A nice soul jackinnj has done some measurements with his Audio Precision. We are talking about nanoVolts! Used opamps were AD825, LT1028 and AD797 together with a LM329 voltage reference.
Email me if you want to see the schematics. (too large to upload)
PA Regulator -- Gold IC socket for error amp -- LM329 Reference:
P-A SR AD825-- on Aries AD797 LT1028
No filter 15.14Uv 5.67uV 6.95uV
A-Weighted 2.38 1.03 1.00
CCIR-486 6.40 2.04 2.02
CCIR-2K(Avg) 3.03 0.941 0.921
22-22K 3.52 2.37 1.70
Jung-Didden SR
No filter 28.60 8.75 19.96
A-Weighted 4.52 1.63 1.06
CCIR-486 12.50 4.20 2.91
CCIR-2k(Avg) 5.91 2.07 1.43
22-22k 5.19 1.77 1.29
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