Hi Colin, good to hear you are back to a decent state of health!!
Bad to hear that you are putting temptation in my path!!!
Sorry for being dim, but could you explain what the extra PS board does and also clarify which boards are suitable for which power/option and the costs.
BTW, I still remember very clearly** hearing your system up in Glenrothes all those years ago - seem to recall we played JJ Cale Cloudy Day - excellent sound!
** in both senses of the word
Dave S
Hi Dave,
It was Dalgety Bay not Glenrothes, but hey a long time ago.
Single Ended A Class Amps with a constant current load, like this one have no immunity from ripple or hum on the power rails, in the old TOCA amps I just increase the Bulk Cap size but that now is very costly. This reduced the ripple and problem solved.
For a quick approximation you can say 1A on a 10,000uF give about 1V of ripple, not to good if you want finite detail.
Next the FET,s in the Amp but not the Constant Current load has about 3V across it fully on, this is wasteful.
So to cut the story short I used a Hum Bucking Technique I have used before on MIL spec PSU's and a Current Multiplying Transistor on a simple but very reliable linear psu design.
So the main Bulk caps bring the ripple down to 1V and the Regulator bring it down to about 10mV.
Now to squeeze the FET and reduce that voltage drop.
The PSU is a tracking type very simple but it works, the Zero volt ref is split and that point goes to the power amp and under normal running no change but as the Output of the amp peaks to about 10V the PSU climbs, +v or -v.
Allowing the output to swing rail to rail, or close.
I deal for those nasty dynamic sounds.
We also use large caps after the regulators, just for peak storage of energy.
The regulator have a very simple current fold back the allow the output cap to charge up slower at about 6A, and not 50+Amps.
I do hope this helps a little my writing technique has always been crap.
