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遊走各大論壇 kkzzst 嫁到
唔好迫人買你D嘢,好冇?

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本帖最後由 pallee 於 2019-10-13 15:33 編輯

回覆 1# fast20181

I am on negative side of it.

First of all, this guy knows nothing about electronics (really nothing). He is paid for promotion purpose. He tells myths only.

Powerless pre-amp is just coupling transformer. Basically it is unnecessary. All these features (EMI removal, filter) are better done in power amp (not externally). Inversely, adding a powerless pre-amp may deteriorate the signal transfer (lower THD+N, lower S/N, more noise, more phase shift).

Powered pre-amp has a unique function. It corrects the gain curve across the audio frequency range and makes it a straight line. Also, it helps to normalize the loudness and provides a better volume control. It is useful (needed) in the past (e. g. Vinyl).

In digital world, it is less useful as audio signal after DAC is already gain linear and normalized. And nowadays it is more popular to do volume control on the signal (before amplification), not on the output (after amplification). That makes the gain stable (more linear, more balanced, less noise, less error) and avoids distortion (due to unstable transistor operation). In expensive product, you can find the volume control chip (after DAC chip, before amp). In cheap product, it just programs the DAC chip for volume control.

But sometimes it is still good to add a powered pre-amp between DAC and power amp for more accurate signal or dedicated frequency band adjustment (hardware EQ).

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If the music source (DAC, CAS, DAP) has volume control, just plug it to the power amp. That is.

The simpler, the better.

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透過一對由鈹膜合金製造的交連變壓器進行音訊放大,毋須經過膽管或原子粒,令音色更乾淨自然,將頻率響應提升至10Hz~45,000Hz

complete nonsense

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If the music source (DAC, CAS, DAP) has volume control, just plug it to the power amp. That is.

Th ...
pallee 發表於 2019-10-13 15:24



    愈簡單愈好,有見地!

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