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Last night I built an large and ugly mumetal sarcophagus around the Dave Slagle’s choke and located it a bit aside from the location it was before. The efforts killed perhaps 98% of noise. I did not have good mumetal cans but I have .004 sheet of NETIC® and CO-NETIC®

http://magnetic-shield.com/products/alloys.html

So, I kind of made an ugly container with 15 layers of those sheets. The effect was very positive.  Now I have extremely low noise, something that might be discarded from my point of view. Still, if I move my sarcophagus with choke away from the amp or put around a heavy steal shield then I have ALL residual noise gone, I mean gone absolutely.  Unfortunately the choke is too large to have more shielding on it, the fact that Dave Slagle’s “does not believe in shielding” also does not help. 

So, there are 3 areas where I am looking now to end these problems.

1)      To find more effective shield for my current coke – I want an absolute silence from my MF channel.

2)      Putting a larger grid stopper then I usually use, let say 1-2K. Yes, it will be more impact to the low-pass filter against the Miller capacitance but it would also decouple the choke from the grid and might substantially refuse the effect of the coil in the grid act as a microphone.

3)      To find another choke, a very-very small toroidal choke, designed foe ultra low current that would be in heavy duty sealed mumetal can or even double can. The choke would be so small that it would literally sit on the cable with no leads. I am talking with Brian Sowter about the prospect of such a choke build in case if my above efforts would not succeed.

Still, I have seen the Promised Land and if I have my currant large nickel-core Dave Slagle’s choke in her sarcophagus outsider of the amp then the MF channel is so dead quiet that  it is imposable to say if the channel even on. And it is with AC on filaments!!!

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