Frequency response of the Rocky in left (blue trace) and right (red trace) channels into a 32-ohm load.
Frequency response of the Rocky in normal (green trace) and bass boost (purple trace) modes.
Output power in watts of the Rocky vs. total harmonic distortion (THD), driving a 32-ohm load (blue trace) and a 250-ohm load (red trace).
Frequency response
20 Hz to 20 kHz, -1.12/+0.28 dB
Output power (1% THD)
130 mW at 32 ohms
30 mW at 250 ohms
Output impedance
3 ohms at 1 kHz
S/N ratio (1 mW, A-weighted)
-81.5 dB
Total harmonic distortion (1 mW/1 kHz)
0.004%
I measured the Rocky’s performance using my Clio FW and NTI ML-1 audio analyzers.
Into a 32-ohm load (a common impedance for passive headphones), with volume set at maximum, the Rocky delivered 130 milliwatts at 1% total harmonic distortion (THD). Into a 250-ohm load, power output at 1% THD was 30 mW. Frequency response into a 32-ohm load is reasonably flat, falling to -1.12 dB at 20 Hz and rising to +0.28 dB at 20 kHz. Response into a 250-ohm load was essentially the same: -0.97/+0.30 dB. The bass boost function boosts bass by a maximum +3.05 dB in a broad peak centered at 160 Hz. — Brent Butterworth
