Friday, March 9, 2018

Verifying AnalogMagik's Load Tuning Function

I was somewhat doubtful this would actually work before running this set of tests. In my prior experiments, I've found using a MC step-up transformer with various loading values in the phono stage would definitely impact the measured frequency responses. But I had been of the belief that, for the case of MC cartridges without using a step-up transformer, even though the impedance settings would impact the perception of overall tonal balance, the effects should be only in the harmonic compositions or even in the ultrasonic frequency range, presumably expecting no difference in normal frequency response measurements. However, the test results below quite clearly indicate the 500-ohm value indeed leads to the best "flatness" measurements in AnalogMajik. And in fact, this is the value I had found most agreeable with my ears before running the measurements.

I have run the tests using the Avid Pulsare II phono stage, with easily adjustable resistance settings of 10, 30, 100, 300, 500, 1k, 5k, 10k and 47k ohms. Only the most relevant data is shown below. All other values clearly result in inferior flatness data to the 500-ohm setting.

在還沒作實驗前,我也很懷疑這功能是否真的有用。以前的實驗數據顯示,MC唱頭搭配升壓器,不同的唱放阻抗或容抗值是會影響觀測到的頻率響應。但如果直接進入唱放,並未曾觀察到負載改變影響到頻響測量的例子。這裡是用了 Avid Pulsare II 唱放,10,30,100,300,500,1k, 5k, 10k 與 47k的阻抗負載,以及AnalogMagik 來觀察頻響曲線的平直程度。只列出3個最有意義的數據點,可以看到 500 歐姆的結果最佳,其它阻抗值包括未列出的都比較差。而這個阻抗設定,正是我之前用耳朵判定所得的最佳值。

500 ohms:

1000 ohms:

300 ohms:

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