Issue with guitar hum

[Jorock]

Ok, I have stripped everything down to just my guitar going into my amp (Engl Invader 100) Nothing is plugged into the back of the amp (FX loop, midi in/thru) and into a Mesa 2x12 cab.

My issue: I am getting a buzz on the high gain channel (with noise gate off). The buzz doesnt change if I am touching my guitar strings - but it goes away when I unplug the guitar or roll the volume knob down to the off. So my guitar (EB JP7) is picking somethng up. I have plugged the amp into different outlets, I have tried the ground lift switch which cuts some of the buzz out but not much.

This wouldn't be faulty grounding in the guitar would it? my understanding is that if a guitar is poorly grounded the hum does not disappear when the volume is down or even if you touch the strings. My goal is to get the amp as close to dead silent without the use of a noise gate.

Any help is greatly appreciated!

 

[Jorock]

Can you plug into a different guitar?

Those are some great tips man, thanks! - Yeah I plugged in a different guitar and the hum returned but wasnt as prominent. It was an axe with pickups not as hot as the JP7. My thinking is that it is picking up on an electrical field in the room. Its in the same room as my DAW, speakers, monitor etc. but I shut all that stuff off and even unplugged it all from the wall to troubleshoot and nothing changed.

I have heard things about plugging the amp into the same outlet as the recording rig (provided the load doesnt exceed outlet rating) - as they'll both be fed the same power level?

My entire Daw runs off a furman conditioner, and my amp runs off a separate furman conditioner btw.

The tubes are brand new (SED =C=) and 4 new preamp tubes, all biased when installed etc.

Edit: I should also add the hum is only present on the highest gain setting, it goes away on the 1st and 2nd channels - leading me to think its not the tubes.

 

[Anonymous]

if theres a light in your house thats on a dimmer or knob that dims the light...turn it off....these can be the source of NASTY hum.

also, try to isolate the guitar gear to its own dedicated outlet, or the outlet closest to the fuse panel that has nothing else on it. house wiring can wreak havoc on signal to noise ratio.

ALSO...our outdoor lights are all the new kind of "green" spiral bulbs...and when those lights switch on, i get bad hum too...i always turn them off when im jamming.

how close are you sitting to your amp? does it change as you face away, or get nearer/further from your amp? if so, move back.

some hum/fizz/hiss is going to be inherent though...an interesting note just from my personal experience...my egnater tourmaster amp is SUPER noisy on the overdrive channels when im playing at gig/rehearsal volume. i dont want a noise supressor right now, so i just switch to the clean channel (with volume down all the way) to mute the amp when im not playing.

 

[King Crimson]

Ok, I have stripped everything down to just my guitar going into my amp (Engl Invader 100) Nothing is plugged into the back of the amp (FX loop, midi in/thru) and into a Mesa 2x12 cab.

My issue: I am getting a buzz on the high gain channel (with noise gate off). The buzz doesnt change if I am touching my guitar strings - but it goes away when I unplug the guitar or roll the volume knob down to the off. So my guitar (EB JP7) is picking somethng up. I have plugged the amp into different outlets, I have tried the ground lift switch which cuts some of the buzz out but not much.

This wouldn't be faulty grounding in the guitar would it? my understanding is that if a guitar is poorly grounded the hum does not disappear when the volume is down or even if you touch the strings. My goal is to get the amp as close to dead silent without the use of a noise gate.

Any help is greatly appreciated!

Can you plug your guitar into another good known working amp to see if the issue follows your guitar – this is the only easy way to rule out the guitar at this time?

Other than that as "Sickwindsor" suggested you should have a ground circuit tester to verify that the outlet is properly grounded. Just because there is a 3rd prong to accept a ground connection by no means is a guarantee that it is in fact properly earth grounded.

And for the record, no electric guitarist (working or not) should be plugging their precious gear into any electrical outlet without a ground circuit tester - one should be in your guitar case at all times. There’s no way I’m plugging in a very expensive guitar power amp into any electrical outlet if it doesn’t pass the tester.

 

[SpicyPickles]

Potting issue?

 

[Jorock]

Can you plug your guitar into another good known working amp to see if the issue follows your guitar – this is the only easy way to rule out the guitar at this time?

Other than that as "Sickwindsor" suggested you should have a ground circuit tester to verify that the outlet is properly grounded. Just because there is a 3rd prong to accept a ground connection by no means is a guarantee that it is in fact properly earth grounded.

