There are many discrete op-amp plug-in modules out there. Or like you said, build an Aleph Mini or Zen Headphone and skip this build since they already exist in cyberspace.
This project does not use K170/J74 Jfets.
The output devices, although listed in the schematic as Mosfet K2013/J313, are able to be replaced with any similar mosfet, or even bipolar transistors with just a few simple changes.
I'm currently waiting on a chassis for this project, and then all the info will be released.
The output devices, although listed in the schematic as Mosfet K2013/J313, are able to be replaced with any similar mosfet, or even bipolar transistors with just a few simple changes.
I'm currently waiting on a chassis for this project, and then all the info will be released.
The plan is to use opamps but apparently flexible enough to stick in your own discrete basic front end.
You could build Euvl's F5 headphone amp as an alternative too.
While I can't comment specifically on the Erno Borbely jfet front end (having no experience with it), it sounds like essentially what the burson is:
Burson Audio – Supreme Sound Opamp
Papa also has an article on exactly this that I have linked in this thread previously:
https://www.passdiy.com/project/amplifiers/diy-op-amps
Burson Audio – Supreme Sound Opamp
Papa also has an article on exactly this that I have linked in this thread previously:
https://www.passdiy.com/project/amplifiers/diy-op-amps
> the Erno Borbely jfet front end sounds like essentially what the burson is ....
The current generation Burson has BJT input stage with almost 0.3mA input bias current.
Input offset current can be as high as 120µA. So definitely not FET input.
Their earlier generation did look something like this :
ºÍ§Ó*µ响
We built the Pass DIY Opamp in 2008 and like the results a lot.
http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package.html
But you will have a hard time getting it DC stable without a servo.
The problem is that when running in pure Class A, the FETs do heat up.
But the N-JFETs and P-MOSFETs have different tempco.
So they will not track each other in bias even if you have perfect thermal coupling.
There are many discrete circuits from Borbely that has a all-FET frontend followed by a follower.
But I guess that is not what this project is about.
Patrick
The current generation Burson has BJT input stage with almost 0.3mA input bias current.
Input offset current can be as high as 120µA. So definitely not FET input.
Their earlier generation did look something like this :
ºÍ§Ó*µ响
We built the Pass DIY Opamp in 2008 and like the results a lot.
http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package.html
But you will have a hard time getting it DC stable without a servo.
The problem is that when running in pure Class A, the FETs do heat up.
But the N-JFETs and P-MOSFETs have different tempco.
So they will not track each other in bias even if you have perfect thermal coupling.
There are many discrete circuits from Borbely that has a all-FET frontend followed by a follower.
But I guess that is not what this project is about.
Patrick
I think I was thinking of the earlier version when I said that. Thanks for correcting me
. That said, BJTs sound like they will be quite at home with this amp also.I love what you did with the Pass OPAMP. I was intending on using this circuit as Wayne intended, and I might still do that initially, but after seeing what you achieved it is tempting to try something similar.
Here is another discrete opamp thread which is even more interesting :
http://www.diyaudio.com/forums/anal...iscrete-opamp-open-design-28.html#post3184856
Patrick
http://www.diyaudio.com/forums/anal...iscrete-opamp-open-design-28.html#post3184856
Patrick
"it just takes the fun out of it. "
Patrick
Have you integrated a Muse device as volume control on front end of an amp or for something a bit different at the output of something like the front end of BA3 before the output stage?
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