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Old 29th January 2013
Gear Maniac

¡¡happy new summing!!

¡Hi Geeks!

Finally, after four years of research and development (read it learning), four prototypes, many nights without sleeping, and countless soldering hours, I have finished the design of a prototype of an analog balanced line level, active summing mixer. The “MIKROSUM”


16+2 balanced inputs. 2 expansion inputs in jack format, 16 inputs in Tascam DB25.
2+2 balanced outputs. XLR main and copy for monitoring.
Balanced half normalled master insert send/return, in jack format.
Blend switch and pot, for parallel processing/ compression.
Balanced Summing amplifier with 153khz bandwidth.
Master volume control.
Power draw. 40ma aprox.

Noise level: at max volume: -74db aprox
at min volume: -78-80db aprox

As a first “shot” into PCB design, I’m happy, despite corrections and mods I had to do. The definitive PCB version will be better.

Sound Quality: ¡¡Awesome of course!!, transparent, good low end, smooth highs.

I recorded an old Roland JX3P hence my nickname JAY X, that has unbalanced outs, thru the summing inputs, and sounded more coherent: more defined stereo image, more tight bass frequencies, compared with unbalanced recording.

Also I have played stereo CD tracks from computer, thru the summing and differential return inputs, and re-recorded the result into Soundforge, and despite it is not a perfect test, the sound quality of the CD is maintained. I will attach examples ASAP.

Good stereo image: You can notice the depth and placing of instruments, and panning.

I still have to make more tests, so I will make them at a professional studio by February 21, to test the mixer in real studio conditions. It is a recording and mixing studio for rock and pop bands. Among its equipment, they have two NEVE 8816 with fader packs, millennia preamps, and protools interfaces.


I want to thank Jules for the Gearslutz forum, over I stumbled in summer 2008, and became member by December. Tim Farrant for the original thread about summing mixer, Matt Syson for his invaluable help through these years, by messages, emails and comments on the forums. John Roberts, Harpo, and many others that with their comments also helped me to make this project a reality.

This is really a great forum to dream and make dreams come true…despite the time it takes to make it true!!

Thank you very much,
Karim Azeli Jarosch./ J.A.K.AUDIO. ”Analog plugin”