Mutant Snare - Pitch Mod?

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Norgatron
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Mutant Snare - Pitch Mod?

Post by Norgatron » Wed Sep 09, 2020 10:53 am

Has anyone ever modified their Mutant Snare to adjust the pitch of the fixed oscillator (shell)?

Background to my question:

I was trying to dial in a good 808 snare sound and nothing sounded quite right to my ear. Comparing with 808 snares I mean.
I went on a bit of a journey comparing the various 808 snares out there, checking the spectrum to see how they were tuned. It was quite easy in audacity to view the spectrum of an isolated snare and find two peaks. I couldn't get the MS to match them though

Then went to the 808 service manual. The SM is interesting because it gives three possible tunings for the two bridged-T oscillators. The schematic has one set of components, there is a note next to the schematic headline "portion changed" with some updated values, and then there's an official-looking table with "values typical and variable" which includes SD tunings.

You can work out the frequencies from the component values (the equation is provided in the SM) and the change lowers the pitch of the oscillators. The original values and the specification type table are close. It seems that Roland typed in the new values, but didn't touch the schematic or the table. There's a YT clip where someone compares an 'old' high pitched snare with a 'newer' lower pitch too and comments on this change in production. The SM has a load of other changes listed, but these are recommended changes to fix problems. The tuning SD was not wrong per se and closely matches their spec, so it was just apparently something they did after feedback and left it to service techs to decide whether to modify on the original units.

The conclusion is that the bulk of 808s were built after the changes in the schematic and are lower-pitched. Most clones, including the Roland digital stuff follow the changes in the SM and pitch the snare low. the Mutant Snare uses the original schematic values (for the fixed oscillator) which is higher pitched. Higher pitch means the 'high' oscillator is around 490-499 HZ. The lower pitch examples are ranged around 335 Hz.
The Mutant snare only (only!) provides tuning control over one of the oscillators, so to get an authentic 808 snare sound you have to tune it as per the original batches and you can't get it to match the sound that most 808s make.

Hence, I am considering a mod to my MS. Either to change the values or maybe even to try and make the second osc variable too. I wonder if anyone else has even noticed this higher pitch and/or changed values when doing a DIY build.
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