2. amps-preamps
  3. 1115908846

A worse feeling than burning out your amp?

Last night I was planning to get back into making digital music and began setting up my laptop with the necessary software. I had my audio cable (1/8" connector) plugged into my Macintosh, which was playing mp3s. The laptop was ready to go, so I unplugged the cable from the Mac without turning the amp off, which I've done dozens and dozens of times before; BIG mistake. I heard a very loud buzzing sound that lasted about a quarter of a second, followed by a loud pop. I went over to the amp and could smell electronics burning. I turned the amp off and back on, after which I noticed that sound was only coming out of the left channel and it was very broken and full of static. Also, it doesn't matter which input is selected, it plays all sound coming from all inputs now. This integrated NAD C 340 amp is no longer good as a preamp either. What a horrible feeling, but it could have been much worse (my speakers could have blown out!).

Has anyone ever done something similar to their amp and attempted to fix it? I'm at least going to open it up and have a look before I trash the thing. The only bad part about all of this is having to wait several months before I can afford to replace this unit. For now, it's back to the old mass market Kenwood receiver....
jwglista
chadnliz
3,736 posts
 
I ALMOST did some major damage after swapping inter connects, I forgot to turn on one of my amps (the 2 channel main) scratched my head and turned volume way up to see if I could hear any noise in speaker...went for the power buton and at last second remembered to turn down volume....that scared the hell out of me and I didnt even do anything...but man it was close.
P.S. I am going to keep a better eye on bananna plugs!
stevemcx
166 posts
 
From your description it sounds like you lost the ground connection through your interconnect cable, leaving just the "hot" connections on both channels. This will cause most amplifiers to oscillate, often resulting in damage to the speakers, or amp, or both. It would be nice to think that the internal fuses had protected your NAD amplifier, but the fact that some parts overheated suggests otherwise. If you're feeling adventurous, you can check for blown fuses and replace any you find, and try it again. Otherwise, a visit to your local audio hospital is called for.

Note that this problem may occur again with the same front-end gear, regardless of what amp you are using. Losing both ground connections is rare with separate interconnect cables, but becomes more of a problem with “Y” cables - especially with mini-plug connectors. Check your cable carefully and replace it if you think it might be bad.
gmarcotte8f97
66 posts
 
Chadnliz, i did not know that was a condition that we need to avoid (turning on amp when voulme is turned up). i will keep this in mind.

i have fried a pair of channels when i ran built in test tones on an avr. rear speakers had been modified and i'm not shure what the ohm load was. i'm still looking for my multimeter to this day. good thread.
chadnliz
3,736 posts
 
I cant say it would be a problem. I hope that it wouldnt but I had the fear in me all the same, the amp was under the Processor and I just didnt notice, but I had turned volume all the way up to try to hear that tiny bit of noise I get when it is up without material playing. that being said I am still glad I caught my mistake.
yioryos's avatar
yioryos
723 posts
 
Oh the banana plugs eh? I almost fried my ML 27.5 years ago when they touched one another due to a heavy gauge speaker cable attached to them that was stepped upon.Thanks God they auto protect on the Levinson did a superb job.Speaking of UPS,I will say this about Fedex.They dropped my shipment on transit.I realized the problem the minute I picked up the box,as I felt something moving loose inside.Well after a visual I realized the transformer of the Tice Titan was broken off and was just held by the wires.I FIXED IT MYSELF after I gave up on them.They just didn't do anything about it.Nothing at all.
For your NAD Jwglista,aren't you overreacting a little.I mean you said it yourself that it was bought used for 90$.I wouldn,t worry about it that much.A good excuse to upgrade to something better.
Sorry if I come hard on you.My opinion anyway.
Best
George
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