Last article, I introduced how to calculate resistor value for Bridge-T attenuator.
To produce actual attenuator, must choose resistor type to use.
Among audiophiles non‐inductive wire wound resistor NS-2B by DALE is welknown.
I made this attenuator in year 2006, it was very difficult for me to get all values of NS-2B from market.
Then I checked other brand non-inductive wire wound resistor thuru internet.
Finally I’d found audio grade Mills resistor called MRA. Of course it’s non-inductive wire wound resistor.
This MRA has two different grade by wattage. One is 5W, and the other one is 12W.
5W type is as small as NS-2B. So I decided to use MRA 5W type.
For 5W type resistor value was limited up to 27k ohms, even 12W type vlue range is up to 91k ohms
I needed value up to 10M ohms for my design, Attenuator position using more than 91k ohms are 7 steps for low volume side. Then I decided to use my own Riken resistor RMA, RMG type.
So 1-7 steps using Riken RMA, RMG, 8-11 steps using Mills MRA 12W type, 12-34 steps using MRA 5W type.
In last article, I wrote that have to choose resistor value from E24 series. Actually I chose resistor value following Mills resistor line-ups.
I bought Mills resistor from “Sonic craft” located in USA.
I wanted to control volume L and R separately, so I chose 2 set of Seiden rotary switches called 56SG(56006).
It has 34 steps(10 degree) short type 2 circuits.
It took for few days to solder hundred over resistors to rotary switch.
It doesn’t look nice because of my soldering skill, soundwise It’s very nice and very satisfied.
I attach actual wiring diagram below.
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