And for the record, no electric guitarist (working or not) should be plugging their precious gear into any electrical outlet without a ground circuit tester - one should be in your guitar case at all times. There’s no way I’m plugging in a very expensive guitar power amp into any electrical outlet if it doesn’t pass the tester.

Yeah Im gonna go out and buy one of those ground circuit testers today and report back with my findings. I dont have another tube amp but I do have an axe-fx and i notice when listening to my demo tracks that there is a bit of hum in there as well (sounds pretty similar to the amp hum just not quite as loud).

Only challenge here is the they were both plugged into the same outlet at the various times that I recorded. Im off to home depot (glad its saturday)!

 

[MountAnDewMe]

I had a similar issue a while back. Turns out my phase inverter tube became unbalanced. I ordered a new one with balanced triodes and it went right back to normal.

 

[King Crimson]

I dont have another tube amp but I do have an axe-fx and i notice when listening to my demo tracks that there is a bit of hum in there as well (sounds pretty similar to the amp hum just not quite as loud).

Oh man, did you say "axe-fx"?

 

[Jorock]

Ok so heres an update:

I tested out all the wall sockets using a ground circuit tester and everything turns out to be "correct" on the indicator lights.

Secondly, I did some further testing and have turned my rig on, all set to my normal high-gain tone with my guitar plugged in and turned up full guitar volume. (amp is about 1/5 of the full volume knob rotation) - so i did this to get the buzz going, and its the level im trying to record at - its a reasonably low recording volume.

So when I pull the guitar plug out of the input of the amp (I know, not good for circuitry) but its a rare occasion for testing - so when i pull the guitar out of amp input, the hum is gone. So I am quite positive its not coming from the amp and is not tube related. I think the issue is the guitar is picking up stuff out of the air. I unplugged our wifi, turn all lights off throughout home, unplugged anything that might have added noise to the system.

My entire DAW (preamps, computer, speakers, etc) all run off a furman that I left unplugged. When I plug the DAW rig in to the wall - but with the entire DAW rig off - just plugging it in, I get even worse hum (it goes from a guitar noise issue, to a full on ground loop type hum). So using an extension cord, I tried plugging my guitar rig into different outlets on our upper floor of the house. I would then fire the guitar rig up and starting with DAW rig unplugged and then plugging it in it would create the stronger hum. No matter where I had the guitar rig plugged in on the upper floor, as soon as I plug the DAW rig in to the wall with everything turned off, the hum gets worse.

I am wondering if this is a ground loop being created at the breaker panel. We have an old breaker panel, but all the wiring in our home is only 2 years old and was done by a certified electrician. Its an older home and needed re-wiring to meet insurance requirements. I know the breaker panel is vintage but it is a 100Amp box.

Any thoughts from those knowledgeable with this sort of thing?

 

[JamesPeters]

Any thoughts from those knowledgeable with this sort of thing?

I think you should read through at least the first link posted here:

http://www.jensen-transformers.com/an/generic%20seminar.pdf

http://blueguitar.org/new/articles/othe ... d_loop.pdf

http://www.ebtechaudio.com/findloop.pdf

http://www.bapihvac.com/content/uploads ... -Loops.pdf

That Jensen article alone is a gold mine of information on the subject.

 

[Jorock]

Yeah sorry I meant to say, I have read through some of the content. Will continue to read through over the weekend. Still I see a lot of 'ground' related issues, and I dont think that is my problem, I think it is more RF noise and magnetic field stuff that my guitar's excessively hot pickups are grabbing.

The noise/hum does not change when my hands are on/off the strings. It does change when I position the guitar in different places in the room. There are better positions to sit that help reduce it, but thats about it. Between that and noise gates I think that is the best I can do with hi-gain and hot pickups.

 

[Anonymous]

check your solder joints in your guitar.
check your PI tube with a known good tube.


i also get a bit of a tingle when i touch the mic at rehearsal, but only if my lips hit it, and im touching my guitar. my guitars grounding is all fine.

im also reading through all that info!

 

[King Crimson]

The noise/hum does not change when my hands are on/off the strings. It does change when I position the guitar in different places in the room. There are better positions to sit that help reduce it, but thats about it. Between that and noise gates I think that is the best I can do with hi-gain and hot pickups.

At this time I don’t think you have any ground issues or 60 cycle hum either.

