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-   -   637 Amplifiers (http://www.diyaudio.com/forums/solid-state/215127-637-amplifiers.html)

quanghao 25th June 2012 02:17 PM

637 - Class AB Amplifier
 
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OPAM 637 is very popular with the OPA structure is simple.
I'm inspired by it and the amplifier circuit diagram has the same structure to create this amplifier 637.

This is the inner structure of OPAM

quanghao 25th June 2012 02:21 PM

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and , please see it

Bonsai 25th June 2012 02:49 PM

You have removed the LTP current mirror. Although I expec this design will work without it, loop gain will be lower and current balance in the LTP will not be optimum. Both of these will lead to higher distortion.

quanghao 26th June 2012 04:52 AM

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Quote:

Originally Posted by Bonsai (Post 3071861)
You have removed the LTP current mirror. Although I expec this design will work without it, loop gain will be lower and current balance in the LTP will not be optimum. Both of these will lead to higher distortion.

please see this mode OPA 637

quanghao 26th June 2012 04:57 AM

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and one opam 637

quanghao 26th June 2012 07:55 AM

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and the end my amli finis ,

forr 26th June 2012 08:08 AM

The voltage reference of the common base transistors in the cascode input stage is ground and not as in the 637.

quanghao 26th June 2012 08:15 AM

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the constant current circuit diagram for the j-fet input, very little noise and running smoothly!

quanghao 26th June 2012 08:18 AM

Quote:

Originally Posted by forr (Post 3072831)
The voltage reference of the common base transistors in the cascode input stage is ground and not as in the 637.

I changed them and test simulation software running on Mutisim.

a fun change, but pretty good results!

Jay 26th June 2012 09:07 AM

Quote:

Originally Posted by quanghao (Post 3072837)
the constant current circuit diagram for the j-fet input, very little noise and running smoothly!

It is usually not much different in noise that can be seen in simulation of different CCS topologies. Worse, lower noise doesn't always mean better sounding. I'm still not sure if I want to go the trouble building such a complex current source. What is your experience. Is it a big improvement soundwise? I mean, are you just relying on simulation numbers?

ADD: Note that the amp would probably be using regulated front end supply


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