AK449X系列DAC的PCM滤波器设置探讨

mickyluo

503我用过，听不出区别
对了前些天看见论坛在战adi2，我下了本说明书看了下，也有这些滤波方式的介绍，还有详细的频响和脉冲测试图，感兴趣可以下载下来看看

mickyluo

2b青年爱发烧 发表于 2019-3-10 11:01
没找到下载，请问有链接吗？

http://www.rme-audio.de/download/adi2dac_e.pdf
帮你贴出来了，就这么点内容，我觉得NOS模式和红的黄的应该可以听出和绿色的差别
我瞎翻的
他们认为Slow有最完美的脉冲响应，但在15khz上已经掉了1.5dB，然后SD Sharp和SD Slow是IIFR，另外两种是FIR。
NOS模式脉冲响应看起来很完美，但是NOS和Slow模式比Sharp模式会引起更多的aliasing into the audio band and out-of-band noise（看不懂



The screenshots above show the analog output signal of the DAC filters, stimulated by a digital
single sample impulse at 44.1 kHz sample rate. While Slow has the most perfect response, it
looses around 1.2 dB already at 15 kHz, see chapter 31.4. Both Short Delay are IIR filters, the
other two are FIR type. FIR is phase linear over the whole frequency range.

NOS (Non-Oversampling, SuperSlow)
The DAC includes another filter which is called Super Slow in its data sheet. The impulse response
looks perfect, but checking the output signal with an Oscilloscope reveals steps that are
more typical for so called Non-OverSampling (NOS) devices, so we renamed it NOS within the
DAC filter menu. Note that there is no audible distortion, the steps equal high frequency harmonics
that are mostly higher than 20 kHz. Please also note that Slow and NOS filters cause
much more aliasing into the audio band and out-of-band noise than Sharp filters.