Quote Originally Posted by montesquieu View Post
Some oddball designs by Time de Paravicini fall in this category as well .. EAR 861, push pull EL519s, no global negative feedback, supposedly pure Class A (presumably up to the distortion specs at least), uses 'Enhanced Triode Mode' (whatever that is - maybe some variant of ultralinear?) and a custom 'quadrafillar' output transformer. I have to say its performance with my current-hungry Tannoys was pretty outstanding even with a meagre 32 watts, pretty close to what my PP KT88-specced (KT90-equipped) Radford STA100 manages.

You'll find Tom that your RFC Canterburys aren't actually that power hungry and won't draw a lot of current at all, even at modest to loud listening. Minimum impedance is 7.4 Ohms at low frequency and they're nominally a true 8 Ohm load with a sensitivity approaching 92dB/1w/1m at 1KHz, and slightly more, about 93dB/1w/1m at cab tuning (low frequency). The worst case phase angle is around -42 degrees at 60Hz but as impedance is close on 12 Ohm at that frequency, it's not that demanding a swing in terms of current. A good 25 Watt PP valve amp, or a 20w to 30w SE amp using a little global negative feedback will drive them no problem at all. 35 to 40 Watts PP is better. Even a 10wpc SE amp will drive them to pretty loud levels but just wont provide the control or dynamic swings of something with more power and lower output impedance. A modest valve amp like that wont provide the concert-hall dynamics you get with your monster Radford though!

I will be treated to a TRON Atlantic SE amp in the system just for a bake-off of various components with Graham in the not too distant future, so it will be interesting to hear just what 10 Watts of pure class A loveliness can do with them!