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Old 13th January 2007, 01:42 PM   #11
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Kanwar,

The topology suits my goals, and in simulation (which should model the voltage drop correctly) I can easily go to within 2.5V of the rails. That does not seem like a huge loss to me.

As for the heat, I have no idea what you mean. The bias is not high enough to make much heat. It certainly will be cooler then my old Aleph 30.

Also, as a percentage, I doubt the people who make pro amps are in the majority of the forum users.

It seems you have some dislike for this output stage and you may have your reasons, but, as an amateur interested in hi-fi, I am going to have fun making it.

Cheers!
Russ
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Old 13th January 2007, 02:32 PM   #12
x-pro is offline x-pro  United Kingdom
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To continue the topic I attach here a drawing of few different topologies. I've used MOSFETs throughout for simplicity . Top row - fully complementary output and a couple of quasi-complementary configurations. Bottom row - current sharing with P-ch splitter, N-ch splitter and differential P-ch pair as splitter. Last one is a well known option.

Alex
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Old 14th January 2007, 06:29 AM   #13
quasi is offline quasi  Australia
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Default Re: Quasi or not Quasi - that is the question.

Umm....do I get to vote?

Cheers
Quasi
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Old 14th January 2007, 06:48 AM   #14
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Default Re: Re: Quasi or not Quasi - that is the question.

Quote:
Originally posted by quasi
Umm....do I get to vote?

Cheers
Quasi

Now he is Quasi himself, then what would you do Alex......
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Old 14th January 2007, 09:55 AM   #15
x-pro is offline x-pro  United Kingdom
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Default Re: Re: Quasi or not Quasi - that is the question.

Quote:
Originally posted by quasi
Umm....do I get to vote?

Cheers
Quasi
Quasi, I knew you would not miss this thread. Please feel free to vote if you think it is the right way to solve this .

Cheers

Alex
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Old 14th January 2007, 10:10 AM   #16
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Can I vote for complementary?... Allthough I've allways had a soft spot for the quasi topologies nobody would even consider it if there would be a real perfect matched complementary transistors availeble.. or am I mistaken?

grzz, Thijs

ps let's stick to the original thread topic..
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Old 14th January 2007, 10:27 AM   #17
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Quote:
Originally posted by tschrama
Can I vote for complementary?... Allthough I've allways had a soft spot for the quasi topologies nobody would even consider it if there would be a real perfect matched complementary transistors availeble.. or am I mistaken?

grzz, Thijs

ps let's stick to the original thread topic..
Hi Thijs,

yes, I suppose it is true. However the main question was - what to call "quasi" . In my view you can only use this word when you try to imitate a fully complementary topology with non-complementary devices. Otherwise we would call all valve amps and N-channel only amps with a transformer coupling also "quasi". Somewhere we should draw the line .

And it is true that there is no perfect complementary transistors in existance, especially bad the situation with MOSFETs as physics prohibits it. In any case two different structures would behave differently with current, temperature, transient power etc. even if they matched well in a particular point of characteristics. If you use two same devices and drive these symmetrically you can have symmetrical dynamic behavior and I consider that important in audio.

Cheers

Alex
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Old 14th January 2007, 01:12 PM   #18
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oops sorry,

Offcourse ...I agree... it comes down to how the output stage is driven... if the previous stage is such that it could drive a complementary output stage.. then the output stage is quasi-complementary...


in other words.. it the output stage can be sustituted by a complementairy output-pair.. without changes to the previous stage, the output stage can best be called quasi-complementary..


I like your output stage overview btw...
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Old 14th January 2007, 01:22 PM   #19
x-pro is offline x-pro  United Kingdom
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Quote:
Originally posted by tschrama
oops sorry,

Offcourse ...I agree... it comes down to how the output stage is driven... if the previous stage is such that it could drive a complementary output stage.. then the output stage is quasi-complementary...


in other words.. it the output stage can be sustituted by a complementairy output-pair.. without changes to the previous stage, the output stage can best be called quasi-complementary..
I can not agree with that definition . Any VAS can be coupled somehow to any output stage. What about a valve transformer output again? It can be happily driven by a conventional VAS. "Quasi-complementary" means "imitation-complementary", isn't it? If we "imitate" one of the devices in a fully complementary topology than it is "quasi", otherwise it is not.

Put it another way - in a "quasi-complementary" you always can without really changing the topology replace a part of the circuit with a complementary transistor to make it fully complementary. If you can not do it, than the circuit can not be called "quasi".

Cheers

Alex
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Old 20th January 2007, 03:39 AM   #20
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Default More Quasi, please...

I would personally like to see the advancements of Mr. White’s & x-pro's indulgence on this work. I think if there is something good worth exploiting, they may find it.

I find it difficult to understand a persistent negative flow from critics and detractors but then again that is the true fuel to real discovery, even if it only results in a lesson learned.

Shawn.
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