Did'nt even look at that, thanks for pointing that out. I'll spend that cash on some more rc stuff. That would be a sweet amp though.

crossfire told me $150 to fix my 1000d. Could you fix it for less? I'm sure you could use a side project:mdr:

lol, most of the amps I worked on were your typical class AB types. Usually, some kid tried to run 1 ohm load on a 4 ohm stable amp and blew an output transistor. Easy fix. Class D is a different animal since they are switching amps. I don't have an o-scope to troubleshoot those and is needed to measure the reference sawtooth wave and such. Personally, 150 is probably a good deal to make sure it's done right.

Ok, now I have my amp and all the parts taken out of the existing setup. I want to run at least a 1F cap, but the one I have is the typical round style and is too big (3" diameter) to put where I want. I look online and see they now have cap banks in a blingy package. Soooo, I figure I can do that! I'll "just" find a bunch of smaller 10,000uF/25v low-ESR caps, and put them all in parallel for the 1F value. Well, I could only find 2200uF 25v low-ESR caps but it would take 454 of them! Well, that's not gonna work. I'll probably pick up one of those blingy cap bank styles, and get rid of the casing (and stupid LEDs and voltmeter bling). But, I'd like to know where they get their caps? If I could just get the circuit sans case/bling, that'll save some cash. :smile:

those blingy cap banks are funny, but cheap. And large, 5 farads and up aren't uncommon now. On the cap note: is there any way to test a cap? I have two half farads in my van and only 600 wrms but my lights still dim:neutral: would more capacitance help?

Testing caps is pretty easy actually, and you can even verify the capacitance value.

1: Make sure it is totally discharged to 0v. Those large caps will still develop a charge if left alone for a little while, so once it is discharged, hook the leads together (short them) for about 10 minutes.

2: Hook a voltmeter across the cap.

3: Get a known resistor value. Something like 10 ohms @ 10w would work. Measure this with a meter to get an exact value.

4: Charge the cap through the resistor. Time how long it takes for the voltage to get to 63.2% of the supply.

5: Then, take this time (in seconds) and divide by the resistor value. This is the capacitance.

So, let's say it took 3 seconds for a cap to get to 9.1v on a 14.4v supply (63.2%) charging through a 10 ohm resistor. 3 seconds divided by 10 ohms is 0.3, which is 300,000uF.

The "rule of thumb" is to have 1F per 1000w of power. But, a cap will only help so much if the electrical system is weak. Headlights are around 100w each, the heater/blower motor pulls current, not to mention the computer, ignition, headunit, battery charging, etc. The electrical system has to supply all these devices PLUS your 600w system. And class AB amps are around 65% efficient, so the amp is actually requiring around 923w of power. At 14.4v, that's 64A.

Now, the dimming you're seeing is because lights get quite a bit brighter with just a little voltage. So, your alternator is supplying ~14.4v, but then when a bass note hits hard, that voltage drops to, say, 13v. 1.4v difference is pretty noticeable on lights. You probably notice the dimming less when the car is off because the static voltage is at the battery voltage (~13.8v) and batteries can handle pulse loads a little better.

Some people just add better/more batteries, but a battery is at ~13.8v. The alternator is still providing that extra ~0.6v, and if it is already loaded with stuff, the voltage will still dip. You can get an aftermarket high output alternator, but they can be costly. And most people don't realize that a stock alternator actually puts out more current at idle than a high output one. So, at a stoplight, you'll probably still dim.

In short, I wouldn't worry too much about the dimming. You aren't going to eliminate it since you'll always have voltage drop at high currents. But, if the dimming is very bad, it could be a sign of an overworked alternator...

Brian, I have been into car audio for car audio for nearly five years now, the last two of which i have spend alot of time on very knowledgeable car audio forums. From my time spent on there as well as my own research into the subject from writing my 40 page technical report on upgrading a vehicles stock car audio gear I have found that majority of people who I would say really know what they are talking about capacitors for the car audio industry are for the most part a a gimick, and there are virtually no real advantages to using a capacitor. What are used intead in competition rigs (ones that use tens of thousands of watts and have an enormous appetite for electrical power) are power cells (from company's like kinetic and batcap) which basically combine the storage of a battery with the quick discharge of a capacitor.

Im not and electrical engineer (im on of those mechanical guys), but from what i heard from the most knowledgeable guys on the forum the problem with capacitors is their high resistance that for the most part negates there quick discharging capabilities as well as the fact that they cant keep up with the near constant draw comes with some systems.

