Humming sound comming out of speakers

Beta

So yesterday after work I decided to tackle adding Parasound Halo A21 and A23 amps to a Denon 4310CI in my HT system.

As recommended on our forum here, I used the L/R front pre-out on the Denon to incorporate the A21 and run the fronts and the center pre-out to incorporate the A23 and run the center. Speakers are Polk LC265i fronts and LCi-C center (4 ohm speakers).

Gear being incorporated consists of the following:

Denon 4310CI AVR for the surrounds
Parasound A21 amp for the fronts
Parasound A23 amp for the center
APC-H15 power conditioner
Cable box
Sony Blu Ray unit
Parasound Zbreeze fan to cool the 4310CI (connected via 12v trigger)
Parasound Zbreeze fan to cool the A21 (connected via 12v trigger)
AQ King Cobra ICs from the amps to the AVR.
AQ HDMI cables

I had shelving built on the back of my living room wall in my garage to keep my HT gear out of sight. These shelves are fairly high up, making set up and tweaking very challenging.

After four hours of disassembling my gear and then reassembling everything, I excitedly turned the system on. To my disappointment, the fronts and centers had sound coming out of them. However, there is a significant humming sound coming out of them as well.

I could use any trouble shooting thoughts or suggestions anyone may have. I am hopeful this might be a simple fix and that I don't have to embark on another 4 hour disassemble and reassemble exercise. Thanks in advance for any tips or suggestions.

inspiredsports

The first experiment to try is to disconnect the RJ-45 coaxial cable from the back of the cable box and move it a foot away from the back of the cable box. My educated guess is that's the source of your hum.

IF that stops the hum, determine which of your NEWLY ADDED components have grounded 3-wire AC power cords. The short term hack/fix is to use a gray 3-to-2 grounding adapter on each component with a grounded AC cord. Reconnect the RJ-45 and the hum should be gone.

The proper long-term fix is to make sure the breaker box AND cable installation grounds are tied together on the exact same ground rod/water pipe/etc.

Beta

inspiredsports wrote: »

The proper long-term fix is to make sure the breaker box AND cable installation grounds are tied together on the exact same ground rod/water pipe/etc.

Thanks!

I know for certain that my cable run is NOT grounded.

However, I have never had an issue with humming. I was running all my LCi speakers off the 4310CI. No humming in that configuration. This has to be related to my addition of the amps.

Second question....

I am running the A21, A23, AVR, cable box, Bly Ray and both Zbreeze fans through the APC-H15. Could this be a bit of an overload for the APC? I have the APC running to a PS Audio Soloist Premier Special Addition outlet. I do have a Furman Elite-15 PF i that I could add to the mix.

Much appreciated!

Beta

Now, if only I can chase down what is causing the humming of the speakers, I will be in business....:frown:

Beta

inspiredsports wrote: »

determine which of your NEWLY ADDED components have grounded 3-wire AC power cords. The short term hack/fix is to use a gray 3-to-2 grounding adapter on each component with a grounded AC cord. Reconnect the RJ-45 and the hum should be gone.

The power cords on the A21 and A23 each have 3-wire AC power cords. I guess I'll run over to Home Depot and purchase 3-to-2 adapters and see what results I get.

Thanks again!

inspiredsports

The grouding adapters were step 2, and only to be used if disconnecting the cable (step 1) stopped the humming. Did disconnecting the cable stop the hum?

Beta

inspiredsports wrote: »

The grouding adapters were step 2, and only to be used if disconnecting the cable (step 1) stopped the humming. Did disconnecting the cable stop the hum?

Removing the cable did not work. The humming was only coming from the center channel. However, adding the 3-to-2 grounding adapter to the A23 did the trick. No more humming from the A23. Interestingly, I have no issue with humming coming from the A21. No need for a 3-to-2 grounding adapter for the A21

Unfortunately for me, another issue has surfaced. My A21 is making a rapid clicking sound and is shutting down after a minute or so (obviously, not a heat issue as the amp won't stay on long enough for it to heat up).

Deja vu nightmare! I had this exact same problem about 2 years ago when I was using it in my 2-channel set up. My home was built in 1957 and my electrical panel and wiring is original. I am hoping that the issue with the A21 is such that I am trying to draw to much power from the particular circuit that I am running everything in my HT system off?

When I incorporated a PS Audio Power Plant Premier into the mix when the A21 was being used in my 2-channel system, the A21 ceased shutting down and worked flawlessly.

For now I am running the fronts off the A23 and the center and rears off the 4310CI.

Now I need to figure out how to resolve the issue of the A21 shutting down on me.:frown: If anyone has any tips or ideas as to how to resolve this problem, they would be greatly appreciated!

Thanks!

niente

Had similar ground loop hum issue when i added my amp with a 3 prong plug - i found it was coming from the 75 ohm cable (unplug the cable....no hum? )

DO NOT defeat the 3 prong plugs - if it is a groundloop hum it is because your cable IS grounded outside the house and your amp is now grounded via the 3 prong plug though your house wiring - the hum is due to the differnce in the ground between the two

Use the same ground buy running he 75ohm cable thru your APC which probably will gain you common grounding thru the APC's chassis
or
isolate the cable by adding an RF insolator---checkthe web for Jensen RF Isolator

Good luck--!