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Hello everyone! 
I have recently in my possession an old Randall RG100HT rackmount made in USA from the early 1990. Since i live in EU and we're using 220v, the only way to power up the amp was to get a cheap voltage converter (1500w).
It works great as far as everything i've checked me and my technician, except from the send/return (fx loop). When i plug in a patch cable on the send, it makes a small hum sound, which is bearable. And then when i connect the same cable to the return, the hum sound increases more. It's still bearable and when you play guitar it's not that annoying...but it's still there. Also when i used several effects on the fx loop (which i'll use them eventually), still had the same same hum but didn't increased it, except for a few multieffects which made the hum sound huge and unbearable to play! It's sounds like a 60hz hum, just to have an idea.
My technician said that he doesn't know what is causing it, just proposed me to get a ground loop box and connect it between the effects and the amp send/return.
Anyone has an idea what's causing this problem? Maybe is the cheap voltage converter? Should i buy one from Acupwr?
Thanks in advance!
I have recently in my possession an old Randall RG100HT rackmount made in USA from the early 1990. Since i live in EU and we're using 220v, the only way to power up the amp was to get a cheap voltage converter (1500w).
It works great as far as everything i've checked me and my technician, except from the send/return (fx loop). When i plug in a patch cable on the send, it makes a small hum sound, which is bearable. And then when i connect the same cable to the return, the hum sound increases more. It's still bearable and when you play guitar it's not that annoying...but it's still there. Also when i used several effects on the fx loop (which i'll use them eventually), still had the same same hum but didn't increased it, except for a few multieffects which made the hum sound huge and unbearable to play! It's sounds like a 60hz hum, just to have an idea.
My technician said that he doesn't know what is causing it, just proposed me to get a ground loop box and connect it between the effects and the amp send/return.
Anyone has an idea what's causing this problem? Maybe is the cheap voltage converter? Should i buy one from Acupwr?
Thanks in advance!