The REAL John Linsley Hood Headphone Amplifier

As promised here the Gerber files.

The Bill of Material in Post #35 has the following changes for the XEN modified version :
R13,14 -> 470R
Cf1,2 -> leave open
Rz -> 5.1R

It is important that you only use 5mm standoffs to keep the legs of the output transistors short.

The original JLH version has yet to be tested, as mentioned before.


Happy building,
Patrick

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HI Patrick, thank you for sharing your master work.
However, I can't read correctly the files, the traces don't match with the photos of the proto build. Could you kindly check? Many thanks
Guido
 
Patrick please excuse another simple question -

Regarding the R1/R2, R3/R4 resistor arrays for tuning the offset and bias, I am confused as to how to set the initial default value for each array if there is one. For instance should R1 be 2 x 3.3K in parallel... I understand we are splitting this to allow for optional 200uF decoupling cap.

Can I ask what values you began with on your prototype?

Edit... sorry I just saw your assembled boards in post #80 so I have an idea now.
 
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It's ok Patrick, once I saw your built boards it became obviously clear.

Initially the PDF was not clear to an idiot like me, I wasn't sure if... 2+2 R1,R3 3.3K//3.6K meant two of each resistor on each rail. I see now that each group has one spare pad for a 1M if needed.

Maybe it would be better to read:

R1,R3 - Susumu 0805 1x 3.3K // 1x 3.6K and - R2,R4 -2x 0805 20K // 1x 18K...

Just for idiots like me. It's fine really.
 
Yes, in principle.

The problem I have with the On Semi devices are :
a) hfe of N & P devices are quite different.
b) hfe is not quite constant with current.

Function they will.
Whether distortion the same is another question.
But then a bit more 2nd harmonics is also not dramatic.

If you have them, then give them a try.


Patrick
 
You can just order a few from Mouser first and try them, just to make it work.
Then search for Toshiba 2SA970BL & 2SC2240 BL.
(Note that there are now Indian CDIL parts with the same number, so has to be Tos.)
GR will also do, but of course BL is better.

hfe is much more linear over a wider range.
Just a bit difficult to get, but still available and not expensive.


Patrick