London Reference Cartridge with Custom-Made Phono Stage

（中文在後）
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

（中文在後）
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。

 

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:

The Perils of Using Tangential Arms?

 （中文在後）

 Among all the cartridges (>100) I've inspected for friends in the past few years, only 4 showed obvious stylus wear.   Interestingly, 3 of them  were installed on air-bearing arms, the other on a tangential pivoted arm. The photos below are from the most recent case,  showing a chunk in the right-channel side of the stylus chipped away. According to the owner of the cartridge, he followed the advice from an "expert" and adjusted the air pressure to the arm  lower to get "fuller bodied"  sound. 

I believe there is nothing intrinsically wrong with those arm designs, though one should definitely pay more attention to the setup and maintenance aspects. Especially with the air-bearing type, any issue in the air transmission lines can put huge stress on the cartridge and its stylus. 

在幫朋友檢視過的這麼多唱頭之中，真的見到針尖磨損的情況，其實非常少，嚴格講起來算有4個。但無獨有偶，其中3個是裝在氣浮正切臂，而一個是裝在支點正切臂。3支氣浮臂是不同廠牌出品，所以並非哪一支臂的特有現象。附圖是最近觀察到的一個例子，可以看到，針尖右聲道那一側（圖1,2裡的左側），有明顯的缺角。根據主人的說法，他按照一位「達人」的建議，將氣浮臂的壓力調比較低。可能因為如此，在播放唱片唱臂向內移動時，外側（右聲道）一直承受比較大的壓力。

我在之前（音響論壇348期）也說過，直線正切臂（氣浮臂包含在內）的先天缺點之一，是所有的質量都在支點之前，因此有側向力時，唱頭針尖會受到很大的壓迫。而支點正切臂，這方面雖然比較不會造成問題，但因為機械構造複雜，可動部分受到灰塵或溫濕度影響，動作受到阻礙的機率會比傳統支點臂來得高很多。因此，使用這類唱臂的人士，應該要定期檢查保養，特別是氣浮臂，整個供氣的通路一定要確保清潔通暢，壓力要合乎原廠規格。而且在聽到有任何循軌異常時，立刻停止使用，做全面的檢測。

至於唱頭的健康狀態，我一直主張要每半年測量數據，持續追蹤變化。如果有明顯改變，就應該拆下來用顯微鏡仔細檢查有無異狀。這對正切臂的使用者來說，尤其重要。

Before-and-After Data of Cartridge Adjusted by Manufacturer

Before-and-after comparisons of a cartridge that, based on my assessments/recommendations, was sent back to the manufacturer for adjustments in its cantilever angle, etc. Looking at the differences in data below, most people will have a hard time believing they are measured on the same cartridge.

上次兩個被我判定針桿太陡的唱頭之一，原廠調整角度寄回之後，今天去測了新的數據並做了azimuth等參數的微調。看了前後數據的差異，很難相信是同一個唱頭。

Steep Angle Needed for a vdH Black Beauty

This vdH Black Beauty needs plenty of tilting forward. With its top level, the IMD is unacceptably high at about 12%. Lowering the arm high makes it even worse. Raising the arm on the SL1200G to the limit and slight improvements start to show. Eventually need to shim 3 pieces of cards in its front to get the numbers into the 2 to 3% range.

這個 vdH Black Beauty，調整到上緣水平時，IMD竟然高達12以上！降低一些更差，到14。SL─1200G的唱臂調到最高，稍微好一些到11左右。最後竟然前緣要墊3張名片的厚度，才到不錯的數字範圍。

AnalogMagik's Tracking Force Function

（中文在後面）
After finished writing the Part-1 of AnalogMagik review, I started to test the remaining features I haven't spent much time on. The Tracking Force function are verified on two cartridges here, Lyra Kleos (recommended VTF=1.73 according to the user manual) and DS Audio DS 002 (recommended VTF=1.7). Figure 1 is the final VTF for the Kleos after optimizing for the lowest THD using AnalogMagik. Figure 2 is for the DS 002. For the Kleos which is my main reference cartridge for the past 2+ years, even though the change is only -0.04g from the original setting, the sound has become much more refined with high-frequency extension unheard before. Similar improvements are also heard on the DS 002, but somewhat less drastic even though the change in VTF is much greater.

