@noromance: Back in the Decca days, various samples were all over the place in terms of frequency response, high frequency "ringing", tracking ability, etc. The Londons are significantly more uniform example-to-example. Just to clarify: loading a Decca or London with a lower input impedance and/or more capacitance is done not to damp physical resonances, but to address electronic ringing.
In the long phone conversation I had with Decca expert Harvey Rosenberg in the mid-1980’s, he gave me a brief education in a thing named the "tank circuit". The high frequency ringing in pickups interacts with the input impedance and capacitance of the phono gain circuit, that interaction creating a tank circuit. Harvey told me the characteristics of that circuit can be manipulated by changing the input impedance and capacitance of the phono amp, and doing so can actually minimize the electronic ringing common in the old Deccas. He recommended building or buying a variable input impedance & capacitance phono box, and tuning one’s pickup to achieve the desired sound. No, I never got around to that project. ;-) And the Londons don’t suffer from ringing like the Deccas did. It's still there, but greatly reduced.
The owners pamphlet that came with my London Super Gold recommends an optimum input impedance of 33k ohms, and 220pF of capacitance. The London Reference pamphlet makes no recommendation, but I seem to recall reading somewhere John Wright suggesting something close to those for the Super Gold.
Equally important is the tonearm one mounts a London/Decca on. The design of the pickups results in a LOT of physical energy being generated, which can really upset some arms. That was one reason for the Townshend Audio Rock Turntable being so popular with Decca owners. The Rock’s headshell-located damping design sucked up a lot of the energy, reducing another form of ringing (this physical, in the arm itself). The Zeta is a popular arm for use with the Rock. I tried a couple of unipivots, but didn’t like them ergonomically. Too "floppy". ;-)
Those London-curious can find lots of great info on the pickups on the Lenco Heaven Forum website.
