Re: gEDA-user: OT: low noise microphone amp

[John Griessen <john_g@xxxxxxxxxx>]

Greg Cunningham wrote:
 Each channel had 4x A1084 PNP transistors and 4x MPSA06 FETs,
> feeding a NJM4580L op-amp.  I guess the PNPs were the amp & the FETs 
> were current sources (???).

Could have been a follower to give drive power with low distortion.
Not enough info to say.

It's a good design philosophy for that market:   You get repairability, low cost 
of inventory of mfrg parts and repair parts stocking for long life product.

A company in my town is making lighting controls for performers by packing a 
stripped laptop in a wood box with button inputs, slider inputs going to an 
adapter board then into the PCI cards of the PC.  They don't seem concerned with 
repairability...couldn't get them as a customer for a PCB layout and training to 
use PCB.

John G


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