bigugly
Well-known member
Hey Everybody,
I don't post here often and when I do it's ususally to ask some basic questions. I have learned so much from this forum, ever since it was on that "other" board.
I have been quietly building N e v e clones, A P I clones, and power supplys over tha last year or so. As my confidence grew I decided to design my own mic pre.
It started out as a transformer input and output using the Neutrik NTM4 & NTL1 respectively, with the OPA604 as the active gain stage. This has mutated somewhat to include pads for 3 different input transformers: NTM4, LL1587,or LL1583 and 5 different output options: NTL1, LL2811, LL1582, OLI3 (unbalanced), or electronically ballanced using a Burr Brown DRV134 on a daughter board that uses the LL2811 footprint.
I have also added a 2520 footprint if a DOA is desired.
It runs on a bipolar 18v supply that also supplies 48v phantom. All I/O, power, and ground connections are on a 15 pin .100 center card edge connector. Once the pre is plugged into the card connector the phantom power curcuit is complete. I put the 6k8 resistors and a cap on the connector pcb because the preamp pcb was getting crowded.
I'm still working on the enclosure but it is going to be a rackmount 2U high and I will be able to fit 12 of these pre's vertically.
Here is the schematic and pcb for the pre:
PCB
Schematic
Any and all comments are welcome.
thanks again to everybody on this board.
cheers,
James Lee
Big Ugly Van Audio
I don't post here often and when I do it's ususally to ask some basic questions. I have learned so much from this forum, ever since it was on that "other" board.
I have been quietly building N e v e clones, A P I clones, and power supplys over tha last year or so. As my confidence grew I decided to design my own mic pre.
It started out as a transformer input and output using the Neutrik NTM4 & NTL1 respectively, with the OPA604 as the active gain stage. This has mutated somewhat to include pads for 3 different input transformers: NTM4, LL1587,or LL1583 and 5 different output options: NTL1, LL2811, LL1582, OLI3 (unbalanced), or electronically ballanced using a Burr Brown DRV134 on a daughter board that uses the LL2811 footprint.
I have also added a 2520 footprint if a DOA is desired.
It runs on a bipolar 18v supply that also supplies 48v phantom. All I/O, power, and ground connections are on a 15 pin .100 center card edge connector. Once the pre is plugged into the card connector the phantom power curcuit is complete. I put the 6k8 resistors and a cap on the connector pcb because the preamp pcb was getting crowded.
I'm still working on the enclosure but it is going to be a rackmount 2U high and I will be able to fit 12 of these pre's vertically.
Here is the schematic and pcb for the pre:
PCB
Schematic
Any and all comments are welcome.
thanks again to everybody on this board.
cheers,
James Lee
Big Ugly Van Audio