I bought a Roland (Edirol) R-1 (now discontinued) and tested for its
responses. Here's some summary.
High frequency response begins to roll off at around 19 kHz, 1 dB down
at 20 kHz, 2.5 dB down at 21 kHz, and about 6 dB down at 22 kHz. The
antialiasing filter is not sharp enough; 23.8 kHz sine wave is recorded
as 20.3 kHz (i.e., 44.1-23.8 kHz) at about -20 dB. Similarly, 24.1 kHz
is recorded as 20 kHz at -25 dB, and 25.1 kHz as 19 kHz at -45 dB.
Low frequency response is flat down to about 10 Hz, and -6 dB at about
3 Hz.
The device has analog limiter, but it can be turned off. (No trick
needed.)
With the "input level" turned all the way up, the device clipped at
about -12 dB Vrms (about 250 mVrms).
The above data were obtained with sine sweep fed to the right channel
of the device through its "line in" (3.5 mm stereo plug), recorded at
44.1 kHz sampling with 24 bit quantization, with limiter off, all sound
effects turned off, and saved into WAV files. The WAV files were
analyzed in MATLAB.
Just in case someone needed this much info...
Ryuji Suzuki
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