Differences in old and New Cp 251

[Sir Nose]

old cp251 has red and black jacks
new cp251 has black with a white circle and black without a white circle

[MarbledMoog]

I don't think you can actually increase the signals with the attenuator, I'm pretty sure +5 is just the regular sound. -5 would be an inverted signal, that's the use of the new CP-251's. You can invert signals easily with it. To increase a signal, you can use the mixer. I like to use it to increase the sample & hold "width" I guess you'd call it. But too much stuff can make it a higher voltage than what most synths want to see, but Moog made the whole system pretty user-friendly, but they do warn about amplifying too much stuff.