| msm677 |
| is it ok to change the capacitor of my jvc amplifier from 35v 1000uf to 35 3300uf? whats the effect? |
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| DavidWardlaw |
| unless it's a variable capacitor, I don't think you can change the capacitance...the effect WOULD be a better bass response in your speakers (in most cases) |
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| Arx |
| quote: | Originally posted by msm677
is it ok to change the capacitor of my jvc amplifier from 35v 1000uf to 35 3300uf? whats the effect? |
Depends where it is. Assuming it's the one at the output of the power supply section it probably wouldn't hurt anything to replace it with a bigger cap. The effect will be reduced power supply ripple. It depends on the amplifier design, but you probably won't hear any difference.
If you're thinking of replacing it with a different one because the current one is bad, and the 3300 is what you've got on hand, I'd probably go for it.
If you're looking for a tweak to improve your sound, I'd probably look elsewhere.
-Nick |
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| msm677 |
| quote: | Originally posted by Arx
Depends where it is. Assuming it's the one at the output of the power supply section it probably wouldn't hurt anything to replace it with a bigger cap. The effect will be reduced power supply ripple. It depends on the amplifier design, but you probably won't hear any difference.
If you're thinking of replacing it with a different one because the current one is bad, and the 3300 is what you've got on hand, I'd probably go for it.
If you're looking for a tweak to improve your sound, I'd probably look elsewhere.
-Nick |
I think its the power supply cause they're the biggest capacitor in my amp.
if i'm going to improve the the sound, where will I look and what will I change? the capacitor for the transistors?, transistors?, resistors?, please help me. |
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| BlueWizard |
Increasing the size of the Power Supply caps might help increase transient response. When the amp has a huge power demand placed on it, sometimes the power supply can't keep up and the available voltage drops. With bigger Caps, for very short term power demands, this might help keep the voltage up longer.
Unless the Amp is somehow broken, I can't think of anything the average user can do to to the internal components to improve it.
Steve/BlueWizard |
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| msm677 |
| quote: | Originally posted by BlueWizard
Increasing the size of the Power Supply caps might help increase transient response. When the amp has a huge power demand placed on it, sometimes the power supply can't keep up and the available voltage drops. With bigger Caps, for very short term power demands, this might help keep the voltage up longer.
Unless the Amp is somehow broken, I can't think of anything the average user can do to to the internal components to improve it.
Steve/BlueWizard |
the amp is good, I just want to know if I can improve the sound or increase its wattage (if possible) |
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| Arx |
| quote: | Originally posted by msm677
the amp is good, I just want to know if I can improve the sound or increase its wattage (if possible) |
Nope...
Bigger caps may give you slightly less output ripple under maximum load.
I don't think anyone would really hear a difference.
It won't increase the wattage, and any improvement in the sound will probably be insignificant.
To increase the wattage, you probably need to modify the power supply for a higher voltage, which would likely require changing many other parts. It may be cheaper to buy a bigger amp.
-Nick |
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| Sonusthree |
Hi,
You may well hear slightly tighter bass and find that the amp will handle very slightly higher levels before showing compression, (especially with bass heavy music).
Your speakers may give out before you have a chance to find this out. ;)
These kind of mods can, in some cases, have a negative effect on the upper frequencies. The difference between 1000uF and 3300uF in this situation is not massive so, as mentioned before, you may not actually notice the difference.
Regards,
Martin. :) |
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| Arx |
| quote: | Originally posted by Sonusthree
Hi,
You may well hear slightly tighter bass and find that the amp will handle very slightly higher levels before showing compression, (especially with bass heavy music).
Your speakers may give out before you have a chance to find this out. ;)
These kind of mods can, in some cases, have a negative effect on the upper frequencies. The difference between 1000uF and 3300uF in this situation is not massive so, as mentioned before, you may not actually notice the difference.
Regards,
Martin. :) |
The cap is just there to keep the power steady between pulses from the power supply.
Assuming the amplifier a reasonable PSRR you shouldn't really hear any difference, as long as the capacitor's voltage stays above what the amplifier needs to produce the instantaneous voltage it's trying to. If the capacitor isn't big enough, its voltage may be drained by the amplifier enough that it will not be able to produce that voltage, until the next current pulse from the supply recharges it. What you'll end up with is a form of clipping which tracks the power supply ripple. Assuming the cap is even vaguely reasonable, the only difference a bigger one will make is letting your clipping track a slightly less jaggy sawtooth.
