AC Noise from Home Lighting

（中文在後）Among various lighting options for the listening room, LED bulbs (right) are probably better than the compact fluorescent type (left). As shown in the first AC spectrum chart, the fluorescent bulb creates visible noise spikes in the near 50kHz region as well as higher order harmonics. The 2nd chart is the baseline with no light turned on, and there's no visible difference when the LED type is used.

如果聆聽室的照明燈光有選擇的話，LED燈泡（右）應該會比小型日光燈泡（左）好。頻譜圖1顯示日光燈泡會產生50kHz附近的雜訊，而且還有更高的諧波。圖2是未開燈的數據，與用LED燈泡時幾乎無差異。

One reason why Decca-family cartridges are difficult

（中文在後）One reason why the Decca-family cartridges are difficult to tune optimally is the sizable gap between the lateral and vertical compliance numbers (Fig. 1). With most tonearms, the lateral resonance tend to be lower than the 8--12Hz ideal range (Fig. 2) while the vertical too high (Fig. 3). Adding/subtracting mass will aggravate the situation in either of the directions.

Decca系列唱頭很難調整好的其中一個原因是橫向與縱向的順服度差異大，如圖1。在多數唱臂，會造成橫向的共振頻率低於8到12Hz的理想值，而縱向會太高。而加/減質量都會造成其中一個方向惡化。