自製音頻解碼之路(2)

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本文僅為介紹,並非作業指引。內容涉及高電壓、高電流等危險工作,請遵照當地法規同安全指引執行。除非閣下為專業人士,否則不建議進行任何操作。所有、任何後果自負。

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WARNING

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NEVER WORK WITH LIVE VOLTAGE. Always disconnect the power source before working with electrical circuits.

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Ian Canada DIY Project

DIY Audio社區卧虎藏龍,包括Pass Labs創辦人Nelson Pass都係活躍會員。Ian Canada DIY Project係上邊DAC區頗受歡迎嘅項目,之前以FifoPi出色嘅表現而廣受關注。宜家開發嘅產品涵蓋Streamer, DAC, DDC, PSU及時鐘等等,而且幾乎可以獨立使用。配合Pi或脱離Pi使用都得。本次講解嘅係配合Raspberry Pi 4B搭建嘅 串流解碼。開始前,略略提下設計要求:

Parts嘅List

可以參考Ian Canada online Shop

如果輸入界面要埋RCA, OPT, I2S over HDMI就加個

如果要USB輸入(支持PCM、DSD更高碼率)就加

如果升級成UcPureMkIII,用超級電容供電會更好。呢個要視乎個人系統同埋筆直了。

砌機注意

砌OPA861 V/I嘅供電要用以下方法:

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Raspberry Pi儘量隔離,但係吾好造成短路! enter image description here

系統選擇

吾用Roon嘅朋友隨意。 用Roon嘅朋友,Raspberry Pi儘量作為Endpoint。個人測試目前較好嘅係 Silent AngelVitOS ,以直連方式傳輸。

  1. 用Raspberry Pi Imaginer 刷入Raspberry Pi OS for Pi4。
  2. 成功啓動後,將 根目錄 下邊16個 .DAT.ELF 文件,抄落備用。
  3. 刷入VitOS,上電,等10分鐘左右。呢個時候其實係啓動吾到。斷電,掹卡。
  4. 將16個DAT、ELF文件抄落VitOS根目錄。入卡,畀電。得咗。VitOS Manager見到Raspberry Pi 4。
  5. Windows用家,用PuTTY軟體SSH登錄VitOS後台。

pacman -Syu git gcc autoconf libtool libdaemon libconfig

update下。再:

pacman -Syu vi nano

裝編輯軟體。在 /boot/config.txt 裡貼上如下幾行就好,然後重開機。

# AUDIO HAT   dtoverlay=i-sabre-Q2M    force_eeprom_read=0

如果想降頻減少熱量,且讓頻率穩定,聲音也會比較穩定:

# REDUCE FREQ   force_turbo=1   arm_freq=600   arm_freq_min=600   gpu_freq=150   core_freq=200   core_freq_min=200   h264_freq=200   isp_freq=200   v3d_freq=200   sdram_freq=300   sdram_freq_min=300   avoid_pwm_pll=1   over_voltage=-8   over_voltage_min=-8   over_voltage_sdram=-8   over_voltage_sdram_c=-8   over_voltage_sdram_i=-8   over_voltage_sdram_p=-8

如果想關掉,所有樹莓派的LED燈:

# DISABLE LED   dtoverlay=act-led   dtparam=act_led_trigger=none   dtparam=act_led_activelow=off   dtparam=pwr_led_trigger=none   dtparam=pwr_led_activelow=off   dtparam=eth_led0=4   dtparam=eth_led1=4

VitOS默認關掉了WIFI同藍牙,以下係以防其它系統需要:

# DIAABLE WIFI/BT   dtoverlay=disable-bt   dtoverlay=disable-wifi

系統直連

只推薦VitOS,因為人哋已經吾再update。Roon Bridge亦冇再update。 同樣SSH係後台,

ip link

睇睇用緊嘅Ethernet端口,例如:

enp0s25 wlp3s0

記低。然後編輯創建一個profile:

/etc/systemd/network/eth0.network

[Match] Name=eth0 [Network] Address=192.168.100.199/24 Netmask=255.255.255.0 Gateway=192.168.100.1 DNS=1.1.1.1 DNS=8.8.8.8

eth0 因應個人結果而改。上邊所有嘅字串因應個人需要而改,就返 Roon Server 直連端口嘅同一網段。 激活、啓動服務:

systemctl enable systemd-networkd

systemctl start systemd-networkd

systemctl enable systemd-resolved

systemctl start systemd-resolved

搞掂!

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