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  #1  
Old 01-23-2022, 05:53 AM
Per Burström Per Burström is offline
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Default Hum from magnetic pickup

Hi,
I have a Dean Markley magnetic soundhole pickup which I want to use while recording, to complement the external condenser microphone I use. The sound card is actually a mixer, a Behringer X-Air X18.

With my setup I sit with my guitar facing the computer (with an external screen) and the microphones, but when doing this I get an annoying hum from the magnetic pickup channel, mostly at around 180 Hz and 450-500 Hz. Rotating the guitar 90 degrees, either vertically or horisontally, will make the hum almost disappear. I have tried to turn of the screen, but that doesn't help.

I believe the Dean Markley is a single-coil, but I also have a Harley Benton SH30 pickup which I believe is a humbucker, and I do get a noise from that as well... although not as prominent.

Any ideas what I can be? Most obvious is the electrical equipment of course, but I have tried to turn many of them off. When facing the computer with the guitar I also face north, can that affect?

Distance to the computer doesn't seem to affect the hum sound, at least not in an obvious way.

Are there any other magnetic sound hole pickups that are more resistant to this kind of problem?

Thanks in advance!
Per
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  #2  
Old 01-23-2022, 08:13 AM
Rudy4 Rudy4 is offline
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Some humbuckers work better than others. I'd speculate that the amount of bucking you're getting is related to the quality of the design. I had a Fishman Rare Earth that was quiet, but it did sound like a magnetic pickup so I was never totally satisfied with the resultant sound.

Induced A.C. hum can be caused from a circuit running close by your area that is going to another part of your house, so not necessarily your computer setup.
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Old 01-23-2022, 09:07 AM
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keith.rogers keith.rogers is offline
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Scratch the single coil. They are hopeless in many situations. Then, check the lighting. Some LEDs and CFLs will interfere. And make sure you have a high quality cable.

I assume you're plugged into a Hi-Z input with it set appropriately to that mode (if needed - never used one of those mixers). You might also try using a good DI box and go in to a "mic" level input with an XLR cable for better noise control. If the DI box has a ground lift, you can try that, too.
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Old 01-23-2022, 10:28 AM
Per Burström Per Burström is offline
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Quote:
Originally Posted by keith.rogers View Post
Scratch the single coil. They are hopeless in many situations. Then, check the lighting. Some LEDs and CFLs will interfere. And make sure you have a high quality cable.

I assume you're plugged into a Hi-Z input with it set appropriately to that mode (if needed - never used one of those mixers). You might also try using a good DI box and go in to a "mic" level input with an XLR cable for better noise control. If the DI box has a ground lift, you can try that, too.
Thanks for your input! (y)

I have tried to switch off the lights, doesn't help. And moving the guitar to the side, so that it still face the same direction (north) but not directly towards the computer does not help (but as I wrote earlier, rotating the guitar 90 degrees does take it away).

The Dean Markley pickup has a long, built-in cable, and it seems pretty robust. I plug it into one the 2 Hi-Z inputs of the Behringer X18.

In the end this hum will probably not be a problem in the recording as it hopefully won't be heard when I play. Also, the main recording of the guitar will come from the external condenser microphone, the magnetic pickup signal will only be used for adding some delay and other effects.

It's annoying though, and I would like to invest in a better pickup.

I think this is the pickup, but there's no text "Single coil" on mine (but it's pretty old): https://deanmarkley.com/collections/...guitar-pickups. I actually like the sound from it.

/Per

Last edited by Per Burström; 01-23-2022 at 10:33 AM.
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  #5  
Old 01-23-2022, 10:31 AM
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mcmars mcmars is offline
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Not sure on good solution for your setup, but the magnetic PU always seem to have some issues with noise and non acoustic sounds.

I have used the fishman rare earth with the mic and sounds ggreatin living room but howled for me on stage and had to use soundhole cover. I do like the mojotone NC-1 single coil mag PU that is engineered to minimize the typical hum, it really works well and sounds very nice. I just had it installed in my Iris this week after testing it for a month with the wire coming out of soundhole.
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Old 01-23-2022, 11:56 PM
Per Burström Per Burström is offline
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I've found a few comparisons between single coil and humbucker of the same brand on YouTube, for example the Fishman Neo-D, and I realize I prefer the single-coil sound. So I'll try some better than my Dean Markley.

I'll check out the NC-1. Any thoughts on the Shadow SH141?

/Per
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Old 01-24-2022, 01:55 AM
Lost Sheep Lost Sheep is offline
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Quote:
Originally Posted by Per Burström View Post
Hi,
I have a Dean Markley magnetic soundhole pickup which I want to use while recording, to complement the external condenser microphone I use. The sound card is actually a mixer, a Behringer X-Air X18.

With my setup I sit with my guitar facing the computer (with an external screen) and the microphones, but when doing this I get an annoying hum from the magnetic pickup channel, mostly at around 180 Hz and 450-500 Hz. Rotating the guitar 90 degrees, either vertically or horisontally, will make the hum almost disappear. I have tried to turn of the screen, but that doesn't help.

I believe the Dean Markley is a single-coil, but I also have a Harley Benton SH30 pickup which I believe is a humbucker, and I do get a noise from that as well... although not as prominent.

