Rack Hum
-
Voodoo Guru
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- Joined: Wed Feb 23, 2005 8:47 am
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Howdy Dennis,
Sure Have.
They call it 60cycle Hum.
There are several ways to try and get rid of it...
It is just like fighting RF.
First of all,
Be sure you have all the units plugged into the same power line circuit.
Its best if you have some kind of power conditioner like a Furman.
This insures there will be no ground loops between the units.
It also helps with RFI.
Second thing is to be sure all your unit interconnects are good quality Balanced Cables.
If you have already accomplished the above,
then the next step is to try and find the unit that is causing the hum.
Easiest thing to try first is to plug your headphones into the output of the last unit and then start turning off different units until you find the one that is causing the hum.
This will only work on the units that bypass the audio when they are turned off.
Another thing you can try is to plug your headphones into the output jack starting with the last unit and then disconnect its input.
Did the hum go away?
If so then go to the previous unit and do the same thing unit you find the unit causing the hum.
There are several ways to isolate the unit and your imagination can always help.
OK, so you found the unit causing the hum...
What can you do to fix it?
One thing is to install a 3 prong to 2 prong adapter on the power chord.
This will lift the chassis ground and open the ground loop there.
If it does nothing, then remove the 3 prong to 2 prong adapter.
Try different cables. You might have a bad ground or intermittent contact on one of them.
Do you have the Power Cables from any units (or the interconnect cables) running by another transformer?
This can cause induce 60 cycle hum.
Hope this helps you find it.
Its just a matter of tracking it down.
Good Luck,
Sure Have.
They call it 60cycle Hum.
There are several ways to try and get rid of it...
It is just like fighting RF.
First of all,
Be sure you have all the units plugged into the same power line circuit.
Its best if you have some kind of power conditioner like a Furman.
This insures there will be no ground loops between the units.
It also helps with RFI.
Second thing is to be sure all your unit interconnects are good quality Balanced Cables.
If you have already accomplished the above,
then the next step is to try and find the unit that is causing the hum.
Easiest thing to try first is to plug your headphones into the output of the last unit and then start turning off different units until you find the one that is causing the hum.
This will only work on the units that bypass the audio when they are turned off.
Another thing you can try is to plug your headphones into the output jack starting with the last unit and then disconnect its input.
Did the hum go away?
If so then go to the previous unit and do the same thing unit you find the unit causing the hum.
There are several ways to isolate the unit and your imagination can always help.
OK, so you found the unit causing the hum...
What can you do to fix it?
One thing is to install a 3 prong to 2 prong adapter on the power chord.
This will lift the chassis ground and open the ground loop there.
If it does nothing, then remove the 3 prong to 2 prong adapter.
Try different cables. You might have a bad ground or intermittent contact on one of them.
Do you have the Power Cables from any units (or the interconnect cables) running by another transformer?
This can cause induce 60 cycle hum.
Hope this helps you find it.
Its just a matter of tracking it down.
Good Luck,
Voodoo Guru
From Deep in the IDD of the Sub-Harmonix Realm
From Deep in the IDD of the Sub-Harmonix Realm
Hi Dennis.If Mikes suggestions do not help,you might try a Direct
injection box.It is also useful in
padding down line level audio. I use the Behringer Ultra DI-100 and of course there are others available.Ebtech is good too or the I-Box from w2hy.If you choose the DI box,make sure you get one that is active(uses phantom power or 9 volt battery) and not a passive one.
injection box.It is also useful in
padding down line level audio. I use the Behringer Ultra DI-100 and of course there are others available.Ebtech is good too or the I-Box from w2hy.If you choose the DI box,make sure you get one that is active(uses phantom power or 9 volt battery) and not a passive one.
Ok, Did not get your name. But anyway thanks for the help. I've tried one of Mike's suggestions. And so far I have narrow it down to some bad cabling. I now hear very little hum. I will also add furman box to later. I'm also getting a hum when connecting the mixer inline. Anyway I hope to be able to work all of this out.KC7OV wrote:Hi Dennis.If Mikes suggestions do not help,you might try a Direct
injection box.It is also useful in
padding down line level audio. I use the Behringer Ultra DI-100 and of course there are others available.Ebtech is good too or the I-Box from w2hy.If you choose the DI box,make sure you get one that is active(uses phantom power or 9 volt battery) and not a passive one.
I'm not having trouble with the line level.. As far as the I-box. I have a home brew I-Box cost me about $5.00 to build and works great.
I will post all my fining once I'm finishing.
One thing that Mike suggested that really help. He mention using a headset and pluging it into each unit to track down the hum. That help me out a lot. Thanks Mike..