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Sound "crackles" when volume is increased and decreased

slimetcake

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I don't know if 'crackle' is the proper way to describe it, but I hope you'll understand what I mean.

Here's the exact issue:
I have a pair of 6.5" speakers hooked up to my NAD C326BEE amplifier. Whenever I turn the volume knob at fairly loud volumes (anywhere above 9 o'clock) the tweeters make this kind of high pitch crackling sound. It almost sounds like distortion.

Please note that the issue only occurs whenever I turn the volume up or down. The speakers sound fine whenever the volume knob stays in the same place even at high volumes.

I'm almost sure that it has nothing to do with the speakers because they handle loud volumes like a charm. It only happens when I turn the volume knob.

I hope you can come up with an explaination. Thanks.
 
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Thad E Ginathom

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My suggestion...

The volume knob (or rather the pot that it is connected to) itself. is at fault. I don't know if it can be serviced or if the service consists of replacing it.

One test for this would be to use an input which itself has a volume control, and see if the crackle always occurs at the same point on the volume rotation, regardless of actual sound level. Also, does it happen when playing nothing through the amp? ie do you get crackle instead of silence?
 

krell

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open the case, observe the volume pot.you may see some holes in the volume pot.just spray some deoxit like contact cleaner. if you didnt find deoxit, you can use any contact cleaner to clean the traces.spray and operate the volume knob no of times.
i hope this helps.
 

dheerajin

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Actually it is carbon deposition at the sliding contacts of volume knob. One method of cleaning is already mentioned by a FM, another is rotate the volume knob 10-12 times very fast while amp is in off mode and see the difference.

I don't know if 'crackle' is the proper way to describe it, but I hope you'll understand what I mean.

Here's the exact issue:
I have a pair of 6.5" speakers hooked up to my NAD C326BEE amplifier. Whenever I turn the volume knob at fairly loud volumes (anywhere above 9 o'clock) the tweeters make this kind of high pitch crackling sound. It almost sounds like distortion.

Please note that the issue only occurs whenever I turn the volume up or down. The speakers sound fine whenever the volume knob stays in the same place even at high volumes.

I'm almost sure that it has nothing to do with the speakers because they handle loud volumes like a charm. It only happens when I turn the volume knob.

I hope you can come up with an explaination. Thanks.
 

Shivam

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I like WD40 for this purpose. Switch off the amp, open the cover and spray a little amount inside the knob assembly. Turn the knob around multiple times as told above. Do it a few times again after a gap of some hours. Wait for a couple of days before switching on the amp.

(If you use a dedicated contact cleaner, then waiting for a few days is not required)
 

haisaikat

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One method of cleaning is already mentioned by a FM, another is rotate the volume knob 10-12 times very fast while amp is in off mode and see the difference.
+1, this is what even I do for my stereo amp and the distortion goes away for at least 1 week after doing this exercise once. Some amps like the one I have even provide a small hole on the cabinet on top of the volume pot so that it is easy to drop cleaner without opening the case.
 

jagdish_p

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As other FMs have suggested cleaning the vol pot is the answer.

And if you are unable to clean by spraying it with wd40 ignore the crackle. ( I assume it happens only when turning the pot and not during regular listening)
It is irritating but is not harmful.
 

AMITNOIDA

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I had the same problem about a year ago in my Tube amp. The problem is called 'Clipping'. I was as usual slightly worried. But our beloved Virenji checked my amp and found the parts and circuits all are fine. Only thing he suggested is what Dheerajin has already suggested. Rotate the volume switch 10-12 times very fast while the amp is 'Off'. I think you have nothing to worry. You may at most require cleaning of the volume switch after opening the cover, as Thad e Ginathom has suggested, if the fast rotation method does not bring in any result. But first try the fast rotation.
 

Fantastic

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This isn't clipping. Clipping happens when the output signal has reached it's maximum level and tries to exceed that and it distorts and looks 'clipped' on an oscilloscope screen. This is an electrical problem and only due to excessive signal level which the amp is not capable of delivering.

