Hi,
Its pretty clear high psu ripple limits voltage swing, all you need
to do it get it low enough compared to the voltage swing and you'll
gain very little extra power above a certain point. You may still gain
sound quality by reducing ripple depending on circuitry details.
Still its probably better to work on improving the circuits PSRR than
chucking large quantities of capacitance into the supply for low ripple.
rgds, sreten.
Its pretty clear high psu ripple limits voltage swing, all you need
to do it get it low enough compared to the voltage swing and you'll
gain very little extra power above a certain point. You may still gain
sound quality by reducing ripple depending on circuitry details.
Still its probably better to work on improving the circuits PSRR than
chucking large quantities of capacitance into the supply for low ripple.
rgds, sreten.
@TheGabbleDuck that is not verry accurate because current needed by the load is what's discharging the caps, and an 'x' current on a 'y' load can only be achieved by a 'z' voltage, in other words you cannot generalise the capacity needed for a given load, you have to take into account the voltage of the PSU witch gives a finite power and thus a needed current.
Well as it was pointed out here the caps really do influence the power amp performance, the reasons have already been sayd. So yes, i think that is is worth it giving enough importance to the size of the caps, and i agree, it would be better using more paralelled smaller ones than one big cap, it all comes down to the buget of the work needed to be done and the space available inside the case, and why not some maybe important part of it plays the designer's/buider's inspiration and experiance.
Glad too see that
Well as it was pointed out here the caps really do influence the power amp performance, the reasons have already been sayd. So yes, i think that is is worth it giving enough importance to the size of the caps, and i agree, it would be better using more paralelled smaller ones than one big cap, it all comes down to the buget of the work needed to be done and the space available inside the case, and why not some maybe important part of it plays the designer's/buider's inspiration and experiance.
Apologies - that should be 12,500uF not 2500uF, for the 8R load in my last example!
MarianB, I appreciate what you're explaining - but 63.2% is always true, whatever voltage, for the RC time constant, otherwise voltage too would be specified in the time constant calculation. So, two 10,000uF caps, one discharging from 100V to 36.8V and the other discharging from 10V to 3.68V will do so in the same time, for an identical load. I was generalising because it could be 10% of 40V, or of 100V, therefore the calculations had to reflect that, but of course, you have to take into account the minimum V/I for required R, where I made the assumption we were above minimum voltage, and merely wanted to improve things - as in the graph in the first post.
Basically, my point was just about keeping the supply within a given percentage, to maintain voltage swing capability, as I thought that was the main point of contention.
MarianB, I appreciate what you're explaining - but 63.2% is always true, whatever voltage, for the RC time constant, otherwise voltage too would be specified in the time constant calculation. So, two 10,000uF caps, one discharging from 100V to 36.8V and the other discharging from 10V to 3.68V will do so in the same time, for an identical load. I was generalising because it could be 10% of 40V, or of 100V, therefore the calculations had to reflect that, but of course, you have to take into account the minimum V/I for required R, where I made the assumption we were above minimum voltage, and merely wanted to improve things - as in the graph in the first post.
Basically, my point was just about keeping the supply within a given percentage, to maintain voltage swing capability, as I thought that was the main point of contention.
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