Tonewheel figures in dsp/va_footage.h came from setBfree (GPL) #173

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opened 2026-10-25 23:42:37 +00:00 by bcox · 0 comments

bcox commented

2026-10-25 23:42:37 +00:00

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dsp/va_footage.h says (lines 12-14) that its tonewheel generator's figures are setBfree's (src/tonegen.c): the gear table, the 192-tooth wheels, the compartment pairs, the foldback and the leak levels, and that "No service manual was reached to check them against." setBfree is GPL, so this is a provenance problem: these figures should not have come from it.

What is affected:

kGears-style ratio table (va_footage.h:130-134) and the pitch tables derived from it (kPitchClassOctavesRaw, kSharpOctavesRaw, :201-215)
the 192-tooth wheels 85-91
PartnerOf, the compartment pairs (:141-150)
the foldback (VaFootAt, :253-275)
kVaWheelLeakRaw and kVaWheelCrosstalkRaw (:112-115), and wherever va_oscillator.h renders them
probably kVaWheelThirdRaw/kVaWheelFifthRaw (:116-120); check where they came from

What to do:

Take the gear ratios, tooth counts, wheel layout, foldback and compartment arrangement again from Hammond's own service manual (HSM-495, the 2016 reissue of H000-000495: https://archive.org/details/HSM4952016), citing pages. They may come out the same numbers, being facts of the machine, but they need a usable source.
The leak and crosstalk levels are setBfree's choices and Hammond prints nothing like them: replace them with placeholders of our own, or a measurement, marked as such.
Remove the setBfree attribution once nothing rests on it.

Found while planning a tonewheel organ for mini-800, which will source the same things from HSM-495.

`dsp/va_footage.h` says (lines 12-14) that its tonewheel generator's figures are setBfree's (`src/tonegen.c`): the gear table, the 192-tooth wheels, the compartment pairs, the foldback and the leak levels, and that "No service manual was reached to check them against." setBfree is GPL, so this is a provenance problem: these figures should not have come from it. What is affected: - `kGears`-style ratio table (va_footage.h:130-134) and the pitch tables derived from it (`kPitchClassOctavesRaw`, `kSharpOctavesRaw`, :201-215) - the 192-tooth wheels 85-91 - `PartnerOf`, the compartment pairs (:141-150) - the foldback (`VaFootAt`, :253-275) - `kVaWheelLeakRaw` and `kVaWheelCrosstalkRaw` (:112-115), and wherever `va_oscillator.h` renders them - probably `kVaWheelThirdRaw`/`kVaWheelFifthRaw` (:116-120); check where they came from What to do: - Take the gear ratios, tooth counts, wheel layout, foldback and compartment arrangement again from Hammond's own service manual (HSM-495, the 2016 reissue of H000-000495: https://archive.org/details/HSM4952016), citing pages. They may come out the same numbers, being facts of the machine, but they need a usable source. - The leak and crosstalk levels are setBfree's choices and Hammond prints nothing like them: replace them with placeholders of our own, or a measurement, marked as such. - Remove the setBfree attribution once nothing rests on it. Found while planning a tonewheel organ for mini-800, which will source the same things from HSM-495.