APR wrote:

"Eeyore" wrote

I have the schemtics for the A10 and A20 amplifier-equalizers here before
me. They are loaded with 4558s, no 4136s in sight. I looked inside my A10
and found that they were indeed 4558s.

YUK ! Pro ? That's a joke.

When were these designed ? At least drop some 4560s in.

Hi Graham,

I have A20's which I use in my home audio system and cannot fault them. I
have no issues with them that would make me say the IC's should be changed.

Fair enough if you're happy but audio designers like me vomit at the mention of
4558s.


Some people say they are too forward, some have said they are too bright for
their liking. I am quite happy with them.

What difference would you expect a different IC to make over the 4558's?

Less noise and less distortion for two. The NJM4560 is an 'improved' 4558 by an
arm and a leg or two. They're actually pretty repectable. I must have designed
in several million of them.

Graham