Good afternoon Y'all'
Im scratching my head on this one and can use your help. I changed my family room around and put my AV set up on the opposite wall. I had the equipment in a vertical tower and TV stand combo and it was working fine. This is where the bizarre ground loop type of hum issue comes in; I recently got an OPPO BDP 103 and decided to eliminate some gear from my rack (and the rack too). I took out a Linn Karik, Marantz Combo SACD/DVD player, and a dvd recorder I seldom used. Mounted my Panasonic Plasma on the wall and used the TV stand to hold my gear. Made for a clean down size, but now I have a ground loop hum, and a pretty good one through all the speakers. I can hear it on the bass & mid amps powering the L&R mains (the treble amp isn't making any noise, due to the Internal Crossover card I think). The center channel amp, and the amp running the surrounds is also transmitting the noise. The noise doesn't increase with volume changes.
Whats odd, is the same a/c outlet is used, same gear minus what was taken out and the added OPPO. I did go to a short S.E. cable set to the main amps from the long set I had b4, but they are all older audioquest cables (forgot the model name). I have it all running through a Cinepro Powerpro 10 balanced line conditioner. The rest of the system is an Active Linn 5140 system with 3) 5105 amps w/ active crossover cards, passive center channel running off an LK100 bi/amped, going through a Marantz 6004 receiver used as a preamp, & a REL Storm sub. Surrounds & outside speakers are running off an Adcom 6000 5 channel amp using 4 channels. Im also using a Directv HD DVR. Video from both the OPPO & the DVR are running through the Marantz and on to the TV by HDMI.
When I had everything in the tower in the current location, I didnt have anywhere near as loud of a hum as I do now. still had a hum, but it was consistent with the noise level of the previous location.
What I've tried so far;
- I insured the single ended cables from the receiver to each amp were not running near the power cords
- I tried running the amps cords through a power strip, taking out the cinepro. No change.
- The OPPO is the only change to the system. took it out, no change in the hum.
- Unplugged all digital sources - No change
- Unplugged each amp one at a time. This improved it incrementally until all amps were out of the system. I plugged them back in one at a time and got the hum back incrementally louder with each added amp.
- Bought a polarity/ground outlet tester from Home depot - outlets tested correct for ground & polarity.
- I finally ran an extension cord from the old outlet across the room to the Cinepro. This had a big effect on the hum reducing it (but not totally eliminating it) by about 2/3rds
:huh: Now Im getting somewhere.
My initial conclusions;
- The noise is picked up after the source components and receiver.
- I may have something in this circuit that is "dirtying up" the A/C feed. other switches, appliances, etc., bad connections, or some old wiring issues. The house was built in the late 70's, so it may be wiring related
- I am considering running a new, dedicated circuit for the audio sysem.
Any ideas I should check before I go to the trouble of running a separate dedicated circuit?:help: Thanks in advance.