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Old 18th December 2017, 09:47 AM   #1131
Buzzy is offline Buzzy  Singapore
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Is the first schematic in the first post meant to be built ? There are 2 things in the schematic that I do not understand which I have circled in red. Anyone knows what they represent ?

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Old 18th December 2017, 10:33 AM   #1132
AKSA is offline AKSA  Australia
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V4 is a means to assess the loop gain of the amplifier (Middlebrook analysis) and I1 is current source, which could be an LM317, or a DN2540 mosfet, or a two transistor 'ring of two' .

That was a long time ago, 8 years, I'd forgotten about that! It is two stages of my NAKSA power amplifier, in fact, and because it was single ended, sounds very, very good. You may reduce the CCS 150mA down to 40mA and drive high Z cans more than 150R, saving a lot of dissipation, only 520mW total.

Hugh
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Old 18th December 2017, 04:42 PM   #1133
Buzzy is offline Buzzy  Singapore
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I was searching for BJT headphone amplifier in this forum. This is the only other I found apart from JLH headphone amplifier. There don't seem to be as many transistor headphone amplifiers.
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Old 18th December 2017, 06:32 PM   #1134
Nico Ras is offline Nico Ras  South Africa
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Quote:
Originally Posted by Buzzy View Post
I was searching for BJT headphone amplifier in this forum. This is the only other I found apart from JLH headphone amplifier. There don't seem to be as many transistor headphone amplifiers.
Here is another of Hugh's concoctions at about the same time 2007/8 that sounds superb. I have been using it for about 10 years now since Hugh and I searched for the most simplistic class A headphone amps.

My philosophy is the simpler a class A amp the better it sounds, my best take was three transistors, Hugh used only two. I don't even think he recalls this.
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Old 18th December 2017, 10:05 PM   #1135
AKSA is offline AKSA  Australia
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Yes, Nico, I took a hit with a mild stroke in 2012, and I'd forgotten that you'd built both of these rudimentary HPAs!
I hope sincerely you are well and that you enjoy your Christmas and New Year!
Stay healthy, my friend,

Hugh
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Old 18th December 2017, 10:12 PM   #1136
Nico Ras is offline Nico Ras  South Africa
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Hi Hugh,
I hate getting old and lonely. Diane says that when we go out somewhere we are more out of place than two farts in a perfume bottle.

At least you still have the monster bike that is exhilarating and fun. I became a coach potato sitting day in and day out listening to music, while I could not give a rats *** what is happening around me.
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Old 19th December 2017, 05:55 AM   #1137
Buzzy is offline Buzzy  Singapore
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Quote:
Originally Posted by Nico Ras View Post
Here is another of Hugh's concoctions at about the same time 2007/8 that sounds superb. I have been using it for about 10 years now since Hugh and I searched for the most simplistic class A headphone amps.

My philosophy is the simpler a class A amp the better it sounds, my best take was three transistors, Hugh used only two. I don't even think he recalls this.
Wow that looks really simple and portable too. Is this amp meant to be run from 9v or 12 v ?
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Old 19th December 2017, 07:25 AM   #1138
AKSA is offline AKSA  Australia
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Either, Buzzy.
It works best with BF862 and a 2SA1837, best with 12V.

Cheers,

Hugh
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Old 19th December 2017, 08:48 AM   #1139
EUVL is offline EUVL  Europe
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Originally Posted by Buzzy View Post
Wow that looks really simple ....
Can be even more simple : Designing with FETs
"Super-Simple, Super-Fine FET Circuit"

And if you then mirror it about Gnd with PJFET and NPN, you get the F5-like topology of Nelson, or Le Monstre of Hiraga.


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Patrick
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Old 20th December 2017, 10:04 AM   #1140
Nico Ras is offline Nico Ras  South Africa
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Either, Buzzy.
It works best with BF862 and a 2SA1837, best with 12V.

Cheers,

Hugh
Yep, he's right.
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