Amps: Why Internal Caps Matter [Long Thread]

[whazoo84]

So, I wanted to make a thread like this for awhile, but I never really used this account and I've been lurking for awhile, so now I've decided to do it.

The point of this thread is to explain the capacitors that amplifiers use, and how they can majorly effect the amplifiers performance.

So we're gonna start off with the basics: What is a capacitor, and what does it do?

Capacitors are simple little devices, they're like batteries, only they can release their charge inside of a second at any moments notice, and regain that charge just as fast. The most common type that is used in amplifiers are called Electrolytic Capacitors. They use high purity aluminum inside of them attached to a negative and positive (called a Cathode and Anode). However, there are layers of aluminum wrapped into a roll, with paper separating them. This paper is impregnated with an electrolyte, this is crucial to a capacitor. The electrolyte makes or breaks the capacitor, if it's bad quality or the cap in general is bad quality, the electrolyte will usually fail. This will cause it to generate a large amount of hydrogen gas inside of the capacitor. There is a vent on top of the capacitor that will allow this to release. However, there is a lot more than hydrogen in the smoke that comes out, breathing it in is EXTREMELY toxic. Do NOT attempt to explode a capacitor for fun, the safety vents on the top do not always work, the failure can cause them to explode and take off like a bottle rocket, or send shrapnel everywhere like a hand grenade (literally). This can severely injure you, it's happened to me, don't let it happen to you.

Everyone here with a small system and a single battery with a stock alt probably uses a cap to stop their lights from dimming.

As for the caps inside of the amplifier itself, they're usually not big enough to do this, however, new technologies are going to make this very possible, very soon. I'll explain more of this later.

So what are the caps for? They're there to provide a quick burst of electricity as the amplifier needs it. You've all probably seen the amplifiers on the dyno, when they're in dynamic mode, they usually put out substantially more then when on certified. This is because of those capacitors. When they are charged, they provide a large burst of electricity at the optimal voltage for the amplifier to run at internally for a burst. This is why they perform much better this way.

Let's explain this a little more. Let's say the amplifier is going to have two things happen to it: It is rated for 1000W RMS @ 1ohm, it is then put to a 1 ohm load and it will be tested with a 40hz burst tone every 3 seconds, and then a constant 40hz tone.

You put the amplifier on a power supply bank with the batteries charged to 14.2V, and the amplifier is running happily. The capacitors inside charge and it's ready to go.

First test: You put the 40hz tone through the amplifier and it makes 1028 watts, right at it's rating and you're happy with that.

However, you then put a 40hz burst tone to it and you get a whopping 1482 watts out of it, what?

This is the peak wattage of the amplifier, if you'd read the manual, you'd see that it says that it's peak is 1500W. A little more than your shitty Pyle sub can handle.

This is a perfect example of the capacitors doing their job in the amplifier, they provided a quick burst of electricity in large volume for a a short period of time.

However, you see this amazing deal on an amplifier from Power Akoustic, 300$ for 10000W!? You think this is insane and buy the amp right away from a shady eBay seller.

You put it on the dyno, run the same tests, and are extremely disappointed.

You only got 2500W at 0.5ohms certified, and 5000 dynamic, bummer!

But why does the amplifier not put out it's rated power? There are a lot of factors here, one is it being only 300$.

The others though are a possible combination of these things: Power supply of amplifier not being capable of a reliable supply for the amplifier, the capacitors being cheap and underrated for the job, or the output section being overrated.

Commonly it's the caps inside of the amplifier being cheap, and used barely for what they're rated because the manufacturer knows they won't last otherwise.

Take for example the Hifonics Brutus 1200.4X this amplifier suffers from this majorly.

I have one, and I've examined it's power supply, and I can tell you right now they cheaped out in this part of the amp. The caps are all chinese cheap capacitors, rated 1000uF (uF = MicroFarad) at 35v.

Now here's a shocker: overrating the capacitor does NOT increase it's life that much, and I'll explain more in a minute.

For now, let's concentrate on something else: capacitor size.

1 farad(F) = roughly 1 million uF.

So 1000uF is small, right? This depends on where it's used. If you take a capacitor that's rated 100v 1000uF and charge it fully. Then foolishly put your fingers across the terminals (do NOT EVER do this, EVER) you have just shoved a HUGE ammount of electricity through your body at 100v. You're gonna get hurt, really, really bad. I've done this and it hurts like hell, it feels like where the electricity was flowing through is on fire, I shorted a 200V 2200uF capacitor charged to 120V across my arms on accident. Needless to say I fell down screaming and not able to move my arms at all. I was lucky, I survived. My arms can never stay stable again, but I'm alive and that's what matters. Don't be an idiot with these things, I'm telling you this for your own safety.

Now, back to sizing. 1000uF is quite small electrically speaking, it's a common size in most common household items, like laptop chargers, radios in cars and in the house, televisions, and now becoming more common: led light bulbs. However, for large applications like a 1200W amplifier, they don't have any business being in the power supply, unless it's for something small like a controller circuit. However, powering an amplifier of that size is absolutely something they're not meant for, so why did Hifonics use them? Because cheap caps cannot do near their rated voltages for long periods of time without failing. Lots of cheap caps are overrated as well, they just straight up can't even do their rated voltage.

Why do manufacturers do this? Not even I know, good capacitors are usually only a few CENTS more in terms of price. I've imported things from China to sell on eBay, believe me when I say cheap caps aren't worth it. Common brands of shit caps include: Chang, Chenxing (if you ever get an amp with these caps in it, you've bought trash), Chong, GSC, G-Luxon, Ltec, Rukycon, Rulycon, Weicon, ZCKJ, Yihcon/ZHN, JWCO, Evercon, and so many others I can't even list. However, in this list are a few that the technicians here will know I didn't list, I'll talk about those in a moment.

