Ho HUM for my new XPR-2

[thechewtoy]

Well, I went with the XPR-2. After a number of trials and travails getting it home (let's jsut say Fed-Ex is on my list), I got it in, hooked up, and ready to go. Only now I have an extremely loud hum coming out of both mains.

I made two changes to the system. I added an Oppo Digital BDP 105, and the emotiva XPR-2 in place of my old, dying amp. I have confirmed the speakers (B&W Matrix 801s Series 3) are hooked up correctly with monster speaker wire. I have traced the connections to my pre-amp (just in case something came loose). Prior to the change, I had a bit of static in the line from the old amp (traced directly to the amp, not cables), but otherwise everything worked just fine.

I tried a DVD in the oppo digital, and I get great center channel sound and video (meaning the new Oppo Digital player is working just fine), but nothing but a hum out of the main channels. I tried a CD to see if I could help isolate the main channel speakers, and when I turned the pre-amp up to 50% (ie what ought to be ear-bleed levels), I could begin to hear sound quietly over the main channel speakers (through the very loud and persistant hum).

So, pretty sure it's not the wires--everything else worked fine before I changed the amps . . . any thoughts as to that awful hum? What is the liklihood one of the wires just suddenly went bad? Oh, and I've got the amp set on the unbalanced input from the RCA jacks, it automatically selects the 115W power supply, and I've got it on a dedicated power circuit (20A).

Suggestions welcome at this point. I'm at my wit's end trying to track down the hum. I may even drag out my old amp and plug it in to see if the hum is still there. What are the odds I got a bad amp or something?

[garbulky]

Well first do a process of elimination.
1. Don't use a power conditioner and plug the amp directly into the wall.
2. Unplug everything from the amp except for the speakers and see if it still hums. Make sure no electronics - dimmer switches, washing machine, AC, fans are going on at the time.
3. Then plug in just one channel with the most simple device you can find and see if it still hums. If it does hum, staying with one channel switch to another channel. If it still hums, switch the wire and repeat.

[pkelly1504]

I recently hooked up new mono amps to my mains and had a nasty hum out of both main speakers.

I was a ground loop problem coming from the cable TV. To identify the issue I simply unhooked the cable and the hum went away.

I purchased a CATV Isolator by Jensen Industries VRD-1FF and the hum is now gone.

[sharkman]

Sorry that there's been so few responses to your issues chewtoy, have you been able to get it sorted out yet?

[Cory Cooper]

Jan 22, 2013 23:50:05 GMT -5 garbulky said:

2. Unplug everything from the amp except for the speakers and see if it still hums.

Have you tried this? If not, please do. If there is no hum during this test, it's a ground loop issue.

I had a similar issue with my UMC-1/XPA-5 that was solved by a form of star grounding the chassis of both components to a ground post on my power center.

C

[kanderson2009]

I had a slight 60-cycle hum with my XPR-2. A million things can cause hum and you just have to proceed with trial and error changing one element at a time. If no hum when nothing connected to RCA jacks, then very likely NOT the amp.

I solved mine by first cleaning all RCA connections with Deoxit (alcohol should also work), and then using electrical tape to keep my two, custom RCA cables Canare connectors and cable) together so they were always side-by-side from pre-amp to the XPR. Now there is absolutely dead silence.

The XPR-2 is awesome - the more I listen, the more I like. The Magnapan speakers like a lot of power and this amp delivers in spades.

Do web search for Bill Whitlock and Jensen transformers. He wrote one of the best white-papers I've read on ground loops and this was a trick he suggested. Your mileage may vary.

[Mike D]

Great stuff across the board here. I too had a pretty solid hum as soon as I hooked up my new XPR-2, yesterday. After reading through these posts, I did some investigation and found a grounding pole on my Denon receiver. I tied that to the ground of the amp's dedicated circuit and the hum went quiet. I will say, however, that I can still hear the hum faintly, so I wonder if I can change the type of ground wire I'm using to make it completely go away. Any thoughts would be greatly appreciated!

[roto]

Aug 18, 2013 15:28:39 GMT -5 Mike D said:

Great stuff across the board here. I too had a pretty solid hum as soon as I hooked up my new XPR-2, yesterday. After reading through these posts, I did some investigation and found a grounding pole on my Denon receiver. I tied that to the ground of the amp's dedicated circuit and the hum went quiet. I will say, however, that I can still hear the hum faintly, so I wonder if I can change the type of ground wire I'm using to make it completely go away. Any thoughts would be greatly appreciated!

[roto]

Yeah, searching the source of a very slight hum on XPR2 I just received. Someday I'll find it. In the mean time, this amp is how can I say it incredible. Pristine highs. Tight lows (smear on Rotel turned into distinct bass notes), absolutely no distortion at any frequency or power output that I use. I phenomenal amp. Tried many different components over many years. I'll bet this will give any Mc a run for anybody's money. Unlimited power. Runs very cool. I'm beyond delighted! I use with 901's. Just my preference out of listening to virtually everything out there. This amp makes that those speakers sing! I use Emotiva Stealth preamp. Wonderful. Just wonderful!

[DYohn]

What's your preamp?

[vneal]

Do you have a phono preamp hooked to your preamp. If so unplug & listem