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PopcornPlaya, I have nearly completed a full rebuttal of your entire post (ie this is not it), a lot of you math is wrong, and even more of your reasoning is wrong... (Appologies for the delay, but I had to activate my account and wait for my colleagues and I to stop laughing before we could get serious...) and as you made me read all of your crap, make sure you read all of this...

In the last five years I have built some beautiful amps, very powerful (we're talking PA, 50v at 70 amps per channel ie 3500 watts per channel), THDs down to 0.001% and you know what, every single one of them has a big bank of caps, without them the THD measures in whole %.

To run currents under 120 amps I use a cable which contains 1666 strands each 0.12 sq mm in area, a total conductor area of 18.84 sq mm (AWG 5 gauge wire).

To carry currents upto 160 amps we use 2 gauge OFC wire, 145 x 19 x 0.12 sq mm conductors, the conductor diameter is 0.5"... To supply your magical 300 amps, you would need to run two of these cables in parallel (very bad idea at 300 amps) or you would need a cable with a conducting diameter of around 1" (or more when you consider skin effect, have you heard of that?)

Can you show us the pretty plots you refer to? I would love to see the coloured curves...

Allowing the altenator to cool down... WTF for? When you amp is opperating and your altenator is charging it will never be cool. Infact, they are designed to reach maximum efficiency when they are up to running temp.

PopcornPlaya, you think you deserve the $5k for attempting to parrot some false reasoning as to why caps are useless... You suggest that you have taught us all something important... But I am worried that all you have done is provide some critically flawed logic to the good people of this forum.

I fear that if people without technical knowledge to see through your crap read your whole article they might actually end up being dumber for it...

You might be just quoting Richard Clark and Dave Navone and you might think that they are the godfathers of car audio, and they might have written books, (I have not read them, nor seen them, nor do I want to see them) but none of that means that they know what they are talking about...

I'll post the more interesting stuff in the next day or so.

 
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Ding ding... Round 3....

Oh, there seems to be a problem in the blue corner folks, PopcornPlaya is not on the planet. I hope he was not silly enough to try the cap on the tongue test, but then anyone stupid enough to quote someone else that does not know what they are talking about, might just do that too.

I will give him a couple of days for the bruises to subside then we will start again.


Quote from Taught To Tort
“I fear that if people without technical knowledge to see through your crap read your whole article they might actually end up being dumber for it...”

Luckily I only read it a couple of times; I thought I was feeling a bit off!

Still waiting for my $5000

 
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This thread is becoming interesting. I'm staying out of the whole Cap debate, but I do think you all would do better for yourselves by keeping the comments non-personal and attacking the subject not the author. Especially when you are new here. For no better reason than it takes away from how serious people take you when you have something intelligent to say - and it appears that you do have an eductated point of view on the subject, Tort.

My question to you is, how is it not a bad thing that your amplifiers have whole number THD without caps?

 
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You people make me laugh. You all think I'm saying caps are useless. Your inferring skills are very poor. The point of this was to show that caps do not do the common myths that people think they do. Some of those myths include the following:

"Caps improve voltage"
"Caps improve bass response"

Never, once did I say they aren't useful in fixing dimming problems. See, you're putting words in my mouth that I never said. As for getting your money, Richard Clark can be contacted at Car Sound, should you feel the compulsion to prove to him that caps improve voltage or bass response. Not sure what the angst is, but I'm not going to argue with you because 1, I really don't care that much to worry about arguing with you over points you're trying to make that I never cared about in the first place. You appear to have an educated (or informed to an extent) point. Good for you, I'm glad that you took the time to write an educated response for points that I never attempted to make. You want a cookie?

