My Octane LE has blue caps while I see one on -bay wich has black caps, what would be different about this?
Rail voltage??
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Delftenaar
- Posts: 65
- Joined: Fri Mar 21, 2008 12:27 pm
- Location: The Netherlands
Rail voltage??
Can somebody explain me in easy english what this is exactly? Does it make the amp more stable? Or???
My Octane LE has blue caps while I see one on -bay wich has black caps, what would be different about this?
My Octane LE has blue caps while I see one on -bay wich has black caps, what would be different about this?
Audison VRX 1.500.2
Audison VRX 4.300.2
Audison VRX 6.420.2
Genesis Four channel
Genesis Four channel
Genesis DM200
PPI 430iX
Crossfire vr404
Rockford 1051s
Rockford 851x
Steg K2.01
Steg K2.01
Steg K2.02
Steg K2.03
Steg K4.02
Audison VRX 4.300.2
Audison VRX 6.420.2
Genesis Four channel
Genesis Four channel
Genesis DM200
PPI 430iX
Crossfire vr404
Rockford 1051s
Rockford 851x
Steg K2.01
Steg K2.01
Steg K2.02
Steg K2.03
Steg K4.02
Those are capacitors which are connected after your power supply. Normally you can connect a big capacitor before the amp, to filter the input current. This amp has an array of output capacitors as well! It makes the sound very nice and clear.
I would recommend you install it with a 1 farad cap as well, so both of your currents are filtered. Then you'll have ultimate SQ
I would recommend you install it with a 1 farad cap as well, so both of your currents are filtered. Then you'll have ultimate SQ
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Delftenaar
- Posts: 65
- Joined: Fri Mar 21, 2008 12:27 pm
- Location: The Netherlands
I do have a 1F PG cap 
If I am not mistaken, the "supercharged rail voltage" on the case of the amp is just referring to the center capacitor bank. Most of PG's amps have around 10,000 uF or so per rail. I believe the LE octane has a total of 1 farad rail capacitance, so probably .5 F per rail. 10,000 uF is .01 F, so the octane has a lot more rail capacitance (and a lot more money if you have to swap the caps!).
The benefit? Stipud touched on it. First of all, the rail voltage is generated by turning the vehicles 12Vdc into 12Vac, putting it through a transformer to step the voltage up, and then rectifying it to get DC again. Even the best high speed rectifiers will leave some AC ripple in the DC supply. It is technically not AC, as current flow never changes directions, but the AC ripple shows itself by looking like a DC voltage fluctuation. The purpose of filter caps is to charge to instantaneous "high" peak of the voltage, and discharge this when it slumps, therefore smoothing the AC ripple and maintaining a rail voltage that is an average of the lows and highs. There are formulas to help the engineers determine how large of filter caps are necessary to smooth the ripple down to acceptable limits. Anything above this will help reduce it further, but you can't get rid of it completely with just filter caps. That is okay though, because in a well designed amp, the ripple is low enough that it will not significantly impact the THD and Noise. Audio amps are designed to have a lot of internal feedback, and will happily reject most of the ripple component if it is at a nominal value.
So, from a filtering stand point, there is not a lot to gain by adding another $200 worth of caps on the rails. The advantage that has not been discussed is this: The amplifiers power supply will only make a finite amount of power. If the program material asked more of it than it can provide, then the rail voltage will slump. Since the rail voltage on these amps is not highly regulated (IMO a good thing) then basically if you are asking a lot out of it, you get what you get. If the rail voltage slumps, then the output power drops, and the volume goes down. When you throw 1 farad of rail capacitance into the mix you get a lot more stored energy for those hard hitting musical peaks when the rail voltage would normally slump. Capacitors can charge and discharge nearly instantaneously, so it can provide for those peaks and recharge between the beats, make sense?
As for input capacitance, it is not so much for smoothing AC ripple but for smoothing out the vehicle supply voltage when there is high current draw and the voltage sags, the input capacitance discharges and attempts to maintain the voltage at the level they were charged to. The thing to remember about input capacitance is that they will only charge up to the vehicles supply voltage. If you have a charging system in poor or inadequate condition, and it can't keep up with the load on it, then over time as current is drawn the charging systems over all voltage will sag. There is nothing that a capacitor or even another battery can do to help in this case. Both will only charge to the voltage that the charging system is providing. The other thing to remember about input capacitance is it will try to smooth out the voltage sag anywhere it occurs. It does not strictly just help the amp that it is physically near. It will try to maintain voltage it was charged to throughout the whole electrical system.
Hope that helps.
Later,
Jason
The benefit? Stipud touched on it. First of all, the rail voltage is generated by turning the vehicles 12Vdc into 12Vac, putting it through a transformer to step the voltage up, and then rectifying it to get DC again. Even the best high speed rectifiers will leave some AC ripple in the DC supply. It is technically not AC, as current flow never changes directions, but the AC ripple shows itself by looking like a DC voltage fluctuation. The purpose of filter caps is to charge to instantaneous "high" peak of the voltage, and discharge this when it slumps, therefore smoothing the AC ripple and maintaining a rail voltage that is an average of the lows and highs. There are formulas to help the engineers determine how large of filter caps are necessary to smooth the ripple down to acceptable limits. Anything above this will help reduce it further, but you can't get rid of it completely with just filter caps. That is okay though, because in a well designed amp, the ripple is low enough that it will not significantly impact the THD and Noise. Audio amps are designed to have a lot of internal feedback, and will happily reject most of the ripple component if it is at a nominal value.
So, from a filtering stand point, there is not a lot to gain by adding another $200 worth of caps on the rails. The advantage that has not been discussed is this: The amplifiers power supply will only make a finite amount of power. If the program material asked more of it than it can provide, then the rail voltage will slump. Since the rail voltage on these amps is not highly regulated (IMO a good thing) then basically if you are asking a lot out of it, you get what you get. If the rail voltage slumps, then the output power drops, and the volume goes down. When you throw 1 farad of rail capacitance into the mix you get a lot more stored energy for those hard hitting musical peaks when the rail voltage would normally slump. Capacitors can charge and discharge nearly instantaneously, so it can provide for those peaks and recharge between the beats, make sense?
As for input capacitance, it is not so much for smoothing AC ripple but for smoothing out the vehicle supply voltage when there is high current draw and the voltage sags, the input capacitance discharges and attempts to maintain the voltage at the level they were charged to. The thing to remember about input capacitance is that they will only charge up to the vehicles supply voltage. If you have a charging system in poor or inadequate condition, and it can't keep up with the load on it, then over time as current is drawn the charging systems over all voltage will sag. There is nothing that a capacitor or even another battery can do to help in this case. Both will only charge to the voltage that the charging system is providing. The other thing to remember about input capacitance is it will try to smooth out the voltage sag anywhere it occurs. It does not strictly just help the amp that it is physically near. It will try to maintain voltage it was charged to throughout the whole electrical system.
Hope that helps.
Later,
Jason