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New Model D Reissue Problems

Posted: Thu Jul 20, 2017 6:47 am
by RicBayBar
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.

Re: New Model D Reissue Problems

Posted: Mon Aug 28, 2017 8:07 am
by Blackout
hey man....first semitione...sounds like a calibration problem for sure.

second problem re: the same problem still there when you plug the mini directly into a mixer and listen on speakers?

reason why i ask is because the impedance of headphones is always different for models/brands and you might have just got unlucky with an impedance that Mini doesnt particularly like?

My mini certainly doesnt have this prob....what brand headphones are you using...i use Sony 7506


Re: New Model D Reissue Problems

Posted: Wed Aug 30, 2017 10:53 am
by RicBayBar
I'm using Shure SRH440 headphones, but the problem is the same with (a) a set of not very good computer headphones, and (b) some ear buds I use with my iPhone. It is however more marked with the Shures because they have a better frequency response and much higher sensitivity.

I took it back to the store that I bought it from to test it. They have a large system for previewing keyboards with good quality studio monitor speakers, and it sounded like what I expect from a Minimoog, i.e. superb. This leads me to suspect that it might picking up interference from somewhere in my apartment block. I know the older Minimoogs were prone to this because I had one in the 1970s that could pick up radio stations, but only when it was extremely embarrassing for it to do so. Given the fact that the new Minimoog has the same electronics, it is likely that it is equally sensitive to certain types of interference.

Most of my gear is in storage at the moment because I recently moved. I'll be collecting it this weekend though, so I can do some testing without headphones to see how it sounds. I'll also try playing it at another location if the problem persists here.

Re: New Model D Reissue Problems

Posted: Mon Sep 04, 2017 8:46 am
by _ADSR_
My re-issue also has a slight shift in pitch when turning the OSC Mod switch on and then again when switched off.

I just chalked it up to typical analog inconsistencies but I could be wrong.

Re: New Model D Reissue Problems

Posted: Tue Sep 05, 2017 10:30 am
by freiburg
My Reissue has a negligible amount of detuning, when switching on the Osc mod. so it must be a calibration issue. I would consult the original minimoog service manual for that.


Re: New Model D Reissue Problems

Posted: Mon Sep 11, 2017 7:17 am
by Blackout
RicBayBar wrote:This leads me to suspect that it might picking up interference from somewhere in my apartment block.

i dont suppose you have a mobile phone radiation tower pointed at your apartment do you? on a near-by building at the same height as your place? that would do it...and will probably fry your own processor (brain) in a matter of months or years as well

Re: New Model D Reissue Problems

Posted: Tue Sep 26, 2017 12:03 pm
by RicBayBar
The dreadful reception I get on my phone does I think eliminate the close presence of a cell tower. I have also tried playing the high output of the Moog through a small Soundcraft sub-mixer and then into my headphones - the same problem can be heard, so it's not related to headphone impedence. My other keyboards sound fine through that mixer, so the mixer itself is working fine.

After isolating everything else, I am beginning to suspect that there may be either a fault, or some form of calibration issue.

Re: New Model D Reissue Problems

Posted: Fri Sep 29, 2017 10:51 am
by Blackout
ive seen a wall wart send rubbish down the lines of other things plugged into that circuit. Pull other plugs one by one until only the Mini is plugged into the whole room/side of the house.

then call the Moog dist next id say....

Re: New Model D Reissue Problems

Posted: Mon Oct 02, 2017 9:52 am
by RicBayBar
There are no warts apart from the one that comes with the Moog, and I'm wondering whether this is what makes it vulnerable to noise. Minimoogs were after all routinely placed on top of known electrical noise sources such as tonewheel organs and Mellotrons without any obvious issues in the 1970s, and the whole lot was gigged in theatres with dreadful electrical installations, and on open air stages powered by less than wonderful generators. Those Minimoogs did however have internal power supplies which, whilst not being the best power supplies ever, were inside the metal chassis, and therefore more isolated from external noise sources.

Re: New Model D Reissue Problems

Posted: Tue Oct 03, 2017 5:58 am
by Blackout
my power supply is fine but it could very well be faulty, a cap or filter in it could have a problem, you have a good point there.

if i was you i would buy another PS from moog and see if the problem goes away. AT the end of the day you should get a spare PS they dont last forever!!! and if youre only using the on/off switch on the mini for a new reissue it doesnt switch off the PS. So they will burn out in a few years.

At least then it will be one more potential problem ruled out