I finally got around to a modification to my DAC1600 and was wondering if anyone else has tried the same.
I do not use the balanced outputs, since the rest of my system doesn’t support it. I had decided early on that I could pull the unused complimentary PCM63s and stack them onto the existing chips. I was hoping to see how much better/smoother the DAC could be.
Before I pulled them I reviewed the schematics and realized that the complimentary ‘balanced’ half of the circuit was identical to the ‘unbalanced’ circuit with the exception of running the signal through a hex inverter to make the signal a mirror image.
I decided in the end to try and remove the inverters so both chips pass the same signal and sum them after the IV stage at the XLR jack with a custom cable. Tests proved that this worked and is easily reversed back to stock if I ever wanted to.
The difference is subtle, but noticeable if you look for the differences. I have especially noticed that some background acoustic guitar picking sound much more realistic than the stock unbalanced unit the guitars went from sounding ‘hard’ and like steel strings to much more detailed ‘gut’ strings with better attack and decay.
Ultimately I have just created a jumper plug out of an old XLR connector, which sums the two signals and can be passed through the standard unbalanced jack with my normal interconnects. The unbalanced jack shares a trace with half of the XLR so making the jumper plug just connects the two signals which pass it to the unbalanced jack. Pulling the jumper reverts the unit back to a stock unbalanced output so A/B testing is also not too difficult.
Has anyone ever done a similar modification to their DAC? I’ve searched the web but didn’t find anyone who summed the signals after the opamp/buffer section.
I do not use the balanced outputs, since the rest of my system doesn’t support it. I had decided early on that I could pull the unused complimentary PCM63s and stack them onto the existing chips. I was hoping to see how much better/smoother the DAC could be.
Before I pulled them I reviewed the schematics and realized that the complimentary ‘balanced’ half of the circuit was identical to the ‘unbalanced’ circuit with the exception of running the signal through a hex inverter to make the signal a mirror image.
I decided in the end to try and remove the inverters so both chips pass the same signal and sum them after the IV stage at the XLR jack with a custom cable. Tests proved that this worked and is easily reversed back to stock if I ever wanted to.
The difference is subtle, but noticeable if you look for the differences. I have especially noticed that some background acoustic guitar picking sound much more realistic than the stock unbalanced unit the guitars went from sounding ‘hard’ and like steel strings to much more detailed ‘gut’ strings with better attack and decay.
Ultimately I have just created a jumper plug out of an old XLR connector, which sums the two signals and can be passed through the standard unbalanced jack with my normal interconnects. The unbalanced jack shares a trace with half of the XLR so making the jumper plug just connects the two signals which pass it to the unbalanced jack. Pulling the jumper reverts the unit back to a stock unbalanced output so A/B testing is also not too difficult.
Has anyone ever done a similar modification to their DAC? I’ve searched the web but didn’t find anyone who summed the signals after the opamp/buffer section.