Its big! Car audio amplifier...

[moemoe]

Some time ago I read this article: http://www.spiegel.de/auto/fahrkultur/db-drag-racing-autos-mit-getunten-soundanlagen-a-990410.html (sorry, it's german).

But what I rememberd it is this statement:

Enttäuscht war er auch von den amerikanischen Aufmotzern: "Als ich gesehen habe, wie schlecht die mit dem Material umgehen, hätte ich denen direkt in den Arsch treten können." Nachdem die Weltmeisterschaften in den vergangenen Jahren online ausgetragen wurden, Europäer und Amerikaner sich also zum Wettbrummen über das Internet zusammenschalteten, haben die Amis die WM inzwischen abgeschafft. "Vermutlich auch deshalb, weil wir Europäer einfach zu stark sind", glaubt Müller.

Quick translation:

He was also disappointed by the american tuners: "When I did see how badly they treated their material, I immediately wanted to kick their ass. After a virtual world championship via internet over the last years, the Americans now disestablished their participation. One reason could be, that the Europeans are just too good, Müller thinks

[SeanB]

This is a capacitor!

I picked up bigger ones than that at the roadside as scrap. 4700uF 450V.

Today a 1uF 200VAC/250VDC 0.1% standard capacitor in a box, bought at the scrapyard with another 24kg of other stuff for $9. There were a whole lot of decade boxes as well, but those had already met the not so gentle treatment.

[Falcon69]

I used to be involved in alot of this car stereo stuff.

I'm 40 now, and sadly, I'm often finding myself saying, "sorry, what did you say?"

Wish I could go back now and build a bigger one!  Then that way, I wouldn't have to hear (or somewhat hear) what anyone has to say these days!

[Falcon69]

Seriously though.

The SPL/DB competitions that are held all over the USA are just amazing.  The amount of sound that comes out of some of these vehicles is just overwhelming.

You can be 100ft away, and watch the hairs on your chest move from the sound. 

When the competition is held, the Deck (stereo) is usually placed out of the vehicle a certain amount of feet away, or is operated by a remote.  To sit inside of these vehicles without hearing protection, can and will damage eardrums.  You saw in one of those videos of that girl/guy's hair moving. imagine the sound pressure of 10 fold doing that to your ear drums.  It's really amazing the air pressure or displacement some of these 12 or 15 inch woofers can do.

Looking at some of these vehicles, they aren't even street legal anymore. They come in on trailers most of them.  the Windows, especially the Windshield, are Thick Plexiglass and pop riveted or bolted on.  Some of these vehicles run multiple Alternators and Batteries. Huge Capacitor Banks to deliver the quick power needed for when those multiple amplifiers draw power for when the bass notes hit.  If you look in one of the videos another member linked, you can see the windshield vibrating and moving like an inch.  You can also see that same windshield has duct tape all over it. LOL

Alma Gates, rest her soul, what an old women who was seriously involved in alot of these competitions.  I remember one competition I went to, where her vehicle hit over 185db.  That was many years ago. I'm sure today, vehicles are louder then that.

But, on the flip side, these competitions don't just offer SPL/DB competing vehicles. They offer vehicles competing against each other for sound quality, and some of these vehicles are just, well, just WOW! Listening to some of these vehicles, makes you wish you could go drop $30,000 on a system for your own vehicle, the sound is so clean.

I had a vehicle that was pushing 6000 watts.  I had to run a second battery, as well as a dedicated high efficient alternator to keep the system going.  As a precaution, I used an RV relay that turned off connection to the vehicles main battery if the ignition was turned off, that way, If I had i had listened to the stereo to long with the ignition turned off, I could still start the vehicle when the battery had run dead.

[NiHaoMike]

I wonder what they would be able to do once they start hacking hybrids and EVs...

[tom66]

Oh, please.

Tim

The capacitance of earth is only about 700uF.

