Tuesday, April 24, 2018

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。

Monday, April 23, 2018

Using AnalogMagik to Tune London Reference's VTA/SRA

Most Decca-family cartridges have their styli slanted backward as in Figure 1. Naturally, one would assume the tone arm should be raised to achieve better sound. When using AnalogMagik's VTA function to test my London Reference, I found just the opposite. When the top of the cartridge was level, the IMD measured in the 8% range, and jump to ~12% if I raised the arm slightly higher. Only when I tilted back the cartridge to the extreme (as in Figure 2) did I get the best IMD numbers. The sound? Surprisingly delicate, detailed and clean with super dark background, very different from the rough-around-the-edges character that most people expect from Decca cartridges.

Decca 系列唱頭,針尖看起來多數是後仰的,我的 London Reference 也如此,如圖一,所以多數人都會把唱臂調高。但用 AnalogMagik 的 VTA 功能測 IMD, 唱頭上緣水平時 IMD竟然高達8%。再調高更不好,到 12%。反方向把唱頭調低到不能再低,後端快碰到唱片表面(如圖二),才出現不錯的數字如圖三。聽起來如何?出人意料的細膩乾淨又安靜,以前以為 Decca 系列唱頭固有的,稍微不修邊幅個性,竟然都不見了。這真是令人跌破眼鏡的結果。

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Thursday, April 12, 2018

Different power supply units leading to visible S/N ratio differences

Different power supply units leading to visible S/N ratio differences: Using the "Gain" optimization function in AnalogMagik, I measured the S/N numbers on iPhono 2 with its own switching-type PSU (Figure 1) and a large linear PSU by Acopian (Figure 2). The difference is about 1dB and quite consistent in various measurements.

AnalogMagik 有個原本用來找最佳放大倍率的功能,我以它測了不同電源供應給 iPhono 2 的 S/N (訊噪)比。圖一是原廠的切換式電源,圖二是 Acopian 的線性電源。測出的差別不大,約1 dB左右,但數據相當的 consistent。

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