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Cwejman QMMF-4 Calibration / Faulty?
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author Cwejman QMMF-4 Calibration / Faulty?
benniii
dear all,
after months of looking, i finally received my QMMF-4 yesterday :)
besides being very happy, i am wondering if it needs some calibration:

setting the filter to one of the OSC modes, the Q-PEAK barely seems to do anything else than muting the sound at around 8 (see picture for reference).. the Q-PEAK does however work when using an external input.

i'm wondering if this is normal (or if i may lack some understanding of the module, as i cant find a manual anywhere online ... anyone)?

be gracious for a hint!

mdoudoroff
If you’re in either OSC mode and Q-Peak is up there, it should be whining up a storm. Sounds like something is wrong.

Note that illustration of the QMMF-4 you posted is obsolete and does not reflect the shipping version.
benniii
mdoudoroff wrote:
If you’re in either OSC mode and Q-Peak is up there, it should be whining up a storm. Sounds like something is wrong.

mh.. mh... mhhh.... can you define "whining like a storm"? :) .. just would like to rule out it may be working correctly before i send it in.

i do here the oscillators very loud and clear if i'm beyond ~8 with my Q-PEAK. and their pitch is very decently controllable via the CUTOFF. it's just – i can't seem to really precisely filter them. if i go lower than ~8, they're just muted.

mdoudoroff wrote:

Note that illustration of the QMMF-4 you posted is obsolete and does not reflect the shipping version.

yeah, sorry... quickly looked for one online :)
benniii
i made a quick video to show / hear what i mean... would be super gracious for any input.

https://www.youtube.com/watch?v=kV25FfycsNk
mdoudoroff
benniii wrote:
mdoudoroff wrote:
If you’re in either OSC mode and Q-Peak is up there, it should be whining up a storm. Sounds like something is wrong.

mh.. mh... mhhh.... can you define "whining like a storm"? smile .. just would like to rule out it may be working correctly before i send it in.

i do here the oscillators very loud and clear if i'm beyond ~8 with my Q-PEAK. and their pitch is very decently controllable via the CUTOFF. it's just – i can't seem to really precisely filter them. if i go lower than ~8, they're just muted.


Oh, that’s correct behavior then. Once a filter starts self-oscillating, it’s self-oscillating. If you want to filter a self-oscillating filter, then you need to run its output into another filter. You could, say, make Filter 1 oscillate, then patch its output into Filter 2 (making sure Filter 2 is NOT self-oscillating). The problem there is that a self-oscillating filter produces a sine wave, and filtering sine waves doesn’t tend to be all that interesting-souning! But give it a try.
mdoudoroff
In your video, you’re adjusting the Q-Peak back and forth across the threshold of self-oscillation (around 7). You’re either hearing self-oscillation or nothing at all because there’s no other signal coming into the filter. Add an external signal to the master Audio In or to the Audio In for the filter in question, and then play around some more.

The QMMF-4 is really no different than any other filter with regard to its basic Q behavior: raising Q adds resonant peaks and if you go high enough, the filter starts generating a sine wave on its own, largely drowning out whatever external signal is passing through it.

Note that in RES mode, the filter will not self-oscillate. That is by design. RES mode is mainly for pinging.
benniii
awww, excellent! thanks so much – really relieved that nothing is wrong with the module :)

... back to wiggling with confidence
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