Does no one have any car audio? - here's mine

[sdoom]

Hi

sorry ´bout my English, I hope I can make myself understandable. I said, if the engine is running, the capacitor helps getting a higher voltage .

The generator -voltage is higher than the battery voltage, otherwise we couldn´t charge the car´s battery , which actually is no battery, it is a accumulator ( meaning a rechargable battery).

If you take a look at the generator´s voltage, it is not flat, it ´s more like a wave. the big capcitors mounted near the amplifier will charge up to the maximum voltage of that wave , (as simple as a normal rectifing unit placed after a 110V transformer) . Thus giving most amplifiers the ability to produce highe output power as the amplifiers DC-converter will run more effective on higher input voltage. E.g. Hifonics Zeus (series 8) has a variopower DC-converter, the manual says that input voltage doesn´t matter.........well in all tests with those amplifiers they delivered more output power running @15V than they did running at 12V .....

A car battery is not able to charge that fast !

Also the big capacitor is faster than a battery . If placed very close to the amplifiers it will always have a postivie effect, regardless if you use a second battery, bigger alternators or other stuff.

We did a couple of tests with a 1kW- Digiamp inside the car running sinewaves and Musik from a Test-CD , with and without 2x1F capacitors. We monitored the voltage and current draw (via a shunt) and the Caps really flatend the voltage at any current draw.

I agree that the CAP is discharged very fast, too, but it also charges much much faster than the battery does. So an additional / bigger alternator and/or battery help very much to run the 12V-System more stable at high and steady current flow, but for the peaks a capacitor is essential. Again, this only works out if cables (from amp to cap) are thick and short, otherwise the principle of the cap doesn´t work.

______________________________________

The reason why to upgrade the capacitors in the SMPS was said already. most of the times, capacitors in a SMPS are not high-quality. Most car amplifiers are mass-products and the manuf. want to make big money, that´s another reason why most of this stuff is made in China and Korea.

the capcitors in a SMPS on the input side usually have 105°C and lower ESR (Ripple current is higher on the input side) compared to the secondary side capacitors (85°C , regular cap).

As the SMPS runs square signals through the transformer (its closer to square tahn to sine) and at much higher frequency (aroun 20-50kHz depending on the layout) , the time were no voltage produced by the transformer is very short, therefore caps usually are small on the secondary side of the smps. But again, more capacity is more helpfull than less. In the Crunch, there are only 2x3300µF , and I thought for pure subwoofer use that could be a bit more (as I run the amplifier in 2x bridge mode). I used capacitors from a broken amplifier, Low-ESR and 105° and because there was enough room on the curcuit board I installed 8x2200µF . This will keep the output voltage of the DC converter more stable under higher current drains.

[maxw]

I am going to steer clear of the capacitor debate

Finshed Parcel tray



...and started sub enclosure



....for this sub:

http://www.imagesubs.co.nz/products/ls12x.asp

[Stuart Easson]

...I have always gone to great lengths to maintain a more stealthy mode of install, I don't want someone to be inspired to try and rip-off my stuff...

I have a lot of car audio, a lot of recently fixed amps, but I'm embarrassed to admit most of it is not installed.

On the finished list: I have a pair of GMC typhoons, small SUVs, that have Infinity Reference 6x4, 2 way, plate speakers up front, driven by Pioneer head units (DEH85 I think), the rear speakers are KEF Kar and Infinity Reference, 6x9, 2 way, driven by a SoundStream Reference 200 (high power mode). All the way at the back, mounted in the tailgate I have a pair of Onkyo auto subs, 6x9's with a PP xmax of 12mm, and 2 ohms VCs. These are driven from bridged SoundStream SA80s, fed by a 4 into 1 crossover.

For the most part the capacitor debate is pretty easy, if you've used one and like the result, you have your answer.

Technically speaking, I am 'viewing' the results of running an amp at full power. The way current is drawn is not 'steady', nor is it wholely a function of the audio signal being played, so peoples analysis where they assume the caps are working on a DC supply, modulated by the music are much too simplistic. The supply side is more complex than the output side, so any technical evaluation had better show me more a little more depth than the normal ones I've seen. The SMPS is running at anything from a few tens of kHz to a few hundred, and it draws current on this 'schedule'. At these frequencies, the cables feeding the amps have a more significant impedance, and also measurable skin effect. So someone telling about DC currents and averages will only convince me the person hasn't actually thought about or measured the problem...

Stuart

[lilduff88]

what is the RMS on 6by9 speakers. I have an idea but i would appreciate it if someone would let me know.

