Why high-tech vibration isolation/cancellation devices?

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Why is it necessary to use high-tech vibration isolation/cancellation devices? Unperceived by human senses, there's plenty low-frequency background vibration present in any living environment. Figure 1 demonstrates the spectrum reported by the Kurashiki Mini-560F, with its active cancellation function OFF, and nothing is turned on in my system. We can clearly see the energy presence of sub-20Hz vibrations in my listening room. Figure 2 shows the active function ON, and the vibrations now get below the -60dB mark. Removing these unwanted vibrations greatly improves the overall sound reproduction, obviously.

為何需要高科技減震器材？圖1是用倉敷化工 Mini-560F 主動平台的頻譜功能，將主動減震功能關閉時，可以看到，即使音響系統完全關閉，聆聽室有明顯的20Hz以下，人類的感官無法察覺的震動。這是所有環境幾乎都無法避免的問題。圖2是將主動功能開啟，這些震動立刻降至-60dB 以下。將這些背景震動移除，對黑膠播放或其它器材的音質，必然會有立竿見影的改進。順便提到，這已經是在號稱避震極佳的音響架上，所得到的數據。

Is anti-skating still necessary when using the swing headshell?

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Is anti-skating still necessary when using the swing headshell? The answer is apparently YES. In the first chart, the anti-skating is OFF, and the right channel shows much higher distortion. Adding anti-skating force to the maximum on the SL-1200G, then the distortion levels of both channels now become more even. Unfortunately, there's no known way to increase anti-skating even further on this arm.

使用搖擺唱頭蓋，顯然還是需要抗滑力。第一個數據圖是將抗滑關掉，右聲道的失真高很多。加了抗滑，就比較平衡了。

London Reference Cartridge with Custom-Made Phono Stage

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After a long hiatus, the Decca-series's London Reference is now back in action, with a custom made Tom Evans MM phono stage (the only one in the world according to TE). This phono stage has an RIAA curve and load settings targeting the Decca cartridges. The frequency response measurements indeed indicate the effectiveness in smoothing the curve, especially the bass region. Figures 1 and 2 are in linear scale, showing the same cartridge pairing with the TE and iFi iPhono 2, respectively. Figures 3 and 4 are in log scale. Note the high frequency part may be further tweaked by the capacitance setting.

Decca 系列唱頭 London Reference 經過一段時間沒用，又再次回來，搭配特別訂製的 Tom Evans MM 唱放。這唱放有特別為 Decca 唱頭設定的 RIAA曲線及阻抗/容抗負載。頻響測量得到相當平直的正負2dB結果，線性X軸如圖一，圖二是用 iFi iPhono 2的對照。圖三圖四是對數X軸。高頻部分，應該可以用電容負載再微調。

Two Cases of Skewed Zenith

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Is it always a good practice to align a cartridge with its cantilever parallel to the reference lines on the protractor? In the two cases shown here, probably not. In fact in both these cartrdiges, the builders seem to be aware of the skewed zenith angle and install the cantilever slightly at an angle to compensate for the skew.

用唱頭的針桿來對準尺規，而不用唱頭外殼為準，是許多「專家」會堅持的。但看這兩個相當高價的唱頭針尖，底部的zenith角有明顯偏差。如果用針桿來調整，顯然不會得到最佳設定。而在這兩個唱頭，製作者似乎知道有這個誤差的情況，而將針桿安裝偏一點角度來補償，而非平行於唱頭外殼。所以如果看到一個新唱頭的針桿不太正，或許是有其背後道理的。

Another Cartridge Adjusted by Manufacturer

This owner of this brand new cartridge loaned it to me for review a while back. I found the measurement data unsatisfactory with only about 21dB of channel separation, much less than the 27dB spec. The square wave tests showed a lack of damping at the stylus resonance frequency. In test listening it also sounded veiled and colored. The owner followed my advice and sent it to the manufacturer for adjustments. The manufacturer's reply is:

"Regarding the cartridge, we found a technical problem with an uneven damping unit. This existed most probably already partly before delivery, but since all values were within the tolerated area, it did not call attention. It seems as the problem increased by transport / time because when we received the cartridge back, it was not possible to achieve correct values with this damping unit. We have changed the damping unit for a new one and re-adjusted the cartridge."

全新唱頭借給我測試，發現數據遠不如預期。寄回原廠調整後，數據如下，有明顯改善。上面是原廠說明做了些什麼。

After the adjustments, the channel separation measures much better in the 35dB range. Below are the before and after frequency response measurements:

The square wave test results, right channel. The stylus resonance is now better controlled. 

Effects of flat surface near the 1st reflection point

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The effects of a flat surface, here a door, near the 1st reflection point of a speaker are quite visible in the first impulse-response chart. Asking a person to walk over and stand in front of the door makes immediate, visible differences as in the 2nd chart.

喇叭的側方第一反射點附近的平滑面的影響，可以在第一個 impulse response 圖明顯看到。請一位朋友站在門前，就立刻造成第二圖裡明顯可見的差異。

What do the magnet and pole pieces in an MC cartridge look like?

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What do the magnet and pole pieces in an MC cartridge look like? Figure 1 and 2 show a typical example. The cylindrical part is the magnet, and the attached metal parts are the pole pieces. Figure 3 and 4 show the ultra compact version, where the middle dark-colored piece is the magnet and the shiny parts are pole pieces. After the pole pieces are attached to the magnet, they need to get magnetized using an electrical device, as in Figure 5, before the whole assembly can be used.

典型MC 唱頭的磁鐵與磁極，如圖1與2。圓柱狀的部分是磁鐵，其它前後金屬部分是磁極。圖3，4是特別縮小的設計，中間暗色部分是磁鐵，前後是磁極。在組裝成唱頭之前，磁極必須用工具經過灌磁的手續，如圖5。