Soundeasy probe/jig: Zaph versus Neubecker

[jcandy]

Can someone explain the difference between the resistor placement for "calibration" in Dan's Soundeasy jig

http://www.diyaudio.com/forums/attac...amp=1174392176

and Zaph's

http://zaphaudio.com/setup-se-calibrate.jpg

Dan's jig completely shorts the 10 Ohm resistor. Is this not a problem because of the driver DC resistance?

[john k...]

There really isn't any difference from the point of view of calibrating the sound card. All that matters is that the amp does not see a zero ohm load. This is not a problem in Dan's set up due to the load of the driver, as you point out.

The key is that the probes must be connected to a point where they will see the same voltage. This is accomplished in Zaph case (Figure from my Design Guide) by moving the In probe to the same position as the Ref probe. In Dan's jig he accomplishes the same thing by shorting the ref resistance.

I don't show a jig in my Guide because I personally feel it is unnecessary and just adds complication. A couple of test leads and a resistor wok just fine.

[jcandy]

john k...
There really isn't any difference from the point of view of calibrating the sound card. All that matters is that the amp does not see a zero ohm load. This is not a problem in Dan's set up due to the load of the driver, as you point out.

Understood. Thanks.

john k...
I don't show a jig in my Guide because I personally feel it is unnecessary and just adds complication. A couple of test leads and a resistor wok just fine.

Yes. After building the jig I wondered if it was overkill. Live and learn. Thanks again.