(Amp fault) Diagnose this noise? 7 second video

[sj.brodie]

Amp is a NAD3020i, an upgrade to my entry level cambridge however definitely now a vintage model.

This noise occurs only occasionally in the left channel. Seems mainly vocals and higher frequencies are broken up with distortion before returning to normal. Interestingly, I've connected the amp's "rec out" to a Line In on my sound card and recordings made on my computer pick up no disturbance from the amp's output at all. The distortion occurs through speakers and the headphone jack. It is periodical, not persistent. Also I have a feeling I notice it more shortly after switching the amp on and/or adjusting volume (seems to work perfect during uninterrupted long runs)

I'm no expert so I did have a technician look at it with a solder iron when I bought it. He said he could detect no problems but did suggest rotating the pots occasionally which can get dirty.

Take a look at the video and let me hear thoughts on this. Could the problem simply be dirty pots? I hope so since I really love this amp. My first quality entry level...thanks guys

 

[petehall347]

why are you advertising in your links ?

 

[sj.brodie]

why are you advertising in your links ?

ads are not mine, my youtube isn't even monetized, just looking for an answer

 

[DaveVoorhis]

ads are not mine, my youtube isn't even monetized, just looking for an answer

The links are written into your content, which sure looks like link spam. Why are "headphones" and "be" written as links to eBay and a clothing site?

Did you originally post somewhere else and copy your post to here?

 

[sj.brodie]

The links are written into your content, which sure looks like link spam. Why are "headphone jack" and "be" written as links to eBay and a clothing site?

Did you originally post somewhere else and copy your post to here?

Thanks for raising that. I posted this to AV forums originally and copy and pasted the content. Sounds like it could be adware in my browser though, I honestly don't know why or how the adverts were written in. I've managed to remove them

 

[DaveVoorhis]

Thanks for raising that. I posted this to AV forums originally and copy and pasted the content. Sounds like it could be adware in my browser though, I honestly don't know why or how the adverts were written in. I've managed to remove them

There's a rather pernicious form of spamming -- sometimes called crosspost spamming -- that involves copying posts from one forum to another, then later editing the copied post to include links to spam targets, probably to increase pagerank. Your post looked like that.

 

[sj.brodie]

There's a rather pernicious form of spamming -- sometimes called crosspost spamming -- that involves copying posts from one forum to another, then later editing the copied post to include links to spam targets, probably to increase pagerank. Your post looked like that.

Seems to be basic adware. Can't remove from my original av forums post sadly. Hopefully my post here now looks credible enough. No links except for my youtube video.

 

[petehall347]

nice one for clearing that up ..
now back to the diagnosis .. hard to say without hearing it for longer ..
p.s welcome to AK .

 

[sj.brodie]

nice one for clearing that up ..
now back to the diagnosis .. hard to say without hearing it for longer ..
p.s welcome to AK .

Appreciate you having a listen anyway. That was all I could capture tonight, as I said it isn’t very persistent. I’m thinking the fact the distortion is completely absent from the analog output leading to my computers line in might suggest the output is clean and the problem/variable could be the pots (it’s always speakers and headphone jack - already checked the speakers and phones individually) Not certain though and I’m not a components expert.

I’m still able to create perfectly balanced and clear recordings of my vinyl or from any other source for that matter.

I guess my main question is how to easily identify when pots/switches need cleaned and are the symptoms I describe reminiscent of this issue.

 

[petehall347]

best thing to first is deoxit all switches and controls . plus rca jacks to rule those out .. something seems to be losing connection and righting itself ..

 

[Robisme]

Sounds like dirty controls to me.

Rob

 

[ev13wt]

Sounds like the PSU is breaking down to me. With my limited knowledge I'd start with the schematic and the service manual. Then I'd replace the PSU caps after the rectifier bridge.

But I am totally guessing.

 

[sj.brodie]

Sounds like the PSU is breaking down to me. With my limited knowledge I'd start with the schematic and the service manual. Then I'd replace the PSU caps after the rectifier bridge.

But I am totally guessing.

PSU as in power supply...or something else? If it’s a major part failure, id probably just buy a newer amp of the same quality (meaning expensive) they don’t make budget amps like this one these days

 

[ev13wt]

Appreciate you having a listen anyway. That was all I could capture tonight, as I said it isn’t very persistent. I’m thinking the fact the distortion is completely absent from the analog output leading to my computers line in might suggest the output is clean and the problem/variable could be the pots (it’s always speakers and headphone jack - already checked the speakers and phones individually) Not certain though and I’m not a components expert.

I’m still able to create perfectly balanced and clear recordings of my vinyl or from any other source for that matter.

I guess my main question is how to easily identify when pots/switches need cleaned and are the symptoms I describe reminiscent of this issue.

Well, they would only make noise when moved or pushed. Can you recreate the problem with that?

 

[ev13wt]

PSU as in power supply...or something else? If it’s a major part failure, id probably just buy a newer amp of the same quality (meaning expensive) they don’t make budget amps like this one these days

Yes. Caps should be around 70 cents or so.

Possibly its also the power switch itself. Clean its contacts - unplug first

Can you recreate it by moving RCA connectors on the back? Wiggle them while playing music.

It could be the preamplifier itself. Does your unit have pre out, main in or something of that nature? Are there little silver jumpers? You could use an RCA cable to test preamp and amp to narrow it down.

First: move every switch and lever 50 times. The mechanical action may remove most of the bad contacts. If the problem goes away: read the deoxit thread.

 

[sj.brodie]

It could be the preamplifier itself. Does your unit have pre out, main in or something of that nature? Are there little silver jumpers? You could use an RCA cable to test preamp and amp to narrow it down.

Yes, I have the pre amp out but to be honest I've left it alone since buying the amp as I'm ignorant about how to use these/incorporate it into a bigger system. Could you please explain how to test this output? Thanks and thanks to all the other replies so far

Am I wrong in assuming I've already isolated the problem to the volume pot since no disturbance is passed through my Line Out? As I briefly mentioned, the NAD's line out is fed into my laptop for vinyl recording and all of my recordings are perfectly balanced and clean yet playing the same source produced distortion through the left speaker and headphone.

 

[markn2wae]

It sounds like the "record out" is clean (no noise on your computer) but there is still the path to the main amp.

Most amps. use resistors for the headphone jack and you state that you are hearing it there too.

This leaves tone and volume control circuits, and power amp. driver and out stages also.

It sounds like "dropouts" in the sound rather than distortion caused by too much level trying to be produced, but just a guess here, cleaning all switches and controls may fix the issue.

Mark T.

 

[ev13wt]

Yes, I have the pre amp out but to be honest I've left it alone since buying the amp as I'm ignorant about how to use these/incorporate it into a bigger system. Could you please explain how to test this output? Thanks and thanks to all the other replies so far

Am I wrong in assuming I've already isolated the problem to the volume pot since no disturbance is passed through my Line Out? As I briefly mentioned, the NAD's line out is fed into my laptop for vinyl recording and all of my recordings are perfectly balanced and clean yet playing the same source produced distortion through the left speaker and headphone.

Are you touching the volume pot when you hear the distortion?

 

[sj.brodie]

Just want to thank everyone for the replies. I've showed the thread to a technician who may be visiting this week and will repost with further updates