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!
Tags: Aikido, Choke, Choke Input, preamp, Sowter
Posted in Collectible Stuff, DIY Audio | Comments (3)