Monday, August 8, 2011


Scientific Conversions SC944-05

SC944-05LF Top View

SC944-05LF Bottom View

SC944-05 is a handcrafted transformer made by Scientific Conversions. The suffix LF stands for Lead Free.

SC944-05 Waveform

SC944-05 @ 200mv/100ns Div

SC944-05 @ 200mv/50ns Div

SC944-05 @ 200mv/25ns Div

Since the Vpp of the original waveform is around 3.3V, with PE65612 (1:1), I have to use resistors to decrease the output voltage level to 600mV. In the test above, those resistors were not removed, I think that's why the peak will be lower than the second one. If the listening experience is better than PE65612, I'll remove those resistors since they are no longer required due to SC944-05's primary/secondary ratio - 2:1.

PE65612 Waveform

PE65612 @ 200mV 25ns

Obviously, SC944-05 has less noise than PE65612 with nearly the same rise time. However, the jitter is not something we can see directly from the oscilloscope, but I believe that my ears will tell.

Listening and Conclusion

The listening experience of the SC944-05 is all positive, better resolution, more clear and accurate bass and the harmonics compare to PE65612.

I'm pretty sure that I'l never go back to PE65612 definitely!

Note for Usage

The pinout for SC944-05 is almost the same with PE65612, you can replace Pe65612 with SC944-05 directly except for SC944-05 needs an additional hole for its pin 2.

The pin 2 is for "shielding", which connects to the shield between the primary and secondary coils.
Th shielding will greatly improve the noise suppression, hence, except for creating an additional hole for SC944-05 while replacing the PE65612, remember to connect the pin 2 of the SC944-05 to the ground of the primary on transmitter side, and to the secondary ground if used on the digital receiver side.


After 3 hours running-in, I got new conclusion:

PE 65612 is NOT comparable to SC944-05, they are not at the same level!


  1. Ytsejam兄...
    不知您是否有試用過Murata DA101C這顆pluse transformer

  2. Is the SC944-05 superior to the PE 65612?

    Do you need two pulse transformers, one at the source and one in your dac?

  3. To Unkown,

    Theoretically, yes, you'll need another SC944-05 on DAC side.
    However, since the DAC side mod will be my next project, currently I'll leave the DAC side untouched until I finished the source side.

  4. Jason 兄:

    murata 的 spec 看起來很不錯,只是不知道頻寬表現如何,

    會用 SC 的原因,是因為 SC 用數據來證明 jitter 的改善,至少對我來說有個參考。
    不過,小弟認為 SC 的強項,是因為他適度抑制了雜訊。
    很多人一直強調 jitter ,但是小弟到目前的結論,認為雜訊的抑制要比減少 jitter 重要的多。

  5. To Unknown:

    I recall the reason why I didn't use the SC944-05 on the DAC side.
    My DAC is Pure Audio Lotus-1, on the S/PDIF receiver side, there's no transformer installed, only a cap is used. In my case, I was intended to use the transformer to isolate the source and the DAC, especially the ground loop to avoid the noise (that might appear in the ground as well) traverse my whole system. HTH.

  6. Ytsejam兄你好,我看過你的blog後對SC944-05十分有興趣,是否可以跟你購買兩顆來試試看? 我最近在為我的DAC更換USB receiver, 但新換的USB子版GND端被雜訊干擾到高頻失真,必須要用數位變壓器隔離

  7. 附上我更換USB receiver的分享:

  8. wdesign 兄:

    手邊還有2顆 SC944-05 ,我會用 email 跟您聯繫。

    至於 USB,非常感謝您的分享,看來是個不錯的 USB 子板。

    不過,小弟還是傾向用網路傳輸的 AirPlay 方式,若網路規劃良好,穩定性不錯,而且主要是非常方便,只要用 iPad/iPhone/iPod Touch 就可以遙控,加上網路層有很多協定確保資料正確性,以太網路本身就有 Transformer 做隔離,Airport Express 端有 Buffer 來避免因封包遺失造成的 Frame loss 的問題,理論上要比USB Reliable,大概會是比較適合我這種懶人的 solution :)

  9. Ytsejam兄你好,請問還有多的SC944-05嗎?我享用在DSIX線路上!

  10. mail留錯了,,請問還有嗎?