Axiom Home Page Forums General Discussion Technical Questions Axiom 1000 Amp Hum

I just received my Axiom 1000 7 channel amp and I'm having issues with it. The only sound I get out of my 7 channel system is a loud hum. I'm using RCA inputs, front speakers are connected to channels 1 and 2, side surrounds connected to 3 and 4, rear surround connected to 5 and 6, and center channel has one connector on channel 7. Any ideas on what is going on with my amp????

Welcome aboard . Just a little more info would help. What reciever or Pre is driving the amp. Have you used the preouts on your reciever prior to this. Sorry your first visit here had to be sour grapes hopefully this will get sorted.

Sorry about that! I have an Onkyo TX-NR709 and I have not used the preouts prior to this.

My suggestion would be to find something to test the new amp with. an ipod with an adapter to rca would work. Not sure what you have on hand. Seems odd it would be all channels of the new amp. Perhaps a reset of your reciever would be worth a shot.

My money is on a ground loop... I had the EXACT same issue with my amps when i got Time Warner cable installed.... if you unplug your cable box and play music from a CD, do you still have the same Hum...


If you unplug the cable box, unplug the coaxial cable, as well as disconnect the cable box from your receiver.

The solution is a ground loop isolator, which is about 50$.. I bought 2 of them from Axiom... One for each room i have a stereo in..


On a side note, it is highly unlikely it is the amp.. Axiom is putting each amp on the test bench before they ship, to verify everything is good to go...

Don, welcome. The first point is that you're plugged into the outputs specifically labeled "pre out" on the 709. It's extremely unlikely that all the pre-outs are defective, but you can plug one or more of them into your powered sub amplifier to check them for output.

If the pre-outs have output, call Axiom about the 1000.

Sounds reasonable. I heard the hum coming from my subwoofer shortly after I plugged the rca cables into the Onkyo's preouts. It's weird that I did not have any sound beyond the hum. I should have at least heard some music. I will try hooking my ipod up to the amp via the cradle I have and see if it still hums. Thanks!

John, I double checked just to be sure and I used only the preouts from my Onkyo TX-NR709. I've been hooking up my own gear for years and have heard ground loop feedback on some amps I've had through the years. It only took a simple filter to fix it. The difference here is that I have no sound other than the loud hum. I have unhooked all the individual cables to check for a bad cable. I'm leaning toward a amp issue on this one.

This may sound silly, but it's happened before: make sure that you're not plugged into the 709's multi-channel inputs to the left of the pre outs.

Edit: okay you've apparently double-checked that already.

John, you definitely made me laugh because I'm not above doing something like that after having some fine IPA from my beloved left coast. Yet on this occasion I correctly hooked them up. The problem has inspired me to take a break and enjoy a pint whilst I ponder this further.

If you look inside the case, do any of the wires look like they're disconnected? One of mine became disconnected during shipping, so I had no sound out of the box as well. I didn't have the hum, however. I think it was only a fluke that mine had a disconnected wire, but it's worth checking.

I'm sorry that you're having trouble with your amp. Every amplifier goes through a full suite of bench testing in the lab before heading to the line for further testing and then packing. If there was a simple ground loop issue you would NOT only hear hum, there would be music as well.
The first step would be to disconnect all of the input (RCA) connections going to the amplifier and disconnect all of the speakers, except for your front left and right. Turn on the amp and see if there is any noise (there shouldn't be). If you DO hear the same hum, there is indeed an issue with the amplifier. If there isn't any noise, then turn off the amp and connect only the left and right front channel RCAs to the appropriate inputs on the amp for those channels. Power up again and see if you have noise. If you do then there is an issue with the outputs of your receiver, or the cables. Please get back to me with your findings.

Thanks!

Andrew, I appreciate your response along with everyone else who has responded. I removed all the RCA connectors and unplugged the HDMI cable. Cleaned the preouts, connected the front speakers and HDMI cable to channel 1 and 2. I removed the HDMI cable set top box to test for a ground loop.

