Ampeg J-12D - Printable Version

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Ampeg J-12D - vecher - 09-02-2021

Does anyone have any information on this amp.. I replaced all caps .. when i turn it on... no mic connected its quite .. no hum.. but when i plug in a mic i get a load hum when i turn up the volume its a metal case mic as soon as i touch the mic the hum comes.. any clue on why? grounding ??

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RE: Ampeg J-12D - Radioroslyn - 09-02-2021

https://ampeg.com/support/files/Schematics/J%20Series/J-12D/J-12D%20Tube%20Location%20Schematic.pdf

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