NAD 3130 amp popping speakers

Status
Not open for further replies.
Jump to Latest
#22
Strange things goin' in those NADs, ain't them?

Also mine does the popping. The original owner said it has always done that. Mine is a 3020 "Series 20", 1983 I think.

I bet both of us have offset problems, and luckily I have found on the service manual that the offset is adjustable.

That distorted sound could be due to a misfunctioning transistor, but I now believe more in cracked solder joints than before.
 
#23
"I bet both of us have offset problems, and luckily I have found on the service manual that the offset is adjustable. "

Ever heard of 'barking up the wrong tree'?

NAD uses single ended stages.

Even if both ±V supplies came up and down together (wishful thinking) there will be a point at which things power up and down that are not symetrical.

If you want it quiet, buy a DIY add-on relay kit.
 
#24
I have an NAD T761 receiver that was popping on turn-on. Fortunately it was under warranty, so I sent it back to the manufacturer. He said it was a faulty cap in the turn-on delay cct.

I've used NAD amps for many years, at first in my main system and now in a secondary system. They sound more powerful than their power rating, and they are very musical. Worth keeping if you can get it fixed for a reasonable price.
 
#28
"No. If I understand you well, you're wrong, since my NAD uses a complementary output stage, based on 2N3055 and MJ2955. I'm quite sure about this "

The outputs are are not the issue, the front end design is.

I would define 'single ended' to be like the ESP 3A, and 'complimentary' to be like a Leach.
 
#31
Hi Giaime,
A single ended input is very like a tube amplifier input stage. The main difference is that it is direct coupled. Therefore, not as stable.

A differential input has one base (gate) referenced to ground normally through a resistance. Signal is applied here. The other base (gate) is referenced through a resistance to the output. Feedback is normally input here. Temperature variations are cancelled because the two transistors are in opposition. This arrangement is also much more linear as input and feedback signals see the same non-linearity. This should cancel more or less. The diff pair will act to keep the bases (gates) at the same potential dynamically (AC and DC).

-Chris
 
#33
Hi,


The distortion at turn on I referred to in my previous post came back and would not go away today! (at first i thought i was still drunk from the night before :dead: )

I had the volume low with the "soft clipping" on which I thought was ok. 🙄

I turned the soft clipping off, and the distortion went.
I am unsure why the soft clipping was kicking in when it wasn't supposed to (at all volumes):smash:

Found this link

http://www.diyaudio.com/forums/showthread.php?s=&threadid=24377&highlight=

Should I just leave the soft clipping off?

Do people think the "popping" is slowly killing my NAD? :smash:


Kind regards,


Ashley.
 
#36
The distortion came back again so I thought i would replace the speaker cables.

Now it works. 😀

I don't really know anything about amps . I have been trying to get upto speed with cd players. :dead: (starting from the source)

If there is a bad connection with the speaker cable at the amp or speaker does this mean that the amp must work harder because of the higher resistance causing the distortion?

Is speaker cable choice is as important as actual speaker choice ?

Is the ideal speaker cable no speaker cable ?

(I think i saw a Meridian thing that had digital decoder, amplifier,and speaker built into one box!)


Anyway, apologies for the noob questions!


Regards,


Ashley




Kind regards,


Ashley.
 
#37
Hi Ashley,
Temporarily short the circuit breakers out. These are small rectangular boxes (black) on the amp PCB. Two legs soldered on the PCB. See if that improves the sound.
Faulty speaker connections will sound terrible.

-Chris
 
#38
Hi,


I don't have the schematics for the NAD 3130 but I finally got some time to look over the amp by hand with a tourch.

Two things of note:-

1. Two very bulging caps in the bottom right area of the pcb (they look alot more bulged than others)

2. A ceramic capacitor near the heatsinks that looks like its been flame tested!

I do not know for sure if this is the problem.

All i know is the problem (distored left channel) dissappears normally after about 30 mins. Only problem is during that 30 mins its unbearable but it has to be on rather than muted so it can 'fix itself'.


Anyway, I will do the tests suggested.


Plus aquired some B&W speakers, and i am blown away.


Kind regards,


Ashley.
 
#39
Hi Ashley,
Once the set has warmed up, try spraying some cold spray on the transistors. One at a time and wait 15~30 sec. between sprays. Just shot shots. If no joy, do the same with resistors and then ceramic caps. Lastly you could try the electrolytics.
When the set sounds bad again, you are in the area where the problem is.

-Chris
 
#40
anatech said:
Yup, NAD has a single ended input stage. This is inherently going to give a DC offset that will drift more than a standard diff. pair.

-Chris
Click to expand...

pardon my ignorance, but does this mean the coupling cap is critical? and, of course, that there is one there?

Ie, if I open up my 2400thx (rear surround, wouldn't dare use it for anything critical. Yes, it was free.) and find those caps and swap them out....now that I know they are there...

Duh. dc offset. no cap.
 
Status
Not open for further replies.
Top Bottom