Salas hotrodded blue DCB1 build

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RichLund

Member
Joined 2009
I received my matched Jfets today from Spencer. I have 8 x 7.4mA and 4 x 6.6 - 6.7mA.

I understand that it's preferable to have the two inner jfets of the group with slightly lower idss. So is it better to have four perfectly matched at 7.4mA or use the 6.6 - 6.7mA for the inner two like this:

7.4 - 6.7 - 6.7 - 7.4

Is there any harm (dc offset?) to have all four the same idss?
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
Perfectly matched is best for offset and won't be pushing each other also. The pairs you proposed are not slightly different, they are clear non matches. When I say use the slightly lower one for inner position, I mean slight differences between a matched pair beyond the decimal point.
 
LucasAdamson

LucasAdamson

Member
Joined 2009
To be clear - there is NEVER an instance when J1 is not connected. There is a permanent connection there anyway, even without a jumper wire being added. If you scratch away a little at the white paint on the top of the board, you will see that J1 already has a copper trace in place. Adding a jumper wire there only re-enforces that connection.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
Because Crt that made the board layout wanted to reinforce the ground better.
Just install whatever the board depicts, and do as it notes. You will be OK.

If you mean those 3 to the right before the audio section, are to install a connector for someone that wants to tap off the reg or just use it as a standalone reg for other circuits.
 
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