJ Rodarme]

This is another super basic question but I've done research that's once again inconclusive. The general consensus is clipping is when the H/U tells the amp to put out more that it is capable of doing at that instant. I've heard that running too small of an amp will cause that amp to clip, is that true? I've got an audiopipe 2k at 2 ohms, and it just doesn't sound clean anymore. I've also smelt my coils on occasion, and I cool the subs down when that happens. Will my amp ever play clean again? I've got a new 240 amp alternator going in monday and a Northstar AGM going in soon after. It's not a gain issue for sure, the subs are rated for way way over what the amp is putting out and there's no bass boost etc. all settings are flat. My volt drop has progressively been getting worse, but I am playing a little bit louder lately. I'm also thinking about adding a cooling fan or two if it'll help

 

[adriver]

No, clipping is when you are overpowering the signal coming from your head unit to your amplifier with an over set gain. The signal from your head unit to your amp is roughly just a few volts. Then your amplifier, amplifies that signal. The gain's job is to fine tune the amplifier's input to match that head unit's signal strength output, so there is an even exchange between the two.

The gain is more like trying to "finely match the pitch/volume/inflection/SOUND" with your mouth, then your amplifier is singing it loudly with your lungs. Or if you have one person singing it (your head unit) to a crowd. The gain is the "crowds ears making sure the crowd correctly hears the right pitch/inflection/sound", so they know exactly what the are hearing before they sing it loudly.
If you set it to low, its like trying to whisper and yell (and you are wasting volume). If you overset the gain its like trying to angry yell and sing which would kill your throat (clip).

The size of the amp does not effect the clipping, its just whether or not the gain is set right. Most likely your small amp is just not powering enough to notice, unless the gain is way off.

If your gain is off, your amps are powering a signal that is off. The signal is slightly off when your amp gets it, then when you amplify it, you amplify how off it is.


Most newer amps will have an easy way to set the gain, or you can do it with a multimeter, and test tones you can find anywhere, (should be plenty of youtube vids). If you want to spend the money I know Steve Meade makes a few products that will do it precisely and easily.

 

[CJ Rodarme]

My only issue is that I know for a fact my gain is not over set. I could potentially run 1-2 more of these amps safely and not hurt the subs. So maybe it’s not clipping that’s going wrong but its the volt drop (I got a 240 going in and a battery soon to fix that). What I do know is the amp stops hitting clean and gets warm when I run it semi hard

 

[Doubeleive]

clipping just causes distortion, it's like when you are wearing a pair of headphones and turn them up all the and they basically just make distortion and it sounds like crap, so if you have the gain turned up too much you're just going to get distortion that is the simplest way to describe it. MY experience has been when nothing has been changed and the sound starts to deteriorate, then either 1. the battery is getting weak or 2. grounds need to be redone or ground wires replaced, sometimes it can be a combination of the two and even the power wires or fuses or fuse holders.
if you are seeing the volt meter dance around when it wasn't before that is usually a first indicator of said problem. one way to check is to get a voltmeter and check the wires at the amp both ground and power and compare them at the battery, then if there is a drop follow along from battery to fuse and so forth until you find the problem area.

 

[CJ Rodarme]

Okay cool, I’ll give that a try that really helps. I have a feeling it’s the battery

 

[SnowDrifter]

Clipping: The flattening of the lower and upper bound of an AC wave form. Sine wave begins to look like square wave

Why it's bad: A speaker is a conductive coil moving through a magnet. This bit's important. When you have a coil moving through a field with power applied to it, it changes resistance a bit. When this system is in AC, it's called impedance. It presents an inductive load, NOT a resistive one. The presented impedance will change on frequency and box design. What you measure with your multi meter (1 ohm, 2 ohm, etc) is just a resistive measurement. The load presented to the amplifier can be higher than 10 ohms even if you're wired to 1 ohm. It's just part of the electromechanical behavior of the system.

The meat and potatoes of it: Clipping is essentially DC contamination in an AC system. The drivers were designed with a thermal load for impedance, not resistance. When you're clipping, you have an unholy trio of fuckery you're putting the driver through.

1. Clipping provides DC power in a system designed for AC. It messes up the inductive reactance of the system, applying more power than was intended
2. Your average voltage will be higher as you're holding it at the peak of the wave for longer. Again, you're applying more power to the thing
3. Drivers rely on mechanical movement to pump air and give cooling. When you're clipping, you're applying more power, but not more voltage. The magnetic flux created by the voice coil goes no higher, and as such, provides no more mechanical movement to aid in cooling. It's like: Imagine you're revving your engine up but the water pump is still spinning at idle

Now for the amp: Running too small of an amp will NOT CAUSE IT TO CLIP. Under-powering your speakers WILL NOT BLOW THEM. If that were the case, you'd fry your shit every time you had the volume down. It's user error: Hooking up too small of an amp, trying to overdrive the amp to get desired output at lower volumes, only to have it clip and fry your gear at higher volumes. If you set your gain right, you're fine. That being said, I've had much better results when I run an oversized amp - I can push the drivers as far as their mechanical limits will go with little thermal implication. Ever seen an 8k hooked to an SA-12? I could run the thing as hard as the poor sub would suffer without messing up mechanically and never smell coil. Clean power, lots of movement = controlled thermals.



