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Old 24th June 2007, 08:36 PM   #1
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Default simple class a amplifier

hi friends

did anybody tried this circuit. this is from elektor electronics. do this circuit has similarity with JLH.

rk
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Old 24th June 2007, 09:10 PM   #2
lineup is offline lineup  Sweden
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Default Re: simple class a amplifier

Quote:
Originally posted by renjiish
hi friends

did anybody tried this circuit. this is from elektor electronics. do this circuit has similarity with JLH.

rk

Hello indian audio friend ( in UK )

I can see it is Elektuur, and I recall this design Article from my Elektor Magazine collection.

( I have subscribed to Elektor, constantly, since early 1980-ies
- and have all magazine in piles, here in my one-and-only living room.
Rent a small flat, 1 room + kitchen + bathroom )


It looks simple, yes.
But it is NOT SIMPLE & Thsi Amp will work great!
This is a good and Unique idea, which has been properly worked out, implemented.

Nice circuit / amplifier
To achieve Class A MOSFET Sounds.
Definitely an amplifier I like ren jiish


Regards lineup
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Old 24th June 2007, 09:29 PM   #3
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Default Re: Re: simple class a amplifier

Quote:
Originally posted by lineup




It looks simple, yes.
But it is NOT SIMPLE & Thsi Amp will work great!
This is a good and Unique idea, which has been properly worked out, implemented.




Regards lineup

78L06 for biasing input stage is a "bad move" IMO.
Also the output SRPP would work better with vertical mosfets becouse of greater transconductance.
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Old 25th June 2007, 03:16 PM   #4
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dear friends

so i think i can proceed with this project. is it ok if i use irf530 instead of buz72a

this may be an idiotic question i am going to ask, i have eight philips BUW11A power darlingtons. is it possible to it use instead of power mosfets.

if possible , then what will be the consequences

Please advise
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Old 25th June 2007, 04:39 PM   #5
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Sorry but I wouldnt bother using those transistors(datasheet shows they are not darlingtons) for anything other than switching supplies. They have such a small beta and are rather non linear over a large current swing. Look as if they were designed for television duty.
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Old 25th June 2007, 04:57 PM   #6
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sorry it was my mistake. it is BDX63B.
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Old 25th June 2007, 05:02 PM   #7
routhun is offline routhun  United States
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Default PLH may better this one

Hi Renjish,

I've built this one, it cannot drive low efficiency speakers. It has some kind of tube like sound, complete lack of low frequency response. If you like tube like sound it may some what satisfies you. I didn't like this at all!!! So I dismantled this one and built PLH (pass labs JLH using mos-fets), which is way better this one and almost uses same parts. You can even use IRF series MOSFETs.

see my post.

Plh

Thanks,
Routhun
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Old 25th June 2007, 05:03 PM   #8
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Well to be quite honest no bipolar would work correctly in a circuit designed for mosfets. Im sure there are several class a circuits on the forum that could take advantage of them. They could easily be designed into a JLH just by changing the bias, decreasing the current needed through the vas to get the right idle current.
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Old 25th June 2007, 07:38 PM   #9
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hi jerluwoo

what is your opinion. is there any class a circuit that i can use those transistors. i really want to use them.

hi routhun

do u have any idea that class a using darlington.

hi lineup

definitly i will make that simple circuit. i am big fan of power follower and zen amplifiers.

dear friends

please give me a good circuit that i can use BDX63B class a configuration
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Old 25th June 2007, 10:48 PM   #10
lineup is offline lineup  Sweden
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Quote:
Originally posted by renjiish

hi lineup

1. definitly i will make that simple circuit. i am big fan of power follower and zen amplifiers.

2. dear friends
please give me a good circuit
.
freinds

as some of you were not born, when that schematic was first drawn,
note one thing:
Before there were IRF HEXFET, some early HEXFET devices were around
for example made by PHILIPS & other companies.
- BUZ71 - BUZ72
were such first Generation HEX transistors.


Of course great? improvement can be done
to the posted Elektor schematic
As, at any given time, there are new devices around
that the original designer did NOT HAVE, if they even were INVENTED.

We have many members at this board,
that knows IRF530, IRF610, IRF540 & IRF640
better than me.

however, dont think that Master Nelson Pass
is much interested in help a new indian member with this.
He may not hae time to engage in too much triviality.

But we have G. Rollins
who has given Nelson one or 2 new ideas.

And as I said, many others
besides me Lineup
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