I tested both of his basses last night with the Amplug, because I honestly didn't remember the results. The Tobias Toby Deluxe IV had less hum than my EMGs, but some was still there. The Ibanez SRF700 had no hum.
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Summoning Elite Troubleshooters
- Thread starter Crosscheck67
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- 60 cycle hum emg emi ground hum
I tested both of his basses last night with the Amplug, because I honestly didn't remember the results. The Tobias Toby Deluxe IV had less hum than my EMGs, but some was still there. The Ibanez SRF700 had no hum.
@James Collins I saw that video before. Some of his suggestions only work for rock and metal, which I only play sometimes. They don't work with music involving quieter, clean, sustained notes. I always use smooth Jazz when I'm testing home theaters I install for this reason, because it offers a vast tonal spectrum while still allowing you to hear everything. The one suggestion he has that I'm about to try, in line with everyone here on the edge of their seats, is shielding. Given everything I've learned during this process, I'm shocked that a guy with his experience didn't focus on the critical importance of properly grounding the shielding.
Ok a couple things here. @bdplaid your photo. Had I been drinking something, my phone would be covered right now.
Regarding the grounding of everything outside my bass, be it my Dutch oven, my amp, or my outlets, help me understand:
1) I thought priority one is handling the ground inside the instrument, whether it be shielding and grounding that, or using electronics which don't need it. This seems like the hardest and most expensive part and the biggest payoff, allowing us to play anywhere. Otherwise, we'd be storming off stage like Nigel at the Air Force base and wireless companies would be out of business.
2) Given that, why then ground the cast iron pot, or the amp, or the outlet, as they are all much bigger than a pickup/control cavities? If control cavity shielding has enough mass for the ground to drain, shouldn't a thick 7 qt pot have far more?
3) I rode a lot of mixing boards for live sound in the 90s. We usually only had to turn off dimmers and all would be right in the universe, but as a last resort the ground could be lifted to kill the hum, as long as you did it in the right spot in the chain so you didn't kill the vocalist as well.
4) The takeaway I'm getting here is ground, ground, ground, but I have never seen "proper" grounding outside the bass reduce hum, but rather cause it.
Which dots am I not connecting?
1) The shielding typically shunts the noise to ground, be it the shielding in the EMG pickup, or the cavity shielding, or the bridge/strings being grounded and then when you touch the strings you’re becoming the shielding. EMGs are internally shielded to prevent the need for say, cavity shielding, bridge grounding, etc - but that shielding still typically has to have a connection to ground which would typically be through an amp.
2)This needs the connection to ground still
3)Ground loops are different - see "What Is A Ground Loop, and How Do You Get Rid Of It?"
2)This needs the connection to ground still
3)Ground loops are different - see "What Is A Ground Loop, and How Do You Get Rid Of It?"
I didn't want to influence anyone's opinion, so I'll chime in with what I heard after others share (if anyone even does
).
@bdplaid and @tylerwylie
Excellent articles. They definitely broadened my understanding of what's going on.
@bdplaid in our context, my USB interface supports both 1/4" and XLR, and I know they make those 1/4" to XLR adapters for the other end, but would that serve our purpose? I don't know if the 1/4" end is TS or TRS, or if it could end up being the signal equivalent of those little grey "widowmakers" 3 to 2 prong AC adapters for ungrounded outlets, thus defeating our purpose.
Excellent articles. They definitely broadened my understanding of what's going on.
@bdplaid in our context, my USB interface supports both 1/4" and XLR, and I know they make those 1/4" to XLR adapters for the other end, but would that serve our purpose? I don't know if the 1/4" end is TS or TRS, or if it could end up being the signal equivalent of those little grey "widowmakers" 3 to 2 prong AC adapters for ungrounded outlets, thus defeating our purpose.
Is the USB interface connected to ground in some way? This needs to be reiterated - where is the ground connection coming from? If you’re running an interface off USB and it’s connected to your laptop and the laptop is using a 2 prong ungrounded connector (just hot+neutral) there’s still going to be no ground connection.
Grab an amp or something that’s grounded, make sure that ground is connected for the plug, plug in the bass and see if the noise goes away or is lessened. Running through an interface running off a laptop, it’s going to be hard to figure out without some tools or meters if the ground is connected, and if the laptop is running off a 2 prong power plug, ground won’t be connected - if it’s running off a 3 prong plug you’ll have to figure out then if that connection’s made to the USB interface, if that is the case, you then have to test to see if that grounding is extended to instruments plugged directly into the interface.
The next test needs to be as simple as, “if I connect my shielding to ground, what happens to the noise”
I had headphones on. I noticed a very slight change as the pickups were transiting into or out of the pot. Very noticeable change when lid was in-place or fully removed.I didn't want to influence anyone's opinion, so I'll chime in with what I heard after others share (if anyone even does
And thank you for the recipe at the end of the video. I'm afraid flatwounds are all I have onhand. Hopefully it just smooths the flavor.
