Loud buzz - active bass

wubalubadubdub

wubalubadubdub

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Dec 29, 2016
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#1
It has been some time that my Cort gb74 (active only, one single coil and one hambucker) makes an annoying buzz.

In this particular instrument you can "switch off" the equalizer, and while it's off the noise (almost) completely disappears, so I thought that maybe there is some issue inside the eq circuit board (but I am most ignorant in this topic).
What do you think it could be?
 
#3
two fingers said:
So it didn't buzz at all when you first got it?
Click to expand...
Thank you for replying.
I bought it used one year ago and I think it already buzzed a bit, but I didn't care because it was not loud. Two months ago while I was playing the pickups "stopped working" for a while, but the piezos were still functioning (I have read that the piezo signal is amplified by a dedicated preamp).
Right after that strange episode it sounded fine. After some time not playing it I plugged it in and got this hum.
 
#4
wubalubadubdub said:
Thank you for replying.
I bought it used one year ago and I think it already buzzed a bit, but I didn't care because it was not loud. Two months ago while I was playing the pickups "stopped working" for a while, but the piezos were still functioning (I have read that the piezo signal is amplified by a dedicated preamp).
Right after that strange episode it sounded fine. After some time not playing it I plugged it in and got this hum.
Click to expand...

Yeah I would get it to a tech and have him check out all the solder joints. It's likely something simple. But if the magnetic pickups just "went out and came back" they will likely do it again.

Edit: That is, of course, unless you know what you're doing with a soldering iron. Then you can check the joints yourself.
 
#5
two fingers said:
Yeah I would get it to a tech and have him check out all the solder joints. It's likely something simple. But if the magnetic pickups just "went out and came back" they will likely do it again.

Edit: That is, of course, unless you know what you're doing with a soldering iron. Then you can check the joints yourself.
Click to expand...
I checked if there were any loose soldering or short circuits but I couldn't find any.
I hope that I did miss something, but let's say that every joint is solid: in that case is it much worse?
 
#6
Are the pickup active also or does it have passive pickups with active preamp ? If the pickups are passive you could have a ground issue or short to the ground. The ground usually connects to the bridge and runs to the control cavity. You may test that wire with a meter to make sure it is not broken.
 
#7
panther9209 said:
Are the pickup active also or does it have passive pickups with active preamp ? If the pickups are passive you could have a ground issue or short to the ground. The ground usually connects to the bridge and runs to the control cavity. You may test that wire with a meter to make sure it is not broken.
Click to expand...
You can also have a ground issue with an active.

Do you have a fresh battery in the thing?
 
#8
panther9209 said:
Are the pickup active also or does it have passive pickups with active preamp ? If the pickups are passive you could have a ground issue or short to the ground. The ground usually connects to the bridge and runs to the control cavity. You may test that wire with a meter to make sure it is not broken.
Click to expand...
Nope I am pretty sure that they are active pickups.
But by the way, can it still be a grounding thing if the buzz reduces when I touch the bridge (or every metal part)?
 
#9
Old Garage-Bander said:
You can also have a ground issue with an active.

Do you have a fresh battery in the thing?
Click to expand...
Yes actually I changed after that the pickups went out two months ago, then left it untouched (and unplugged) until some days ago. Can it be just the battery that provides too much voltage?
I don't know, maybe it is a nonsense, but I though at first that it could be a problem in the equalizer board (as I said in the first post everytime I turn the eq off the buzz stops)
 
#10
wubalubadubdub said:
Yes actually I changed after that the pickups went out two months ago, then left it untouched (and unplugged) until some days ago. Can it be just the battery that provides too much voltage?
I don't know, maybe it is a nonsense, but I though at first that it could be a problem in the equalizer board (as I said in the first post everytime I turn the eq off the buzz stops)
Click to expand...
Batteries by themselves should not be able to cause a buzz. They are DC.
Not like the DC you get from a bad power supply.
Bad PS hum or buzz is because they have some AC riding on the DC due to poor regulation or filtering.
The hum or buzz frequency is usually either 60hz or 120hz. (Assuming North America)
Batteries generate DC voltage chemically, so no hum or buzz from the power line to filter out.

When you say you shut off the EQ, exactly what does that entail?
 
#11
Old Garage-Bander said:
Batteries by themselves should not be able to cause a buzz. They are DC.
Not like the DC you get from a bad power supply.
Bad PS hum or buzz is because they have some AC riding on the DC due to poor regulation or filtering.
The hum or buzz frequency is usually either 60hz or 120hz. (Assuming North America)
Batteries generate DC voltage chemically, so no hum or buzz from the power line to filter out.