[maxw]

Originally posted by lilduff88
what is the RMS on 6by9 speakers. I have an idea but i would appreciate it if someone would let me know.

Sounds like you dont quite know what you are asking
Which particular 6x9" speakers did you want to know the power handling in RMS for?

[malcom_xavior]

warren g -
what are the urls to some of these forums?

[SupraGuy]

Originally posted by Stuart Easson
...I have always gone to great lengths to maintain a more stealthy mode of install, I don't want someone to be inspired to try and rip-off my stuff...

You've got that right. This is also the reason that I have a good alarm system installed (Which my neighbors will hopefully never hear) and I always turn the volume down whenever I'm near home.

Originally posted by Stuart Easson
Technically speaking, I am 'viewing' the results of running an amp at full power. The way current is drawn is not 'steady', nor is it wholely a function of the audio signal being played, so peoples analysis where they assume the caps are working on a DC supply, modulated by the music are much too simplistic. The supply side is more complex than the output side, so any technical evaluation had better show me more a little more depth than the normal ones I've seen. The SMPS is running at anything from a few tens of kHz to a few hundred, and it draws current on this 'schedule'. At these frequencies, the cables feeding the amps have a more significant impedance, and also measurable skin effect. So someone telling about DC currents and averages will only convince me the person hasn't actually thought about or measured the problem...

Hmmm... Most of the things I see people talk about caps for is to prevent fading lights. In this case, averages do work... Against you.

I have no doubt whatsoever that a stiffening cap is a good thing to have on an amp. It won't make up for an inadequate electrical system, nor is is panacea for all evils of car audio, but it's a good thing nonetheless.

I think of amplifier current draw as being something akin to the air intake into an engine. There are a lot of parallels there. An engine doesn't take a smooth flow of air in, it takes it in small gulps as the intake valves open. So too, and amplifier takes current according to its demand. From some standpoints, it makes sense to just measure the average flow on a volume (coulombs) over time basis, however, there are large variations from moment to moment. A capacitor helps convert these fluctuations into a steady flow, which the battery and electrical system are better equiped to provide.

[Stuart Easson]

Hi,

lilduff, the RMS rating for a speaker is the amount of power the speaker can be driven with, continuously before failing. *Ideally* it is derived from a few things, minimally the maximum heat power the voicecoil (VC) of the speaker can stand, and the maximum low freq physical excursion the cone, VC and spider can stand. Most car speaker manufacturers completely ignore the excursion limits, basically because it depends on freq and enclosure, and then they ridiculously overrate the thermal capability.

For some guidelines, If you look at the physical specs and the driver has a 1" voice coil, a 'good' VC has a thermal power rating that is around 35w, there are cases above and below, but this is a realistic start. There is no way it can be 200w, or any other random, huge number their marketing dept came up with, it is physically impossible. As the diameter increases, so does the surface area of the windings, and the amount of heat the VC can dissipate. But it increases as the square of the diameter, so other things being equal a 2" VC can cope with 150w, a 3" VC gets into the hundreds. Long term there will be other factors that contribute, all that heat has to go somewhere, the speaker frame will begin to heat up and eventually the power has to get into the open air. If your speakers are trapped in a very small space, they will again begin to overheat after max power for long periods...the VC glue will fail or the the expansion of the copper windings will distort the former too far and the VC will rub against the magnet assembly, perhaps shorting out in the process.

Hope that helps

Stuart

[minitruck_freq]

i have a pile of crap going in my truck 1 of these days. for now its all sitting in my bedroom collecting dust.

Alpine CDA-9833
Audio Control Overdrive line driver
Audio Control 24XS xover
Audio Control EQL
Vifa 7" PL18WO's
LPG 25NFA's
Image Dynamics ID10
Arc Audio 4050 CXL
Arc Audio 2500 CXL

i have a Tru Technology T-4.65 i may use instead of the 4050. havent decided yet.

[maxw]

Originally posted by minitruck_freq
i have a pile of crap going in my truck 1 of these days. for now its all sitting in my bedroom collecting dust.

Alpine CDA-9833
Audio Control Overdrive line driver
Audio Control 24XS xover
Audio Control EQL
Vifa 7" PL18WO's
LPG 25NFA's
Image Dynamics ID10
Arc Audio 4050 CXL
Arc Audio 2500 CXL

i have a Tru Technology T-4.65 i may use instead of the 4050. havent decided yet.

WOW, thats some expensive kit!