Passive summing mixer design

Hi Guys,

I designed this tiny PCB, this is a passive 8 x 2 summing mixer with a pcb mount DSUB25 connector. Circuits will be chained to build a 32 inputs summing mixer. I've been using that1512 for make up gain. I got very good results with it, sounds very clean and wide. I wanna try other circuits for comparison, i was thinking about testing my summing mixer with BA283 stage with a VTB1847 transformer, for more coloration. Any suggestions about other circutis i should try for make up gain?

Thanks!

JC

https://drive.google.com/open?id=0B_n67A1hN3qtZGtMdjNybnF6XzQ

Cheers

Ian

Do you have some mic pres?  Try out whatever you have on hand and see what you like. Personally I like the sound of API style makeup gain with passive summers.

Thanks for your inputs guys,

Ian, this is very detailled, thank you for this doc!
I am using 10K resistors on standard channels
for 16 inputs, Rsh is 1153 ohms in my design (impedance is 600ohms and attenuation around 30dB)


I tried this with my 1073 clone and it sounds amazing, also tried it with cleaner preamps and it sounds fine too... unfortuinately, i have no tube preamp at hand but will definitely try this as soon as i can!

Hy is er PCB or Girder file to by for this 8 x 2 summing mixer with a pcb mount DSUB25 connector?

regards

znjamznjam