When you say you shut off the EQ, exactly what does that entail?
Click to expand...


The batteries can cause some kind of buzzing. A couple of weeks ago we were practicing on Thursday and I could hear some distortion in my IEM's so I figured the batteries were going (EMG soapbars set up for 18v). So Saturday night I put in new batteries and plugged in long enough to check everything worked. Sunday morning at church there was a BAD buzz coming from the bass to the point I had to hurry home and get a different bass and come back. Later that day, I put the old batteries back in and dead quiet. Monday I stopped on the way home and got some new, good batteries and tried those. Also dead quiet. I don't know what it was but the old, cheap batteries I put in, even though they read just over 9v on my meter were causing noise.
 
#12
Matt Liebenau said:
The batteries can cause some kind of buzzing. A couple of weeks ago we were practicing on Thursday and I could hear some distortion in my IEM's so I figured the batteries were going (EMG soapbars set up for 18v). So Saturday night I put in new batteries and plugged in long enough to check everything worked. Sunday morning at church there was a BAD buzz coming from the bass to the point I had to hurry home and get a different bass and come back. Later that day, I put the old batteries back in and dead quiet. Monday I stopped on the way home and got some new, good batteries and tried those. Also dead quiet. I don't know what it was but the old, cheap batteries I put in, even though they read just over 9v on my meter were causing noise.
Click to expand...

A battery does not generate hum or buzz.

Unloaded voltage measurement of a battery is not a good test of how well it will function in circuit.
A battery might read OK out of circuit, but when supplying current the voltage can be much lower.
If that lower voltage is still above the minimum design requirements for all components in the circuit then all is well. If not, then the device will not function as designed. This can include the device making noises that it would not with proper voltage applied.

The cause of the noise is due to components in the device running at less than optimal voltages.
 
#13
Old Garage-Bander said:
A battery does not generate hum or buzz.

Unloaded voltage measurement of a battery is not a good test of how well it will function in circuit.
A battery might read OK out of circuit, but when supplying current the voltage can be much lower.
If that lower voltage is still above the minimum design requirements for all components in the circuit then all is well. If not, then the device will not function as designed. This can include the device making noises that it would not with proper voltage applied.

The cause of the noise is due to components in the device running at less than optimal voltages.
Click to expand...


I'm not going to argue on the cause of the noise. You're probably right. I meant it to point out that it might not be out of line for the OP to try a fresh, known to be good battery or two during the troubleshooting.
 
#15
Old Garage-Bander said:
The hum or buzz frequency is usually either 60hz or 120hz. (Assuming North America)
Click to expand...
Now that you point out actually I think that there are actually two different noises: one that may be more or less 120 hz, but still low frequency, the other is h is a high frequency noise that shuts whenever I touch some metal part (thanks to the grounding, I gues). That second sound is quieter and has always been there.

Old Garage-Bander said:
When you say you shut off the EQ, exactly what does that entail?
Click to expand...
Well, talking soundwise it quite reduces the volume and make it sound like a passive bass (just the sound, it is not an active/passive switch). What the switch actually does I think is just cut out the eq board from the circuit, but as I said I am not an expert at all.

ps. What does an eq board look like?
 
#16
wubalubadubdub said:
Now that you point out actually I think that there are actually two different noises: one that may be more or less 120 hz, but still low frequency, the other is h is a high frequency noise that shuts whenever I touch some metal part (thanks to the grounding, I gues). That second sound is quieter and has always been there.


Well, talking soundwise it quite reduces the volume and make it sound like a passive bass (just the sound, it is not an active/passive switch). What the switch actually does I think is just cut out the eq board from the circuit, but as I said I am not an expert at all.

ps. What does an eq board look like?
Click to expand...
Thanks. I was just trying to figure out if when you turn it off, if you used a switch of some kind or defeated it some other way.
 
#17
Just to add my 2c worth here. I have a Cort Artisan 4 active/passive bass. It developed a very annoying distortion (buzz), that persisted in passive mode. Also lots of interference & crackling in the signal. After reading this thread, I went out, bought a fresh Duracell 9V, and bingo! Problem solved.
Initially I thought it was some issue w/ PC setup, and wasted a bunch of time tinkering with audio setup. So there you go. I suppose you could say there is a flaw in the Cort's electronics that allows a weak battery to influence the passive sound, but I still love that bass.
 
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