Posted on Saturday, 23rd July 2011 by Auw Jimmy
This is the final choke upgrade that I’ve been waiting for quite long time. After some discussion on the phone with Brian (1 day before his birthday), finally I finalized the order. Custom made from Sowter UK, a Choke specified for Input position. Spec wise, it should be 30H with 75mA current capacity. Rated at 500V as this one will be placed in input position – so safety first!
FYI, most designer will not go with Choke Input approach. First, because the Capacitor rated at higher voltage is so cheap and widely available. It’s easy to get Capacitor rated at 630 VDC and the cost is so far very reasonable. Second, Choke at Input is a kind of “waste” in terms of voltage. It only produces DC around 0.9x from the AC voltage source, compared with Capacitor which could produce DC around 1.414x from the AC source. Kind of voltage waste? Sort of…
Back to the choke, DCR is optimized at Level 2 raised from the standard spec (well, if you know me so well, mostly I don’t go with standard spec). At Level 2, the DCR targeted around 260R from 300R at standard spec (but I got better on real measurement). I could have option up to around Level 4 which could reduce the DCR around 1/5 times lower, but it will lift the height of this choke to 6 Kg. I don’t mind to pay more for manufacturing process and material cost, but I do mind with the 6 Kg shipment cost and the tax!
Side appearance from this Sowter Input Choke. Well designed, neat, but also heavy. I could be happy if Sowter would set a bigger hook-up wire though (the provided one is not too big).
Measured DCR, around 192R which is around 30% improvement from the standard spec (300R). Good job, Brian (Sowter)!
The weight is near 2 Kg. Kinda heavy for such small choke (30H / 75mA). I wonder if I order the Level 4 which could reach up to 6 Kg weight. Well, 6 Kg only for a choke? You gotta be kiddin’…
After my last order arrive (the Hubbell and Leviton switch arrives), I could come up with the finalization of the Chassis and start to plug the upgrade on my Aikido PreAmp.