Now, to get more specific:

Taught to tort... 1. Where did I claim to be the author of the writings? I believe I directly stated that Richard Clark wrote this. 2. Did I ever say that caps are useless? Nope, not once. 3. If you'd read, the $5,000 you get is for proving to Richard Clark that caps improve voltage, and/or bass response. Where were you on the day reading comprehension was taught? 4. The 300 amps part, since you can not read and comprehend the words "What if", that means that the words that folow are going to be an example. Sorry, again, must have missed that day at school. 5. You've built lots of amps... congratulations, I'm really proud of you. It really makes me happy to know another attention ***** that's here to point out every little thing they do is on here. Really,it does. Perhaps you and your colleagues could also sit around dissecting points that weren't attempted to be made at another of your "social gatherings", ie a game of soggy biscuit.

Miktrain:
Wow, you think you're real funny cause you can come on here, much like this taught to tort character, and post up your opinion, which happens to be a rebuttal of things that you incorrectly inferred. Show me where I was trying to prove caps useless? The point was to prove caps do not increase voltage, take strain off the e-system (that's electrical in case you missed that one too), or improve bass. As for posting a reply. Sorry, I've been a little scarce around here lately, mainly because I'm in the process of moving, selling my car, and working 12 hours a day. Forgive me that I haven't been on here to make a rebuttal, as my life really revolves around what some punk kid's opinion says on a website. Reeally, I do apologize if I haven't been on here to tell you how ignorant you are for attempting to infer things that I didn't say. You want $5000, prove to R.C that caps increase voltage (help keep it at a steady 14.4 volts), help bass, or whatever you choose to prove to him. Fact of the matter is, you idn't thoroughly read it the couple of times you read it, or you'd have saw that that was the point.

Wow, the internet phenomena, too bad it can't teach people how to read...

 
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Because I have seen people who can hear the difference, I once met a girl who could effecively hear phase changes down to 10 degrees. (Yes we tested this).

I have a mate who detected (by ear) a 0.1% clip that lasted for 5ms on the top of a bass curve. I sometimes think I can pick it too, but I am too often not correct to be able to state that I can. I was slightly incorrect when I said whole %, it's more like 10 - 12% THD and that I know I can hear... and I do not like it, caps are a cheap solution and the output sounds great and everybody is happy, so why not have them?

 
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Bottom line caps work people have used them for years thats not being disputed I hope, But popcorn when you come in someones thread and type "BULLSHIT" and then attack me like you did with no evidence just someone else's writings it makes you look bad. And for the rest of you guys who like throw names around it does nothing to credit you! You have to scientifically prove something that gives you credit becuase you did the work.A good debater will do his homework,study the subject in depth.Then come to the table with facts.One fact we all have here is that they work. Anyone here who has used them becuase they had a problem with dimming and then installed one and now they don't sounds to me like it works? Anyway good luck proving it hope to see some facts someday!!!

 
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i always thought that it was well understood that caps in systems are just to prevent the ghetto dimming and ensure that the amp isnt draining more power from the battery at any given time than what the car needs to function properly. people get them for other fantastic reasons?

 
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No, The way it read (I still remember the thread, though with near a case of beer it's a little fuzzy at the moment) it appeared to me you were saying that it would fix voltage issues. I was saying bullshit to that, not the fact that they didn't combat dimming. They are, often times, useful to combat dimming. Problem is, people depend on them to fix all of their dimming issues. Sometimes, regardless of size, they do nothing to combat diming (I've installed multiple caps on 1000 watt systems and that did nothing for dimming, conversely, I've installed a 1 farad cap on a 100 watt system and it fixed the dimming to where you couldn't detect it (with the human eye). Do they always work? No, but they do work lots of times. They're a cheap fix for something that the same moey could have fixed much better.

 
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the real fix is a higher amp alternator and a 2nd battery, no?

 
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I guess I didn't phrase my question correctly. What I was curious about was not why do you care about the difference in THD - that's obvious. My question was why do the amps you build have such high amounts of THD without a big bank of Caps?

 
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Most of your post was set to prove that the caps are useless.

By keeping the voltage stable, caps would take strain off the charging system.

