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。

 

Speed stability test results on Technics SL-1000R, Part#2

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Technics SL-1000R speed stability data reported by the PlatterSpeed apps on iPad. No doubt this turntable is for now the world champion in this category. As references, the 2nd chart is the measurement on my SL-1200G. For people who don't consider speed stability as an important attribute of a turntable, do find a chance to listen to the sound of a solo piano or violin playing through this turntable.

用 iPad 上的 PlatterSpeed 軟體測試 Technics SL-1000R 的轉速穩定度，果然真的是目前的世界冠軍。比 SL-1200G（圖2）又更準一些。認為轉速穩定度不重要的人士，建議找機會聽一下這台唱盤播放出來的獨奏鋼琴或小提琴聲。

Speed stability test results on Technics SL-1000R

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Speed stability test results on Technics SL-1000R using AnalogMagik. As I mentioned before, flutter == 0.05% is the lowest number I've seen using AM for measurements, similar to what I got on my SL-1200G. If the PlatterSpeed apps is used instead, most likely we will see 0.015%. BTW, this is the best stability of all turntables I've tested so far.

這是用 AnalogMagik測試 Technics SL-1000R的轉速顫抖率，得到 0.05%，與之前測試 SL─1200G的幾乎一樣。若是用 PlatterSpeed來測，應該會得到 0.015%。這是所有我經手過的唱盤裡最佳的數值。

僅作參考：一台很新的K牌金色重量級唱盤，測得數據是：

The Perils of Using Tangential Arms -- Follow Up

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The Perils of Using Tangential Arms -- Follow Up

The owner of the cartridge followed my advice and sent the cartridge to the manufacturer. It has just been returned and, upon inspection, I was shocked to realize how much of the original stylus shank had been worn out (Fig. 1) compared to the newly installed one (Fig. 2). For those "gurus" out there recommending air-bearing arm users tune the air pressure lower to get "fuller bodied" sound, please take a look at the two photos and reconsider your stance on the matter.

Here's the earlier post for reference:
http://bingrungtsai.blogspot.com/…/the-perils-of-using-tang…

唱頭的主人聽了我的建議，將它寄回原廠，現在已經回來了。我在顯微鏡下看了之後才驚嚇地發現，和新的針尖（圖2）對照比較，原先的針尖（圖1）磨損掉的部分，比想像中還大很多。雖然磨損這麼嚴重，當初測試聆聽時，在聽了一個多小時後，才開始察覺到弦樂高頻有些許沙啞感，而且這還是因為我累積了一些這方面的聽感經驗，才會開始懷疑。所以除非用顯微鏡定期檢查，多數人對所用的針尖已經磨損，都很少察覺。而建議將氣浮臂的氣壓調低來得到比較「厚聲」的「達人」們，在看了這兩張照片後，是否要重新考量一下？

先前的背景資料：
http://bingrungtsai.blogspot.com/…/the-perils-of-using-tang…

Instrument-Based Method to Troubleshoot Hum

For years I've been advocating using instruments to aide troubleshooting hum issues, especially in vinyl playback systems. Due the diversity of component designs/implementations, the hum may be from the most unexpected causes/sources, and very often the resolution can only be found by trial-and-errors and step-by-step reductions before reaching the best outcome. Here's another recent example in my system.

After replacing the stock PSU for iPhono2 with a beefed up Acopian unit, I am quite happy with the sonic improvement, but when standing close to the speakers I can hear some humming, more prominent than my other phono stages such as the Avid Pulsare II. Even though no one can hear it at the listening position, I know the issue has to be addressed to reach optimal sonic performance, because the hum is just an indicator of how easily all kinds of unwanted noise can get into the system.

This morning I hooked up the measurement setup, and after trying out various grounding connections, I finally found the solution. Again, the best configuration is quite unexpected, and may not work at all in another system.

Before:

After:

Turns out in the case, it's best NOT to ground the Acopian PSU and the iPhono2 chasis. Using the relative scale, one can easily see the reduction in each step.

Both grounded, the 60Hz component is set as 0dB: 

Disconnecting the ground wire on the Acopian PSU gets about -7dB:

Disconnecting the iPhono2 chassis ground gets roughly another -2dB: