ProtoDAC TDA1387 X8 project

[hifinet]

An anecdote to pass along regarding C3/C4 caps. A DIYer emailed me that he had just built a ProtoDAC with parts he sourced himself. He was disappointed with the sound quality, "doesn't seem much better than my old Justboom dac-hat". Should he get a reclocker?

He used two 2200uF Panasonic for C3/C4. The C3 and C4 caps are in parallel, and the total capacitance is 4400uF, which is too high. I recommended removing one of them, which would get the capacitance close to the target of 2000uF. Response: "Fantastic, more bass and a deeper soundstage."

There is a sweet spot for the C3/C4 capacitance based on the I/V resistor (lower the I/V resistance the higher the C3/C4 capacitance). If the C3/C4 capacitance is too high, the soundstage gets thin (lacks depth, becomes flat, etc.).

I also recommended that he try a lower capacitance coupling capacitor, down to 4.7uF (he was using a 10uF PP). In my experience, the Jantzen 10uF Standard Z tends to smear a bit. A lower value capacitor can tighten up the image. The high pass frequency cutoff is 3.386 Hz with the 4.7uF and 1.59Hz with the 10uF, so that isn't much of a factor.