Minimoog Model D Osc 3 Control switch defies expectations

In a Moog Mood? Here's a forum for discussion of general Moog topics.
megavoice
Posts: 343
Joined: Fri Jan 07, 2011 12:27 pm

Re: Minimoog Model D Osc 3 Control switch defies expectation

Post by megavoice » Wed Apr 27, 2016 8:38 am

Stevie Ray wrote:Megavoice -- replacing ageing electrolytic caps in the power supply can only be a good thing. As others have noted above, replacing caps in the audio signal path can affect the the sound and character of the instrument so that's up to you. Personally, I replace ALL electrolytic caps and I've only ever noticed an improvement in audio quality and noise levels after doing this. Replacing the electrolytic caps in an ageing PSU is the first thing you should do in any restoration project IMO.


Thanks for the info.
I already know all this, and years ago when my Chroma didn`t work any more properly the first my former tech advised me was, to do a complete cap Job at first, and my very first question after was if there would be any risk of sound changing, but he denied immediately.
So I let him do the Job and the Chroma still sounded as "dusty" and "dirty" like before.

But once he told me as for the Minimoog, and I cannot reproduce what he told me as I`m no tech, people complained about the sound after having done the cap job on the PSU.
So he never did and with a great exception in comparison to all other vintage synths he still rejects doing any alterations on any Mini`s PSU, even NOT replacing it in total.

So that`s all I can tell about.
"Losers always whine about their best. Winners go home and fu** the prom queen." —Sean Connery to Nicholas Cage in "The Rock" (1996)
I've never seen any real prom queen here in my country, but if we had some they'd
**** with everyone.

User avatar
MC
Posts: 2874
Joined: Tue Aug 12, 2003 2:20 pm
Location: Secluded Tranquil Country

Re: Minimoog Model D Osc 3 Control switch defies expectation

Post by MC » Wed Apr 27, 2016 9:25 am

There's some truth in not re-capping a Minimoog.

Well into its production in the 1970s, they re-designed the power supply to make it cleaner and when it was installed it caused the VCOs to lock together. You NEVER want VCOs to lock together as this ruins the sweeping effect of multiple detuned VCOs. It turns out that the original power supply had just enough noise on the power rails that it prevented the VCOs from locking together. If you re-cap, you risk making the rails too clean and the VCOs will lock.

Imperfections can sometimes be a good thing. Turns out this is also true with the old Moog modulars. I almost did a re-cap on my RA Minimoog until I uncovered this "imperfection".

Minimoog is one of the rare exceptions though. In general a re-cap is a very good idea on any analog synth.
Gear list: '04 Saturn Ion, John Deere X300 tractor, ganged set of seven reel mowers for 3 acres of lawn, herd of sheep for backup lawn mowers, two tiger cats for mouse population control Oh you meant MUSIC gear Oops I hit the 255 character limi

megavoice
Posts: 343
Joined: Fri Jan 07, 2011 12:27 pm

Re: Minimoog Model D Osc 3 Control switch defies expectation

Post by megavoice » Wed Apr 27, 2016 9:35 am

MC wrote:....Minimoog is one of the rare exceptions though. In general a re-cap is a very good idea on any analog synth.


YES.
"Losers always whine about their best. Winners go home and fu** the prom queen." —Sean Connery to Nicholas Cage in "The Rock" (1996)
I've never seen any real prom queen here in my country, but if we had some they'd
**** with everyone.

User avatar
thealien666
Posts: 2791
Joined: Mon Nov 14, 2011 8:42 pm
Location: Quebec, Canada

Re: Minimoog Model D Osc 3 Control switch defies expectation

Post by thealien666 » Wed Apr 27, 2016 9:54 am

MC wrote: If you re-cap, you risk making the rails too clean and the VCOs will lock.


Not really.

If you replace the original caps with the exact same values nothing should change, since the circuits were originally designed with caps of those values (imperfections and all).

BTW, unless your Mini was left/used in a harsh environment (very hot) those high quality japanese (Matsushita) electrolytics capacitors will probably be almost as good as the day they were made. I can confirm that they are on my own Minimoog D with ESR readings still well below nominal values even over 40 years later. So I agree with MC, but not for the same reasons, no recapping needed there.

Some caps that might need replacing are some Mylar ones (with color stripes) on which the external coating is cracking and delaminating. But even those still show correct values (both ESR and capacity), and the Mighty Mini is still working fine despite those.

Image
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion

Post Reply