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The point of the SIT is that it behaves like a triode but at lower voltages and higher currents, so it doesn't need a matching transformer to deliver power to 8 Ohms. Like tubes, SITs have soft overload clipping. When brief bursts of musical energy occur, SITs react with rounded waveform tops instead of sharp and hard clipping of solid-state. SITs have a curve which looks a lot like a triode vacuum tube; low at first and climbs steadily. The distortion curve is similar, a steady rise instead of a valley with high distortion at both ends.
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circuit complexity and number of components through which the audio signal must travel, resulting in any residual distortion having a very simple distortion spectrum. His more powerful designs that go beyond what can practically be realized in Class A (such as the
Threshold and Pass Labs products) operate in Class AB1 but retain a heavy bias so that they operate in Class A during quieter passages, and great emphasis has been given to avoiding or minimizing switching effects.
85:" topology patented by Pass, to give extremely low distortion levels, and more recently the XA series of amplifiers, which advantageously combines aspects of the Aleph design with the "supersymmetry" technique. Recently, Pass Labs has introduced a loudspeaker, and Pass DIY has increasingly explored the field of high-efficiency and full-range speakers as a complement to minimalist amplifier designs.
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Typically using MOSFETs as the gain devices, (often as current sources rather than voltage sources), most of his designs operate in Class A, with all the low distortion of small signal benefits generally associated with that. He is also known for his advocacy of "minimalist" designs, which reduce the
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in a single-stage, single-ended, Class A circuit without feedback or degeneration. The SIT chip combines a square-law input character with a low impedance output to form the only solid-state gain device, which Pass claims, "behaves like a triode tube." There is no output transformer on the SIT amps.
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In 1974, he received his BS in physics from the
University of California-Davis. During his studies, he and Mike Maher founded the small speaker company PMA. From 1973 to 1974, he was employed at ESS and assisted Dr. Oskar Heil with crossover design, woofer selection, and final build cabinetry of
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In the mid 1980s, Pass designed the well-reviewed Adcom GFA-555 amplifier. This was a
Bipolar Junction Transistor (BJT) based design. Nelson also designed the GFA-5XXX MOSFET-based series of high-bias class-AB amplifiers for Adcom (i.e. -5300, -5400, -5500, -5800).
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26:. Pass is vocal that listening tests remain valuable and that electrical measurements alone do not fully characterize the sound of an amplifier. Pass holds at least seven U.S. patents related to audio circuits.
56:). During his time there he demonstrated an Ion Cloud loudspeaker at CES in 1980, based on ion wind technology. He sold Threshold Electronics in 1997. The company continued without Nelson Pass under the name
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in 1991. Pass (and his companies) designed and produced the Class A "Aleph" series of single-ended amplifiers. Pass Labs produces the X series amplifiers, which make use of the "
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on
December 5, 1974. Later, Joe Sammut became the third partner. Threshold is perhaps best known for the "Stasis" amplifiers (a design later also produced under license by
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site. He often interacts directly (and somewhat tersely) with audio hobbyists. His nickname among the DIY audio community is "Papa".
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audiophile, consumer grade loudspeakers. Nelson Pass holds 6 patents related to magneplanar speakers.
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353:"First Watt / Pass Labs SIT-2 Stereo Amplifier 10 excellent watts! Review By A. Colin Flood"
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331:"SET And SIT Amplifiers Nelson Pass on his exciting new designs. Article By A. Colin Flood"
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Friend or Foe? High End
Designers Reassess the Importance of Audio Measurements
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After graduating in 1974, he and René Besne founded high-end amplifier company
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http://www.diyaudio.com/forums/showthread.php?postid=1600879#post1600879
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Steven R. Rochlin - Superior Audio - Enjoy the Music.com.
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http://www.stereophile.com/solidpoweramps/678/index.html
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http://www.audiokarma.org/forums/showthread.php?t=74228
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Patents with "Nelson" and "Pass" in the inventor list
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118:community by way of published articles (notably in
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16:Prolofic Audio Amplifier Designer & Enthusiast
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153:"Nelson Pass: Four Decades of Innovation"
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258:Discussion of Nelson Pass work at Adcom
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22:(born June 27, 1951) is a designer of
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313:Home Theater Geeks 42: DIY Geekfest
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283:"Adcom 5800 - Nelson Pass, others"
269:"Adcom 555II - Nelson Pass ?"
151:Harley, Robert (August 12, 2015).
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386:The Pass Labs DIY site
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373:The Pass Zen Amplifier
130:Design characteristics
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50:Threshold Electronics
35:Studies, PMA and ESS
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333:. Enjoythemusic.com
329:Steven R. Rochlin.
396:The DIY Audio site
231:"Magnepan patents"
157:The Absolute Sound
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220:Interview with NP
120:The Audio Amateur
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428:1951 births
297:"Xs Series"
205:NP@diyaudio
20:Nelson Pass
407:Categories
359:2016-07-29
337:2016-07-29
162:August 17,
139:References
124:First Watt
99:First Watt
89:First Watt
301:Pass Labs
116:DIY audio
95:Pass Labs
79:Pass Labs
73:Pass Labs
54:Nakamichi
44:Threshold
30:Career
64:Adcom
164:2022
110:DIY
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