Digital-Larry Posted March 5, 2021 Share Posted March 5, 2021 I'm using HX Effects in 4CM with my Mesa/Boogie Express+ 5:25. a) I noticed a fair amount of noise that is coming into the front end of the amp when using its highest gain "burn" channel. I unplugged my guitar - it did not go away. I unplugged the HX FX from the amp 's input - it did go away. Another post I read here suggested that disconnecting USB might help, which it does - quite a bit. I guess that's some sort of ground loop issue? My computer is plugged in "over here" through a UPS and the Mesa is plugged in "over there" not on a UPS. Think it would make any difference to plug them into the same place? I'm OK unplugging USB to record, and I don't much use that channel anyway, but just curious. b) When you put the unit into bypass mode, you are essentially plugging your guitar into the amp's effects return. I just based my patch off off 14D, the stock 4CM patch. Is there any way to get "bypass" to work properly in this arrangement? Thx! DL Quote Link to comment Share on other sites More sharing options...
phil_m Posted March 5, 2021 Share Posted March 5, 2021 USB ground loops are quite common when you connect a processor to an amp and a computer at the same time. Sometimes USB isolators can help. As far as the bypass, you’re correct. You can’t use the Bypass All setting with the 4CM because you need to leave the FX Loop block on. You could create a bypass snapshot where everyone but the FX Loop is off. 1 Quote Link to comment Share on other sites More sharing options...
jonandtice Posted March 5, 2021 Share Posted March 5, 2021 (edited) Sometimes the 4CM cables can create a ground loop and you need to isolate one of the cables but it sounds like you have it narrowed down to the USB. I have the same USB problem but it isn't really that bad until I have something running that makes my graphics card work hard. So I think in my case, the graphics card or the PC power supply is leaking power when there is high demand from the graphics card. Also, it's worse when my guitar pickups are facing the PC. The closer I am, the worse the noise. Edited March 5, 2021 by jonandtice Adding detail 1 Quote Link to comment Share on other sites More sharing options...
Digital-Larry Posted March 5, 2021 Author Share Posted March 5, 2021 Yeah it's probably worse with the guitar plugged in, but this test was done with the input jack unplugged (rather than the guitar not plugged into the cable which would leave the input open rather than shorted to ground). I'm looking at USB isolators, they are a bit pricey ($35 to $300!) but what the heck, I'll get a cheaper one and see what happens. I have an Arturia Beatstep which came with a wacky dual headed USB input to deal with ground loops as well. Thanks! Quote Link to comment Share on other sites More sharing options...
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