Archive of the former Yahoo!Groups mailing list: MOTM

previous by date index next by date
  topic list  

Subject: accurate DC and AC in one package

From: "J. Larry Hendry" <jlarryh@...>
Date: 2000-07-19

OK, here are some other thoughts for a mixer that could offer the best of
audio mixing coupled with some accurate DC mixing too. Feel free to
criticize, subtract from, and add to. That's what this list is all about.

The mixer would have 2 or 3 dedicated high accuracy DC inputs. One might be
considered 1 volt/oct and have no attenuation at all. Input # 2 (and 3 if
so equipped) would be accurately summed with the first in a nice DC op amp
like Paul's favorite 1013. Then the other 1/2 of the 1013 would invert the
DC back to normal polarity. A "DC-only" output would be provided at that
point. You could also provide inverted DC out too if you have the jack
space.

The mixer would also have 4 more inputs with reversing attenuators that
would be AC or DC. However, they would not be the "high" accuracy of the
other DC only inputs. Op amp selection for these inputs would be something
Paul really likes for AC and the amount of DC drift could be ignored. These
four inputs would be summed with the other 2 or 3 high accuracy DC-only
inputs to provide one "mixed-all" output.

So, this mixer would have 6 or 7 inputs-- four AC or DC reversing and 2 or 3
DC inputs with at least one without any attenuation. So, you have 4
reversing knobs and one or two non reversing knobs. The mixer would have 2
or 3 outputs. One would be the high accuracy "DC-only" outputs (and maybe
an inverted output). The other output would be a combination of ALL inputs.
You could put a master level control on this output too. So, you could
have all the features I hear people wanting. High accuracy DC (3 in 1 out),
reversing inputs for AC or DC, ability to mix AC and DC, and the DC does not
get compromised with the "drift" or other bad things until the final output
op amp that is selected for audio performance. You have the good 1013 DC
output before you get to that stage.

Thoughts?
Just a stooge Larry