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· Registered
17 Posts
Discussion Starter · #1 ·
Are there any tutorials available for using the Thiele-Small parameter calculator? A search of this thread for Thiele-Small' and 'Thiele' brings no results for instruction, just issues with the calculator.

Lots of between the lines questions to be answered. Example: I see the diagram in the help file, but what is a "non-inductive" sense resistor? What kind should I buy? Tips for set up? Weighting? Multi-meter? How do I know I got good results, etc.
There seems to be a lot more that goes into it than just plugging some wires into a driver and pressing calculate.

· Banned
5,013 Posts
I can help you on the resistors.

Non-inductive resistors are constructed in such a way that there is no inductance (carbon composition, not wirewound or metal film) or wirewound but with the winding direction changing halfway through so the inductance cancels out. Even metal film resistors are often trimmed to the desired value by cutting a spiral in the film, forming an inductive coil. A straight piece of wire has a tiny amount of inductance, but it is the larger amounts we are concerned about, like with wirewound construction.

I just purchased some non-inductive resistors from Mouser for impedance measurements, I think they were $3 or $4 each. My whole order with two of each value came to just under $30.

1. for high-impedance headphones
1 kOhm, 5 W, 1%, wirewound, non-inductive, axial lead, through-hole
71-NS5-1K Mouser #
NS0051K000FB12 Dale-Vishay #

2. for speakers
100 Ohm, 5 W, 1%, wirewound, non-inductive, axial lead, through-hole
71-NS5-100 Mouser #
NS005100R0FB12 Dale-Vishay #

3. for cables
10 Ohm, 5 W, 1%, wirewound, non-inductive, axial lead, through-hole
71-NS5-10 Mouser #
NS00510R00FB12 Dale-Vishay #
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