Not necessary at all. The D90/D115 do not need an inrush limiter. They have line fuses....The D90 originally had a relay and in some instances proved to be a problem. I have removed them with no ill effects. Both the D90 and the D115 use a tube voltage regulator that does provide the high voltage with a bit of a delay on turn on, until the tube starts to conduct. The D115 already has a relay and a thermistor to allow the caps to charge up and therefore it's not needed. Regarding the H/K I don't know the circuit. Which D90 do you have, the B version or the plain?
Opinions on ICL, Inrush Current Limiter
I have a friend and technician that works on my vintage tube gear. In my opinion he does very excellent work. However on every amp and preamp whether its ARC D70MKII, D90B, HK-Citation II, Lafayette KT600 etc., he wants to put in a In-rush Current Limiter circuit. I always ask the original designer (i.e., fameous!!) did not employ this circuit, why do you? He is adament about putting one in. It does seem to help the big amps as they slowly come up to power and I have tried to hear a loss in dynamic range but I can't...after it warms up.
So any opinions on this circuit? Should the ICL be put in vintage gear? or was it too expensive?? Are there pros and cons? Thanks any comment would be greatly appreciated. Larry
So any opinions on this circuit? Should the ICL be put in vintage gear? or was it too expensive?? Are there pros and cons? Thanks any comment would be greatly appreciated. Larry