Please help with emg pickup noise

[ericar]

Hi
Please tell me what is wrong with this. EMGs have 3 wires to hook up. There is the shielding, white and red. I have no tone or volume controls.
I have the shield wire to both the negative on the 9 volt and the ground of the audio output, the red to the positive of the 9 volt and the white to the positive of the audio output. What am I doing wrong? Every wiring diagram includes either volume or tone controls. I keep getting a lot of hum.

 

[ericar]

i should add, the white wires go to a 5 way switch but there are no tone or volume controls. just an output.

 

[line6man]

Is this a high or low frequency noise?

Just a thought, but if you are skipping the pots, the output of the pickup is running into a very high impedance load, which means that the resonant frequency is higher.
Try placing a resistive load parallel to the pickup(s) to kill off some treble. You may be hearing a lot of high frequency noise content.

 

[Super Turbo Deluxe Custom]

The black wire (- from the battery) should go to the 3rd stereo prong on the jack.  The shield goes to the grounded components or ground on the jack.  When a mono cable is plugged into a stereo jack, which is what the EMG system has, it makes electrical continuity between the ground and - poles of the battery.  It in effect grounds the battery and closes the circuit; turns it on.  If you're attaching the - lug of the battery to the shield, it's doing the same thing, but it is always on.  But, I don't know why that would make it hum.  Also, you didn't mention whether or not you're doing it, but a normal ground wire to bridge isn't necessary and any secondary shielding of the cavities is advised against, per EMG. 

 

[line6man]

The black wire (- from the battery) should go to the 3rd stereo prong on the jack.  The shield goes to the grounded components or ground on the jack.  When a mono cable is plugged into a stereo jack, which is what the EMG system has, it makes electrical continuity between the ground and - poles of the battery.  It in effect grounds the battery and closes the circuit; turns it on.  If you're attaching the - lug of the battery to the shield, it's doing the same thing, but it is always on.  But, I don't know why that would make it hum.  Also, you didn't mention whether or not you're doing it, but a normal ground wire to bridge isn't necessary and any secondary shielding of the cavities is advised against, per EMG.   

And yes, the negative terminal of the battery should never be grounded!
It goes to the ring terminal of the jack, so that the preamp will only draw current when the bass is plugged in.
The internal buffers use opamps that draw something like 85uA, which is VERY little current, but nonetheless, your battery will drain much faster if the buffer is always drawing current.

 

[ericar]

Hi Again
Thanks for the answers but let me go through the wiring again. The set is the SA 3 single coil set. I have the 3 shields soldered together. The 3 white wires go to the 5 way switch and then the output of that switch goes to the tip of a 1/4" plug (used to test, will eventually be soldered to a jack). The 3 shields are also soldered to 1 wire that goes to the ground of the 1/4" plug and 1 wire that goes to the negative of the 9volt. The 3 red wires are soldered to the wire that goes to the positive of the 9 volt. There are no other connections. The hum is a very loud hum that I would call low frequency. Much like cheap single coils around flourescent lights. I will eventually put a switch in the red wire coming from the 9 volt so I can manually shut the power off. There is no shielding involved but I understood EMGs didn't need shielding.

Thanks for looking at this.
Eric

 

[ericar]

You guys are going to kick me off the forum for this. More of the story. I have put this guitar together to use with my Roland VG99 only. My emgs will be plugged into a gk3 pickup and sent to the vg99 and then into my computer and then to studio monitors. I have tried plugging the emgs into 2 different gk3 pickups and get crazy hum. when i plug any other guitar pickups (emg and dimarzio and ibanez) into the gk3, no hum. I just tried my noisey emgs into my sons line 6 amp and got no hum. It looks like I am doing something wrong by gettint rid of the volume and tone controls and this is doing something to the output going into my gk3.???? I know this is complicated but any help would be appreciated.

 

[richship]

To simulate an EMG volume control full up, try attaching a 25K (or thereabouts) resistor from the signal output to ground.

I assume you are using an external GK where you plug the 1/4" guitar output to an 1/8" jack on the GK that send the signal down one of the pins on GK output. I've done that with EMGs with no problem (and it sounds like you have too).

 

[line6man]

Hi Again
Thanks for the answers but let me go through the wiring again. The set is the SA 3 single coil set. I have the 3 shields soldered together. The 3 white wires go to the 5 way switch and then the output of that switch goes to the tip of a 1/4" plug (used to test, will eventually be soldered to a jack). The 3 shields are also soldered to 1 wire that goes to the ground of the 1/4" plug and 1 wire that goes to the negative of the 9volt. The 3 red wires are soldered to the wire that goes to the positive of the 9 volt. There are no other connections. The hum is a very loud hum that I would call low frequency. Much like cheap single coils around flourescent lights. I will eventually put a switch in the red wire coming from the 9 volt so I can manually shut the power off. There is no shielding involved but I understood EMGs didn't need shielding.

Thanks for looking at this.
Eric

Does the hum go away when you use two pickups together? You said these are single coils, and that's pretty much what single coils do.

 

[Super Turbo Deluxe Custom]

To Line6man, EMGs, even the single coils don't hum.  Does the J-Bass EMG pickup you have hum?  It's a single coil.  And to Eric, there is no need to add a switch for the (+) pole of the battery.  Attaching the (-) pole to the stereo prong of the jack disconnects the battery when the cable is unplugged.

 

[richship]

I assume he's not using the stereo jack switch because it will always be plugged into the GK box. I put a DPDT switch on mine that connected the ground and also lit an LED to remind that it was on.

 

[ericar]

I would like to give the resistor thing a try. Do I just solder it between the 2 output wires? Does it matter which end of the resistor gets soldered to either wire?

Thanks

 

[line6man]

I would like to give the resistor thing a try. Do I just solder it between the 2 output wires? Does it matter which end of the resistor gets soldered to either wire?

Thanks

No, you solder it between the signal and ground. It might be easiest to solder it across the output jack.

A resistor has no polarity, btw.

 

[Super Turbo Deluxe Custom]

I wanna say that "Kreig" had an EMG equipped instrument with no pots and no switches hardwired to the jack and it worked fine.

 

[line6man]

I wanna say that "Kreig" had an EMG equipped instrument with no pots and no switches hardwired to the jack and it worked fine.

There is no reason for it not to work, and in fact, in theory, any guitar with active pickups should have less of a problem with noise than a fully passive guitar, because the output impedance is relatively low straight out of the pickup.

 

[richship]

There's always the obvious power issue. Did you measure the voltage accross the battery when it is on? Or at least made sure the battery was good with a tester or swtiched to a new one? They will still work when not powered, just not very well.