New Posts  All Forums:

Posts by jcx

your soundcard likely uses 1% resistors, and the ADC, DAC chips have R/L channel tolerance of that order too   so you really need to dig into measurement technique, calibration, or clever ratiometric techniques to get it all lined up to definitively talk 0.1 dB, ~ 1% accurate measurement 
the rational, "scientific" version of "all amps sound alike" has always been subject to the caveats that they have the same frequency response into the same load (include output Z effects)   amps can sound different - most often because you are listening at different volume, frequency responses differ by greater than known thresholds, rarely because of distortion, maybe more often from clipping at different power levels, audible hum, noise differences... 
forum search might find a few threads
I don't do "better sounding" - the TPA6120, wrapped in a good (fet input?) op amp's feedback loop is simply accurate to beyond any demonstrated human audible resolution limit within its ~+/-14, 400mA output limits if you aren't up to high performance PS psrr design then you can even Class A bias the 2 of them in a package into Class A push-pull up to a few Watts in normal pcb heat sink mode or over 5 W/chip  if you turn them belly up and clamp to a heatsink these DSL line...
a lot of time could be saved by reading up on Clark's Amplifier Challenge - $10k on the line and no winners https://www.google.com/#q=richard+clark+amplifier+challenge or the Stereophile Carver Challenge - their own selection of "STOA Tube Amp" and idiosyncratic speakers in their own listening room versus a tweaked for frequency response null $600 Caver SS amp - any want to guess the outcome - or why Stereophile never adopted the style of testing as a standard?
j310 is wrong type fet - short channel uhf amps make lousy ccs   the circuit could have current gain in the bipolar mirror - then you could use a lower current long channel fet as the current reference   or you redesign it with LED biased bjt ccs and bypass fet availability altogether - still have to measure LED Vf and/or trim but initial parts variation is a fraction of jfet parameter spread       of course modern CFA op amps designed for DSL line driving, -100 dB...
except that jitter at sub nanosecond levels hasn't been shown to be audible in controlled listening tests - the audiophile jitter reduction sub industry hasn't published new controlled testing verifying their claims - its all hand waving, anecdotes and FUD   published peer reviewed jitter audibility thresholds are from decades old papers that show 100s of nanoseconds for random jitter, 10s of nanoseconds for correlated or tonal jitter   jitter so low it is...
voice coil motors are just a efficient geometry for coupling the current in a wire to a concentrated mag field to generate a force/motion over a restricted range     for sound radiation you have to add some solid surface to push the air - sometimes this is just a cap, a dome/inverted dish the same diameter as the voice coil, there are also ring radiators, the common cone you see everywhere...   the relation of sound wave generation and desire for decent loudness and...
definite safety issues with big Ne magnets - cuts, even broken bones are real issues when they fly together or at any Fe nearby   I really can't see your school safety officer allowing such large magnets without serious supervision, shop inspections for loose tools, handling precautions if they had the slightest clue how much force, energy product are involved - and how non-intuitive the risks are - humans aren't expecting lumps of stuff to suddenly fly     as far as...
New Posts  All Forums: