Happy birthday mr nelson pass

ack

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I had not seen his wiki page - thanks for that. The following caught my eye:

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 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.

I always thought his Pass Labs designs are not pure class A all the way and this confirms that.
 

GaryProtein

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Jul 25, 2012
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Happy Birthday!

I love your XVR1 !
 

Al M.

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Happy Birthday!

I love your Pass B1!
 

Barry

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Happy Birthday Mr Nelson Pass! Thanks for building great equipment; and, most important, sharing so much audio electronic information with the world's audio lovers and DIY audio community.
 

PeterA

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I had not seen his wiki page - thanks for that. The following caught my eye:



I always thought his Pass Labs designs are not pure class A all the way and this confirms that.

This information is in some manuals and can be noticed in Stereophile test reports. My XA160.5s are rated for 160 watts 8ohm/320 watts 4ohm in Class A and leave Class A after that to their full power. That is what the needle meter in the front faceplate on my particular amps is all about. If it moves to the right, it leaves Class A.

Happy Birthday Nelson Pass. Love your gear and have owned many Pass amps and preamps over the years. I have fond memories of the Aleph 2 and still own the Aleph 3.
 

NorthStar

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66
 

ack

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His class A designs deliver the full rated power in class A. Look at Northstar's post.

You must not have read it yourself:

For several years Pass Labs has specified the nominal wattages at which our amplifiers leave push-pull Class A operation into an eight ohm load.

take a closer look; they make power claims at the point where is switches to AB, therefore, their designs can put out more power, just not in pure class A. It's like saying my car to do 0-60 feet in 1 second, and God knows this means for 0-60mph. Still, their Class A rated power is quite comfortably high.
 
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PeterA

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Dec 6, 2011
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His class A designs deliver the full rated power in class A. Look at Northstar's post.

This seems true, if by "full rated power" you mean the Class A power specification they publish and the model name designation they give. 160 watts is the "full rated power" (in Class A) of my XA160.5 amps into an 8 ohm load. It doubles to 320 watts (in Class A) into a 4 ohm load. However, these amps have even more power after that in class AB. The rated power spec is conservative in terms of total power. Thanks for that link, Northstar. It's an interesting read.
 

slowGEEZR

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You must not have read it yourself:



take a closer look; they make power claims at the point where is switches to AB, therefore, their designs can put out more power, just not in pure class A. It's like saying my car to do 0-60 feet in 1 second, and God knows this means for 0-60mph. Still, their Class A rated power is quite comfortably high.

Right. It's a language thing. For instance, the full rated output for the XA100.5 is 100 watts at class A. Of course it puts more out in class B, but the rated power I refer to is the class A, as that is what it is advertised at, 100 watts. I think of the class B as a bonus power rating.
 

twitch

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Jun 17, 2010
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Right. It's a language thing. For instance, the full rated output for the XA100.5 is 100 watts at class A. Of course it puts more out in class B, but the rated power I refer to is the class A, as that is what it is advertised at, 100 watts. I think of the class B as a bonus power rating.

Steve, I think what you meant to say was Class A/B not Class B, for Class B is used minimally in serious audio amps for it's crossover distortion possibilities.
 
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