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Need some help with an amp.

Once again, I need some information/help. I just got an Aragon 2004 from ebay. I am getting some humming/buzzing from the speakers. It is louder from the left speaker than it is from the right.

I disconnected everything, unplugged everything except the amp and the left the speakers connected and I'm still getting a hum. So, I plugged everything back in.

Now, for some observations.

1. Everything was plugged in and connected. My preamp was in standby. The switch on the amp was off. I unplugged the interconnects from the amp, so that amp is sitting there, plugged in with the speakers connected with the switch off and nothing hooked up to it in terms of interconnects. I grabbed an interconnect and got a loud hum from one of the speakers. The only thing that the interconnect was connected to was the preamp (NOT the amp).

2. I went to plug the interconnects back into the amp. The preamp is still in standby and the switch on the amp is off. With one of the interconnect plugs in my hand, I was reaching behind the amp to plug it in, my bare arm touched the amp and I got a little shock. Not a big one, but I can definitely feel a small current.

3. With the preamp in standby and the switch on the amp off and the interconnects disconnected from the amp, I touched my bare arm on the case of the amp and grabbed the connector on the interconnect with my other hand and felt the "shock" on my bare arm.

Can anyone tell me what's up?

Thanks.
tonyangel
tonyangel OP
309 posts
 
Well, I contacted my local high end shop. The owner is a pretty nice guy. He referred me to a shop that happens to be less than a mile from my office. He tells me that he's been using this guy for 30 years and that he really knows what he's doing.

I'm going to drop the amp off tomorrow and let him take a look at it and see what it needs. If the amp can be fixed for a reasonable cost, I'd really like to keep it.

Thanks for all of the info.
bjesien
1,359 posts
 
It's shocking that you want to keep it. Make sure the seller will take it back after you get it looked at. I would ship it back and get the refund.
marakanetz's avatar
marakanetz
5,473 posts
 
Seller may compensate repair expenses which should not be too bad.
heyraz
177 posts
 
I have the same amp. Assuming yours hasn't been worked on and your safety ground is intact, it should blow a fuse if there's a dead short to chassis. Have you checked your house wires for correct polarity? If the neutral and hot are reversed I could imagine an opportunity for leakage to chassis. Ground loop is also up on my list for causing the hum.
tonyangel OP
309 posts
 
OK guys. I really appreciate all of the words of wisdom and experience. I went and picked up my amp today. I got to talking to the guy, and it turns out that he does all of the repairs for most of the high end shops in my area and is the NAD warranty guy, so I feel pretty confident about his work.

He went through the amp to check things out and make sure that all was in order. He replaced the quad opamp ICs and the coupling caps. The good news is that the hum/buzz got better and it doesn't shock me anymore.

The bad news is that I still have a slight hum/buzz that I can hear when I put my ear next to the speaker. It isn't anything that I can hear from any sort of listening position, even during quiet passages, but it's there nonetheless; and I know its there.

More good news though, when nothing is hooked up to the amp except the speakers, I get dead silence. Due to limited space, I have my amp in an elevated area and it's connected to my preamp by way of a ten foot long IC cable. When I plug the IC cable into the amp (with nothing connected to the other end and it's just dangling) I get the hum/buzz. I think the long IC is picking something up. When I tried the test with a shorter IC, I got dead silence again.

As I said, now I think that the long IC cable is picking something up. I just can't figure out what. Either that, or there's something wrong with the IC. What do you think would be the odds of that? It's from Blue Jeans Cable.

Thanks.
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