pmillett Sangaku DIY R2 Error User Guide
- October 27, 2023
- pmillett
Table of Contents
pmillett Sangaku DIY R2 Error
Sangaku DIY – R2 error
The Sangaku DIY PCB has an error that results in a DC offset to appear on the
unbalanced outputs and the preamp outputs. It is not an issue for balanced
headphones as the offsets will cancel.
The mistake is that the signal was taken from the wrong side of the 100 ohm
resistor on the JFET buffers between the nutube plates and the opamp output
stages. To correctly cancel the DC offset, the signal should come off of the
drain terminal of the lower (CCS) FETs Q6 and Q7.
This can be reworked in two possible ways:
-
Swap the two leads on the JFETs Q6 and Q7, like this:
You need to keep the leads from shorting. You may want to put some insulation (like the insulation stripped from a piece of hookup wire) on one or two leads. -
Cut the traces on the back side of the PCB as shown below, and add a wire as shown, to move the signal.
