Emax

Hi all,

I have been spending some time working on cleaning up my Emax outputs.

First thing I did which was a success was to remove the unneeded 
backlight driver - this totally cured a whine coming from the outputs.

After removing that, I then noticed some standard basic noise coming 
from only the Right/Mono output.

I did a lot of testing to make sure it was the output, including 
switching desk channels, switching cables, and even switching the whole 
output board out for another one (I have a spare Emax). The noise was 
always the same, and always out of the same output.

Ok, so I looked at the schematic, and saw the L and R output circuitry 
is different. This is to provide the summed mono output if only one lead 
is connected.

So, I figured I'd just mod the circuit so they were both the same.

I lifted R39 at the IC40 pin 3 end. I lifted R33 at the IC40 pin 2 end. 
And I removed R24 and replaced with a short. (see attached pic)

This has made it better, but I am still noticing the R output as more 
noisy. The broadband nose is better, but there is also a more defined 
noise. kinda like bandpass noise I guess.

So.... has anyone got a clue why this is? Why is the output noisy in the 
first place? Maybe I shoulda left R33 and R34 in place? But I don't see 
anything in the schematics that would suggest the output from the 
individual SSM chips is any different on the L and R sides of the bus, 
so I don't think the circuit needs to be any different for a true stereo 
output.

Any help appreciated! Thanks!


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