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Moog Grandmother Power Supply
Old 1 week ago
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Moog Grandmother Power Supply

Wondering if anyone with more technical expertise than I has any thoughts on the following: I have (and love) a Moog Grandmother but had been experiencing a ton of noise (low hum + high squeal, both low but audible) with it. I'd been ignoring it/eqing it out, assuming that such things were simply the price one paid for analog deliciousness. But working on a really quiet project, I finally got fed up w it, hunted around for source, and found that it was the power supply (used a same voltage/amperage PS from another device, all problems gone). Emailed Moog, they were great, sent me a new power supply. Buuuut: the power supply they sent was SIGNIFICANTLY lower amperage. Original power supply was 12V 2A, new power supply is 12V 1.2A. It was also labelled on shipping invoice as Minitaur PS, not Grandmother PS

I emailed Moog support about this, and they very quickly replied back, "yeah, it'll work, don't worry about it." But...I can't help but worry about it. I know that running synths at too low an amperage can cause lots of damage, and it seems insane that their original power supply would provide a ton of unnecessary power. So does anyone have any thoughts on this? Any experience with Moog circuitry/architecture and have a sense of whether 1.2A is indeed enough for a Grandmother?

Last edited by Nacho79; 1 week ago at 02:12 AM.. Reason: typo
Old 1 week ago
Lives for gear
Short of measuring the current draw of the GM with a multimeter I would trust that Moog is right that it will work with the 1.2A supply. I'm sure they've tested it in house.

EDIT: Other people who have reported the same issue with the GM PSU have received a Mother-32 PSU from Moog as a replacement. This PSU supplies 1A and works fine with the Grandmother, so you should have no problem with the 1.2A supply they gave you.
Old 1 week ago
Lives for gear
Rob Ocelot's Avatar

Underspecced current likely wont hurt your synth, at least the analog parts of it. The digital portions (including the MIDI interfacing, memory and stuff like that) might be affected. Overspecced current usually isnt a problem unless it's severely over the current rating, and even then it's mostly the excess heat coming from the power brick.

*Current type will be a problem: Do not mix up AC and DC current.
*Voltage polarity can be a problem if the equipment (usually cheap) doesn't have protection diodes
*Undervoltage can cause some problems (sometimes they are *good* problems, like when you run an analog pedal at a lower voltage) but generally is safe.
*Overvoltage can kill your equipment.

My experience with modern Moog equipment is they are pretty tolerant of voltage and current differences -- within reason. My DFAM came with a 12V supply but it runs happily on 9VDC center positive (which means I can put it into a pedal power supply chain as long as there is enough current and not have to lug another wall wart around). My Moogerfooger Ring Mod doesn't seem to care if you feed it 9 or 12 volts either.
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