60 Hz Noise Reduction


How do I eliminate 60Hz hum from my audio system?

HISTORY:
I recently purchased an Acurus A200 to increase the volume level of the front channel of my second system. When I connected the unit I noticed a 60Hz hum coming from both front speakers. I'm thinking the new set up has created a ground loop, or the units with no AC ground plug (2 prong AC plug) have a floating ground. The 2 prong AC units are Denon AVR3805, and Velodyne ULD15. So I would like to get some ideas of things I can do to eliminate the 60Hz hum This set up is a hodge podge of equipment left overs from the past.

OLD SET-UP (No 60Hz Noise)
Denon AVR3805 driving front, center, and surround speakers.
Denon preamp out to ULD15 controller/amp driving ULD15 sub.

NEW SET-UP (60Hz Noise)
Denon AVR3805 reciever which powers center, and surround speakers which are Monitor Audio bookshelf speakers. Denon pre-amp out to ULD15 Series II controller/amp driving Velodyne ULD15 sub. ULD RCA output to Acurus A200 amp input driving Monitor Audio GS10 for front.

Ideas Appreciated
Aaron
aweaver555
Just guessing you have a CATV box connected to the system. Disconnect the coax cable from the CATV and check for ground loop hum. If hum is gone buy an isolation transformer for the CATV coax cable.
http://www.jensen-transformers.com/an/generic%20seminar.pdf

http://www.jensen-transformers.com/an/an004.pdf
Same thing happend to me years ago (60hz hum) and the answer was the Jensen transformer. I paid approx $50 and never looked back...
Hi Rudd,
no cable box just TiVo.
Wow I would have never thought about low frequency noise coming from a cable box.

Just curious where did you place the jensen transformer, and which model for future reference.

Thanks Again
Aaron
Great article on noise isolation/elimination very helpfull.
I think I nailed it by attaching earth ground to Denon Receivers chassis ground.

Definetly will keep the Jensen ISO MAX CI-2RR isolation transformer for any future noise issues.

Thanks So Much
Aaron
no cable box just TiVo.
Aweaver555
Where does the TiVo receive its signal from?

I think I nailed it by attaching earth ground to Denon Receivers chassis ground.
Aweaver555

Not a good idea. If the Denon has a two wire polarized plug that means the equipment was designed and manufactured with double insulated ac power wiring, therefore an equipment ground (third wire) is not used. An earth ground connected to the chassis could degrade the sonics of the unit. More than likely the signal ground of the unit is connected to the chassis. By earth grounding the chassis EMI/RFI AC noise could enter the electronics of the unit through the ground wire.

Jensen VRD-1FF

http://www.jensen-transformers.com/datashts/vrd1ff_manual.pdf
Denon Chassis Ground
yes the Denon has 2 prong polarized AC plug.
I'm assuming that if I connect the chassis to AC ground instead of earth ground it would cause the same EMI/RFI noise problem. or worse correct?
I ordered the Jensen ISOMAX CI-2RR, and will install, and remove the earth ground from the Denon reciever chassis.

TiVo/Cable Loop
The Cable TV, and TiVo coxial are not connected to the Denon unit. However from these treads I'm going to connect the coxial cable through the isolation coax line in the Panamax power management system.

Thanks Again
Aaron
I'm assuming that if I connect the chassis to AC ground instead of earth ground it would cause the same EMI/RFI noise problem. or worse correct?
03-15-10: Aweaver555
Equipment safety ground, ("U" shaped hole ground contact on the AC wall receptacle), is often referred to as earth ground. I assume that is where you connected the ground wire from the Denon chassis to earth ground.

TiVo/Cable Loop
The Cable TV, and TiVo coaxial are not connected to the Denon unit. 03-15-10: Aweaver555

How about the audio-out from the TiVo? I assume you have interconnects,ICs, that connect CATV audio to the H/T audio system. The ICs complete the ground loop circuit from the CATV coax grounded shield through the audio equipment and out the equipment grounding conductor of the Acurus A200 to the equipment grounding conductor of the AC wall receptacle.
Jim
Hi Jim,
Well I don't believe it, but I disconnected the house cable line, and the noise went away. This line goes to a 4way splitter which supplies the TV, TiVo, and VCR/DVD.
I believe the splitter has a DC pass through.
I reconnected the house cable with none of the devices connected, and then reconnected seperately to determine which device was the source. Unfortunately when any single device is connected the noise returns.

When I do any of the following the hum goes away.
1-AC ground video splitter.
2-House cable through Panamax coax Isolation line.
3-AC ground denon chassis. (not a good solution)
4-drive front speakers with denon only.
For items 1 thru 3 there is a very very low level high frequency noise almost impossible to hear.
I'm wondering are items 1 & 2 good solutions, and what should I do about the residual noise?

Please note the TiVo, Wii, Playstation, and xbox go to a Philips AV switch that outputs to a 720 upconverter, which than supplies an hdmi signal to the TV. The TV supplies a digital audio to the denon reciever. Not sure if that helps.

Thanks Again
Aaron
I reconnected the house cable with none of the devices connected, and then reconnected seperately to determine which device was the source. Unfortunately when any single device is connected the noise returns.
When you get the Jensen iso transformer install it between the main CATV coax and the "line in" of the splitter . That should solve your problem.

For a temporary fix you could use a ground cheater on the power plug of the Acurus A200.
Jim
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