When you say you're dropping voltage more, where are you measuring from? What wire are you using, what lugs are you using, what fuse block are you using, and how's everything secured? Pics would be helpful here

If you need help setting gain, let me know or shoot me a PM. I've developed a method that's pretty close to the dd-1 and relies on a multi meter. No it's not what you think it is. I can also give you a hand in person next time I'm back on the west side in early May

 

[adriver]

If your system was good before, and now has gone bad without changing anything; (unless I'm mistaken) there is really only 3 things I can think of that it could be: A component went bad, a ground got loose, or a ground got corrosion/rust.

If you really want to go into detail over your entire system (amps with specs, speakers/subs with specs, wire sizes in every segment, connectors, grounds, fuses, distribution blocks, battery, alternator), etc.. we might be able to come up with something where your specs aren't the greatest. If your big 3 is right, your grounds are as big as power wire, and your battery is not corroded, that's probably going to cover the most likely. Maybe a wire took some damage and broke some strands or a connections came loose.

What kind of voltage drop are we talking? How much and when does it happen? This sounds like something you would have noticed before, but what's the alternator you're running now? 2,000 volts at 14.4 volts is a 138 amp draw. If your vehicle is off, that's 166 amp draw. If 2,000 is max, I see one audiopipe amp listed at 1300 watts RMS which is 90 amp load from just that one amp. I'm wondering if you've been underpowering your amp for a while now, and it started to effect it. (Don't know how that would work, but just throwing out ideas).

 

[CJ Rodarme]

Okay so here are my specs. 145 amp GM alt, all OFC power ground etc. I’ve got my 75.4 and the audiopipe off a distribution block, but I’ll be going with a northstar AGM80 cell as soon as I possibly can. Stock battery, not sure how old, going to replace that too. All new grounds etc but maybe they aren’t very good, I had a hard time with getting them tight. I might end up putting my mechman 240 in today but we’ll see. My RCAs are too long and not very high quality either but not the worst. All the connections etc are 2 weeks old so that rules out corrosion and rust.

Now for example of the voltage drop last night I was out cruising with my buddy and at a stoplight I turned the head unit up to 28/40 and bass knob full tilt and my voltage dropped to like 12 so I immediately turned everything off. I smelt a little bit of coil but everything is still solid. I really can’t go above 20 for extended periods above 18-20 (depending on the song) without major drop. Also I’m not running bass boost etc, pure gain.

 

[adriver]

You need the big 3, along with power and ground wires of adequate size for the entire system.
Your alternator is too small to keep up with that amp if its playing ******* heavy music. Your vehicle is going to use most of that 145 amps just to run. Things like your fuel pump, fuel injection, ecu, gauge cluster,... are going to use amps no matter what. Your head lights, turn signals, AC, window motors, … might be on and pull more. E-fans pull about 20-30 along depending on which ones you have.

Your 55w headlights ( / 12 when off, and / 14.4 when running = 4.5 amps or 3.8 amps. Then x 2 of em is 9 amps or 7.6 amps. Now add the taillights, and marker lights, turn signals, dash lights/cluster.. It all adds up. If you want to search out there you can find the approximates of different components, or go use a multimeter to find exact numbers. If you really want to get an overrated estimate, you could easily just look at your fuses to get an idea. You should also be able to use a multimeter right off the alternator when at idle to get a good idea of your bare minimum. You should be using (what I would guess is) about 90-120 amps, (without efans). Then take your stereo systems entire wattage usage, and figure out your amps ( watts / volts = amps).

CORRECTLY FIGURE OUT YOUR END GOALS, then add anything else you might want to put in your vehcle. Even charging a cell phone is 1 or 2.1 amps. Inverters, fogs, exterior lights, compressors,... Figure out your MAX POSSIBLE usage through your electrical system, and plan for that. Its much cheaper and easier to do it 15% bigger the first time to plan for a "what-if" that you might do down the road. If you put wire in that's 3 sizes bigger than you need, and an alternator that's twice as big as you need, it won't hurt anything other than your wallet. That covers the basics of your voltage drop.



The other problem is your gain not being set correctly. You need to set it correctly, and then use a bass boost to control the bass. Your gain shouldn't change. Your gain is matching the signal prior to being amplified. Its like trying to scream into a bullhorn which is going to sound like shit, and you only make it as loud as you can tolerate. Setting the gain is like being clear into the bullhorn so you can then turn up the volume.

 

[CJ Rodarme]

I’ll probably do a dual alt bracket sometime in the next couple months. And I know Yukon’s come stock with 100 amp alternators so I feel I should be better off with the 240 than now as far as what the stock stuff pulls. Thanks for the info