Directional Hum

[keurosix]

My Activator equipped Modulus Graphite is lacking a ferrite bead, and does seem to have a directional hum. When rotating the guitar, I can find a hot spot where it is rather noisy. It also is noisy when lifted horizontally with the front facing the ceiling. This is a custom circuit with 3 pickups and one filter & Q activator circuit. Would one bead work to minimize this hum?

 Here's a pic of the circuit inside:

 A close up of the pots:

 This is easily one of the best sounding guitars I ever owned (3 PU's = tone for days!), so I would like to get it cleaned up & as good as it can be. I may have to repaint the shielding too? Any recommendations? Kris

[adriaan]

Don't forget to paint the inside of the cavity cover too.

[freefuzz]

the ferrite ring won't solve your hum problem. it protects you from high frequency noise, though. the hum you are getting is coming through the pickups, and standing away from hum sources such as transformers (amps, preamps, low voltage lightbulb supplies), fluorescent bulbs, and dimmers. latter 2 often buzz more than hum.

[freefuzz]

stading close to, i meant. standing away will get rid of your hum.

[keith_h]

Add televisions to the list.  
 
Have you determined what you are facing when the hum
occurs? Where are you at (home, gig, etc)?
 
Keith

[olieoliver]

Have you tried it on different rigs.
 
I get no noise at all playing thru my SWR or my Eden amps. But every bass I own that have active electronics get noise, either hum or FM radio when I play them thru the Peavy combo they have at our church. It's an older amp and not in very good condition either.  
 
OO

[adriaan]

In the case of that Peavey, the hum probably originates from the amp.

[keurosix]

Well, I get a most noticable hum from my Europa when close to any one of my rigs: Large: SWR SM900, Medium SWR SM400, & small SWR working man 12. I use the WM12 at church, and it makes for a really nice chair, although a bit noisy. When I compare my other guitars with the same rigs, the Modulus Graphite is next in loudness, then my Epic and Dean Edge6 (EMG PU's?) are virtually dead quiet. The Modulus Graphote seems to have worn areas in the conductive paint, and a big raw wood area inside around the input jack. The back plate has foil on it, but the PU cavities are not coated with any paint or foil.
Anyone have an idea why my Europa is the most noisy of all my guitars? It does have the ferrite bead.
Kris

[David Houck]

Are the trim pots noticably higher on the Europa than on the Epic?
 
(Message edited by davehouck on March 31, 2008)

[keurosix]

Dave,
I have to bring the trim pots all the way up on the Europa to get almost as much output as the Epic. Pickups distance away from the strings is about the same on both guitars. I know that proximity has a great effect on this hum such as how close to my rig that I play, yet each guitar behaves very different what with all other settings equal. Should I foil line or paint the PU cavities on the Europa? Would this quiet her down?
Kris

[David Houck]

I don't know; but since no one else seems to be having this problem with a Europa, I would tend to hold off and try other things first.

[mica]

The pickups are internally shielded with an expanded copper Faraday cage, there's no need to add additional shielding materials in the pickup cavities. The bead will make it possible to use with wireless.  
 
I don't remember your Europa being very old, but the earlier versions of the electronics do have less output. There is a simple modification available that will increase the output.  
 
But, if your bass is more than a few years old, you should probably send the electronics in for an RF upgrade. It's not terribly expensive, and we also do the mod for the increased output.  
 
You mentioned the hum is most noticeable when you are close to your rigs. How close do you have to be to hear the hum and how far away do you have to be for it to drop off?
 
Your proximity to the rig, less than a meter if I understand correctly, is not something that we anticipated in the design. Pretty much any Alembic bass or guitar gets very unhappy when you bring it right up to an amplifier.  
 
I am a little confused, but is the Activator equipped Modulus or the Europa the most noisy? Also, is the sound your hearing really a low-frequency hum like 60Hz, or is it a higher-frequency hiss? Is it the same in both pickups? And, is it the same sound in both basses?

[keurosix]

Hi Mica,
I will need to do more experimenting with setting up my amp in another place, and how far I need to be away from the amp for the noise to go away. In my music room, I cannot get away more than 4 ~ 6 feet, and the noise is still present. The Europa is the noisiest, then the Modulus. However, when I find a quiet direction by rotating the guitar while in playing position, the Modulus gets really quiet, but not the Europa. It seems like the Europa is really fussy, and can't get really quiet. The sound I am hearing is a higher frequency, not a 60 cycle hum, and really pronounced when the filter is rotated up at the top quarter of travel. It seems to be the same sound in both pickups and also the same sound from both guitars. I have 3  amps I check the guitars with, and the sound is the same through each amp. I swapped out my instrument cable, but that only contributed minor. I am ruling out the Epic because it is really quiet. My Europa was manufactured in 2002. Would the electronics need the RF upgrade? The output is definately lower than the Epic and the Modulus. Also, would the Modulus benefit from a ferrite bead, and a more complete conductive paint touchup?
Kris