My NAD C372 is not well....

[GO-NAD!]

Yesterday, we had guests visiting and we had backgound music playing - it was below conversation volume. All was well for most of the day, when I noticed that the sound was becoming distorted. I shut it down, just to play it safe.

This afternoon after work, I decided to try to narrow down the problem. I didn't think it was a ground loop, because it had been set up the same way for the last couple of years without a problem. But, I tried a different circuit anyway, with all components fed from the same outlet. No change. It doesn't sound like a ground loop anyway - no buzz or hum - just...distorted, even at low volume.

I cut the DCX out of the setup - no change. I disconnected the tuner and CD players in turn - no change. The only common denominator that I can see, is the amp. It's affects both channels as well.

Is there anything else I can try, without diagnostic equipment? I haven't taken the cover off, as I wouldn't be able to tell if anything was wrong anyway - unless something was burnt or melted. I would've smelled it anyway, I'm sure.

I'm not very happy, as you can imagine. It's out of warranty, so I'll have to pay to get it looked at. I'll be off the week between Christmas and New Year's, so if it can't be fixed in the next few days, it'll be very quiet in the living room. I suppose we could just watch movies downstairs every day...

 

[Adam]

Woah, sorry to see that. I hope that you don't have to watch movies the whole vacation.

I looked around briefly and found this. I know that you don't want to get into the amp just yet, but it mentioned a couple of things that were good ideas. First, have you tried the headphone jack to check if there's distortion there? Also, it mentioned checking the cables, but I think your process of elimination would have handled that unless all of your cables somehow went bad (i.e. you eliminated it).

 

[Haoleb]

if you are getting distortion on all the inputs, on both speaker A and B outputs and at all volume's it is probably something in the power supply. Alot of times if you dont have the proper voltage in certain areas you get distortion. Of course this is not a self fix you can attempt from the sound of it.

I used to own the C-370, and at one time had a channel drop out on it so i am somewhat familiar with the amp as they are pretty similar. Another thing to check is take your jumpers out between the pre and power sections and see if you can further narrow it down. Try both the fixed and variable preamp outputs.

 

[GO-NAD!]

Woah, sorry to see that. I hope that you don't have to watch movies the whole vacation.

I looked around briefly and found this. I know that you don't want to get into the amp just yet, but it mentioned a couple of things that were good ideas. First, have you tried the headphone jack to check if there's distortion there? Also, it mentioned checking the cables, but I think your process of elimination would have handled that unless all of your cables somehow went bad (i.e. you eliminated it).

Never thought about the headphone jack. And yeah, I'm pretty sure it's not a cable issue. After pondering it further, I think I'll just drop it at my dealer's shop and have them sort it out. I figured that even if I narrow the problem down further, it's not like I'm gonna fix it myself.

Thanks for taking a break from building your post count to respond, Adam. Uhm...wait a minute.....

 

[GO-NAD!]

if you are getting distortion on all the inputs, on both speaker A and B outputs and at all volume's it is probably something in the power supply. Alot of times if you dont have the proper voltage in certain areas you get distortion. Of course this is not a self fix you can attempt from the sound of it.

Yeah, I would think that it would be at a common point in the circuitry (like the power supply), as the distortion is always there, no matter what configuration I try.

I used to own the C-370, and at one time had a channel drop out on it so i am somewhat familiar with the amp as they are pretty similar. Another thing to check is take your jumpers out between the pre and power sections and see if you can further narrow it down. Try both the fixed and variable preamp outputs.

Do you mean supplying a different power amp from the C-372 pre-amp section? Then, use a different pre-amp to drive the C-372's amp section? If so, yeah, that could narrow it down. I could use my RX-V1800 for that purpose, I guess.

But then, as I mentioned to Adam, I might be just wasting my time, because in the end, I won't be fixing it. If I'd thought of it last night, I might've tried it though. I have it sitting in my vehicle right now, so that I can drop it off right after work today.

Thanks for the input. Wish I'd thought of your idea....

 

[highfigh]

Yesterday, we had guests visiting and we had backgound music playing - it was below conversation volume. All was well for most of the day, when I noticed that the sound was becoming distorted. I shut it down, just to play it safe.

This afternoon after work, I decided to try to narrow down the problem. I didn't think it was a ground loop, because it had been set up the same way for the last couple of years without a problem. But, I tried a different circuit anyway, with all components fed from the same outlet. No change. It doesn't sound like a ground loop anyway - no buzz or hum - just...distorted, even at low volume.

