Compression driver hum/whine

joeybutts

Hey fellas! I've been battling a noticeable hum out of my front three 1099's, powered by an Emotiva UPA-5 and sourced from Denon X4700H.

Before I start pulling equipment and troubleshooting figured I'd ask if there is an easy fix/way to fix. I feel like this was mentioned previously but can't find it. I also think it got worse when I connected the surrounds (volt8s).

Thanks for any help!

Tom_S

My money is always on a ground loop somewhere in the system when these issues come up. Are your amps & other gear all plugged into the same plug strip? Do you have a cable/Sat box connected?

jhollander

If this is your first use of the 1099s could be combination of high sensitivity and no signal on the inputs of the amp. Might try playing a music CD and see if the hum exists in between songs. I've got a 10 second silent track I use for testing.

joeybutts

@Tom_S said:
My money is always on a ground loop somewhere in the system when these issues come up. Are your amps & other gear all plugged into the same plug strip? Do you have a cable/Sat box connected?

Thanks Tom! I was thinking if it was a ground loop issue it would eminate from all speakers, yes? But there is nothing from the volt8's, just the 1099's.

joeybutts

@jhollander said:
If this is your first use of the 1099s could be combination of high sensitivity and no signal on the inputs of the amp. Might try playing a music CD and see if the hum exists in between songs. I've got a 10 second silent track I use for testing.

Thanks John! The noise is present with a source through the AVR or not. I do think it was present without the surrounds hooked up but quieter. So it got worse if I remember correctly after hooking up the surrounds.

Before thinking there is something wrong with my amp, anything else to consider?

Tom_S

Did you have the surround interconnects hooked up to the amp earlier or did you only hook them when you got the volt8s and noticed the hum?

ugly_woofer

I think that Tom is on the right track, I would start by pulling the interconnects from the amp, if the hum is gone the amp is good. then connect one at a time and work back through the gear until you get the hum back, and find the ground loop or faulty component.

jhollander

I've also switched 120v circuits between the amp and preamp with an extension cord. I try to get the circiuts on separate incoming lines (circuits on separate sides of the electrical panel).

Tom_S

Joey, I feel your pain. Ground problems can be tough once you get beyond a few pieces of gear. I noticed your Denon has the same power connector as my Onkyo - they only have 2 connections, leaving the earth ground floating. If I plug USB audio interface into the receiver and have the laptop plugged into an outlet on the opposite wall, I always get some hum. Unplug the laptop and run on batteries - no more hum. Funny - both the laptop & receiver have no connection to earth ground on the AC plug and the common leg is supposedly isolated by the power transformers in each. But then you add a TV, cable line, & DVD player in the mix and who knows where the ground voltage is really flowing.

Pro-sound gear was so much easier, thanks a central power distro box.

joeybutts

Wow, thanks guys.

I do believe I had the rca's connected prior to the speakers being connected.

I will try disconnecting since it sounds like the only why to fish out the issue. I do have a separate outlet near by that I can try if it comes to that.

joeybutts

So I fiddled a little today and have determined that I must have wires picking up EM interference somewhere. When I slide out the amp from the rack you can JUST hear a hum, acceptable in my opinion (though I wish it was dead silent.)

I moved the plug to a different circuit and that didn't help any, I DC'ed the rca's and the speakers went silent.

I was thinking of trying to just run the speakers all off the receiver and see how that works. Just for shits and giggles.

Unless you guys can think of something else?
Thanks again.

4thtry

Have you tried replacing your RCA interconnects with one of these:
https://www.parts-express.com/Axxess-AX-AGL610-2-Ch-Ground-Loop-Isolator-266-007

ugly_woofer

Are the power cords both 3 pronged and therefore grounded? If they are you can try using a cheater adapter to convert one plug to a two prong, and while I wouldn't leave it that way, it's another way of showing a possible ground loop.

joeybutts

@4thtry said:
Have you tried replacing your RCA interconnects with one of these:
https://www.parts-express.com/Axxess-AX-AGL610-2-Ch-Ground-Loop-Isolator-266-007

No! But a little disheartening thinking about buying three of those.......

The Emotiva is two prong but believe the denon is three.....