Funny, you spent time reading and then reposting the opinion of a 'punk kid'

Did you try my other test?
Here is the next one

Take the 9 volt battery used in the tests and place a piece of wire across the terminals.
What happens? About 100mA flows, the wire will get a little warm if it is very small. After a few seconds remove the wire and measure the voltage, you will see that there is still plenty left. Why? Because of the internal resistance.
CAUTION DO NOT DO THIS WITH NiCADs OR NiMH TYPES IT IS DANGEROUS they can deliver many amps for a brief period

Now try it with your cap IF YOU DARE! The entire contents of the cap will be discharged through the wire in an instant. Either burning the wire, welding it to the cap or worse still the cap will explode in your face in the process DO NOT TRY THIS AT HOME KIDS

This is the reason the 9 volt battery kept the bulb alight for longer it has a higher resistance therefore it can not deliver the goods. Not as “proved” by the test in the original posting

This is the reason that caps are used because they respond faster.

You posted the quote therefore you should accept the rebuttal.

 
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someone please lock this already this thread has done nothing

 
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cliff notes plz

 
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***head, desk, bash***

I think I might have blotted my copy book there and made quite a large faux par... I think I know what you are getting at and I think you might be right, ripple on the input should not cause harmonic distortion. But I can assure you that it will cause other forms of distortion (exactly what they are I will have to investigate).

IIRC harmonic distortion usually comes from the pesky FETs oscillating when they shouldn't be, but a variance on their supply might be what's causing the oscillating. I shall re check that on Monday (it's Friday morning where I am now) when I am back at the uni (I'll do some real experimenting) and tell you exactly what the exact difference is... Bugger... Well spotted...

I hope the following makes sense...

In short the big bank of caps are there to remove ripple... Some psuedo scientist once tried to tell me that since a car's audio system ran from a 12v DC battery there was no ripple... Wait for it, because ripple ONLY came from rectified sine waves...

Okay back to the point, the voltage present at the input of your amp has some very lovely variable (but generally around 100Hz) ripple on it.

<maths bit>
One cylinder four stroke engine, in a four stroke the spark plug fires once every two revolutions if the engine is running at 3000 rpm (ie 50 revs per second = 50Hz) the spark plug will be firing once every two which means the spark is running at 25 Hz.

Now for a real engine, 4 cylinders = 4 x 25 = 100Hz, 6 cylinders = 6 x 25 = 150Hz, 8 cylinders = 8 x 25 = 200Hz etc.
</maths bit>

Ofcourse I know it is really more complicated than that. There are other sources of noise too, not just variances in engine RPM. If you have a variable duty cycle fuel pump then that will be switching in and out too, electric windows wind up and down, windscreen wipers, water pumps, radiator fans all that stuff, but there are only so many hours in a day and we cannot model everything... 100Hz is a handy standard we use (in Australia at least) because the maths is easy and our mains comes out the wall at 50Hz which means on a mains amp we'll expect 100Hz ripple too, so our filtering techniques merge together nicely...

Even if you have a Formula 1 (or Cart) enigine with 8 cyclinders doing something like 15,000 RPM that would produce a ripple in the low KHz range. All of this is most unfortunate for us because that is smack bang in the middle of the most important part of our hearing range.

That lovely big bass THUMP we all like to feel takes a LOT of grunt to produce trust me, getting a twin voice coiled 15" kevlar or carbon fibre cone (or two, or three?) weighing about a 0.5lb to move 0.5" 20 to 200 times a second is not easy! If your 12 volt line drops right as the output FET is about to tell it to move, it aint going to do it effectively... And that is something you SHOULD be able to hear (if your ears are any good).

It should also be noted that this voltage drop is what causes your headlights to dim, so if you cannot hear the problem, you can see it... That is the major reason for the caps being there. I have an idea that they might also help a little with low frequency response, but this is currently under test in my lab at uni.

