Pass Labs X250 manual

P age 1 Pass X250 Owner's Manual[...]

P age 2 The X250 stereo a mplifier e mbodies the d esign tech nology and re fineme nts of th e larger "X" series ampl ifiers i ncluding extensi ons o f the pat ented Sup ersy mmetry circuit. The Supersy mmetr y cir cuit topolog y w as granted a U .S. p atent in 1994, and is th e result of 19 years of e ffort by Nelson Pass. The ampli fier[...]

P age 3 Setup You can posi tion th e ampli fier any w here y ou want, but i t requir es ventil ation. We do not recommend placing i t in enclose d cabinets or s mall closets w ithout means for air to circulate freely . The ampli fier idl es at ab out 270 w atts. Let’s tal k about power requir ements. The ampli fier dr aws abou t 2.3 am ps (conti [...]

P age 4 get fixed. We go to a lo t of trou ble to make prod ucts reli able, a nd the failure r ate o f our amplifiers is ver y low . This is sm all comfor t to the few , but take it easy an d giv e us a call i f you have probl ems. People are i nteres ted i n how long it takes for these ampli fiers to break i n. It tak es about a n hour for them to[...]

P age 5 Interconnects and Speak er Cables W e hav e a general recommen dation a bout interc onnects, whi ch is that they shoul d cost less than the a mplifier . W e have tri ed a lo t of pro ducts and most o f them w ork w ell, but as a practical matter w e cann ot make bl anket rec ommend ations. The ampli fier is not sensiti ve to s ource i nterc[...]

P age 6 Warranty Information This prod uct is w arranted for part s and la bor from t he dat e we ship i t. Check w ith th e factory authoriz ed distr ibutor in the countr y y ou are purc hasing this pr oduct for speci fic warr anty information. Distri butors are only r equir ed to offer w arranty serv ice on Pass products th at they have sol d. Th[...]

P age 7 Once it was r ecogniz ed that ex cessiv e use of negativ e feedback w as creati ng proble ms with the soun d, sev eral desig ners addr essed th e proble m by si mply r educing th e amount of feedback and regai ning the perfor mance by payi ng more at tenti on to the c haract er of th e amplify ing ci rcuit itsel f. Feedback st opped being a[...]

P age 8 Rushing to market in the 70’s wi th their low T IM distortion designs, c ompanies e m ploy ed either simpler or more complex circuits to achieve high slew rates. The ampl ifiers that had si mpler circuits w ith fewer parts t ended to so und better than th e amplifiers w ith complex circuits an d a lot of parts. They also cost l ess an d b[...]

P age 9 Supersym metry does n ot reduce t he distorti on and noise pr esent in either hal f of the output of the balanc ed circuit. Co mparing the distortion curv es before a nd a fter the ap plicati on of supersymm etry , we see essen tially no difference in ei ther h alf of the balanc ed pair consi dered alone. It is the b alanced differen tial c[...]

P age 10 ultimat ely w e f ound t hat w e could operate it w ithout feedb ack as l ong as w e put a he althy bias current thr ough it. For these am plifiers this is abo ut 600 w a tts worth. This is not pure Class A operati on in th e contex t of 1000 w atts output, but it has proven t o be the a ppropriate am ount. The result is a s eries of am pl[...]

P age 11 intrinsic ma tching between th e circuits, (c) th e distor tion o f each hal f wi th supersymm etry, and (d) the differenti al dist ortion w ith supersymme try. On this cur ve (B) we can cl early see that intri nsic sym metry due to the matching of the tw o halves r educes th e distorti on by a factor o f 10. Supersy mmetry (D) creates a m[...]

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P age 13 X250 distor tion curv e[...]

P age 14 X250 SPECIFICA TIONS All figur es obtai ned after 1 hour w armup, with r egulated 120 V AC power line. See manu al notes ab out AC p o wer line reg ulation. Gain 30 dB Freq. Response -0 dB at DC , -3 dB at 100 kHz Power Output 250 watts maxi mum @ 1% T HD, 1 kHz , 8 ohms Distorti on refer to accompany ing distortion c urve Maxi mum Output [...]