That model is so simple if not say trivial, that it still keeps a negligent name of the prototype project. We have finished that within a month or so. This toy is conventional USB DAC + balanced Headphone Amp, however, it made from the best for today components and now #9038S the only USB DAC+HPA with 550mW@16ohm, SNR -122db(A), THD .0002%@-3dbfs@32ohm, and 10g weight.
The device can operate in 3 modes:
1) Normal Mode -LED is always On, no flashing.
2) Performance Mode – LED flashing 2Hz when no signal detected, THD performance optimized for Fs 44.1-48kHz but PLL lock slower and the first-second signal is muted.
3) SE Mode– LED flashing 1Hz when no signal detected, 2nd harmonic artificially increased to emulate SE tube behavior.
To switch between modes you need to interrupt #9038S power during its startup when LED very fast flashing. Then next turn on #9038S will be started in the next mode(1-2-3-4-1-2-3-4.. cycling)
Note: the latest #9038S Gen2 has 4rth operation mode "IEM" with limited max output power at -15dbfs level for safe operation with low-impedance and high sensitive In-Ear Monitors up to 4ohm, LED is Off when no signal detected. Also, #9038S G2 adopts soft-start function to a seamless start with any(as I hope) iOS/Android devices without external power-bank. However, no one of iOS devices and part of Androids will able to provide USB power enough to drive #9038S G2 for max power. Don't be surprised to see msg like this: "USB OTG device requires external power source", that's why we always suggest Y-splitter.
iOS/Mac devices need to use player app like Neutron to get volume control.
Retail cost: TBD($70)
Materials: sandblasted/anodized aluminum/ES9038Q2M/AD8397
Power: USB 5V power rail no internal battery, 90mA idle current, the device contains up to 4000uF of capacitance and IOS/Android devices can
start OTG operation only with Camera_Adapter and USB OTG Y-splitter cable respectively
Input: USB-C, PCM up to 24b/192kHz
Output: balanced output 2.5mm jack A&K pinout
No adaptors allowed! You can kill the DAC.
Output impedance: .05 Ohm@1000Hz Agilent U1733C
Output power: >340mW@32Ohm@1kHz@THD=1%
Output power: >550mW@16Ohm@1kHz@THD=1%
measured at +.5dbFS level, typical PC USB2 port powered
Frequency response: 10-85kHz +.05/-.2db@ 24b/192kHz
S/N ratio: -122db(A) referenced to 3.399VRMS @32ohm THD+N = 1% @
+.5dbfs typical PC USB2 port powered
DR AES17 120db unweighted
THD@1kHz@-3dbFS .0002% typical for Performance Mode 24b/44.1kHz@32Ohm
THD+N@1kHz@-3dbFS <.0004% typical for Performance Mode 24b/44.1kHz@32Ohm
THD+N@1kHz@-3dbFS <.0009% typical for Performance Mode 24b/44.1kHz@16Ohm
THD+N@1kHz@-3dbFS <.0004% typical for Normal Mode 24b/44.1kHz@32Ohm
THD+N@1kHz@-3dbFS .25% typical for SE Mode 24b/44.1kHz, almost only 2nd harmonic
Conventional PC USB2 port, 32ohm load THD+N vs Power
Conventional PC USB2 port, 16ohm load THD+N vs Power
Conventional PC USB2 port, 70ohm load THD+N vs Power
Conventional PC USB2 port, 110ohm load THD+N vs Power
Conventional PC USB2 port, 70ohm load -6dbfs THD+N vs Frequency
Conventional PC USB2 port, 70ohm load Frequency response
Conventional PC USB2 port, crosstalk