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注册时间2010-9-11
最后登录2011-12-13
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交易诚信度0
注册时间2010-9-11
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老勃的数百万资金有点夸张,其实首先是是态度问题,然后就是对技术的理解。(当然我觉得老勃很多话都有偏见,大部分不赞同,但对他于DAC的的确能一针见血)
说说我提到的那个DAC吧,指标是:
Two-channel, oversampling D/A processor with Wolfson WM8740 24-bit DACs and Texas Instruments TMS 320VC5501 digital filter. Digital inputs: S/PDIF coaxial or TosLink optical, USB. Digital input sampling frequencies supported 44.1kHz, 48kHz (32kHz, 88.2kHz, 96kHz, S/PDIF only). Digital outputs: S/PDIF coaxial and TosLink optical. Analog outputs: balanced (XLR), single-ended (RCA). Frequency response: 20Hz to 20kHz ±0.1dB. THD (1kHz, 0dBFS, 24-bit data): <0.001%. S/N Ratio: 112dB. Total correlated jitter: <130ps. Channel separation: >100dB at 1kHz, >90dB at 20kHz. Output impedance: <50ohms. Maximum output level: 2.1V RMS (unbalanced), 4.2V RMS (balanced).
第3放测量的部分结果如下:

Fig.1 Cambridge DacMagic, frequency response at –12dBFS into 100k ohms with 96kHz-sampled PCM data and Linear Phase filter (left channel blue, right red), Minimum Phase filter (left green, right magenta), and Steep filter (left cyan, right gray). (2dB/vertical div.)

Fig.2 Cambridge DacMagic, 1/3-octave spectrum with noise and spuriae of dithered 1kHz tone at –90dBFS with 16-bit data (top) and 24-bit data (bottom). (Right channel dashed.)
个人认为其接地仍有改进余地,不过对于这个价格已经没有什么好求的了。
这台机器最大的玩法是可以使用不同的滤波器!可选的滤波器为线性相位、最小相位或者陡峭滤波。(那些DIY的解释一下这有什么区别吧,能用什么方法达到?)
看看这台机对极低电平的1kHz的信号的还原,用线性相位滤波器:

Fig.6 Cambridge DacMagic, Linear Phase filter, waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit data (left channel blue, right red).
再看看用最小相位滤波器之后:

Fig.7 Cambridge DacMagic, Minimum Phase filter, waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit data (left channel blue, right red).
看看最后STEREOPHILE给出的总结:
Although its USB input is really of only utility quality and shouldn't be used for serious listening, the Cambridge Azur DacMagic otherwise offers superb measured performance. In fact, considering its street price of $400, this level of performance is astonishing. I am not surprised that Sam Tellig liked the DacMagic's sound.
极佳的测量性能,烂大街的价格。400美金也就是2800元,成本不到1400大元
那些DIY DAC的是否脸红!?! |
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