Question on noise.
Posted: Tue Sep 30, 2014 8:26 am
Hi Frank , I've just been having some trouble with white noise/hiss with the SKRM modules (and other FV-1 builds). I just wonder if it can be eliminated in any way.
I will try and give a good example of what is going on first.
I use the SKRM module for these tests and on the input of the SKRM I have a simple unity gain op amp buffer based around an OP275 but have also used a bog standard TL072, the input impedance is around 470k and the output is taken directly to the SKRM and I know that to have the input filtering components already in place. The output from the SKRM is taken to the other half of the op amp which is also a unity gain buffer with both input and output impedance set to around 100k.
Signal is good as I can just get the clipping led to light if I play loud enough but have it backed of just enough not to cause clipping.
The issue I am having is a large amount of hiss on the output, I have also programmed the FV-1 to just pass the input straight to the output of the SKRM so that what goes in should be what comes out.
If I remove the SKRM and pass the signal only through the analogue side of the circuit then there is zero hiss so it would seem the white noise/ hiss is coming from the FV-1 for some reason. Is there something I need to check out or is a lot of filtering stages needed on the input/output to combat this issue?
I look forward to opinions on this hiss problem.
I will try and give a good example of what is going on first.
I use the SKRM module for these tests and on the input of the SKRM I have a simple unity gain op amp buffer based around an OP275 but have also used a bog standard TL072, the input impedance is around 470k and the output is taken directly to the SKRM and I know that to have the input filtering components already in place. The output from the SKRM is taken to the other half of the op amp which is also a unity gain buffer with both input and output impedance set to around 100k.
Signal is good as I can just get the clipping led to light if I play loud enough but have it backed of just enough not to cause clipping.
The issue I am having is a large amount of hiss on the output, I have also programmed the FV-1 to just pass the input straight to the output of the SKRM so that what goes in should be what comes out.
If I remove the SKRM and pass the signal only through the analogue side of the circuit then there is zero hiss so it would seem the white noise/ hiss is coming from the FV-1 for some reason. Is there something I need to check out or is a lot of filtering stages needed on the input/output to combat this issue?
I look forward to opinions on this hiss problem.