As far as the effect on upper frequencies goes, I've never had anyone demonstrate any difference, or even give me a sound theory how it could be different.
The only reason I could think of is that the current pulses from the supply will become shorter in duration and higher in magnitude. Maybe the higher frequencies on this could leak into the amp? Any thoughts?
But regardless. I wouldn't waste my time without at least measuring the supply ripple to see if it's even significant under heavy load.
-Nick |
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| msm677 |
| quote: | Originally posted by Arx
The cap is just there to keep the power steady between pulses from the power supply.
Assuming the amplifier a reasonable PSRR you shouldn't really hear any difference, as long as the capacitor's voltage stays above what the amplifier needs to produce the instantaneous voltage it's trying to. If the capacitor isn't big enough, its voltage may be drained by the amplifier enough that it will not be able to produce that voltage, until the next current pulse from the supply recharges it. What you'll end up with is a form of clipping which tracks the power supply ripple. Assuming the cap is even vaguely reasonable, the only difference a bigger one will make is letting your clipping track a slightly less jaggy sawtooth.
As far as the effect on upper frequencies goes, I've never had anyone demonstrate any difference, or even give me a sound theory how it could be different.
The only reason I could think of is that the current pulses from the supply will become shorter in duration and higher in magnitude. Maybe the higher frequencies on this could leak into the amp? Any thoughts?
But regardless. I wouldn't waste my time without at least measuring the supply ripple to see if it's even significant under heavy load.
-Nick |
how do i measure the supply ripple? |
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| john |
Changing 1000 uf 35V to 3300 uf 35V will have negligible effect on the performance of your car amplifier. As a part replacement, The higher capacitor rating will work fine.
Setting up a 1 farad capacitor at the power supply section will result in an audible difference. Tighter bass but a roll off on the higher frequencies might result.
Setting up test instruments to measure supply ripple is costly and a waste of time since the result will be insignificant to the performance of the car amp.
Check Cabling, This might improve the sonic performance of your car audio system by using a good sounding quality cables.
Tweaking the circuitry of the car amp and changing some parts will yield both positive and negative results but this voids the warranty and a costly endeavor outweighing the resulting sonic performance of the car amp. |
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| cliff |
| quote: | Originally posted by john
Changing 1000 uf 35V to 3300 uf 35V will have negligible effect on the performance of your car amplifier. As a part replacement, The higher capacitor rating will work fine.
Setting up a 1 farad capacitor at the power supply section will result in an audible difference. Tighter bass but a roll off on the higher frequencies might result.
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Could you explain why you think this could affect the treble response? |
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| jnb |
Electrolytic capacitors have series inductance. This resonates with the capacitance. The resonance is sometimes underdamped and is sometimes within the audio band. Larger capacitors can be worse than smaller ones (obviously this is a generalisation).
If this wasn't so, it would probably be only a good thing to increase the capacitance from 1000uF to 3300uF, provided the circuit would not be overstressed in any way. |
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| cliff |
Non of that is relevant to a PSU reservoir cap!
And what do you mean by "overstressed"? |
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| jnb |
| quote: | Originally posted by cliff
Non of that is relevant to a PSU reservoir cap! |
An amplifier stage is in series with it's supply capacitor for AC. The source impedance will be different across the spectrum.
You may have been referring to the 1F cap before a switch mode supply, I'm not sure but you weren't specific.
| quote: | | And what do you mean by "overstressed"? |
Just thinking of inrush currents and so forth. |
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| cliff |
| quote: | Originally posted by jnb
An amplifier stage is in series with it's supply capacitor for AC. The source impedance will be different across the spectrum.
You may have been referring to the 1F cap before a switch mode supply, I'm not sure but you weren't specific.
Just thinking of inrush currents and so forth. |
It sounds to me like you have just completed "Audio Amps 101" :)
Do you really think (THINK about it) that doubling supply capacitance lowers treble response? Silly nonsense. So you get the "best" treble response with NO capacitance?
There are many other parallel paths that give low HF impedance paths.
Car batteries supply lots of inrush current, worst case is that the fuse will need uprating. |
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| Arx |
| quote: | Originally posted by cliff
Car batteries supply lots of inrush current, worst case is that the fuse will need uprating. |
What capacitor are we talking about.
If it's between the SMPS and the amplifier itself, worst case is that the switching power supply isn't designed with a big capacitor in mind and blows its choppers.