For the most part what needs to be done for a high end audio system running more power is an updated charging system. this includes a high output alternator, the rating of which depends on your install, but anywhere from 200 to 300 amps is what to shoot for. Also the battery should be upgraded as well as possible additional batteries or preferably the power cells that i mentioned above. Additionally the Big 3 is recommended, this is a process that upgrades the wiring in three areas. the first is the connection from the alternator (presumably a high output unit), second is the ground from the engine to chassis, and the third is the wiring used for hooking up the amplifiers.

Now my car audio setup that i posted a link of in an earlier post isn't what i would call an extreme setup, Im running a total of 1300 watts RMS, but to give my gear what it needs for optimal performance im using the following:

-I have replaced the stock alternator with a unit from Ohio Generators that puts out about 220 amps.
- I have upgraded the stock battery to an optima yellow top as well as added an additional power cell from batcap for my 1000 watt amp for my sub
-I have done the Big 3 with large gauge quality copper wiring (stay away from the cheaper aluminum ones)

I don't think caps are a gimmick, but you have to consider what your system is used for.

If for all out SPL, then no, they have no use. SPL is all about a single short note "burp". Caps won't help much here. For general listening to music which is highly transient, I believe it DOES help. Caps by nature store and release large bursts of energy when required. If anything, they even out the current flow from the charging system. So, instead of 20A, 100A, 20A, 100A, it's more like 40A, 80A, 40A, 80A, or something like that. Just "irons out" those current pulses when the bass hits. And just like most any electrical device currently on the planet, the charging system "prefers" a more steady drain of current.

You could argue that a cap actually is another load on the charging system, but that's not a valid argument. With the exception of minor losses, what the cap takes in, it releases.

Do they help your amps? No, not really. They MAY provide some benefit here, but only for amps with unregulated power supplies. Mostly, they are cosmetic to make lights dimming less noticeable, and to provide a more even current draw from the charging system.

I totally agree on the upgraded charging system though, but everything has to be upgraded: alternator, regulator, and battery/batteries. But I generally don't worry about that unless I'm over 500w continuous power (that's a LOT of power for general music since the mojority of content is "peaky").

I suppose that may be true, but for the cost of a capacitor you could nearly be get a power cell that even further reduces the draw on other components due to its storage of electrical energy as well as its ability to quickly supply it when needed.

The main issue that i have seen, especially at a couple of the car audio shops in my town is that they pretty much recommend a capacitor to anyone having charging system issues... so people are spending hundreds of dollars on a capacitor plus the installation that doesn't really do much when thy could be spending that same amount of money on components that will actually remedy their issues (alternator, batteries and wiring).

Well, those car audio shops are wrong. I hate places that spew blanket statements like that, especially when false. If they are having charging system issues, then the only thing a cap might do is mask it. I suppose it's just a matter of understanding what a cap is, how/where to use them, and what it can and cannot do.

For me, it's just to iron out the peak pulses in current, and it works great for the power levels I run and how I use the system.

About the quick charge/discharge issue: That's another reason why I was leaning towards a low-esr cap bank instead of one large one (that and space constraints). Just using multiple caps that total the same value as one large one has better transient response. And the use of low-esr caps reduces that resistance your peers refer to.

Just playing around with the new RF amp and my old PPI amps, I decided to take the covers off and show why I say they don't build them like they used to. Keep in mind the specs:

RF T600-4
4 x 100w rms @ 4 ohms
4 x 150w rms @ 2 ohms
2 x 300w rms bridged @ 4 ohms

PPI PC2400
2 x 100w rms @ 4 ohms
2 x 200w rms @ 2 ohms
1 x 400w rms bridged @ 4 ohms

PPI PC2600
2 x 150w rms @ 4 ohms
2 x 300w rms @ 2 ohms
1 x 600w rms bridged @ 4 ohms

Now for the pics of the guts.

First up, the PC2400 vs the RF T600-4. Note the size difference and circuits despite the RF being rated for 50% more power:

http://scriptasylum.com/forumpics/rf_vs_ppi_1.jpg

Next is the PC2600 vs the RF. These amps are rated for the same total power. Just look at the circuits on this bad boy :smile:

http://scriptasylum.com/forumpics/rf_vs_ppi_2.jpg

thanks for the cap info. your pics don't work for me, i wanna see guts!
edit: i got them to work