capacitor help

i'm counting down the time until this becomes a capacitor works vs. capacitors don't work thread. I love those.
Yeah, especially when the same topic gets posted every two weeks...

Funny how that works.

And technically...he's not lying...lots of speakers can take 6kW; for burps //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 
Maybe this one-

hk12x212hp.jpg


HK12X2

1500W RMS

3000W MAX

Sensitivity: 88.9dB @ 1w/1m

Mounting Depth 8”

Mounting Diameter 11”

Vented Box: 3.0 cu/ft

Port: 48 sq/in 14.5” Long

Sealed Box: 1.5-2.25 cu/ft

I bet it has the mostsest awsome Spl evar because its got big power handling.

 
Yeah, especially when the same topic gets posted every two weeks...
Funny how that works.

And technically...he's not lying...lots of speakers can take 6kW; for burps //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

i swear i'm the only fcking newb who knows how to use the search function. having said that.. i need to make a new amp thread **** IT!!!

//content.invisioncic.com/y282845/emoticons/search.gif.e79a63b2b580b39b282dff402646b704.gif//content.invisioncic.com/y282845/emoticons/search.gif.e79a63b2b580b39b282dff402646b704.gif//content.invisioncic.com/y282845/emoticons/search.gif.e79a63b2b580b39b282dff402646b704.gif

 
Anyways heres a technical guide to stiffening caps-

2.9 What is a "stiffening capacitor", and how does it work? [JSC]

=======================================================================

"Stiffening Capacitor" (note capitals) is a trademark of Autosound

2000. However, "stiffening capacitor" (note lowercase), as a generic

term, refers to a large capacitor (several thousand microfarads or

greater) placed in parallel with an amplifier. The purpose of doing so

is to provide a sort of reserve power source from which the amplifier

can rapidly draw power when it needs it (such as during a deep bass

note). The electrical theory is that when the amplifier attempts to

draw a large amount of current, not only will the battery be relatively

slow to respond, but the voltage at the amplifier will be a little lower

than the voltage at the battery itself (this is called "line drop"). A

capacitor at the amplifier which is charged to the battery voltage will

try to stabilize the voltage level at the amplifier, dumping current

into the amplifier. Another way to think about it is that a capacitor

in parallel with a load acts as a low pass filter (see Section 3.10),

and the voltage level dropping at the amplifier will appear as an AC

waveform superimposed upon a DC "wave". The capacitor, then, will try

to filter out this AC wave, leaving the pure DC which the amplifier

requires.

The following sections provide more detail about when and why to use a

stiffening capacitor.

2.9.1 Do I need a capacitor? [MZ]

-----------------------------------

Before installation, it's often difficult to predict whether or not a

capacitor will be beneficial to you. It's generally best to install

the audio equipment prior to making the determination, so that you can

address which symptoms need to be remedied and assess the severity of

the symptoms. This will not only help you decide whether or not you

need a capacitor, but also how much capacitance would be beneficial.

The most common symptom in need of added capacitance is headlight

dimming (and sometimes dimming of the interior/dash lights). It's

caused by a drop in system voltage associated with excessive current

draw. While there may indeed be several loads drawing substantial

amounts of current from the electrical system (eg. heat, AC, and so

forth), it's usually the transient draws that best manifest themselves

in noticeable dimming. This is partly because our visual systems are

most sensitive to detecting rapidly changing intensity levels rather

than steady absolute differences.

Once you've assessed whether or not the dimming is noticeable (and

sufficiently annoying), you must decide whether a capacitor is

warranted or if you'd be better served by upgrading the alternator.

After initially having your alternator and battery checked out (some

places will do this for free), the choice should be based on the

severity of the dimming.