So when it comes to good caps like Nichicon, Nippon Chemi Con, Sanyo, Elna, and Matsushita/Panasonic, they will last forever running at their rated voltage. The brands above are known for having the electrolyte evaporate before the caps themselves fail. It's ridiculous how they usually don't even cost that much more, meanwhile they can make the life of the amplifier, now the quality of the cap has to do a lot with it's size, let me explain why.

You get a cheap amplifier with cheap caps that are overrated so they don't fail. However they are smaller in capacitance because as the voltage increases, the physical size of the capacitor increases. This also goes for the capacitance rating of the capacitor.

This cheap amplifier is rated for 1000W, but on the dynamic test you only get 750W, a little short of the rated 1000W.

You take it to a technician and he sees that the power supply capacitors are too small for the amplifier to produce the power. He then replaces them with larger, quality capacitors.

You then bring the amplifier back and dyno it again. What do you know, it's made 1050W! (Please note: it's never this easy of a fix to get an amplifier to do it's rated power, it's usually more of a mod than this.)

This is just a basic example of the importance of capacitors. For those interested in what caps are good, check http://capacitorlist.com/ a small website set up for people to know what caps are good and bad.

Okay, so now here's where things are gonna get technical, so buckle up there is absolutely no tl;dr for any of this.

Remember, with cheap caps not lasting and them having to overrate them? I'm gonna explain why for those who wish to know why they fail and why having good caps makes a world of difference.

If you were to compare a Rockford Fosgate amplifier to a Hifonics, what you'd find is appropriately sized capacitors for every application, and power supplies ready to rock and make the amplifier pump out some serious power. With Hifonics, you'll find the absolute minimum to get the rated power, but this does cut the cost of the amplifier.

So the way this plays out is usually the bare minimum not being enough, the peak it'll put out is likely going to be RMS output, and not much better.

So the simple reason for this is because the cheap caps are smaller because they need to have a higher voltage rating so they do not fail. However, with the good caps, they can be larger due to them being able to handle their rated voltage.

A little while before, I explained that caps being overrated can also cause them to fail.

This is true, and I'll explain why.

With capacitors, electrolyte will age and eventually wear out, or dry up. If you have good caps, they will likely dry up before they fail, but there is one flaw to this. If you take a good capacitor, let's say a Nichicon rated for 35V 1000uF, and run the capacitor at 12v all it's life, it's not going to last. The electrolyte in the capacitor cannot run too far below the rated voltage, or it will fail prematurely from the electrolyte wearing out. To prevent this, on a standard system the manufacturer will likey use capacitors rated at 16V 3300uF. This leaves some space in between running max voltage all the time, while not deviating too far. This makes for a perfect match, it also allows a capacitor to have a larger capacitance. This means a larger burst of electricity can be given to the amplifier when it's needed. Now you have an amplifier that can do it's rated power with no problems. However, the amplifier with the cheap caps will either struggle or not be able to do it's rated power at all.

One last thing for the technicians who I'm about to trigger the shit out of.

*breathes in*

CapXon and similar brands (like Su'Scon and Samxon) are NOT BAD BRANDS.

There is so much evidence of this being false it's not even funny. I have Mackie powered PA speakers and powered mixers that are FULL of these things. By that I mean there are no other brands of cap inside of them except on the preamp circuits. All of the caps test good within spec and the amplifier operates with no problems.

Why do these brands have a bad reputation? Manufacturers using these caps out of spec.

These are the best caps China has to offer if I'm honest. However, manufacturers know this and they use them like they're japanese high quality capacitors. They use them for tasks they are not specified for, such as having a ripple current rating that's too low. A good quality cap would likely not be too badly effected by this. However, with CapXon, they're seen failing in amps and LG monitors and tvs all the time. Why? Ripple current being too high for them to handle, you can check on YouTube for videos of this being explained and proven.

I've seen brands like Su' Scon, Samxon, and even Jamicon in places where they were mission critical, and they are fine due to the cicuits they were installed in being quite well designed. I see Samxon in Dell power supplies a lot, never have a problem with them there. I see CapXon in Mackie amplifiers all the time, never have a problem with them. I see Jamicon in Trane furnaces every day when I work cleaning furnaces and servicing them, I've seen these caps over 10 years old still operating just fine.

In the end, what I'm saying is don't jump to conclusions all the time about certain caps, I've seen this kind of stereotyping a lot and there's a lot of proof against this. I see it every day.

Last but not least, amplifiers being able to stop voltage dimming on their own.

As you all may have seen or may not have seen, there are a new type of capacitor starting to hit the market: the super capacitor.

EricBigDWiz uses Maxwell supercaps rated for 2500 FARADS. These are HUGE and can release an absolutely massive ammounts of electricity, but they are too big to big to fit into an amplifier, so what next? They make smaller ones, that's what's next, they keep getting these capacitors smaller and smaller. Now, you can get a 500F capacitor that is the size of a small cell phone battery bank (those cheap round ones you see everywhere). This means you can put many of them together to get them to work with the voltage of the amplifier.

There's also a new feature these caps have: most of them have 3 pins on them, one of them is a controlled release of the charge. This means they can release the charge slower, allowing for longer peak amplifier outputs. If anyone knows the Rockford Fosgate T15K, this amp has around 180 400F capacitors in it. This is why it can put out so much wattage without even trying, if they put these capacitors in more amplifiers, we'd have many more amplifiers that were low cost that could put out peak power easier.

That's it for tonight, It's 4am and I probably left out some stuff. If I did tell me in the replies and I'll edit more into it.

Any things people want to add let me know, I'll add it to this.

Have a nice night guys.