Ok I tested the three outlets in my music room, both receptacles. Of course the one I use isn't grounded. The only one that is grounded has the appropriate amount of voltage, but shares a circuit with stuff in another room, because this 100-year-old house was updated by a frikken monkey.
So. I turned off and unplugged everything. I then plugged my amp into the grounded outlet, plugged my bass straight into it, and lots of hum filled the room, with the expected quiet spots turning in a circle.
I guess now it's on to shielding and grounding. Sigh. This will suck, because I only have copper shielding, and not the additional aluminum that was suggested.
Shielding question: is it worth shielding the jack cavity? I worry about room, as I would also have to insulate the jack with electrical tape...this is my first go at proper shielding and grounding. I have copper tubing cut for the wire channels, I will be grounding each cavity as well as the jack itself.
Did you make sure that your MRI machine was completely powered down and off grid before you conducted any kind of testing?
" I had an MRI to see if I was claustrophobic"
- Steven Wright
That made me bust out laughing!
On my bass, I shielded all the way from the upper edges of the pickup cavities to the outer edge of the jack cavity. I think I insulated the inside of the jack cavity with electrical tape after I finished, though I don't remember tbh. Either way, though, I've never had a problem. Not with noise, and not with anything shorting out on shielding.
By the way, stick with copper. I'm pretty sure copper is a better conductor, it's certainly easier to solder, and aluminum doesn't gain you much if anything.
Another by the way, I know it sucks to be going through this, but at the end of it all (and I do believe you will beat this), you're going to be equipped to answer questions regarding hum in a way few people will ever be. There will be some poor sot in the future who's having hum issues in his apartment near a transformer, and you're going to be able to help that person.
This is frikken exhausting. I really tried, but the hum remains using the USB interface and the Amplug. No discernible difference.
I shielded both pickup cavities, control cavity, and battery cavity, but not the jack. I was worried about space. I ran copper tubing through each wire channel and soldered both ends in place to the shielding, then ran a ground wire through each and soldered both ends as well. Did the same for a ground wire from the control cavity to the bridge, soldering and mashing under the back lip.
Oh, I also shored up the insulation under each pot with electrical tape.
From here, the only thing I could try is shielding the jack cavity, but I just don't believe it will make a bit of difference. Patience is wearing thin, and the only things that look promising are pickups from 96 art or Nordstrand, and a Hum Debugger. FML.
I shielded both pickup cavities, control cavity, and battery cavity, but not the jack. I was worried about space. I ran copper tubing through each wire channel and soldered both ends in place to the shielding, then ran a ground wire through each and soldered both ends as well. Did the same for a ground wire from the control cavity to the bridge, soldering and mashing under the back lip.
Oh, I also shored up the insulation under each pot with electrical tape.
From here, the only thing I could try is shielding the jack cavity, but I just don't believe it will make a bit of difference. Patience is wearing thin, and the only things that look promising are pickups from 96 art or Nordstrand, and a Hum Debugger. FML.
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Based on your tests using the pickup only, IMO it's the pickups. And the 96 Art pu's were the only ones to even remotely reject the RFI. If it were me, I'd have a conversation with them, and try a set of their pickups.
And a tip of the hat to you, because I'd have abandoned the bass and sold it long ago.
And a tip of the hat to you, because I'd have abandoned the bass and sold it long ago.
The shielding job looks excellent. And I like that you built some redundancy into the shielding. At this point, I wouldn't worry about shielding the jack cavity. At least you know that this part of the troubleshooting is covered.
Next up: hum canceling pickups and a hum debugger and an amp plugged into a grounded outlet. And it may take all of those to get you a quiet bass. But if that's what it takes, then that's what it takes.
Next up: hum canceling pickups and a hum debugger and an amp plugged into a grounded outlet. And it may take all of those to get you a quiet bass. But if that's what it takes, then that's what it takes.
EMGs are supposed to be hum canceling. I’d start with the latter 2 first. Especially if he digs the tone of EMGs. If not, plenty of alternatives to look at but first check the string to string spacing.
I live in a noisy environment as well and some of these amps I record through have RF rejection on the input which is really nice and they provide the connection to ground for the shielding to do its thing. Just take the DI and send it in and sounds great.
you’d just need good metal to metal contact between the lid and pot all around the rim, but cast iron isn’t necessarily the best for the job.
Actually now that I think of it it would be easier just to wrap the test setup in aluminum foil. You don’t need to ground the test setup to the foil at all, and you want to take steps so it doesn’t short on the aluminum, I’d wrap the whole test setup in paper towel or newspaper then foil around it. Will be easier to hear any noise through aluminum foil too anyway.
Basically the idea is to put your test setup including the amplug into a faraday cage so if you still hear noise you know there is something weird going on still in the test setup.
I think this was already mentioned multiple times but you’re using a fresh battery too right?
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