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Grandmother Power/Noise issue

Tabletop Semi-Modular Analog Synthesizers

Grandmother Power/Noise issue

Postby procorat » Sun Dec 09, 2018 3:44 pm

Hey guys!

I recently bought a GM and I noticed that when I move the power cable I have a cracking/scratchy noise coming out of my monitors. Also, I can hear a bleed through of the last note I play in the background even though I’m not playing anything. Even with the OSC and main volumes all the way down, you can hear the notes coming out of the speakers very dimmed. When I insert my headphones balanced cable in the back, the note bleed through and the power supply noise goes away. Any clues as to what could this be?
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Re: Grandmother Power/Noise issue

Postby Rufus the Dog » Sun Dec 30, 2018 9:07 am

Hi - not sure if you are in the Facebook GM group but if you are you might have seen my recent post.

The power supply that comes with the GM has the mains earth pin connected through to the 0 volt / barrel of the DC plug which means that ultimately mains earth is connected to GM audio out 'chassis' and can give rise to earth loops etc. if the other end of your mains lead has an earth pin of some sort. In the UK that is pretty common with our 3-pin plugs

I used the plug top power supply from my Novation Circuit that has a plastic earth pin (3 pin mains in the UK) and I no longer get any crackling sound if a gentle rotate the DC connector.

I haven't checked for bleed yet


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Re: Grandmother Power/Noise issue

Postby ummagumma » Sun Dec 30, 2018 2:42 pm

Rufus that is great info, thx for posting

seems to explain the issues ppl have been having
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