HI TPA.

I have a slight DC offset on my IVY analog stage. It is not that much but after amplification in my class A amplifier i do have a DC offset. The offset is greatest on the left channel and when measuring on the balanced output. Very little on SE.The DAC is a COD and the source is from Ian FiFoPi. The I2S is wired through a OTTO1 selector switch (2nd input is your S/PDIF Transceiver module ).

Is there any way to correct this on IVY analog stage? Better match components or ad capacitors?

I used 0.1% resistors, wima capacitors and Nichicon electrolytic caps. OPA1632 and LME4562 are used. All parts are from digikey or farnell.
I have not fitted these components according to recommendation from Russ: IVY and COD SQ improvements
The IVY stage is powered by a Salas Ultrabib 1.3. This is trimmed to within 1 mV (+/- 15v). No ground loop found.

Best regards Mikkel

Resized_20180319_104706.jpg (166kb) downloaded 17 time(s).

Hi Brian

Thanks for your reply.

DAC with no XLR cables connected:
Left: (+) 2 mV & (-) 3,3 mV
Right: (+) 3,8 mV & (-) 6,6 mV

Amplifier (Nelson Pass A75) with no XLR cables connected:
Left: 1 mV
Right: 3 mV

DAC connected to A75 with XLR (measured on the output of A75):
Left: 13 mV
Right: 74 mV
Playing Music:
Left: 65 mV
Right: - 3mV

Not sure why the small offset change when music is played and from right->left...?

All the measurements are pretty stable and verything is in working temperatur.
All XLR connectors are isolated from the chassis, both on the A75 and DAC.

Best regards Mikkel