A commonly-used estimate for determining the appropriate size capacitor

is 1F/kW (one farad per kilowatt). For example, a system running at

300W would need a 0.3F (or 300,000uF) capacitor. However, there are

several variables at play here, including the capabilities of the

vehicle's electrical system (which generally varies from idle to higher

RPMs), the efficiency of the amplifiers, and the listening habits of

the user (ie. the tone controls and the type of music). These factors

should all be considered when making the determination. Moreover, the

voltage drop can be so severe that added capacitance is nothing more

than a band-aid. That is, even several Farads of capacitance would not

be able to sustain the voltage for as long as the drop persists. This

is when an alternator upgrade may be in order.

2.9.2 Can I just upgrade my headlight wiring instead? [MZ]

------------------------------------------------------------

Although headlight wiring upgrades can often be beneficial for

achieving a higher steady-state illumination, it will not improve the

dimming situation. Since the headlights are not the cause of the

voltage fluctuations that are producing the dimming, upgrading the

wiring will not fix the problem. The voltage fluctuation is present at

the battery terminals, so it will be transmitted to the headlights

regardless of how the headlights are wired. If you think of the

fluctuation as an AC signal, then it becomes readily apparent that this

circuit can be represented by an AC signal in a voltage divider.

Decreasing the resistance in series with the load by upgrading the

headlight wiring actually serves to slightly enhance the AC signal at

the headlight's terminals. In other words, the dimming effect could

become even worse by upgrading the headlight wiring!

2.9.3 Will the dimming go away if I upgrade the amplifier power/ground

wiring? [MZ]

-----------------------------------------------------------------------

A common myth in the car audio community is that upgrading the power or

ground wire to the amplifier will result in the amplifier drawing less

current and therefore decreasing the voltage fluctuation. While the

logic is sound, the premise is not. Most amplifiers on the market have

semi-regulated supplies which don't maintain a steady power output at a

range of supply voltages. This is reflected in the power ratings

provided by many manufacturers; some provide ratings for their

amplifiers at two different voltages, and the lower voltage almost

always causes the amp to deliver less power. In general, the

difference in power output tends to correspond well with the supply

voltage such that the current draw remains roughly constant (assuming

somewhat similar efficiency). Consequently, upgrading the power/ground

wiring, which serves to increase the voltage at the amplifier's

terminals, will not reduce headlight dimming.

2.9.4 What do I look for when buying a capacitor? [MZ]

--------------------------------------------------------

The single most important attribute is the capacitance value (expressed

in Farads). Put simply, more is better. Another important

consideration is to make sure the maximum voltage rating of the

capacitor safely exceeds the operating voltage of your vehicle's

electrical system. In addition, ESR and ESL values may be provided

with some capacitors to essentially indicate the amount of voltage drop

that occurs when a capacitor is delivering current. Smaller values are

better in this regard.

2.9.5 How do I install a capacitor? [MZ]

------------------------------------------

If you conclude that your best course of action is to install a

capacitor, it should be installed in parallel with the amplifier and,

generally speaking, should be wired with approximately the same gauge

wire used for a single amplifier (usually 8 ga. is sufficient even for

rather large capacitors).

Before permanently installing it, it must be charged. Failure to do so

could lead to blown fuses and lots of sparks! Some capacitors come

with charging resistors. If yours does not, you can simply buy an

automotive bulb and wire it in series with the capacitor's + lead while

the capacitor is grounded. The bulb will continue to dim until the

capacitor is fully charged. Once the capacitor is charged, it should

be treated as you would a car battery; caution must be used to be sure

not to short the terminals.

The final step is to permanently install it into the car. There's been

much debate about where to install the capacitor. It's been argued

that the placement is important because it requires shorter wire

lengths. While this is true, there has never been any evidence

supporting the notion that it should be installed as close

(electrically) to the amplifier as possible. In fact, electrical

theory demonstrates that it's more effective at quenching the dimming

effects by installing it as close to the device exhibiting the symptom

(ie. the headlights) rather than the device that's drawing the bulk of

the current (ie. the amplifiers). However, the benefit to doing so is

negligible. Therefore, hooking it directly to the battery, the

amplifier terminals, or the distribution block are equally valid

solutions as long as the mounting location is safe, the wire lengths

are reasonably short, and there's an adequate ground present.

 
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