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Help with Op-Amp substitute & pin / package adaptor

Question asked by Lt030 on Sep 19, 2012
Latest reply on Sep 20, 2012 by JeradL

Hello List-


Just found this list and signed up so here is a short introduction of myself.  I am a music - record producer, audio engineer, mixing engineer / artist, analog - digital component level tech that also plays synthesizer and bass guitar.  I will add a couple links below for those that may be interested in hearing my latest work but now I need help in finding a replacement op-amp for some microphone pre-amps that I am "racking up" for myself.


The microphone pre-amps that I am working on are from a lesser known and now defunct American manufacturer that was located in Michigan and produced mixing desks - modules that where primarily aimed at the television and radio market.  The name of the company was ADM - Audio Design & Manufacturing. They produced gear from the 1960's into the 1980's.  The pre-amp models that I am concerned with are known as the

ADM-2780 and the ADM-780.  The 2780 is a slightly newer version of the 780.  The op-amp that I need to replace is a LF-356 in a TO-99 metal can package.  They where installed using a socket which is nice however I'm not having any luck finding a replacement that can handle + and - 20 volts which is what the circuitry runs on.   I do have replacement LF 356 opamps however they are 8 pin DIP package and the socket soldered to the PCB is for the metal can TO-99 style.  I will attach the schematic for the 2780. The op-amp in question is marked "A3".  Looks to me as though A3 is the last 20db of gain so removing that opamp would be fine for most pop music - rock n roll however I am not 100% sure on the best way to remove it.


    Anyone know of a 8 pin DIP to 8 pin TO-99 socket??




Thank you in advance!!   Here are two links I promised-  one is the video for the first single from the band called  "The Rope".  I mixed, played synthesizer and mastered their self titled debut EP and am now in post production for their full length album that I am producing, engineering, playing synthesizer and mixing.


Here is a link to the iTunes download for the EP


Once again, thank you in advance for any and all help!!


Best wishes-


David Daydodge

Mpls, MN