Mordpol 8 Channel Mic Preamp(Amek m2500)

This is my most recent project(by March 2012). It's an 8 channel microphone preamp containing eight Amek 2500 mic preamps with symmetric outputs.

Finished & working 8 channel mic preamp

Each channel has 48V phantom power, phase switch and a -20dB PAD - everything I need at a session. I already did some recording with it, the results where definitely great. It's an extremely quiet piece of gear - actually more quiet than my Motu PCIx Interface.

Top view of finished preamp

I designed all the PCBs myself - one-sided PSU & Gainswitch PCBs and two-sided preamp PCBs. As I wrote before, the preamp is based on the transformerless mic preamps of the Amek m 2500 studio desk, but I wanted the preamp to have balanced outputs instead of unbalanced ones, so I added another NE5534 - just like in the 9098 - which worked out perfectly. Also I changed all the ZTX214s to BC560s because I didn't find any 214s and the rev. log gain pot was replaced with a 12 ganged lorlin rotary switch(mounted on the front PCBs). For the switching stuff(48V, PAD, Polarity) I used relays, because I had loads of them lying around.

Two-sided preamp PCBs

The last thing I want to do for now, is to get the copper transformer safety housing coated black, but that's nothing too urgent. I think the rest is ok for now, maybe I'll get a better 19" case with engraved face- and backplates and some redesigned front PCBs in the future, because I'm not absolutely happy with the results of my metalwork and the front-switches and XLR jacks lack of quality, what makes them too damageable - shouldn't be that way. Don't try to save money with cheap XLR jacks or switches - I learned that lesson ;-)

Backside view with yet uncoated transformer cap

So that's it for now, feel free to drop me some lines if you have questions & thanks for reading!