RFI Picked up by Amp

[lukemh987]

Re: RFI Picked up by Amp

Does this happen with the effects loop connected by just a (good) cable...no pedals?

Yes, it happens when i connect send to return with a single good cable without any pedals in the loop. It also happens with no FX loop engaged, though the RFI isn't quite as loud.

I mentioned my cable brand since, while they seem to be of high quality, they perhaps are not high quality *enough* to prevent the interference.

At this point, I'm not sure if a fix to the amp itself is needed (the tech didn't think so) or if I just need to use some kind of modded cable to divert the RFI, as NegativeEase mentioned.

 

[Mincer]

Re: RFI Picked up by Amp

So, I am guessing it just acts like an antenna. Does this happen if the amp is in another building?

 

[lukemh987]

Re: RFI Picked up by Amp

So, I am guessing it just acts like an antenna. Does this happen if the amp is in another building?

It's been fine in other settings, as when it was with the tech at the shop.

 

[Hsb]

Re: RFI Picked up by Amp

Have you tried plugging it in to a different outlet in your house? How are you powering your pedals?

 

[lukemh987]

Re: RFI Picked up by Amp

Have you tried plugging it in to a different outlet in your house? How are you powering your pedals?

Yes, tried it all over the house. I'm powering my pedal board with an Accel FX Power Source.

I'm thinking the problem lies with the amp acting as an antenna though, as suggested earlier in the thread, since this happens when the FX loop isn't engaged and it's just a lead plugged into the amp (doesn't matter if a guitar is connected at the other end of the lead).

 

[Hsb]

Re: RFI Picked up by Amp

And you have tried the pedals without the Accel, straight from the wall or on batteries?

 

[Mincer]

Re: RFI Picked up by Amp

Are there any appliances or wi-fi around at home that isn't present in these other places?

 

[beaubrummels]

Re: RFI Picked up by Amp

Couple notes for the OP

“Quality” of cables has little to do with whether they defeat or carry RFI or not. Construction of the cable, as hinted by NegativeEase and David, does.

Furman power supplies do not address interference noise. They only protect against spikes and irregularities in the source power.

If the amp does it by itself, I would wonder if you are plugging a three prong cable into a two prong outlet at home without grounding the third plug? If the interference is line-of-sight, does turning or moving the amp change the level of interference? Have you checked the power of your home at the outlets and the house is wired correctly with no issues? (How old is the house?). Just trying to eliminate variables. Is this a townhome sharing power across units? (I’ve had problems where power equipment and appliances running at the neighbors put noise into the line my house.)

 

[Hsb]

Re: RFI Picked up by Amp

Couple notes for the OP



If the amp does it by itself, I would wonder if you are plugging a three prong cable into a two prong outlet at home without grounding the third plug? If the interference is line-of-sight, does turning or moving the amp change the level of interference? Have you checked the power of your home at the outlets and the house is wired correctly with no issues? (How old is the house?). Just trying to eliminate variables. Is this a townhome sharing power across units? (I’ve had problems where power equipment and appliances running at the neighbors put noise into the line my house.)

Kinda what I was getting at also. Or if his pedal power supply is picking up something.

 

[lukemh987]

Re: RFI Picked up by Amp

Couple notes for the OP

“Quality” of cables has little to do with whether they defeat or carry RFI or not. Construction of the cable, as hinted by NegativeEase and David, does.

Furman power supplies do not address interference noise. They only protect against spikes and irregularities in the source power.

If the amp does it by itself, I would wonder if you are plugging a three prong cable into a two prong outlet at home without grounding the third plug? If the interference is line-of-sight, does turning or moving the amp change the level of interference? Have you checked the power of your home at the outlets and the house is wired correctly with no issues? (How old is the house?). Just trying to eliminate variables. Is this a townhome sharing power across units? (I’ve had problems where power equipment and appliances running at the neighbors put noise into the line my house.)

The outlets are three-pronged. Moving the amp and plugging it into different outlets hasn't done anything to remedy the problem. I live in an apartment, which was recently renovated but probably dates back to the 70s, so the power definitely is shared across units. I have a small reader that plugs into the power outlets and tells you if there are any problems with the outlet (open ground/open neutral/open hot/correct/hot ground rev/hot neutral rev), and that says the outlet is fine ("Correct").

I appreciate the questions–hopefully my responses get us closer to figuring out how to resolve this problem.

 

[lukemh987]

Re: RFI Picked up by Amp

As a quick follow up, the amp picks up no interference when there are no instrument cables plugged into the amp at all – meaning nothing plugged into the loop or into the front of the amp.

 

[NegativeEase]

Re: RFI Picked up by Amp

The outlets are three-pronged. Moving the amp and plugging it into different outlets hasn't done anything to remedy the problem. I live in an apartment, which was recently renovated but probably dates back to the 70s, so the power definitely is shared across units. I have a small reader that plugs into the power outlets and tells you if there are any problems with the outlet (open ground/open neutral/open hot/correct/hot ground rev/hot neutral rev), and that says the outlet is fine ("Correct").

I appreciate the questions–hopefully my responses get us closer to figuring out how to resolve this problem.

Another guess is you have voltage potential between the ground and neutral in your home. Pretty common in residential installs