[Uup]

I picked up bigger ones than that at the roadside as scrap. 4700uF 450V.

Today a 1uF 200VAC/250VDC 0.1% standard capacitor in a box, bought at the scrapyard with another 24kg of other stuff for $9. There were a whole lot of decade boxes as well, but those had already met the not so gentle treatment.

I know larger capacitors are available. When that particular equipment came in the other day, seeing those two enormous 3300uF 400V capacitors reminded me of the OP's monster car amplifier pictures. So I posted for fun. The picture doesn’t convey how ridiculously large those capacitors really are!

The largest capacitors (physically) that I usually encounter in equipment passing the work bench are BHC (Now Kemet) 470uF 450V, but are difficult to source locally so have been using their 400V types. Working voltage is fine for the application.


Today, a rather unusual Japanese made power supply came in...






It has 6 10,000uF 100V capacitors for the AC to DC board.




What? You picked up a 4700uF 450V capacitor?

That's not a capacitor...

This is a capacitor! 



Well, actually 193 10F capacitors on the three lower PCBs of the DC to DC boards!

That’s 1,930,000,000uF if removed and individually totalled!

 

[T3sl4co1l]

Oh, please.

Tim

The capacitance of earth is only about 700uF.

Yeah, but good luck finding any commercial part that'll do a billion volts.

[AmmoJammo]

[Falcon69]

AmmoJammo,

Looks good.

if you don't already know this, (i learned when I was working for a company installing custom Stereos), if you mix sawdust in with resin, pretty thick, and smear it all over the box inside, it does one of two things....

1.  Seals up the inside of the box
2.  Creates a bumpy effect inside the box which will break up the sound waves inside the box so they don't reflect back into the subs.

Doing this will actually make your sound quality, DB, and SPL better.

[TheEnd]

1F caps are pretty common to fit in an install, some of the bigger multi battery installs have 1 capacitor per battery, although there's a big argument over whether they work or not.

Same old audiophile stuff, some people will say they can hear the difference, others will have supplys, multimeters and test gear and say they do nothing useful.

Remember when you could get a single blade razor, and now it's doubles, quads, and 6 blades these days, car audio caps have gone the same way.
If anyone can buy a 1F power cap, how do you stand out?

http://www.lanzar.com/sku/VCAP10000/Vector-100-Farad-16-Volt--Hybrid-Double-Capacitor-

100F cap, you wouldn't want to touch a spanner over the terminals on that...

Anyway, flashing blue LEDs... just take my money!!!!

[dannyf]

I feel bad for that car.

[RobertoLG]

Looks really cool

[SirNick]

OK, so.... that's a ported enclosure then?  What's the tuning frequency?  How much volume per driver?  Doesn't look like all that much, what with the enormous basket, although you're starting to run out of car as it is.

Car audio people tend to get batteries and caps confused.  A 1F cap will relieve some of the Vbatt droop for transients, but your dubstep bassline will just pull the cap down to the sustained battery voltage.  Either way, if the amp is built worth a crap, it has sufficient PSU capacitance internally to handle XXms loads for the kick drum's bite, and adding another externally isn't really necessary.

[SL4P]

I always enjoy seeing those 2000W (peak) chinese music boxes on display, that dim the power supply LEDs even on quite gentle tracks.
I reckon they'd be hard pressed putting out 10W rms.

[TMM]

AmmoJammo,

Looks good.

if you don't already know this, (i learned when I was working for a company installing custom Stereos), if you mix sawdust in with resin, pretty thick, and smear it all over the box inside, it does one of two things....

1.  Seals up the inside of the box
2.  Creates a bumpy effect inside the box which will break up the sound waves inside the box so they don't reflect back into the subs.

Doing this will actually make your sound quality, DB, and SPL better.

That's funny because the SPL competitors i know swear by coating the inside of their boxes with resin to achieve a glass-smooth finish. They claim it is worth 0.1-0.2dB. I still think they are mad. A few millimeters deviation in surface finish isn't going to do anything substantial to bass frequencies which have wavelengths measured in meters.