You probably already thought of this but I’ll throw this out there. You mentioned your DAW on or off you still get the hum. What monitor do you have for your DAW? If it’s a old style CRT then no matter what within 15’ or less you’re going to get hum. If it’s a newer style LCD then it’s of no consequence.

One other thing, your Engl Invader E 642 has some fairly strong power transformers in it. If your guitar is with volume up within a few feet of the amp while it’s powered up and running you will get variable hum depending on the position of your pups to the power transformers – this is inherent in all tube amps.

 

[stephen sawall]

Marked for later .... great links...

 

[Anonymous]

how close are you sitting to your amp? does it change as you face away, or get nearer/further from your amp? if so, move back.

 

[base341]

I had a similar issue with an ESP Horizon i purchased a while ago.
I finally figured out the guitar had come originally with active pickups in it so it wasn't grounded to the bridge like a non trem guitar with passive pickups would be. I drilled a hole from the bridge pickup cavity to the bridge anchor screw and ran a ground wire to it.. Problem solved..
I'm thinking this could be your problem if touching the strings makes no difference.

The other thing I found was already suggested here as well.. Dimmer lights in the house make my amp go crazy. hahaha

 

[King Crimson]

. . . Dimmer lights in the house make my amp go crazy. hahaha

I had this issue many years ago too. Turned out the amp was manufactured by a company named "Voyeur" and didn't like to be in bright lighting - go figure.

 

[Jorock]

The best thing is for me to hear the recordings so I can better judge the sound you are describing. It sounds like you are very intelligent, diligent and driven so I will help as much as I can.

Thanks sickwindsor, I really appreciate that! I have added some clips in at the bottom of this post to highlight the sound in three scenarios. One is volume knob being changed on guitar, second is noise gate on amp switching in and out, and last is guitar moving around the room.

check your solder joints in your guitar.
check your PI tube with a known good tube.

Solder joints appear to be proper. I will add some pics in to my next post of the cavity of the guitar.

You probably already thought of this but I’ll throw this out there. You mentioned your DAW on or off you still get the hum. What monitor do you have for your DAW? If it’s a old style CRT then no matter what within 15’ or less you’re going to get hum. If it’s a newer style LCD then it’s of no consequence.

One other thing, your Engl Invader E 642 has some fairly strong power transformers in it. If your guitar is with volume up within a few feet of the amp while it’s powered up and running you will get variable hum depending on the position of your pups to the power transformers – this is inherent in all tube amps.

Yeah Im using an LCD monitor and have tested with it on and off, makes no difference. Yeah the Invader has massive transformers in it lol, I figure they could definately be susceptible... I am sitting close to the amp as you suspected. But two nights ago as part of this rigorous troubleshooting I moved my amp into a different room down the hallway and kept my guitar in the "control room" and nothing changed. I even tried the opposite, put my guitar on a stand down the hallway, kept the volume knob up and had the amp in the control room; again no change

how close are you sitting to your amp? does it change as you face away, or get nearer/further from your amp? if so, move back.

I'm sitting about 3 feet from the amp head with my back to it and the guitar in my lap, but as I mentioned above, I have tried other things and they dont make much difference.

http://snd.sc/OVeM5F <- hum from guitar as I roll volume up and down
http://snd.sc/OVeP1g <- hum recorded as i switch noise gate of amp in and out
http://snd.sc/OVeQCc <- hum recorded as guitar is moved around different positions, and at the end of the clip i put it right up to the face of the amp.

 

[Jorock]

I have added some pics of the guitar below and done some further digging. As it turns out I have come across several posts in various forums of guys who have the Dimarzio D Sonic in their guitars. It is apparently an extremely hot pickup and some have reported that after contacting dimarzio with similar issues - it was revealed that it is not a "true" humbucker design. As a result it is more prone to noise. Ernieball must know this judging by the pics of the guitar cavity below:

You can see the cover plate I removed from the tone pots cavity has a metal backing on it, and there is a ground wire that touches this cover when it is fastened. Also EB has put a brass plate down in the bottom too. I think I may just have to do my best with noise gates and eq tricks in post-production. :-s

 

[Jorock]

The silver foil backing on the back cavity guitar is to block out RF frequency's. The ground is normally run to the bridge of the guitar.

All the instructional posts I've read about using copper tape to shield the cavities of the guitar talk about making sure they are all connected together and that a ground wire is soldered to the shielding as well, which I think is why this guitar has that little arm sticking up under the plate when its in place.

I'll have to take a closer look but I believe that it is still grounded to the bridge somewhere internally.