Chris J
Headphoneus Supremus
Bipolar Junction Transistors can have lower noise than JFETs."
Depends of the resistance before the opa, depends of the schema, I had had a bad experience with the remplacment of a JFET with a Bipolar.
The noise was not realy a probleme, but the continus curent was...I have changed the resistance before the opa and it's ok, sometime we have to change the schema for the opa.
The oscillation is not the only risk, and it's can be corrected if you study the theory and the datasheet (adding caps etc..).
Some opa can remplace similar opa without any risk, we can find the right match on inernet.
Generally I think it's more safe not to inverse JFET and Bipolar, but I am not electronician...
I would just explain than rolling amp can be dangerous, and the opa are rarely at there best in a schema not made for them.
But we can experiment the sound of an opa on several schema, it's always the same nature, and we can find the sound than we prefer.
The matrix can be safe for a lot of opa, I don't know.
All of this is more or less true, but there are always exceptions
i'm 99% sure that the LM4562 has BJT inputs.........
In theory, you can usually get lower noise with a BJT input stage than with a JFET input stage.