Vintage Synth Repair

I think that the 1458 is a dual 741 -- yes, awful.  A 4558 is an 
improved version.  

GB

>If I remember correctly the 4558 consists of 2 simple op amps, can't 
>remember the number of the single unit but it is nothing special.  I too 
>had oodles of trouble with the 4558 in the early days and stopped using 
>them.  For performance the 72 series bi-fets are first class and I think 
>I'm right in saying that the pin out is the same.  Specifically the 
>TL072 or TL082 will do the same job, only many times better and they are 
>super stable, but please check out the pin-outs as it is several years 
>since I used either.
>
>I believe the 4558 is 2 off 451!  'Orrible little beasts they were.
>
>Regards
>
>Brian G3OYU