Quote:
Originally Posted by jdandy
Art.......Impressive. The square wave performance out to 100kHz is exceptional. It would be interesting to see the first four tests with a 1kHz signal, a more typical test frequency for audio square performance. Thanks for the photos.
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Thanks for the comments.
When I get some free time later I'll run the test at 1kHz, plus I'll test my Krell preamp so that you have a reference.
I'm slightly limited by the sound card, as good as it is (Asus xonar), but it appears as though all distortion products are at or below 0.001%, across the audio band.
I might also run the thd tests again with global feedback reduced to 0dB, which I can do easily enough by changing a couple of resistor values.
In terms of subjective performance, I prefer it over my three other preamps.
Soundstaging is excellent and the treble is very pure and sweet, and free from grain, but very detailed at the same time. Everything else is beyond reproach too.
With 30dB of global feedback the treble was slightly less liquid, and transients took on a slightly too hard quality, but around 10dB seems optimum.
There is a DC offset controller which thermally tracks the preamp's drift, but it's outside the feedback loop.
Btw, the -3dB point is 1.7MHz, set by the input filter.