[Falcon69]

NO!  Not a smooth free finish.  That's why you throw sawdust in the resin and mix it before pouring it.

You want a bumpy and jagged effect.  That's where the waveforms will get broken up and not reflect back into the speaker.

A glass smooth finish is a No No

[AmmoJammo]

AmmoJammo,

Looks good.

if you don't already know this, (i learned when I was working for a company installing custom Stereos), if you mix sawdust in with resin, pretty thick, and smear it all over the box inside, it does one of two things....

1.  Seals up the inside of the box
2.  Creates a bumpy effect inside the box which will break up the sound waves inside the box so they don't reflect back into the subs.

Doing this will actually make your sound quality, DB, and SPL better.

That's funny because the SPL competitors i know swear by coating the inside of their boxes with resin to achieve a glass-smooth finish. They claim it is worth 0.1-0.2dB. I still think they are mad. A few millimeters deviation in surface finish isn't going to do anything substantial to bass frequencies which have wavelengths measured in meters.

smooth inside, rounded corners in the right places, and a flared/rounded exit on the port will always gain something, plus other things, like rounding the back edge of the woofer cutouts, removing the plastic covers from the subs magnets if they have one, and even duct taping parts of the box can all gain fractions of a decibel

In competition, you could win or lose by 0.1dB, and I've beaten people by 0.1 and 0.2dB before, so every 0.1dB counts!

[dannyf]

A few millimeters deviation in surface finish isn't going to do anything substantial ...

Whether they do it is not important;

Whether they are believed to do it is very important.

[SirNick]

This stuff is actually regularly measured WRT to the front baffle of a speaker.  E.g., should the tweeter be placed symmetrically or offset to one side?  How close to the edge?  Should the edge be rounded?  What about rounding the edge of the cutout?

It is mostly all fractions-of-a-dB stuff, but the usual purpose is to smooth out (or at least distribute the imperfections in) the frequency response due to reflection and refraction.  Not so much affecting the absolute loudness.  Even chamfering the backside of a driver's cutout is intended more to prevent non-linear response, and usually only in the case where the baffle is a significant portion of the driver's depth.

For bass frequencies, the difference is mostly immeasurable -- somewhere in the noise.  Rounding the port is helpful -- mostly to prevent turbulence at the mouth from being distinctly audible.  (Hey, that could even give you a couple tenths of a dB lead.)

So yeah, all these things do contribute in minute ways, although I have my doubts that most aspiring Sonic Boomers have access to equipment with accuracy high enough to measure the differences in a repeatable fashion.  Just as likely to skew the results from a butterfly farting half a meter away.  Could be wrong though.

[AmmoJammo]

OK, so.... that's a ported enclosure then?  What's the tuning frequency?  How much volume per driver?  Doesn't look like all that much, what with the enormous basket, although you're starting to run out of car as it is.

subs are inverted (for now anyway) box is 350 litres tuned to about 36Hz, although I believe its actually slightly lower, closer to 34hz :p

I would have rathered closer to 400 litres, but wanted to keep it below the window line.

[cimmo]

What a waste of human endeavour.

[Falcon69]

What a waste of human endeavour.

Nah, there's good satisfaction rolling by your x-girlfriend's at 3 in the morning on a Sunday night bumping your system..........then come back every half hour.

[SeanB]

4AM the next door guy will be waiting for you with a baseball bat, a shotgun, a jerry can of petrol and a lighter.

When the guys upstairs would not listen after 3 nights straight I went down and turned off the power. If I had been nasty _____________________________________________. Peace ensued, and they kept the volume down afterwards.

[jlmoon]

[ In a "Crocodile Dundee" voice ]

That's not a capacitor...

This is a capacitor!

That's also not a capacitor...

This is a capacitor!

no, that's a Door Stop!