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Re: Moog/Realistic MG-1 Mod Guide

Posted: Thu Feb 19, 2015 2:15 am
by spiders
Hey there. I'm trying to build the noise generator, but I'm a little confused by the schematic. It appears that the collector of q1 has been left open. Is this correct? Thanks so much for doing all this work, this is an awesome trove of information on a cool synth.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Thu Feb 19, 2015 8:17 am
by facon
That is correct. That's what's generating your white noise. Q1 is reverse biased with the collector left open. This uses the transistor in the same way a Zener diode is used in reverse breakdown.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Mon Mar 16, 2015 3:33 pm
by e_just
Has anybody else compleated the minimoog filter mod? After instaling this mod, the peak emphasis does nothing untill it is turned up to about 90 %, then quickly goes into self oscilation. Im not sure if this is normal.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Mon Mar 16, 2015 3:35 pm
by facon
That didn't happen to me. Did you recalibrate?

Re: Moog/Realistic MG-1 Mod Guide

Posted: Mon Mar 16, 2015 3:59 pm
by e_just
I did not, how difficult is it to recalibrate?

Re: Moog/Realistic MG-1 Mod Guide

Posted: Mon Mar 16, 2015 4:10 pm
by facon
It should take around 10 to 15 minutes if you're already disassembled. You can find the procedure on page 18 of the manual: http://manuals.fdiskc.com/flat/Realisti ... Manual.pdf

A lot of DMMs have a frequency reader that you can use. A frequency generator will also do the trick. Otherwise you can use a tuner. I think I just used my Cleartune tuner app to calibrate it. For example, 660 Hz is E at 5 semitones: http://en.wikipedia.org/wiki/Scientific_pitch_notation

If you're having problems calibrating because of the emphasis pot, you'll know that something isn't right. Regardless you should check all of your solder joints to make sure everything is good.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Mon Mar 16, 2015 5:10 pm
by e_just
One thing I failed to mention is that I installed a new 50KA peat emph slide pot from Syntaur. I wonder is the pot is bad or possibly the wrong value.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Mon Mar 16, 2015 5:13 pm
by facon
e_just wrote:One thing I failed to mention is that I installed a new 50KA peat emph slide pot from Syntaur. I wonder is the pot is bad or possibly the wrong value.


That could certainly be it. Doing multiple things at once makes this stuff more difficult to track down. Doublecheck the pots solder joints and verify it works correctly with a DMM.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Tue Mar 24, 2015 7:04 pm
by j1971986b
I've been looking at a few of these mods, I have a couple of questions and although I've wanted to grab hold of a Moog for around 15 years I've only recently purchased my MG-1 so please excuse my ignorance.
Firstly, looking through the guide I see the second "minimoog" type filter, how different in sound is it from the default mg-1 filter? I only ask because if there is a particularly different sound would it be possible to wire in a toggle to choose either filter by switching signal path?
Secondly, again excuse my ignorance, if the pitch jack on the back can be connected to an expression pedal and the modulation slider essentially being a mod control, would a modder be able to wire in pitch and mod wheels?
Thirdly, I need to find a full new set of sliders
.. Any help?
Lastly, I'm not only the worst diyer in the world (i take things apart, break them and get angry), I'm also in contention for the place of worlds worst solderer. Is there anyone in the UK that can do these mods? UK based users or stores etc... Help is greatly appreciated

Re: Moog/Realistic MG-1 Mod Guide

Posted: Thu Apr 16, 2015 9:43 am
by Lackan110f
Hi, first of all - thank you Falcon for posting all these tips - they really worked great and I have done almost all of them (and then some extra), and my MG1 has turned out awesome!

Here is a demo of all the new stuff:
https://www.youtube.com/watch?v=QuztPaTRY9Q

And here is a demo tune only using my "new" MG1:
https://www.youtube.com/watch?v=li2joEBwFgw

There is a few additions, the multi trig-circuit needs to have a 90k at R7 for better multi-triggering.

When doing the LFO -> osc2 pitch, it is easy to put in a switch and then tap the ENV-signal from pin7 if the U13 op-amp. Then you get FM on the osc2 from both LFO and ENV.

Then you can use the same set up, but instead of going to the osc2 pitch, you plug it in to the PW's. Then you get switchable PWM either from LFO or ENV.

