Periodic Audio Silicon DAC
Dec 24, 2023 at 11:51 PM Thread Starter Post #1 of 3


Headphoneus Supremus
Nov 22, 2008
Wherever the music takes me
Apr 9, 2024 at 2:10 PM Post #3 of 3
150mw per channel into 32 ohms. Lots of hype about being powerful for that spec. Then there's this about the amp stage.
We're getting the pilot production next week. The RT6863 has a lot of use in a lot of mid-high end applications, it's probably why Semtech (Based in Camarillo, CA) bought the entire chip line. The 6863 measures quite well, almost as well as the INA1620. But, while op amps are important, the power supply is even more important. We use a pretty beefy ±5VDC true split rail supply with 300mA per rail available. That means the power supply can provide at least 50% more current than the op-amp can draw - so you're not going to current limit because of the power supply.

Additionally, the ±5VDC with the gain of setting in the Silicon means that 0 dBFS results in a 2.3Vrms max output - which would be 3.25V peak. The RT6863 can swing within 800mV of rail at full current output, so we still have a nice 900 mV voltage safety margin at full power output.

Lastly, because we use a true split ±5VDC rail, we can directly DC couple the DAC to the amp, and then the amp to the headphone. Low frequency roll-off is limited by my AudioPrecision, which I ran down to 0.5 Hz (and that last measurement took FOREVER). The AK4377ECB is one of the few high res, high sampling rate DACs that are spec'd down to 0 Hz operation. Do you need it? Probably not - but it's there if you want it...:)

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