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Here is another question that almost from the DIY-Audio universe.
 
Dima is finishing Zaratustra II amplifiers. It will be quite interesting beast and I’m slowing begin to think about the power supplies – it will be my responsibility. The Zaratustra II will be up to 175W of pure class “A”, without an ability to switch into class “B”. I said “up to” because it will have quite a few interring innovations that make taking about the Zaratustra II power…  hmmmm...complicated.

Anyhow, sine the output stage sucks constant high current and since I would like it... to sound good we are planning to go for Input choke, with my usual LCRbigC filter. So, I am hunting for the choke.

The output stage will be operating between 3A and 5A. At 3A the critical inductance should be around 30mH and at 5A it should be around 18mH. I usually use triple of critical inductance. Trying few different chooks during the construction of Melquiades (where I was buying them and listening them) I learned that it is very hard to beat the pane-vanilla Hammond chokes. They are silent in Input choke application and they sound better then any other chokes I tried. For high currents I usually order a custom “Ripley” version where a choke submerges twice into Ripley Epoxy - it make it dead silent.

So, the Hammond has two 100mH chokes:

195T5  -  5A  -  .64R - 14Pouns - $69

and

195T10  - 10A - .42R - 35Pound - $260

Both of them can do the job, but I’m a little concern that the first choke might be too small if I drive though it 5A. Also, those chokes run this max current they… kind of vibrate… The 10A is 7x8 inches… it is big. In addition, I’m conserved the with lover current it should give up lower inductance, would it be?

It will take for Hammond 2 month to” Ripleynize” my choke and I need to make decisions if it will be 195T5 or 195T10.  I personally inclined to go for 10A version as if for whatever reasons the filter will, not work as I expects then I could always drive it in necessary operation by shunting the PS and driving more current via the filter. The alternative version would be use of two 5A chokes, combining them in series or parallel connection, depends of what I need…

Any bright ideas?
The caT

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