What good does having a million watts or tons of current do if you're trying to pass it all through a 16 or 18 gauge inductor ? This is besides the point that some folks are using 20+ gauge wire to feed the signal to the speakers. How much instantaneous or sustained power ( voltage & current ) can you cram through a wire like that ?
With all of that in mind, higher capacitance power supplies are always a good thing. You get less ripple from the AC, increased rejection of AC noise, can sustain longer duration high intensity peaks, bass is firmer with increased "slam" and more consistent tone, etc... Obviously, one gets to a point of diminishing returns and depending on the amount of power being drawn by the amp and the level of reactance from the speaker, the point of diminishing returns can vary pretty drastically. As a given rule though, good sized SS amps should have at least 80,000 to 100,000 uF of capacitance at the minimum. This is especially true if running low impedance speakers with a high level of reactance / reflected EMF.
As mentioned above, there are different ways to achieve high levels of power supply reserve and filtration though, so "big uF's" are not all created equally. One of my preamps uses two 20,000 uF's with bypass caps whereas another uses four 10,000's, a dozen 100 uF's and bypass caps across all of those. The total values are close ( 40,000 vs 41,200 uF ), but as one can see, very different approaches were used. Given that an SS preamp draws such a small amount of power as it is, the main reason for using such a large quantity of capacitance would be for increased filtering of the signal and to keep the impedance of the power supply as low as possible. The higher the impedance of the power supply, the more likely it is to be "modulated" by high levels of reflected EMF. While this is much truer of power amps, the reflected EMF that an amp has to deal with IS passed onto the preamp in terms of altering the load that the preamp sees.
All things being equal, more is better in both categories. That is, so long as the quality is maintained while achieving the higher figures. Sean
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With all of that in mind, higher capacitance power supplies are always a good thing. You get less ripple from the AC, increased rejection of AC noise, can sustain longer duration high intensity peaks, bass is firmer with increased "slam" and more consistent tone, etc... Obviously, one gets to a point of diminishing returns and depending on the amount of power being drawn by the amp and the level of reactance from the speaker, the point of diminishing returns can vary pretty drastically. As a given rule though, good sized SS amps should have at least 80,000 to 100,000 uF of capacitance at the minimum. This is especially true if running low impedance speakers with a high level of reactance / reflected EMF.
As mentioned above, there are different ways to achieve high levels of power supply reserve and filtration though, so "big uF's" are not all created equally. One of my preamps uses two 20,000 uF's with bypass caps whereas another uses four 10,000's, a dozen 100 uF's and bypass caps across all of those. The total values are close ( 40,000 vs 41,200 uF ), but as one can see, very different approaches were used. Given that an SS preamp draws such a small amount of power as it is, the main reason for using such a large quantity of capacitance would be for increased filtering of the signal and to keep the impedance of the power supply as low as possible. The higher the impedance of the power supply, the more likely it is to be "modulated" by high levels of reflected EMF. While this is much truer of power amps, the reflected EMF that an amp has to deal with IS passed onto the preamp in terms of altering the load that the preamp sees.
All things being equal, more is better in both categories. That is, so long as the quality is maintained while achieving the higher figures. Sean
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