Active current source

[Nixie]

http://www.tubecad.com/2006/12/blog0088.htm
Doesn't that active current source seem pretty similar to Pass' Aleph patent?

[peranders]

The current source looks very basic to me. How does Mr. Pass' current source look like?

[Nixie]

I'm talking about this one: "the current varies with the output swing, drawing the most current when the output swings down close to the negative rail voltage, and drawing the least current when the output swings close to the power supply rail voltage"

[Wavebourn]

It is what I always did: pushed crossover distortions to higher powers (A+C design), or avoided them completely using emitter, or source, or both followers, loaded by a constant current source that follows the output signal, "drawing the most current when the output swings down close to the negative rail voltage, and drawing the least current when the output swings close to the power supply rail voltage". I don't understand what is new in their design, and which "invention" are they going to protect by the patent?
It is the same cheating with fancy words, like similar British patent, about "Current Dumping that uses bridges".

[Wavebourn]

Here is my example of what they are going to patent:

[Wavebourn]

..and here is again my example of crossover distortions shifted to less audible powers:



The question is, will they try to sue me if I decide to sell my projects that include what they patented after I designed them? Are publiucations on forums enough to protect me against their lawers?

[Wavebourn]

Also, removing crossover distortions from opamps, very old and good working trick... However, resistors don't provide a current that follows output signal, but anyway the current they provide shift bias so crossover distortions if ever exist are less audible than on zero power...

[Wavebourn]

...and, finally, complementary "Tango" pairs, when BJTs are biased in A class, results again in shifting crossover distortions to less audible powers.



(the example above uses unbiased version when powerful driver works in class A: http://www.diyaudio.com/forums/showt...44#post1072644 )