Synth-DIY Yahoo! Groups Archives

Main Emax Right/Mono Output Noisy

2013-10-13 by Nik Kinloch

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!


[Non-text portions of this message have been removed]

RE: Main Emax Right/Mono Output Noisy

2013-10-13 by nikkinloch@...

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Re: Main Emax Right/Mono Output Noisy

2014-06-23 by bry_204@...

Hi, I'm noticing the same noise problem with my unit. Are your outputs from 1-8 clean? I only have issues with the main outs.

Did you ever completely fix the noise issue?

I'm surprised no one else is talking about this on here, it's like night and day with the difference in the noise floor, not to mention that high pitched whining noise is annoying as hell.