PSU choke questions

[A Jedi]

Which of the two 270 Ohm resistors should the choke replace? Should I do both if I can fit two chokes? Should the choke bodies be grounded to the ground lug? Thanks gang.

[theGopher]

Why not try for yourself and find out? That's part of the fun of DIY audio!

OK, you can replace one or both resistors with chokes but they must have the same or similar DC resistance to the 270 Ohm resistors they replace. Triad C7-X will be fine. Try replacing one resistor and then both resistors with the chokes and see if you think the sound improves at each stage. the general view is that two chokes result in a 'blacker' background, but YMMV.

There are other things you can do with the Crack like pseudo dual mono PSUs, with or without chokes, to reduce PSU noise and increase channel separation, but that's taking things a whole step further and you'd probably be better spending the money on an upgrading to a  Crackatwoa with its regulated PSU.

Yes, connect the frame(s) of the choke(s) to ground and don't twist the input and output leads of the choke together.

[grufti]

You can model the results with PSUD2 from Duncan's Amp Pages. It's free software and well regarded for what it is.

http://www.duncanamps.com/psud2/

[A Jedi]

Why not try for yourself and find out?

Honestly, because I don't have golden ears. So I figured I'd go with the crowd.

[Tom-s]

If I could redo my Crack. I'd go with one choke, don't hear the extra one. There's a guy on here with a single 30H or so choke from Hammond; type 194E. That could be an alternative option for the double 10H triad, if you can make it fit. Otherwise i'd replace the second resistor with a single triad.