Eric is a genius of a man. This is his reply why he went from 0.47 uf to 0.68 uf.
Hi Matt,
The bigger the value in uf of a coupling cap the Better, that is the bigger, the lower the low frequency limit to start dip / decline.. ... But there is a compromised / optimal value.
For example ( just for demonstration, by no means this is the actual value without calculation ) a cap of 0,47 uf has the lower frequency to dip / decline from at say 12 Hz. a bigger 0.68uf cap will be 8Hz to dip..What is the difference? we cannot actually appreciate that as both are ultra good and low.
In the old days, this coupling cap may have been just 0.1uf ( or even less ) when higher value caps are rare, especially those high quantity ones.
Nowadays, we usually use 0.47uf as standard,, that is why all 0.47uf caps from Mundorf whether silver oil or silver gold - All gone !!!, So it is then go for the next level to 0.56uf, Wow, it is also gone !!! Luckily, there are 4 pieces of 0.68uf left for me... then 0.68uf all gone...
Why don't we go to 0.99uf in the first instance? Because it is not necessary, 0.47uf is good enough for all human hearing. also the bigger the cap ( size also ) the higher the price... 0.68uf IS more expensive than 0.47uf ....
So the commonly picked at 0.47uf for coupling cap IS a compromise, for result and cost.
Cheers
Eric
