Hey folks! How are you all doing?
I've recently had some bad luck with pedals and RFI.
I've usually been able to deal with it (with varying degrees of success) using low pass filters (RC) in the power supply and at the input of the circuit. It works ok, most of the time, but seems to be a bit random.
Is there anything else I could be doing to improve it?
In addition to your usual noise filter capacitor (large value electrolytic), try adding a very small value MLCC in parallel from DC + to ground. Try some value between 4.7 pF and 22 pF. The large electrolytic caps don't help much with radio frequency noise.
Is a transmitting tower near your house?
Is your enclosure metal and grounded?
Thanks for the replies!
Quote from: mauman on April 16, 2022, 04:30:03 AM
In addition to your usual noise filter capacitor (large value electrolytic), try adding a very small value MLCC in parallel from DC + to ground. Try some value between 4.7 pF and 22 pF. The large electrolytic caps don't help much with radio frequency noise.
I've never used such small values of MLCC in parallel with the electros (only the more usual 100nF), will give it a try
Quote from: alanp on April 16, 2022, 04:34:41 AM
Is a transmitting tower near your house?
Not that I know of, but I do have a lot more trouble with RFI at home than at practice
Quote from: Aentons on April 16, 2022, 01:25:48 PM
Is your enclosure metal and grounded?
It is, and it certainly helped, but did not solve the issue
Is it mainly gain boosting pedals you are having issues with? Does powering via battery help?
Quote from: Aentons on April 16, 2022, 05:30:00 PM
Is it mainly gain boosting pedals you are having issues with? Does powering via battery help?
Most of the time it is the gainy pedals, indeed. Batteries usually do not help much (of course they help with a little of hum, but not with RFI)
Can you sysyematically isolate the problem? I had a bad guitar lead cause that once. Id start by swappping out leads with known good ones
If you are using shielded wiring, make sure to only ground the shield on one end. Also, avoid ground loops.
I live near a large tower, but I always thought my RFI problem was specifically tied to pedals. Turns out that within my guitar, the input wire was routed to the jack such that it was basically laying across the cable tip when inserted. As soon as I fixed that it got a lot better. I still get some RFI with fuzz/octave type-pedals, but even that is reduced from before.
Thanks for the insights, everyone
Quote from: nzCdog on April 18, 2022, 05:56:17 AM
Can you sysyematically isolate the problem? I had a bad guitar lead cause that once. Id start by swappping out leads with known good ones
I'm thinking it might be guitar related (my cheap Epiphone is the worst), but, as I mentioned, gain pedals are where I typically listen to it
Quote from: Govmnt_Lacky on April 18, 2022, 11:00:10 AM
If you are using shielded wiring, make sure to only ground the shield on one end. Also, avoid ground loops.
Yeah, I definitely need to learn better grounding practices (I'm thankful if you guys have any suggestions of reading materials)
Quote from: Bret608 on April 18, 2022, 05:09:33 PM
I live near a large tower, but I always thought my RFI problem was specifically tied to pedals. Turns out that within my guitar, the input wire was routed to the jack such that it was basically laying across the cable tip when inserted. As soon as I fixed that it got a lot better. I still get some RFI with fuzz/octave type-pedals, but even that is reduced from before.
Will have to open my guitar and check it, might be the case