You have three connections to your volume adjustment, shunt, or regular it does not matter: 1. Input 2. Output 3. Ground.
With a shunt, you simply make the input to output resistance fixed and vary the output to ground resistance with an adjustable resistor.
A 10K pot hooked up conventionally and set to give you a low volume will have:
* 9.85K resistance between Input to output and
* 0.15K resistance between output and ground
When you crank it all the way loud you will have:
* 0.01K resistance between Input to output and
* 9.99K resistance between output and ground
Input to ground stays at 10K regardless of the volume setting.
Your shunt should be a fixed resistor of 5K and a 10K pot. The resistor goes between the input and the output, the pot goes between the output and ground. When the pot is turned all the way down, you should be measuring close to zero ohms between output and ground. As you turn the pot up, your resistance should rise on a log scale.
With the pot facing you and the three terminals pointing up you will have terminals 1, 2 and 3. Hook "2" and "3" together and ground them. Hook "1" to the output RCA. With the pot turned all the way down (to the left) you should measure close to zero ohms between "1" and the ground. As you turn it up, the resistance should come up slowly. If a slight turn gives you 1K resistance, that will sound like full on. A slight turn should give you less than 100 ohms.
Low volume will measure just like a normal pot talked about above
* 5.0K resistance (or the value of your resistor) between Input RCA to output RCA and
* 0.15K resistance (or less) between output RCA and ground (resistance across your pot).
The resistance your source will see will vary from 5K to 15K as you turn the pot less the impact of the amps input resistance.
Draw it out on paper and you will see your problem. A 5K/1K ratio will give you pretty much full blast. You only have three resistances to measure. Measure them and you will find your problem.
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Long Live Dr.Gizmo
