1176 hum solution

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FotisGR

Well-known member
Joined
Jun 11, 2005
Messages
190
Location
Greece
Working on my G1176 i found that there is a small but audible hum when the in and out gain pots are at maximum gain. Adding little capacitance to power supply (470uf/50V) the hum gone forever. I give a quick point to add this cap to the pcb. http://www.qsl.net/sv3eao/1176%20mod.gif.

Cheers
Fotis
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have you tried this : ?

1176_ground_edit_idea.gif
 
Yea, this is a good plan.

I recently built a stereo 1176 with the DC PSU built on a separate board. I beefed up the smoothing caps, and had two regulator sections for the -Ve supply, one for the audio and one for the lights/relays etc. The two channels were separated by RC smoothing. I just brought the DC in to the 1176 boards from this board and tapped into the +/0/- rails. Works really well and is virtually hum-free!

To be honest, the lowest hum level was obtained after I sat down for a few hours with a big piece of paper and worked out the best grounding method for all the controls. I worked out the best setup for "telescoping shields" (there's a band name :grin: , a Telescopes/Kevin Shields tribute!) and used screened cable for all important audio and control signals.

Mark
 

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