Thanks for all the suggestions! Lots of comments below...
Agree with all
@micguy comments. Just wanted to point out that the lack of RF rejection in a preamp circuit is unlikely to act the same in 3 different brands of pre. From the prior description of the issue, sounds like you have the exact same issue with all three basses, which I find odd if it's preamp-based. (But anything's possible, I guess.) I would expect different manifestations of the issue in different preamps. I suspect you'll find some other component has the issue and something about the setup makes it not repro in passive.
They're not acting *exactly* the same, meaning the eq / volume on each of the preamps may or may not affect the tone of the radio signal.
I used to own that exact same Behringer interface. I guess one could argue they're good value (as they're practically giving them away for free!) but they also another product in a long line of JUNK from Behringer.
I'm not saying the interface is necessarily the problem here, but that's where I would start troubleshooting. Whenever there's a problem and anything Behringer is involved, I suspect Behringer until proven otherwise. Is there any chance you could try a different interface?
One thing I know for certain with these Behringer interfaces (from personal experience) is that they can be very noisy unless they are grounded through other gear. It doesn't help that your wall outlets are properly grounded if you plug your bass straight into the bus-powered Behringer interface and then into an ungrounded laptop. If this scenario (where nothing is actually grounded) may apply to your situation, try grounding your signal chain somewhere.
Yeah. I agree that Behringer is not a high quality piece of gear and I generally avoid the brand. That being said, I've been generally happy with this interface. As it turns out the problem is there even when not using the interface. I.E. when I plug straight into my head (Mesa D880+) I get the radio loud and clear through the headphone out, through the speaker cabinet, and through the direct out (to the interface) with ground both engaged and lifted. So, it's pretty clear that it's not just the interface.
Do you have cable TV or Dish? If you do one or the other. Disable it for a few minutes and see if the problem goes away.
No cable TV or Dish, but cable internet. I suppose I could try unplugging the modem / router, but I'd be surprised if that were the issue.
Check out the Furman SS surge protector on
Sweetwater or Amazon. I’ve used it for gigging and protection of my gear — but many comments claim to be the reason why electrical noise is now eliminated.
I have one, but I'm getting the problem through the interface when it's powered by the computer USB and the computer running on battery power.
It would be interesting to know the source of the radio interference. I would suspect, as you are a San Franciscan, that this would be AM radio - specifically 810 KGO broadcasting at 50kW. That's a LOT of power, and Clear Channel AM travels along the ground for several miles. (Old timers working near those transmitters used to talk about picking up radio in their tooth fillings).
When you next hear it, run out and see if you can find the same broadcast on your car radio, or listen for station identification at the top of the hour. Check this out: geo:37.526389,-122.100556
Clear-channel station - Wikipedia
I should update my profile. We moved out of state and are no longer in SF. It's coming from an FM station. Not sure where exactly they're located, but it can't be too far since it's in the same small town on the Olympic Peninsula that we're in.
You state: Pickup cavities are shielded and grounded correctly.
1. Can you describe in greater detail how the cavities are shielded? If there is no shielding on the back of the pickguard around the pickups, then RF interference (RFI) might get in this way. The fact that the RFI goes away when in passive mode makes this less likely.
2. Does this shielding include the partition with the pre-amp? If not, then this needs to be shielded.
3. Are you using 1/4" phone plug cables? Some cables are better than others at shielding RFI. Again, the fact that the RFI goes away when in passive mode makes this less likely.
4. Is the RFI present when the bass is connected straight into an amp, rather than the Behringer interface? If yes, then S.F.Sorrow's reply explains the situation.
These are considerations for completeness sake and may be irrelevant to your situation.
To answer your questions:
- Cavities are fully shielded with copper tape, that runs up along the lip of the control cavity. The back of the pickguards are completely shielded as well with copper tape. I tend towards perfectionism and made sure to check that there was continuity at all necessary places.
- Not exactly sure what you mean by "partition with the preamp". For each bass, I've got the control cavity with the preamp and then of course the routes for the pick ups. All of these are shielded. Although I'm not sure if the control and pickup cavities are connected via ground. Not sure if that matters.