I cut the DCX out of the setup - no change. I disconnected the tuner and CD players in turn - no change. The only common denominator that I can see, is the amp. It's affects both channels as well.

Is there anything else I can try, without diagnostic equipment? I haven't taken the cover off, as I wouldn't be able to tell if anything was wrong anyway - unless something was burnt or melted. I would've smelled it anyway, I'm sure.

I'm not very happy, as you can imagine. It's out of warranty, so I'll have to pay to get it looked at. I'll be off the week between Christmas and New Year's, so if it can't be fixed in the next few days, it'll be very quiet in the living room. I suppose we could just watch movies downstairs every day...

Any smokers in the house? If so, I would bet the controls/mechanical switches need cleaning. Distortion is a common symptom of this. If you have a ground loop, it would hum and it wouldn't show up suddenly.

 

[GO-NAD!]

Any smokers in the house? If so, I would bet the controls/mechanical switches need cleaning. Distortion is a common symptom of this. If you have a ground loop, it would hum and it wouldn't show up suddenly.

Nope, no smokers. Yeah, I never thought it was a ground loop either.

 

[AcuDefTechGuy]

Wouldn't it be a lot more fun to just buy a new amp?

 

[GO-NAD!]

Wouldn't it be a lot more fun to just buy a new amp?

Don't do that! You're like that little demon sitting on my shoulder...

I'll get it fixed. But you know, if it should turn out to be bricked (I highly doubt it), I know exactly what I would like to replace it with:

Emotiva Audio USP-1 Stereo Preamplifier

and

Emotiva Audio XPA-2 Two Channel Power Amplifier

or

Emotiva Audio UPA-1 Mono-Block Amplifier X 2

It's the shipping cost to Canada that really bites my a$$. And, she'd KILL me!

 

[Alex2507]

And, she'd KILL me!

You've been dead before.

 

[AcuDefTechGuy]

Don't do that! You're like that little demon sitting on my shoulder...

I'll get it fixed. But you know, if it should turn out to be bricked (I highly doubt it), I know exactly what I would like to replace it with...And, she'd KILL me!

C'mon. Who ya kidd'en here.

Ain't ya got rights?

Ain't life too short?

Ain't it Christmas and New Years?

 

[GO-NAD!]

You've been dead before.

Now I have a demon on each shoulder!

 

[Adam]

Why not save a bunch of money and get a receiver if the NAD is truly no more? How much power do you need?

Oops, sorry - I should be making fun of you for not spending more money and for being afraid of your wife. Right, then.

 

[GO-NAD!]

C'mon. Who ya kidd'en here.

Myself, apparently...

Ain't ya got rights?

When she lets me take 'em out of storage and dust 'em off. (I almost said "...out of the closet...", but I realized that Alex would be all over that)

Ain't life too short?

Absolutely!

Ain't it Christmas and New Years?

Right again, smarta$$.

Seriously, if that amp was bricked, I know she'd cave. She likes music too. The reality is, to replace the C-372 with a C-375BEE would cost $1600 here! NAD prices have really jumped since I bought my amp and I wouldn't even think about paying that much. I could justify the cost of the Emotiva gear though. I can't imagine that it would cost more than a couple hundred to ship it here. I'd still come out ahead with components that exceed the NAD's features and power.

Ok, that's it! Stop it! Your giving me ideas!

 

[Adam]

(I almost said "...out of the closet...", but I realized that Alex would be all over that)

He does like 'em right out of the closet. Nice and fresh.

 

[GO-NAD!]

Why not save a bunch of money and get a receiver if the NAD is truly no more? How much power do you need?

Are you channeling her? That's what she'd say. But, in the end, I could convince her...

Oops, sorry - I should be making fun of you for not spending more money and for being afraid of your wife.

You wish you had a wife to be afraid of. Actually, she has been extremely accomodating of my audioholism. I'm lucky to have her. And no, she isn't looking over my shoulder...

 

[GO-NAD!]

He does like 'em right out of the closet. Nice and fresh.

Ewwwwwww!

(NTTAWWT)

 

[Adam]

You wish you had a wife to be afraid of.

You should see the looks Niki gives me when I spend too much time on here.

 

[ski2xblack]

Replacing power supply caps, rebiasing, back to factory spec should run $100-$150 at a reputable repair shop. Keep that in mind when considering a new amp!

 

[GO-NAD!]

You should see the looks Niki gives me when I spend too much time on here.

She must have a fixed expression on her face then...