An API312 Style Preamp

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bjosephs

Well-known member
Joined
May 10, 2021
Messages
104
Location
Massachusetts
Just posting some pictures of a preamp I built forever ago. The design is basically the 312 on PCBs I designed. The transformers are Cinemag. There is a proper gain control and an output attenuator that I never use. Phase, pad, and phantom on the pushbuttons.


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What made you choose 990’s over 2520’s or 1731’s?
At the time probably availability and to a degree familiarity. To this day I have no idea what the right 2520 clone is to invest in. I’m open to suggestions because I’d love to try some.
 
What ratios of transformers did you use?
990 prefer input of 1:2 or 1:4..and output 1:1.
2520 in 312 are 1:7 and output 1:2 or 1:3.
Hey but this diy you do whatever sounds best to your ears!
 

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