The front channels worked as advertised. I connected the center, surround (front and back), and the subwoofer to the amp. The hum was obviously a ground loop (Thanks Dakkon!, you saved me a lot of time troubleshooting for a ground loop). I have had ground loops before, but never as loud as I heard on Monday. The issue of not having sound from my system is a mystery to me. I cranked up the volume on my receiver and only heard a "hum on steroids". The kind you normally hear right before you see smoke coming from your favorite amp. I spoke with Brent and ordered an Axiom ground isolator. I will update my post tonight after I hook everything back up to the amp.

The ground isolator will not help if you are not getting sound from the audio, also I am not a big fan of them anyway with high end amplification, actually makes things sound worse when I tried one. For me it was easier to use a cheater plug on my 350's and now things are dead quiet.

Sure, no problem.. when i had my ground loop issue, the hum was so loud it drowned any other sound. The result was, it sounded like only a hum was present even though there was source material "under" the hum....

I agree, it's a HUGE pain in the butt... Glad you were able to resolve the problem in a quick and efficient manner.

Don, yes please give us an update on your previous post, because it isn't entirely clear. What does "worked as advertised" mean as to the front channels? If they played music without the hum, this doesn't appear to be a ground loop hum, which would affect all channels.

John, i think he started with the L/R speakers and there was no issue. Then, he continued on to the rest of the channels with the same result....

Alex, is "same result" no hum or the previous hum?

I interpret that phrase as,

no hum

John, I'm proud to announce that I now have all the issues sorted out! I indeed had a ground loop issue along with an issue with the new speaker wire I had purchased. I missed the plastic coating that was still present after I stripped the insulation off the wires. The only reason I found it to be an issue was that my new M80 speakers arrived today. Since I won't receive my ground isolator until Friday, I took the 1000 amp offline and hooked the M80s up to my surround receiver to test them to ensure they were in working order. I had some volume from the left speaker but it was very intermittent and scratchy sounding, but the right was totally dead. I checked my connections and tried it again with the same results. Just out of curiosity I used my flashlight to take a closer look at the speaker wire and found that it still had a plastic coating encapsulating the wire. I was so fixated on other issues that I totally missed the simplest thing it could be (The first law of troubleshooting, start with the simplest component it could be, then work your way up to the most complex). Having been a helicopter mechanic for 28 years, you'd think I would have known better. I stripped the thick plastic coating off on both right and left speaker wires, reconnected and was rewarded by the rich sound of the M80 speakers. I repeated the process for all my other speaker wires, unplugged my cable set top, reconnected my speaker wires and RCA connectors to my amp. I fired the amp back up and the sound blew me away!! It was in fact a brain fart on my behalf. I'd like to thank all who weighed in on my problem. It reaffirms my belief that I made the right decision in choosing to do business with Axiom.

Sir Quack, I agree with you on the use of a ground isolator. Every time I have used one, it seems to take some of the color out of the sound. If I have to, I will go to a cheater plug, but I'd like to use it as a last resort. I'd rather not defeat the safety ground unless I absolutely have to.

John, to clarify what I meant by "worked as advertised" is that the amp did indeed produce sound. Yet the sound was weak and intermittent. Yes it produced sound, but it was in no way impressive, nor made me feel good about the coin I laid out for it. Once the issues were sorted out, I uncorked a bottle of my favorite American Double Imperial IPA. I can't say the wife is impressed, but then again, she's very rarely impressed when it comes to my electronic toys. My next project is to build or buy a tube amp to be dedicated to the M80s when I'm listening to my favorite jazz and blues albums. It's something I've missed since I was a kid listening to the Grand Old Opry on my old mans tube amp system. There's just something about the richness of the sound that only a tube amp can produce. Maybe it's just nostalgia coloring my view, but it sure would be nice if Axiom started building tube amps (hint....hint).

Very good, Don; enjoy. And yeah, it's just nostalgia, not technology.

IronHorse, you just opened the door to AV heaven.
i'm so glad for you. :-)