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Filter analysis plots & questions


ris8_allo_zen0
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Hi all,

I've tested the filter response of my MBSID with a tool made by me (see this post: http://www.midibox.org/forum/index.php?topic=8548.0), using LP mode, no resonance and cutoff from 0 to 127. The results are in the PDF attached here.

I have some doubts about the 1dB loss on all frequencies when the filter is active. Is it normal or it's a fault of my 6581R4 ? I can hear the difference and it's quite annoying for me... or at least for my unexperienced ears...

I made that program just for these kind of tests on a simple PC, hoping it'll be useful to do some diagnostics to each own SIDs' filter... tell me what you think!

Best regards

Enrico

plot_lp.pdf

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  • 3 weeks later...

Can you do a filter response with full resonance??

I'm quite surprised by the sweep to be honest, it seem that as you increase the frequency, the filter cutoff becomes less resonant. There's also a big jump between 96 and 127 which i've always heard when sweeping my own 6581. This may account for the logarithmic sounding sweep around that sweet spot (on mine it's about 70-90%).

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Can you do a filter response with full resonance??

I'm quite surprised by the sweep to be honest, it seem that as you increase the frequency, the filter cutoff becomes less resonant. There's also a big jump between 96 and 127 which i've always heard when sweeping my own 6581. This may account for the logarithmic sounding sweep around that sweet spot (on mine it's about 70-90%).

Sure I can... but not now, sorry!

In the meanwhile, could you post the program's output (or even a graph like I did) so we can compare the results?

I'm attaching the Openoffice spreadsheet to generate that graph on my post.

Best regards

Enrico

plot.zip

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