There is also a 10k trimpot for adjusting the Cut Off, put this on the panel as well so you can close the filter to zero.

Thanks again, Falcon!

Re: Moog/Realistic MG-1 Mod Guide

Posted: Sat Apr 25, 2015 4:02 am
by Tomas
Curious to hear how that minimoog filter mod sounds if anyone tried it and can post a demo

Re: Moog/Realistic MG-1 Mod Guide

Posted: Thu Apr 30, 2015 9:43 am
by Lackan110f
I also did the Minimoog filtermod, you can hear it in the examples I posted above. Alas, I did not do a "before/after" demo, but you can really hear how "meaty" the filter is.

I am not sure exactly how big the difference is from before, but it is definitely not getting any less good with the mod. But to me (after playing with the modded MG1 for a while) the best mods by far is the sustain pot and extra low oscillator octave. And PWM. And FM. And wide KBD TRACK. And… and… and… :D

Re: Moog/Realistic MG-1 Mod Guide

Posted: Tue Feb 16, 2016 4:50 pm
by Alrod
I am so glad I found this site! I recently purchased two MG-1's. Both need some work. I want to mod one, and keep the other stock. For a little history, I am actually a guitarist with a Pro Tools based studio who basically uses soft synths for recording synth parts. I was arranging a cover of Death Cab for Cutie's "Black Sun" and fell in love with the synth parts. For certain parts, my soft synths just weren't doing it sonically for me.

I had a brief conversation with Chris Walla and was told that on the choruses he used a MG-1 tied to the ACME SAM-16 sequencer. There's a sequence running through the whole track that gets muted and unmuted at different points. It's 15 beats, which is why the theme never falls the same way twice in the choruses. He played the changes along with the sequence in the choruses using the MG-1's polyphonic oscillator, which is post-gate but not affected by note information. Anyway, that is how my obsession with the MG-1 began.

So far I have had to replace some of the MM5823N IC chips, and reconditioned the sliders on one of the units so for. Th only mod I have done is increasing the audio output level by removing the R102. Next I want to do the Minimoog filter as well as tune Osc 1 & 2 one octave lower mod.

For tuning Osc 1 & 2 one octave lower, I see there is the option to add a switch rather than lowering it internally. I prefer the switch method since it will allow me to switch between lower and the stock higher. Unless I missed it, I did not see the instructions including the switch. Can anyone point me to those instructions, or let me know how it's done step-by-step? I build my own pedals so I do have experience with soldering the various components as long as I have the instructions. When it comes to reading schematics and figuring things out that way, I am not very good.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Tue Feb 16, 2016 8:33 pm
by facon
I never ended up putting a switch in mine, so I didn't draw it up. You could use a dpst or dpdt switch to put 169k resistors in parrallel with the 120k resistors that are there. That would give you 70k when the resistors are in the circuit or back to stock 120k when they are out. Take a shot at drawing out how to layout the switch. Basically, you would connect the poles to one end of the resistors in the board (R2 and R28). One set of throws would be unconnected (for stock 120k), the other sets would have the 169k resistors connecting to the other ends of R2 and R28. Let me know if this makes sense.

Re: Moog/Realistic MG-1 Mod Guide

Posted: Tue Feb 16, 2016 11:48 pm
by Alrod
facon wrote:I never ended up putting a switch in mine, so I didn't draw it up. You could use a dpst or dpdt switch to put 169k resistors in parrallel with the 120k resistors that are there. That would give you 70k when the resistors are in the circuit or back to stock 120k when they are out. Take a shot at drawing out how to layout the switch. Basically, you would connect the poles to one end of the resistors in the board (R2 and R28). One set of throws would be unconnected (for stock 120k), the other sets would have the 169k resistors connecting to the other ends of R2 and R28. Let me know if this makes sense.



Thanks, it does make sense, but i am a visual person and would need to see it drawn out. I am just not a smart as guys like you when it comes to things like this. I am not an electronics technician, but I play one on internet forums :lol:

My skills really just amount to DIY projects like pedals, and working on gear with line by line instructions and photos. When it comes to experimenting or troubleshooting, I get lost. I do have a mini dpdt switch so I would probably use that over a dpst.