Το άρθρο δεν το έχω. Θα μπορούσα βέβαια να φορτωθώ σε αλλοδαπό φίλο να το σκανάρει, αλλά δεν θέλω να γίνομαι τσιμπούρι και να βάζω άλλους να παιδεύονται για χάρη μου. Επίσης δεν δίνω ιδιαίτερη σημασία σε υποκειμενικές εκτιμήσεις ήχου, για τον απλό λόγο ότι δεν έχω εμπιστοσύνη.
Πάντως τα σημεία που θέτει ο Κόλλομς είναι όλα αντικειμενικής φύσεως, άρα επαληθεύσιμα (ή διαψεύσιμα):
- 1. Push broad band radio frequency noise into the power supply outlets
- 2. Push broad band radio frequency noise out of the line and ground connections
- 3. Push broad band radio frequency noise into the speaker lines (up to 500MHz with up to 2V at 50kHz)
- 4. Make the output impedance, a passive filter, variable with frequency and dependant on speaker loading
- 5. Allow the amplifier to be marginally or completely unstable with high or open circuit output loading
- 6. Employ soft compressor clipping circuits prior to full power clipping
- 7. Employ high order negative feedback to improve in-band distortion figures
- 8. Use feedback to provide numerically high damping factor at low frequencies and claim that this guarantees fine bass (regardless of the interface to the loudspeaker)
- 9. Use steep low pass filters to limit the upper high frequency range, partially negating the purpose of wider bandwidth, e.g. SACD, source material while resulting filter phase shifts may be audible in the working band
- 10. Have input circuits which are highly susceptible to higher frequency input signals including upper band noise shaper noise and DAC artefacts, and which then contribute to poor treble sound
- 11. Have output circuits with poor high frequency resolution resulting in high levels of intermodulation products at the high frequency end of the spectrum
- 12. Have 'sampler' noise shaped noise floors which vary dynamically with the level frequency and complexity of the input signals
- 13. Have comparatively small power supply reservoirs, in the light of their low frequency output current potential
- 14. Have thermal dissipation limitations due to the small power module size which means that thermal dynamic variations are present in the performance with time
- 15. To protect the fragile output stages all kinds of pre-clip, and aggressive fold back protection regimes are included which are frequency dependant and are also programmed for duty cycle
- 16. Operate at an equivalent sample rate which is insufficient for good resolution above 7kHz. DSD 1 bit pulse-width modulation operates at 2.4MHz, nearly ten times the rate used in Class D amplifiers
- 17. Deliver high constant DC voltages relative to local ground (up to 70V) at the output terminals (of course not between the +,- terminals) and hence the loudspeaker connections and cable
Είμαι βέβαιος ότι ο dStam έχει διαμορφωμένη άποψη για όλα αυτά βάσει των τεστ που έχει διεξαγάγει κατά καιρούς.
"Θαυμάζω την κομψότητα της μεθόδου σας. Πρέπει να είναι ωραίο να καλπάζεις με το άλογο των αληθινών Μαθηματικών, ενώ εμείς οι υπόλοιποι αγκομαχάμε στον ποδαρόδρομο" - ο Άλμπερτ Άινσταϊν στον Τούλλιο Λέβι-Τσίβιτα