Any ideas what I can be? Most obvious is the electrical equipment of course, but I have tried to turn many of them off. When facing the computer with the guitar I also face north, can that affect?

Distance to the computer doesn't seem to affect the hum sound, at least not in an obvious way.

Are there any other magnetic sound hole pickups that are more resistant to this kind of problem?

Thanks in advance!
Per
Just for kicks, I think I might try getting a long extension cord and moving my entire setup outside, away from all power sources and wiring inside the walls. Powering everything from a single phase (as a single extension cord would do) and a distance away from all other sources of electomagetic flux (make sure your setup is not under (or over power lines). If the problem persists, then it may indeed be your hardware. If it disappears completely, it is something in your locaion,.

A lot of work to experiment this way, but could be illuminating.
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Old 01-24-2022, 06:23 AM
Mandobart Mandobart is offline
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Have you tried not using the HI Z? The high impedance setting is for use with piezoelectric pickups that have an output impedance in the millions of ohms (megohm) range.

Magnetic pickups have one-thousandth (.001 ×) the output impedance of a piezo (kilohm).

Is your Behringer running off battery or AC? It could be a floating ground issue. I would try grounding the case of everything the signal passes through.
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Old 01-24-2022, 02:39 PM
Per Burström Per Burström is offline
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Quote:
Originally Posted by Mandobart View Post
Have you tried not using the HI Z? The high impedance setting is for use with piezoelectric pickups that have an output impedance in the millions of ohms (megohm) range.

Magnetic pickups have one-thousandth (.001 ×) the output impedance of a piezo (kilohm).

Is your Behringer running off battery or AC? It could be a floating ground issue. I would try grounding the case of everything the signal passes through.
The Behringer X18 runs on AC.

I tried to use one of the "normal" (non-HiZ) inputs, and it does indeed make it a little better, but the hum is still present. But as I wrote in my initial post the hum goes away if I rotate the guitar (and thereby the pickup) 90 degrees so the side and not the front of it face my equipment.

Anyway, the hum will not be a problem in the recording anyway as it's drowned by the signal when I actually play the guitar.

A bigger problem though is that the Dean Markley in a very obvious way change the acoustic sound from the guitar. But I guess all sound hole pickups that actually lock to the top of the guitar will do that?!?

Anyone that has experience using the Shadow Nanonmag end of fretboard pickup? That must be the solution with the least effect on the guitars acoustic sound?!?

https://www.customworldguitarparts.c...sh-nmg-pu.html

Edit: Found a thread covering the Nanomag here: https://www.acousticguitarforum.com/...d.php?t=593692

Last edited by Per Burström; 01-24-2022 at 02:45 PM.
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  #10  
Old 01-26-2022, 09:17 AM
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keith.rogers keith.rogers is offline
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Quote:
Originally Posted by Per Burström View Post
The Behringer X18 runs on AC.

I tried to use one of the "normal" (non-HiZ) inputs, and it does indeed make it a little better, but the hum is still present. But as I wrote in my initial post the hum goes away if I rotate the guitar (and thereby the pickup) 90 degrees so the side and not the front of it face my equipment.

Anyway, the hum will not be a problem in the recording anyway as it's drowned by the signal when I actually play the guitar.

A bigger problem though is that the Dean Markley in a very obvious way change the acoustic sound from the guitar. But I guess all sound hole pickups that actually lock to the top of the guitar will do that?!?

Anyone that has experience using the Shadow Nanonmag end of fretboard pickup? That must be the solution with the least effect on the guitars acoustic sound?!?

https://www.customworldguitarparts.c...sh-nmg-pu.html

Edit: Found a thread covering the Nanomag here: https://www.acousticguitarforum.com/...d.php?t=593692
There are no magnetic pickups that accurately reproduce the sound of an acoustic guitar, IMHO. Which is not to say some don't sound pretty good in some uses, maybe even better than other pickup options, e.g. USTs, for some types of playing or venues. For [home] recording they probably come in somewhere below 3rd place after mics. (That's right, there's no 2nd place after mics.)

If rotating the guitar changes the hum, you've got a source of EMI in the room (or walls!). It could be an old tube guitar amp, or just anything, but poor shielding and improper grounding can all contribute. Try different, shorter, perhaps better cabling (again, a good, short cable to a DI with a balanced run to the preamp), and watch where/how they are arranged. A decent humbucker is going to produce a lot less noise. (I replaced a single coil Fishman with the same looking humbucker version to fix a problem in a friend's guitar - he played sitting down in front of an old Acoustasonic amp.)
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  #11  
Old 01-26-2022, 09:31 AM
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First thing I would do some quick subtractive diagnostics ,if you have not already done it

Set up the exact same way without the microphone, and see if you are still getting the hum.
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Last edited by KevWind; 01-26-2022 at 12:06 PM.
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Old 01-26-2022, 10:21 AM
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Try grounding the strings. However, I can't think of any convenient way to do that (clip leads behind the saddle?).
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  #13  
Old 01-27-2022, 11:49 AM
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Some on-board systems were designed before wireless systems were in wide use, and are not properly shielded. If thats the case, not much you can do, except use a cord. Thats, if youre using wireless. Maybe Im off base.
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