Can I stick a capacitor on my speakers. - AVS Forum
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post #1 of 12 Old 06-28-2013, 09:00 AM - Thread Starter
 
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Like a car, can one attach a monster capacitor to their speakers?

Image provided as an example.



The idea, bolt something like the above capacitor onto the back of the speaker and wire everything up per normal or would I just make a tremendous spark and fry a really nice speaker system.
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post #2 of 12 Old 06-28-2013, 09:07 AM
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In car audio, the cap goes between the battery and the amp. Not wired as I understand you are proposing
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post #3 of 12 Old 06-28-2013, 09:12 AM
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Quote:
Originally Posted by BeeMan458 View Post

Like a car, can one attach a monster capacitor to their speakers?

Image provided as an example.



The idea, bolt something like the above capacitor onto the back of the speaker and wire everything up per normal or would I just make a tremendous spark and fry a really nice speaker system.

If I recall correctly capacitors only work well with DC. (i.e. car power); not 120v AC or speaker music.

Besides, cap's only supply a few seconds of power at most, usually just enough to smooth the AC ripple of DC rails etc etc

You're best off to just buy a better set of speakers/amps.
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post #4 of 12 Old 06-28-2013, 09:25 AM
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Yeah, a capacitor between your amp and speaker won't really do much good. You'd just be adding capacitive inductance where it isn't needed.

The capacitor doesn't work really the same for AC signals as with DC. They really can only provide a quick burst of power to help compensate for current dips in DC voltage.

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post #5 of 12 Old 06-28-2013, 09:28 AM - Thread Starter
 
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Originally Posted by nater1 View Post

In car audio, the cap goes between the battery and the amp. Not wired as I understand you are proposing

Yes, I was suggesting between the AVR and the speaker. I've never done anything more with a car's audio then replace the battery, the speakers or the receiver.

Can one wire their AVR according to what you suggest. The point being, are AVR manufactures robbing us poor consumers of performance, due to them putting little itty-bitty capacitors in the AVR box?

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Originally Posted by BassThatHz View Post

You're best off to just buy a better set of speakers/amps.

Thanks! In real terms, I'm looking to an Emotiva, XPA-5 as a solution. My OP is just a curiosity question.
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post #6 of 12 Old 06-28-2013, 10:01 AM
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Quote:
Originally Posted by BeeMan458 View Post

Yes, I was suggesting between the AVR and the speaker. I've never done anything more with a car's audio then replace the battery, the speakers or the receiver.

If wired like that, the capacitor is simply a high-pass filter, acting as a crossover and actually reducing your bass response.
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Originally Posted by BeeMan458 View Post

Can one wire their AVR according to what you suggest. The point being, are AVR manufactures robbing us poor consumers of performance, due to them putting little itty-bitty capacitors in the AVR box?

Not exactly. The wall socket provides lots of voltage and current already. Car systems are limited by the battery voltage, so the amplifier current requirements are higher, and the large "stiffening caps" mitigate the peak demands somewhat.

In a grossly oversimplified analysis, a 1000 watt amp in a car wants 83.33 amps at 12 volts to reach full power. A 1000 watt amp in a home setting only draws 8.33 amps at 120 volts. Since the supply voltage is much higher for home and pro gear, the instantaneous current demands are much smaller.

Also - keep in mind that putting a 12-volt rated capacitor across 120 volt mains should cause a nice explosion.
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Originally Posted by BeeMan458 View Post

Thanks! In real terms, I'm looking to an Emotiva, XPA-5 as a solution. My OP is just a curiosity question.

That's a nice amp.
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post #7 of 12 Old 06-28-2013, 11:38 AM - Thread Starter
 
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Quote:
Originally Posted by lilmike View Post

Also - keep in mind that putting a 12-volt rated capacitor across 120 volt mains should cause a nice explosion.

Note: crossing the streams is bad.

Thanks for the explanation.
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post #8 of 12 Old 06-28-2013, 01:42 PM
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That's right, don't EVER let the streams touch biggrin.gif
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post #9 of 12 Old 06-28-2013, 08:36 PM
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Hi BeeMan,
Quote:
Originally Posted by BeeMan458 View Post

Can one wire their AVR according to what you suggest. The point being, are AVR manufactures robbing us poor consumers of performance, due to them putting little itty-bitty capacitors in the AVR box?
Keep in mind that that particular capacitor is not meant to improve audio performance - it is meant to solve a specific problem (and it also looks cool). The problem, due to battery capacity or inadequate gauge wire, is the car's lights flickering from the draw of the amp. Of course, that problem can adversely affect audio performance, so in that case solving the problem does indeed improve performance. But it's wholly inappropriate for an AVR.

If you look over the reviews, how it looks and the lights flickering are the only two reasons anybody buys these things.
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post #10 of 12 Old 06-29-2013, 10:08 PM - Thread Starter
 
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Originally Posted by MarkHotchkiss View Post

If you look over the reviews, how it looks and the lights flickering are the only two reasons anybody buys these things.

Thanks for the reply.
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post #11 of 12 Old 07-01-2013, 11:59 AM
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Quote:
Originally Posted by BeeMan458 View Post

Yes, I was suggesting between the AVR and the speaker. I've never done anything more with a car's audio then replace the battery, the speakers or the receiver.

Can one wire their AVR according to what you suggest. The point being, are AVR manufactures robbing us poor consumers of performance, due to them putting little itty-bitty capacitors in the AVR box?
Thanks! In real terms, I'm looking to an Emotiva, XPA-5 as a solution. My OP is just a curiosity question.

I am appalled that you think you would benefit from a capacitor between the amplifier and the speaker, but you have no idea whatsoever such a thing would do for the sound.

Even in car audio capacitors are used to store electricity (power) for those times when the battery and alternator are not enough. They are hooked up on the power input side of the amplifier. They are never used on the output side of an amplifier. (that excludes the small capacitors used in a speaker's crossover network).

The big capacitors inside the AVR are part of the power supply circuit and used to smooth the DC power. If you buy a good AVR, you can assume the power supply capacitors are properly sized for the current needed by the amplifier.
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post #12 of 12 Old 07-01-2013, 12:47 PM
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Quote:
Originally Posted by hoffdano View Post

Quote:
Originally Posted by BeeMan458 View Post


I am appalled that you think you would benefit from a capacitor between the amplifier and the speaker, but you have no idea whatsoever such a thing would do for the sound.

I'm not appalled because with some box/driver combinations a large series capacitor will add several dB response, which can work kinda cool if its right before the bass roll off.

http://lautsprechershop.de/index_hifi_en.htm?http://lautsprechershop.de/hifi/aka_tief_c_en.htm

"Subwoofer tuning with capacitor in series"

This author finds a ca. 6 dB benefit in some cases, which agrees with some of my findings.

It works with some box/driver combinations and is null with others.

The same thing can happen with midrange drivers and tweeters and result in undesired peaks.

I've seen these in commercial speakers. I'm sure they are completely intentional. I haven't seen any lately but the Acoustic Research AR-LST was one such speaker if memory serves.

Back in the days before +/- power supplies people would get completely blindsided by this effect because the big cap was there to block DC and was outside the feedback loop - about 4,700 or 6,800 uF. . The original Acoustic Research AR3 would pull this stunt.
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