An API312 Style Preamp

Help Support GroupDIY:

bjosephs

Well-known member
Joined
May 10, 2021
Messages
49
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.


BA0FA540-F19F-4B89-994D-60B0E6ADDD0D.jpeg
 

Attachments

  • A85423C7-98F3-4864-AB59-015D9ADEAA6B.jpeg
    A85423C7-98F3-4864-AB59-015D9ADEAA6B.jpeg
    175.2 KB · Views: 22
  • 988A07DB-F2E6-43BE-906C-6B2C2AC6E8A1.jpeg
    988A07DB-F2E6-43BE-906C-6B2C2AC6E8A1.jpeg
    185.5 KB · Views: 18
  • 0566AB9D-1E31-4B1F-B996-588E5B11E75E.jpeg
    0566AB9D-1E31-4B1F-B996-588E5B11E75E.jpeg
    197.7 KB · Views: 21

bjosephs

Well-known member
Joined
May 10, 2021
Messages
49
Location
Massachusetts
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.
 

3nity

Well-known member
Joined
Dec 30, 2005
Messages
3,524
Location
MTL, CANADA
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!
 
Top