If any of you out there are considering building or designing your own gear, or if you can get it built or designed by someone else I HIGHLY recommend the 2SK1048 and 2SJ162 MOSFETs the best I have ever seen and what I always use. Get the genuine HITACHI ones (no I do not work for Hitachi) and you won't look back.

A couple of last points, PopcornPlaya, on my office desk I have a tiny(?) 300,000uF 18volt cap, next week, I am going to charge it up and discharge it with some suitable piece of conducting material, most probably a large screw driver, (I am taking bets on whether I can weld the screw driver to it) then I shall do it again and measure the current flowing out of it for you...

Also I am still looking for a 65 amp 800 watt load that I consider safe and a 12 volt battery that might go somewhere close to safely supplying it so that I can test the voltage drops and energy content, because I know that you have been misled there... I am just a little frigtened to be in the lab at the same time as the 'experiment' and I doubt that the lab is bomb proof so some form of remote measuring equipment might also be needed!

 
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taught_to_tort where is that rebutal you promised? I am looking forward to your thoughts

PopcornPlaya where are you? It is a bit hard to have an argument if only one side is contributing. I would have thought that being as smart as you think you are, there would be some answers or proof that I, or some of the others on this list are wrong. Ask your "Godfather" for some help and while you are there ask for my $5k
Perhaps I should take your silence as admitance of defeat?

 
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I'm not sure if he'll be back. I'm pretty sure he ditched the Civic and got a Brand new Scion.

 
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atl b4 cap. But I wasted my $ on 3 of them b4 I knew that. But its ok I got it all 70% off from Best Buy when I worked there.

 
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At least I know someone reads what I write! It'll be here soon(ish) I have been distracted by serveral other projects. Obtaining equipment for some destructive testing has also been difficult, people won't *lend* me stuff they might not get back!

Mr PopcornPlaya, I have something for you, I got my two (tiny) 300,000 microfarad caps, paralleled them and charged them to to 14 volts. Then (from a *safe* distance (less than a foot away) I dead shorted them with a 1" diameter copper rod and measured the current. You know what? the caps temperature increased by a whole degree, and the cap stayed stuck (welded on) to the copper rod, all of which I expected... What shocked me was that you were wrong, my data logger plotted a lovely massive current spike, 600 amps high and about 10ms wide... I nearly fell over! How could that be? The second time, the current spike was around 10% higher again, but it's width was down to around 8ms which means that it discharged quicker the second time. What would have happened if I'd had two or three 1 Farad caps?

It should be noted that one foot is hardly a safe distance when doing this sort of thing, the first bang damn near changed the colour of my pants, and caused a mild panic in the lab next door. However the inevitable second test attracted a crowd of eager on lookers!

Also it should be noted that at 14 volts a current of 600+ amps flows through resistances lower than around 0.025 ohms, this means that whilst I have not measured it, the total resistance of my cap and copper rod was less than 0.025 ohms... So the ESR of the caps was??? Who cares... it's tiny and 600 amps moved...

 
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Well done bro..I have said it before about tesla coils and there use of the capacitor not just as a voltage carrier but amps as well and with out it in the circuit the coil will not resonate and discharge cuasing the electric light show that it does. Good work man.

 
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He is still posting on other topics

taught_to_tort
(from a *safe* distance (less than a foot away)

You are braver than me!

 
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Do you have any info about Flux Capacitors?

 
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I'll have to call the doc and marty and go over some notes, but I think I can get something to ya by mon!

 
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bwahahhahahah, Right on. Maybe you can get Harry's to import them overnight from japan.

 
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I'll add 'get flux cap info' to my to do list...

 
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Sorry, a bit out of my field.

See PopcornPlayer, that's how you do it, if you don't know... say so! not BS on and hope to baffle eveyone.

 
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it was a joke dumbass learn to read!

 
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Must not have seen back to the future!

 
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Ok, you got me there, it had been a long day but at least I did not try to BS on!

 
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its cool just didnt understand what ya meant by bs on!