第一部份的評論交稿之後，開始測試 AnalogMagik其它還沒仔細研究的功能。Lyra Kleos（廠方建議針壓 1.73）最佳化後的針壓如圖一，DS Audio DS 002 （廠方建議針壓 1.7）最佳化後的針壓如圖二。調整後，兩者高頻變得細膩很多，尤其是已經用了2年多的 Kleos比起之前，「高貴感」進步幅度相當明顯。

New cartridges should all come with photos like these

The two cartridges belong to my friends. In my inspection I believe the cantilevers were both overly steep, resulting in the SRAs in the +96-degree range when the top surfaces were level. After adjustments at the factory, they came back included photos showing much more reasonable angles. For the cartridge manufacturers, providing such photos should be fairly easy, and such material will greatly help the users in correctly setting up the devices. Additionally, this makes monitoring the health of the cartridge much easier over time.

Note the angle of the coil is now only slightly away from parallel to the pole pieces. Adding tracking force and drag should put it into near perfect angle.

這是兩個針桿太陡的唱頭，原廠調整後寄回來，他們所附的照片。強烈建議所有新唱頭都應該附上這樣的照片，對用家來說會少很多調整上的麻煩。日後也容易追蹤健康狀況的變化。

注意現在線圈的角度，只偏離磁鐵的平面一點，加上針壓等外力，就應該與前後的磁鐵平行了。

"Powerful Bass" of Phono Stages?

When some people/reviewers commented certain phono stage has "powerful bass", it's better to take it with a grain of salt. Unlike pre-amps or power amps which do not have any EQ circuit in their signal paths, a phono stage has a reverse-RIAA EQ built in. And some designers will "cheat" a little by tweaking the EQ curve to achieve the desired "sound" for the device. So when we find a phono stage to have very impressive bass performance, it's likely not from the superior circuit design or strong power supply unit, just a trick of modifying the EQ. 

The three phono stages tested below are all priced at the ~8000 USD range. Using the same cartridge Lyra Kleos (without changing any parameters) to feed the test signal, I measured the high-frequency responses to be virtually identical. Whereas below 5kHz, the 2nd and 3rd devices obviously display higher output levels, ranging from a couple of dB to the extreme case of nearly 5 dB at the lowest end of the spectrum.

Incidentally, the first two are UK brands, and the 3rd one from the USA. In my experience, phono stages made by the US-based brands tend to have boosted bass responses similar to the 3rd device.

前後級擴大機沒有等化線路，而唱頭放大就必須有「反」RIAA等化。低頻很厲害的唱放，其實可能只是在等化曲線上做了些手腳，並非它的線路或電源部分有多特別。如下面3個圖的比較，用同一個唱頭不改變任何參數，得到的高頻響應幾乎完全相同。但 5kHz以下的，就開始出現明顯的差異。這3台的美金定價都在8000左右，前2台是英國牌子，第3台是美國的。

IMD numbers of the ELP laser player

What kind of IMD numbers the ELP laser player will show if running the AnalogMagik's VTA test through it? The ELP uses two ~2-micron laser "dots" to read the groove hence no SRA-related issue. IMD should be very low in theory. Initial measurements below show pretty good numbers, though not much better than a well-adjusted cartridge. I suspect the test record needs to be cleaned even further to get better measurements due to the ELP's susceptibility to dust. In any case, at least this shows AnalogMagik's IMD measurements are mostly in line with expectations.

在 ELP 黑膠雷射唱盤，用 AnalogMagik 的 VTA測試，會得到什麼結果？初始測試顯示，IMD 數值算相當不錯，但沒有比調整得好的唱頭更低。因為 ELP 對灰塵很敏感，可能要把測試唱片洗得更乾淨，才會有更好的結果。但這些數值至少顯示，AnalogMagik的 IMD 測量是有可信度的。而且，之前一直認為 ELP 的聲音雖然細節少，但失真很低，是有其道理的。