Moog MG-1, Rogue, and Prodigy - Filter and cap mods

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thealien666
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Re: Moog MG-1, Rogue, and Prodigy - Filter and cap mods

Post by thealien666 » Mon Jan 12, 2015 8:23 am

I stand corrected. Thanks.
Last edited by thealien666 on Mon Jan 12, 2015 9:12 am, edited 2 times in total.
Moog Minimoog D (1975)
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facon
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Re: Moog MG-1, Rogue, and Prodigy - Filter and cap mods

Post by facon » Mon Jan 12, 2015 8:39 am

CZ Rider wrote:Check the footprint on those sliders, the 50K emphasis are inverted. Learn someting new every day!
Good catch!

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facon
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Re: Moog MG-1, Rogue, and Prodigy - Filter and cap mods

Post by facon » Mon Jan 26, 2015 11:48 am

I'm getting pretty close to finishing up on testing all of the mods. Is there anything I'm missing on my list that anybody would suggest?

PERFORMANCE MODS
Replace wrong resistors back to capacitors according to schematic
Minimoog Filter mod - Increase filter coupling cap values, lower input impedance and change filter cap and resistor values to match Minimoog
Add continuous glide and re-trigger circuit to keyboard tracking (stripboard layout provided)
Replace 5837 Noise chip with analog noise generator (stripboard layout provided)
Tune Osc 1 & 2 one octave lower
Osc 2 Detune slide pot to full octave up and down
Increase filter modulation level
Increase audio output level
Change Ring Mod input from Osc 1 square only to post-switch/pre-mixer Osc 1


ADDITIONAL FUNCTIONALITY MODS
Add Sustain pot
Osc 1 and 2 PWM controls
Osc 2 Detune/pitch modulation pot (very cool flanger meets autowah effect with sync in!)
Poly pitch modulation pot
FM pot
VCA modulation pot
LFO speed switch (fast, normal, slow)
Osc 1 octave up switch
Ring Mod carrier from LFO (instead of Osc 2 Square) switch
Internal or External switchable Saw to Triangle to Sine convertor (stipboard layout provided)
Internal or External VCA ASDR (stripboard layout provided)
Separate headphone and master volume pots

BACK PANEL CONNECTIONS
CONTROL VOLTAGE:

VCA
VCF
Envelope
V-Trigger
Gate
LFO In/Out
Keyboard In/Out
Sync In

AUDIO:

Post Filter/Pre-VCA In/Out
Pre-Filter Audio In
Noise In/Out
VCO
Osc1 - Pre-mixer
Saw In/Out
Osc1 Post-Switch In/Out
Osc2 - Pre-mixer
Saw In/Out
Osc1 Post-Switch In/Out
S&H In
Poly Pre-mixer In/Out
Ring Mod Audio In
Ring Mod Carrier In
Last edited by facon on Thu Jan 29, 2015 3:57 pm, edited 2 times in total.

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facon
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Re: Moog MG-1, Rogue, and Prodigy - Filter and cap mods

Post by facon » Wed Jan 28, 2015 12:25 pm

Back to the topic of filter cap mods, even though the MG-1 uses opamps in the following stage of the filter, I've found that the following modifications makes an improvement, IMO:

Swapping the filter caps for .068uF
Change the resistors in the ladder filter (except R77) to 150
Changing the coupling caps to .22uF
Changing the input impedance resistors from 1M to 47K

I simply copied the same specs of each from the Minimoog Model D. The filter now seems fatter and smoother. While I liked the stock MG-1 filter, these put it over the top for me and is especially noticeable during a filter sweep with the resonance up high.

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Stuka
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Re: Moog MG-1, Rogue, and Prodigy - Filter and cap mods

Post by Stuka » Thu Jan 29, 2015 3:45 pm

facon wrote:I'm getting pretty close to finishing up on testing all of the mods. Is there anything I'm missing on my list that anybody would suggest?
...
Just the instruction manual(s) that show how to do all these mods! :wink:

All kidding aside, thanks for taking the time to do all this ~
Looking forward to taking your list along when I start my MG-1 overhaul!!
Little Phatty Solar CV, Minitaur, Slim Phatty (x2), MF-101, MF-102, MF-103, MF-104M, MF-105M, MF-108M, CP-251 (x2), Animoog app, Filtatron app, Model D app, Model 15 app...and some 5U modular and Doepfer stuff...

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facon
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Re: Moog MG-1, Rogue, and Prodigy - Filter and cap mods

Post by facon » Thu Jan 29, 2015 3:48 pm

Haha, I want to make sure I'm as thorough as possible. The last thing I want is somebody screwing up their synth. A lot of them are very easy to do, but some are a bit advanced. I have a lot of tagboard layouts and schematics just scribbled on paper. The time consuming part is getting the schematics into Eagle, designing the layouts in DIYLC and taking pictures. I'm getting anxious to post as well.

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Re: Moog MG-1, Rogue, and Prodigy - Filter and cap mods

Post by calaverasgrande » Sat Jul 10, 2021 4:07 pm

was there ever an update on this?
I'm rebuilding my MG1 now and find these mods interesting.
A couple that I am researching right now.
Disconnect OSC 1 from LFO, so only OSC 2 is modulated. This is for that synced osc fun.
Filter FM with some kind of source selection. The easy thing would be to just take a feed off the mixer and feed that to the filter. But I'd like the ability to pick a single source pre-mix. Could see the usefulness of FMing the filter from a source that isn't going to the mixer.

Another cool one that I am not how to accomplish would be routing the ENV to the MOD buss. So there would be a 4th choice for LFO in addition to square, saw and random. That should work really well with disconnecting OSC1 from LFO mod and syncing OSC 2 to OSC 1.
Taurus III, Digitone, Dark Energy, OB6, MG1, Grandmother, Blofeld

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