New Model D Reissue Problems
Posted: Thu Jul 20, 2017 6:47 am
I bought a Model D about a month ago, and have noticed a couple of potential issues.
Firstly, the Oscillator Modulation switch lowers the pitch of the instrument by a little less than a semitone when switched on. This could be a calibration issue, which would not be that unusual considering that the instrument has travelled from the US to the UK,
and may not have been handled as gently as it should have been.
Secondly, when listening with headphones, there is a "heterodyning" effect around middle C, D, and E which is especially noticeable when playing with a single oscillator with a harmonically rich waveform with the filter fully open. Closing the filter doesn't alleviate the effect until it has closed sufficiently to remove most of the harmonics from the waveform. This suggests that whatever is causing it happens after the filter.
The effect is audible whichever of the three oscillators is selected and at all volumes of both the oscillator in the mixer, and the headphones. I have tried several pairs of headphones from cheap ones to studio monitor quality, and the effect is there on all of them, so it isn't an artefact of the headphones themselves. Selecting different footages moves the effect up and down the keyboard, e.g. 4 foot waveform manifests at C, D, E (less on adjacent keys). The best description of the effect is as if a non-audible fixed high frequency is cross-modulating the sound, much like a ring modulator would produce.
Please note that this is with the headphones plugged directly into the headphone socket of the instrument. It also occurs with the headphones plugged directly into the "high" main output. It gets more noticeable as the instrument warms up.
I sent an Email to Moog about this early last week, but have received no reply as yet.
Firstly, the Oscillator Modulation switch lowers the pitch of the instrument by a little less than a semitone when switched on. This could be a calibration issue, which would not be that unusual considering that the instrument has travelled from the US to the UK,
and may not have been handled as gently as it should have been.
Secondly, when listening with headphones, there is a "heterodyning" effect around middle C, D, and E which is especially noticeable when playing with a single oscillator with a harmonically rich waveform with the filter fully open. Closing the filter doesn't alleviate the effect until it has closed sufficiently to remove most of the harmonics from the waveform. This suggests that whatever is causing it happens after the filter.
The effect is audible whichever of the three oscillators is selected and at all volumes of both the oscillator in the mixer, and the headphones. I have tried several pairs of headphones from cheap ones to studio monitor quality, and the effect is there on all of them, so it isn't an artefact of the headphones themselves. Selecting different footages moves the effect up and down the keyboard, e.g. 4 foot waveform manifests at C, D, E (less on adjacent keys). The best description of the effect is as if a non-audible fixed high frequency is cross-modulating the sound, much like a ring modulator would produce.
Please note that this is with the headphones plugged directly into the headphone socket of the instrument. It also occurs with the headphones plugged directly into the "high" main output. It gets more noticeable as the instrument warms up.
I sent an Email to Moog about this early last week, but have received no reply as yet.