RFI problems appearign in FOH sound... Currently using a Shure Wireless Digital pack. Believe the source/issues begin with RFI on stage. None of the other guitar players have it. In a HS auditorium with wireless network in the space. Have issues with RFI (Hi Freq not ground hum) only while on stage. School stage lighting is off. We use our own LED lighting, but issues remains with our lights on or off. Noise increases at certain positions on the stage. Have tried a passive bass, direct cable, DI between bass cab and FOH sound. Most of the nosie appears to be coming through mains regardless of connection configuration. Also tried a Furman power conditioner. OBTW the rig is a Schecter Studio 5 through a Genz Benz Neo 212T and Shuttle 9.0. Thoughts??
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RFI Noise with Wireless or Wired connection
- Thread starter Aldonis
- Start date
If changing instruments and cabling doesn't seem to change things, does the amp put it out even with nothing connected? I don't know the routing or controls of that amp, but see if it's affected by changing channels, patching a straight cable in the effects loop, etc. SOMETHING in there would seem to be acting as an antenna...
RFI can be a pig to figure out.
Best diagnostic technique is to test every component of your signal chain via a process of elimination. Be methodical, and use spares (borrowed cables, bass, amp, wireless, etc.) to swap out one element at a time.
It's easiest if you can shorten the chain at first.
Try running your bass straight into a good DI, no pedals, and a short instrument cable. Try ground lift on and off.
If that's still, noisy, them there's no point checking anything else.
Best diagnostic technique is to test every component of your signal chain via a process of elimination. Be methodical, and use spares (borrowed cables, bass, amp, wireless, etc.) to swap out one element at a time.
It's easiest if you can shorten the chain at first.
Try running your bass straight into a good DI, no pedals, and a short instrument cable. Try ground lift on and off.
If that's still, noisy, them there's no point checking anything else.
Good advice from Steve. You have to break the problem down and systematically look at every part.
Try the amp on its own with only the bass plugged in, isolated from anything near it that can generate noise. That includes cell phones, tuners, and anything else. Any cables connecting to the amp should be as short as possible. If a cable runs on the stage, lie it flat, snaking it back and forth, do not have any loops in it.
Sometimes RFI can get into the front end of your amp. Some amps are better designed to deal with this than others. On the other hand, you may have a bad ground connection. Check that the jack nut is tight, there may be an issue with a loose solder joint inside the chassis. There are measures that can be taken such as adding an RF shunting capacitor at the input jack. A tech should be able to help with this.
Try the amp on its own with only the bass plugged in, isolated from anything near it that can generate noise. That includes cell phones, tuners, and anything else. Any cables connecting to the amp should be as short as possible. If a cable runs on the stage, lie it flat, snaking it back and forth, do not have any loops in it.
Sometimes RFI can get into the front end of your amp. Some amps are better designed to deal with this than others. On the other hand, you may have a bad ground connection. Check that the jack nut is tight, there may be an issue with a loose solder joint inside the chassis. There are measures that can be taken such as adding an RF shunting capacitor at the input jack. A tech should be able to help with this.
- Feb 12, 2006
- 61,041
- 5
- 220,978
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Your amp is fully rfi protected, though its possible your bass or the pa's mic input wiring (especially if there's a patch bay) is not.
Is the amp quiet without being connected to the pa?
Have you tried the pin 1 lift switch on the back of your amp?
Try the amp and bass alone, no wireless. Try it with another bass.
Is the DI set up for mic or line level? Is the console perhaps expecting mic level with the amp set for line level? If so, you will pay a 30dB noise penalty which will be audible with no signal. (This will also result in terrible gain structure at the console)
Is the amp quiet without being connected to the pa?
Have you tried the pin 1 lift switch on the back of your amp?
Try the amp and bass alone, no wireless. Try it with another bass.
Is the DI set up for mic or line level? Is the console perhaps expecting mic level with the amp set for line level? If so, you will pay a 30dB noise penalty which will be audible with no signal. (This will also result in terrible gain structure at the console)
- Feb 12, 2006
- 61,041
- 5
- 220,978
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
He has not done these steps without a DI connection to the mixer. This is IMO a critical step.
With high frequency noise, there are many possible paths that noise can enter the system, and just as important, there are combinations of connections that can expose a system to faults that would not (or could not) occur alone.
Tried a DI box (Radial) and went DI out to FOH and DI through to amp on stage. Had same noise issues... It seems to be most prevalent in mains and not on bass amp/rig on stage. I have not tried reducing the length of run from DI out to digital snake (whether from DI on Genz Bens amp or Radial DI). I have tried lift on DI to establish if it was a ground hum - it was not. Good call on systematic troubleshooting. I will also try another channel on the board...
- Feb 12, 2006
- 61,041
- 5
- 220,978
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Does your bass, through a DI box with nothing else involved make noise through the PA?
Have you tried different mic cable and snake channel?
Have you verified that the power is properly grounded/bonded at FOH? (A big cause of rfi)
Have you tried different mic cable and snake channel?
Have you verified that the power is properly grounded/bonded at FOH? (A big cause of rfi)
What agedhorse said.
Because you left the amp connected to the DI as well as your bass, you proved nothing. Bass/amp/DI/XLR cable plus two 1/4" patch cords, is a much more complex source of potential RFI interactions, than bass/DI/one XLR and one 1/4" cable.
And that's not even taking the snake and other FOH gear into account.
RF interference is harder to track down than regular 120Hz AC noise, and you have to think in terms of systems rather than individual components.
I will connect just the bass via DI. I will also shorten all cables. My sense is the issue is from the DI of the amp/cab to the snake. The cat5 snake is shielded and I don't have problems with other instruments/guitars/mics. Looked and upgrading pickups and preamp as well. Thought I may just get better sound noise... LOL. I believe the stock EMG's with this piece are dual coil.
Also thought about a better faraday shield, but my understanding is that doesn't help unless your instrument is plugged in (not wireless). Please correct me if I am wrong...
Also thought about a better faraday shield, but my understanding is that doesn't help unless your instrument is plugged in (not wireless). Please correct me if I am wrong...
- Feb 12, 2006
- 61,041
- 5
- 220,978
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
CAT 5 snake? Exactly what is it (brand, model and specific communication protocol?). Shielded gas nothing to do with RF noise in the audio, it's purely to minimize disruption to the high frequency bit stream by outside sources as well as to minimize radiation of the digital signal itself. Note that not all digital snakes use the RJ shell as the shield connection, some are intentionally ungrounded at one or both ends. I hope you are not trying to use CAT 5 as an analog snake...
Regarding FOH power, I wasn't concerned with whatever pseudo-conditioning placebo you might be using. Has the actual ground-earth bonding system been tested to be sure it's in place and correct? Without this being correct, nothing else matters.
You have some significant troubleshooting to do, everything is in the details.
Regarding FOH power, I wasn't concerned with whatever pseudo-conditioning placebo you might be using. Has the actual ground-earth bonding system been tested to be sure it's in place and correct? Without this being correct, nothing else matters.
You have some significant troubleshooting to do, everything is in the details.
