Phono II and III 3.18 time constant resistor value.

[bob orbell]

Hi all, its me again with some information, well a lot of information about the 3.18 time constant resistor value. This was first put in the FAQ for the WAD Phono II as 14454 ohms, I tried this mod and so did many others, I found the sound now far to bright as did others, so lets move along, I have been doing a shed load of research and calculations along with a old school friend who was fantastic at maths. Now, the time constant equation is t=RC which is 3.17988, this is not how it works as there are so many other factors and calculations to be taken into account, for example, preceding valve R out anode load resistor the 180k following valve grid leak resistor stray capacitance and more. So with the help of my chum and 5 sheets of A4 paper, a scientific calculator and many hours or work the figure we came up with is 2177.812 ohms, I fitted a 2K2 in Phono and have spent a lot of time listening, there is a welcome lift in HF and no sibilance at all. Comment's welcome please. Bob