I am also wondering about the details regarding the input pad, because I would like to mod my input pad to be -10dB in attenuation.

In the Access 312 circuit, is the pad an H-Pad, a T-Pad, or a U-Pad?

I'd like to change the resistors to produce a -10dB pad. I think right now the pad is about -19dB with resistors R8 = 120r, R9 = 470r, and R10 = 470r

The input Z of my input transformer is typically 1500 ohms. And I think its typical for a mic output impedance to be 150 ohms, right?

So I am not sure a -10dB pad is possible with my given impedances?

I used a T-Pad / H-Pad calculator at

http://www.nu9n.com/tpad-calculator.htmlThe calculator could not compute a -10dB pad with these impedances...

and the only way I got close to the current -20dB pad was by making both input and output impedances both 600 ohms...

The results from the T-Pad were R1 = 491, R3 = 491, and R2 = 121 (bridge power load resistance)

Just trying to figure this out. If any one knows please offer your understanding. Thank you