- Yes. 1/4" phone plug cables. I've tried all the ones I have. Older, newer, higher end brands, shorter, longer, instrument, speaker. No change.
- Yes. I get when it's coming through my amp without the interface involved.
I would have the grounding in your house checked by an electrician. A simple plug in tester can easily be fooled.
Is anything in your signal chain actually grounded?
If the grounding in your house is truly proper, find a way to ground your bass more directly. For example, something first in your chain that really is grounded.
Good question. I guess I don't know. Not sure how to know or how to check or how to be sure that it is.
Does it happen with an Amplug that is only connected to the bass? Does it happens with other active basses?
Go scientific method on it.
Haven't tried an amplug (or similar yet). I don't currently one own. Although I do still get the radio station when I plug into an iRig2 into my iPad (running only on battery and not plugged in). However, it is considerably quieter.
Happens with all 3 of my active basses.
We have had some experience in this area. If the radio station is really close to you, it may be dang near impossible to deal with, especially AM. But, as said, the stations will often help to deal with this - it is part of the FCC regs. One of my engineers did this for 2 am stations here in LA and has some amazing stories about how the RFI shows up. When using wireless, a nearby station can even swamp the receiver detector and reduce the range to near nothing even if you don't hear the interference!
Is the battery compartment shielded? It could be riding in on the DC line. Shield it and twist the battery cable a few times to get some common mode rejection. Ideally it should be a shielded cable.
Can you insert a plug (to turn on power) and then short the contacts? This will show if it is riding on on the input cable. Or plug in a short input cable and short the end.
Does it happen only at home? Maybe it's not worth dealing with?
A real bugaboo - hope you solve it.
Battery is in the same compartment as the preamps. I'll check to see if the battery cables are twisted.
Not sure what you mean by this "Can you insert a plug (to turn on power) and then short the contacts?"
Seems to only happen at home. Being new to the area, I haven't had the opportunity to play in many other places. But at the 2 other houses / studios I've played in, no problems.
I live within LOS of radio and TV transmission towers, as well as a multitude of other RF interference sources. I have had all sorts of issues with all sorts of different basses and gear, and I manage to (almost) always eliminate the issue, or at least get it to a point where it's not noticeable and/or doesn't matter. A few things:
1) Most likely the reason why you can hear the radio station through your active preamps and not passive is because of the gain stages in the active preamps amplifying the signal. If you are close enough to the transmission source, you'll pick it up, has nothing to do with the quality of the preamp. Any gain source will amplify the signal.
2) have you checked all - and I mean ALL - of your cables? Cables can act like antennas. I'd check them one by one - however -
3) As others had suggested, it's most likely coming in through the power supply - this can be exacerbated by a bad solder joint or wire in whichever equipment you are using (most likely the Behringer has something bas or exposed) . Grounding doesn't matter in this case. IIWY, I'd isolate the power supply being used. Ferrite beads may work, but I found that this worked like a charm:
https://www.amazon.com/gp/product/B0871R7BJQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I had two pedals that were very bad in picking up radio stations, even with isolated power. This fixed them right up, took away all signs of the broadcast and interference.
4) Finally, if you're getting other hum, try the EHX Humdebugger. Works wonder for single coil hum and other interference.
Hope this helps. Like I said, I have been dealing with similar issues for years and I've always been able to find an acceptable solution.
- Makes sense about the much higher gain of the active preamps. If it were coming through in passive mode would I be able to hear it if I turn up the input gain on the amp or interface?
- Yep. Checked them all. :-(
- It shouldn't be the power supply of the amp or interface, since I'm getting it through my iRig2 and iPad as well. I'll try that Joyo noise blocker.
All of these suggestions are helpful. Unfortunately, most of these are things I've already looked into.
What I keep coming back to is checking in with the radio station and also the possibility that I've got a ground loop in the cavities and that I may need to look more carefully at that. I understand the concept of ground loops vs. star grounding, but in practice is another story.
Two of the basses are ones that I wired myself. The East is in a Warmoth bass that I put together. The Bartolini is in a bass that I built. The Aguilar is in a Marusczyk bass. So, the probability of incorrect ground wiring certainly exists, even though I tried my best to ground properly.
