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Old 09-11-2018, 10:13 PM   #10
wwenze
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Join Date: Dec 2002
Posts: 33,117
I created a new type of measurement thanks to this amp...

I call it: THD with white noise on the other channel

Because this thing has such disappropriational and abysmal crosstalk performance, I realized that this has no impact on sine tone testing since both channels are reproducing the same thing, but in actual usage the sound on the other channel is going to leak over and degrade the performance.

So for this test, I make the other channel produce white noise of the same RMS.

Result: It degrades the THD+N performance to pretty sad levels, mainly because of the extra noise.

33 ohm:


Note the much higher noise floor of the yellow graph as a result of white noise from the other channel leaking over.

The observant eyes would notice the green graph noise floor is worse than in the other measurements. This is because I have both soundcards on the some computer and so this is the common-mode noise. Still lower than the noise from crosstalk.

On the plus side, crosstalk seems to be lower when powered by the computer. RMAA reports around -59dB with a 16 ohm load, albeit not at 1.9V (slightly lower voltage was used since SXFi AMP cannot output 1.9V with a 16 ohm load).
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