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Posts by jcx

Shannon-Hartley Channel Capacity Theorem is the Engineering Definition that best allows comparison of analog vs digital "channels" like recording/playback chains https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem   vinyl does have the ability to record higher than human hearing upper frequency limits - at greatly reduced amplitude - but the practical cutting and playback amplitude limit vs frequency starts decreasing well within the conventional audio...
part rolling is insidious because of the psychoacoustic confounders of delay and sighted listening (even level matching with some tube circuits, varying tube parameters) - but with the appearance of being a "fair" test to those who haven't read up on human sensory testing   the "scientific" method really requires multiple amps of the same model - likely even modded for production tolerances to match to 0.1% amplitude over frequency, load variations - like "blueprinting"...
in theory if the amp doesn't have annoying nonlinear distortion, then noise and peak output are really the only considerations after the Realizer's headphone calibration through the amp and headphone, correcting frequency response, phase, channel balance...
LED backlit monitors have been accused of using too short wavelength blue LED, of course by someone wanting to sell you a solution: http://www.benq.com/microsite/eye-care-monitors/lbl.html
pan pot "painting on" soundstage from close miced feeds is pretty standard for the over 1/2 century of Stereo mastering - DAW today can add R,L delta delay to improve the sensation of musical instrument "position" in the mix comments from Moulton's site:
speakers have the advantage that the soundstage "stays put" as you move your head - your brain, auditory neural complex has deeply embedded your own head, ears modification of frequency and phase response with varying external sound source angle   and your brain expects the sound sources to be modified as your head moves - when they aren't as in normal headphone listening the model your brain is trying build of the external sound sources is confused, soundstage...
laptop AC power adapters can have horrible line coupling, add "ground loop" hum even though nominally isolated for safety rating, legal use of unpolarized 2 pin mains power plug
when you cost out burning a audio CD don't forget the tax: https://en.wikipedia.org/wiki/Private_copying_levy
some Class D, switching amps only have bridged outputs so tying R, L Black together is a no-no since both are active outputs, not common ground   some tube amps with output transformers are reputed to be able to damage themselves without low enough resistive load on the output winding       a resistor divider on the output can match the gain better for the headphones
if the question is measuring ES amp's audio performance numbers then you need a ~500:1 Capacitor Voltage Divider - Polystyrene are as good as it gets (Teflon being squishy is more microcphonic, and has poor availability)   the C seen at the ES output should be similar to a ES headphone load - at least as much as a Resistor is compared to a dynamic headphone Z   then you likely need a buffer too before your soundcard or a pro audio analyzer   not real hard but if...
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