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Old 18th February 2005, 09:49 AM   #1
beppe61 is offline beppe61  Italy
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Default Nelson Pass discrete op-amp.

Dear Friends,

I would like to know any opinion or experience on the following article:

http://www.passdiy.com/pdf/diyopamp.pdf

Did anyone build the preamp proposed in figure 8 ?


Kind regards,

beppe61
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Old 18th February 2005, 10:18 AM   #2
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Fig 8 is princip of simplest discrete opamp. What are you waiting ? Go to to the nearest patent office and there you can find thousands of examples ( better ) circuits.
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Old 18th February 2005, 10:27 AM   #3
beppe61 is offline beppe61  Italy
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Quote:
Originally posted by Upupa Epops
Fig 8 is princip of simplest discrete opamp. What are you waiting ? Go to to the nearest patent office and there you can find thousands of examples ( better ) circuits.
Dear Mr. Upupa,

Thank you very much for your kind reply.
Actually I am looking for a simple circuit with a minimum of active components (3 max) suitable for a nice line preamp.
I have already posted one with just two BJTs.

I would be very grateful if you could give me some info about similar minimalist line preamp (possibly schematics eh, eh).

Kind regards,

beppe61
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Old 18th February 2005, 10:46 AM   #4
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Why only 3 components ? 3 components are 3 components and you can't wait miracles, although it is written by Mr. Pass. If you can make very good discrete amp ( only little bit complicated ), look at pages of Borbelly Audio.
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Old 18th February 2005, 11:32 AM   #5
beppe61 is offline beppe61  Italy
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Quote:
Originally posted by Upupa Epops
Why only 3 components ? 3 components are 3 components and you can't wait miracles, although it is written by Mr. Pass. If you can make very good discrete amp ( only little bit complicated ), look at pages of Borbelly Audio.
Dear Mr. Upupa,

Thank you very much for the valuable suggestion.
I guess it is possible to obtain nice results with simple topologies like in the case of Pass Aleph P and L preamps for instance.
I must also confess you that I am not so good at DIY.
So I hope to have less difficulties in implementing simpler circuits.
I don't think that good results imply complexity on principle.
My approach is becoming a little "ZEN" if I can say that.
Simple but good and effective.
Few good components used in their best working conditions.
May be I am completely wrong.
Don't know really.

Kind regards,

beppe61
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Old 18th February 2005, 12:04 PM   #6
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Dear beppe, blind faith to apostle of simplicity NP is good think, but exist also others apostles. For me is it Erno Borbelly and Walt Jung. Maybe, when you will read other " holy " book, you will change your opinion.
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Old 18th February 2005, 12:08 PM   #7
Bricolo is offline Bricolo  France
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I think that Mr Pass (and others) wrote great articles, have an excellent knowledge, but some people misunderstand the concept.

The "keep it simple" principle is something beautifull, but making a good sounding and working product out of a simple topology is really an art. Everything simple isn't perfect, far from that. Many people misunderstand the concept, and think that every simple topology works better than every complicated one. That's untrue. Otherwise, no company would produce amps with more than 3 parts, is 3 parts would sound better and cost much less.
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Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease
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Old 18th February 2005, 12:12 PM   #8
beppe61 is offline beppe61  Italy
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Quote:
Originally posted by Upupa Epops
Dear beppe, blind faith to apostle of simplicity NP is good think, but exist also others apostles. For me is it Erno Borbelly and Walt Jung. Maybe, when you will read other " holy " book, you will change your opinion.
Dear Upupa,

Thank you again for your valuable suggestion.
As I can see you are Erno Borbely "supporter", do you remember his two fet line buffers ?
I will try to rescue the schematics and I will upload them.
What do you think of them?
They had +/- 24V dual power supply.
He wrote that they are very good to drive a power amp.

I look forward to hearing from you.

Kind regards,

beppe61
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Old 18th February 2005, 12:25 PM   #9
beppe61 is offline beppe61  Italy
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Quote:
Originally posted by Bricolo
I think that Mr Pass (and others) wrote great articles, have an excellent knowledge, but some people misunderstand the concept.

The "keep it simple" principle is something beautifull, but making a good sounding and working product out of a simple topology is really an art. Everything simple isn't perfect, far from that. Many people misunderstand the concept, and think that every simple topology works better than every complicated one. That's untrue. Otherwise, no company would produce amps with more than 3 parts, is 3 parts would sound better and cost much less.

Dear Mr. Bricolo,


I think that audio market (like every other business) is only marketing driven by now.
Do you think that a very beautiful front panel of 1 cm is needed for a good sound?
I don't think so.
The front panel is there to give to justify a big retail price.
There are so many examples of very simple preamp and amps that got the consensus of audio lovers.
Just look at the AKSA amps for instance.
If you want my opinion I strongly think that sometimes equipments are unecessary complex.

Kind regards,

beppe61
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Old 18th February 2005, 12:31 PM   #10
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To Bricolo : I have no doubt about deep knowledges of Nelson Pass , many times I had read his inspirating notices. But many times I had listen distortion coming from his amps, which lead me to the convicion, that all is good promotioned joke . People easy take easy solutions, but it is not my case. I understand to this concept, but I don't agrre.
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