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hagtech wrote:

Yes, steel chassis can be both good and bad.  It likes to conduct magnetic fields, so you have to treat things appropriately.  A little spacing under a choke can go a long way.  Otherise you have a 120Hz motor.  I have another trick that helps with the far field.  The stray magnetic spray from the Hammond chokes is pretty big.  Helps to measure it to see which directions it has maxima and minima.  Then you mount the coil with the proper aim.  Usually away from the input tubes.  My trick is to use two chokes instead of one.  Wire them up in parallel or series, then mount them side-by-side and magnetically out of phase.  You get quite a bit of far field cancellation.  I did this in the Trumpet.

Very good idea. I use in Super Melquiades another way to deal with the problem. Since it was a separate PS chassis I did not care a lot about the “away from the tubes”. However, since I had zillion transformers and chokes on it I got my chassis sing as a good contralto. Whatever I tried (lifting, turning, bagging, playing) did not make it silent. I was at the verge to rebuilding it with none-magnetic material but then  I invented a “brutal force damping”. I took a heavy wooden stick and began to hard-push the PS’s chassis until I found a point where the pressure was able to change the chassis noise. They I drove a large ¾ bolt, 5 inch long across the entire chassis. After this I turned the amp and by slowly screwing the nut on the damping's bolt I was able to comfort out the noise from the chassis. Next time I will be smarter and I would never make PS with steel chassis. (I hope it will be no "next time")

The Ripley Chokes and the "Brutal force damping" device on the Super Melquiades PS...

In fact when I next time open this 100 pounds monsters I will try to turn the chokes opposite to each other trying to do what you do.

hagtech wrote:

I like your idea of double-dipping the chokes.  I wonder what can be done to stock chokes.

So do I wonder! I have quite few good inductors that just too nosy in the input choke applications. If I were serious about the building then thing then it would not be difficult to bake them of to dip them in mozzarella… BTW, if you cal to Hummond and order the Ripley version from Sales then they most likely would not know what it is. You have to talk to the tech support there and ask them to explain to a sale person what would it be. I was waiting my 6X500mA/10H chokes for 4 months as the damn sales people did not believe that they exist and they keep sent me the regular one. BTW, before the 1992 the single deep into epoxy was a standard Hammond procedure for the chokes over 100mA. 

hagtech wrote:

So maybe the AA guy is crazy?

With my legacy at the AA sewers do you need to ask ME this question?

Rgs,
Romy the caT

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