It's very unlikely when only tripling the size, but if it's designed badly it can happen.
If it's an input filter cap or something, go nuts, but you could just as easily buy one of those big 1F caps and hook it up at the power before it goes into the amp.
I don't think that will improve much either on an amp that isn't ridiculously large.
-Nick |
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| jnb |
| quote: | Originally posted by cliff
There are many other parallel paths that give low HF impedance paths. |
Such as?| quote: | It sounds to me like you have just completed "Audio Amps 101" :)
Do you really think (THINK about it) that doubling supply capacitance lowers treble response? Silly nonsense. So you get the "best" treble response with NO capacitance? |
Thanks for your comments.
cliff, are you disputing the existence of ESL or something else WRT it?
http://www.diyaudio.com/forums/show...663#post1189663 |
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| msm677 |
hey, hey, hey peace to all:)
I just want help on something. I appreciate the help I got from all of you guys and learned a lot. but please, no argument in here. peace :) |
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| jnb |
Peace to you too, msm677.
cliff, feel free to private message me or start a new thread if interested. |
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| john |
http://en.wikipedia.org/wiki/Stiffening_capacitor
Aluminum electrolytic: Polarized. Constructionally similar to metal film, but the electrodes are made of etched aluminium to acquire much larger surfaces. The dielectric is soaked with liquid electrolyte. They can achieve high capacities but suffer from poor tolerances, high instability, gradual loss of capacity especially when subjected to heat, and high leakage. Tend to lose capacity in low temperatures. Bad frequency characteristics make them unsuited for high-frequency applications. Special types with low equivalent series resistance are available. |
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| Arx |
| quote: | Originally posted by john
http://en.wikipedia.org/wiki/Stiffening_capacitor
Aluminum electrolytic: Polarized. Constructionally similar to metal film, but the electrodes are made of etched aluminium to acquire much larger surfaces. The dielectric is soaked with liquid electrolyte. They can achieve high capacities but suffer from poor tolerances, high instability, gradual loss of capacity especially when subjected to heat, and high leakage. Tend to lose capacity in low temperatures. Bad frequency characteristics make them unsuited for high-frequency applications. Special types with low equivalent series resistance are available. |
Keep in mind, though, that "high-frequency" is a relative term.
-Nick |
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| Arx |
Okay.
Quoted from page 3 of that article:
"This is because the equivalent series inductance does not vary significantly with capacitance"
So, how again does a bigger capacitor hurt treble?
Maybe I'm misunderstanding what they're saying, because I had always heard that bigger caps have more inductance.
Perhaps it's just that paralleled caps have less?
-Nick |
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| john |
Bypassing and decoupling refers to energy transference from one circuit to another in addition to enhancing the quality of the power distribution system. Three areas are of concern: power and ground planes, components, and internal power connections.
Decoupling is a means of overcoming physical and time constraints caused by digital circuitry switching logic states. Digital logic involves two possible states, "0" or "1." Decoupling is required to provide sufficient dynamic voltage and current for proper operation of components during clock or data transitions when all component signal pins switch simultaneously under maximum capacitive load. Decoupling is accomplished by ensuring that a low-impedance source is present for the power and ground distribution network. Because capacitors decrease in impedance up to the point of self-resonance, high-frequency noise is effectively diverted from the power distribution system. Low-frequency RF energy transference remains relatively unaffected.
Three common types of capacitor usage exist: bulk, bypass, and decoupling. All capacitor values must be calculated for a specific function. In addition, properly select the dielectric properties of the capacitor, and not leave it to random choice from past usage or experience.
A capacitor may also be used in other applications such as timing, wave shaping, integration, and filtering. When discussing capacitors among associates, proper description and use of the capacitor is required. · Decoupling. Removes RF energy injected into the power distribution network from high-frequency components consuming power at the speed the device is switching at. Decoupling capacitors also provides a localized source of DC power for devices and components, and is particularly useful in reducing peak current surges propagated across the board. · Bypassing. Diverts unwanted common-mode RF energy from components or cables. This is essential in creating an AC shunt to remove undesired RF energy from entering susceptible areas in addition to providing other functions of filtering (bandwidth limiting). · Bulk. Used to maintain constant DC voltage and current to components when all signal pins switch simultaneously under maximum capacitive load. It also prevents power dropout due to dI/dt current surges generated by components. |
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