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In the Forum: Audio Discussions
In the Thread: Input choke for Low Currents?
Post Subject: dueling reactorsPosted by hagtech on: 1/16/2007
I wonder what the difference is between class A and B insulation is.  Never noticed that parameter before.  The 10 amp choke (I like their word reactor) must have some very large guage wire, as the resistance is really low.  Clearly, both chokes will do the job.  The question you ask is which will perform better.  Fortunately, it seems the usual issues with cost and size can be ignored for the moment.

Personally, I like to over-rate cores when possible.  As a core reaches magnetic flux saturation, the inductance will drop like a rock.  Everything heats up.  So what you will see is that at low currents, inductance will rise slightly.  They used to sell "swinging" chokes for this application in that the inductance was purposely non-linear with current.  It helped maintain continuous current operation over a wide range of operation.  The larger core also runs cooler.  And it looks menacing (that's good).

Another difference is in the windings.  How much to they stick out from the core?  How many layers of copper?  The more, the worse.  Outer windings do not couple magnetically as well as the inner ones, resulting in external stray fields.  Smaller guage wire actually works better, as the gaps between windings is less.  Square or flat conductors are a great thing to have. 

One advantage of using two smaller chokes is that you can wire them up such that the external fields buck each other. 

My opinion is to buy two of the small ones.  Design the chassis such they fit side by side.  You can then try three possible combinations for sonic and measurable performance parameters.  Single, series, or parallel.  Also bucking or not.  I'd guess parallel is best, but ya never know!  If the singlet works fine, then you have a spare part for later.

jh

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