Crackling in the volume pot ( potentiometer ...not called a ' volume switch') is due to dust or flaked off track particles inside the volume pot. The spray cleaner will clear that . If the conductive track is damaged then even a spray will not work. You will need to replace the pot.
Spray some cleaner through the holes on the case of the pot and rotate the pot " gently " forwards and backwards. Sometimes very vigorous rotation could damage further an old conductive track. Spray a couple of times.
WD40 takes a long time to evaporate and can leave a messy oily residue. Dedicated contact cleaners dry up very fast. Deoxit is available on Electronics, Cars, Fashion, Collectibles, Coupons and More Online Shopping | eBay but very expensive now. Other brands are also available at much lower prices. Will be better than WD40 for this application.

After cleaning turn on the amp and check it again. If you have some residual noise switch off the amp and spray clean once again. Usually this solves the problem. Noise might recur after several weeks when you can clean it again "gently " !
 

cyber_cat

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Plug in a pair of headphones to check whether the volume pot is showing error at the same position. This way you can be more sure before you try to clean the pot.

Do you have another pair of speakers or an amp lying with you or that you can borrow to use them in your current system ?

Is your system brand new. What is the date of purchase ?

Cheers
 
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Thad E Ginathom

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Clipping: you can hear it at, for example, weddings, where the sound guy seems to believe that driven to distortion is the right setting :eek:. I have even seen this done to classical performances :mad:

The non-electronics-orientated among us usually know that the component is called a pot[-entiometer], but still feel more comfortable talking about volume controls. Bear with us :)
 

slimetcake

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You have all been very helpful, and I thank you for that.

I took the advice of turning the amplifier off and rotating the knob very fast 10-12 times.

After having tested the sound one more time I can gladly say that I'm now free of that annoying crackling sound when changing volume.

My setup is quite new, so it made me a bit worried to have an issue like this already, but fortunately it wasn't that difficult to sort it out.

Thanks again everyone :eek:hyeah:
 

Fantastic

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.....The non-electronics-orientated among us usually know that the component is called a pot[-entiometer], but still feel more comfortable talking about volume controls. .....
:)
Just like any language issues, just tried to correct the usage of terms.
No offense mean to anyone. I think it should be helpful to those struggling to use the ( usual ) proper terms. However ,I'm not perfect either. ;)
 

greenhorn

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If you can get a proper contact cleaner like deoxit, then suggest you not use WD 40.

WD40 is not the right thing to use. It might end up making it worse in the long term. It's just a lubricant.
 

Thad E Ginathom

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:)
Just like any language issues, just tried to correct the usage of terms.
No offense mean to anyone. I think it should be helpful to those struggling to use the ( usual ) proper terms. However ,I'm not perfect either. ;)
:) On my to-do list: find out the difference between a potentiometer and a variable resistor. Apparently there is one. For a long time I thought that potentiometer was just a posher name! Yes, I'm with you on spreading education and correct terminology: more please! :eek:hyeah:

Last week I discovered this site: The Scots Guide to Electronics. It's open to non-Scots ;) and I think it is going to be a great help to me and others who might be electrically challenged. It goes all the way, too, from what a resistor is to sampling theory and how a CDP works.
 

dheerajin

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no need to purchase any specialized liquid..any pure spirit (alcohol) would do the efficient cleaning..if you dont find such thing then..try with after shave...and see the difference...dont smell the volume knob after that..that smell meant for ladies..:D
 

efernand1

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Hi

Electronic Repairers use something called CTC..Carbon Tetra Chloride...it is available at a chemist and seems to works well.
 

greenhorn

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:) On my to-do list: find out the difference between a potentiometer and a variable resistor. Apparently there is one. For a long time I thought that potentiometer was just a posher name! Yes, I'm with you on spreading education and correct terminology: more please! :eek:hyeah:
If you haven't already figured it out, a variable resistor should be a two terminal device, and the resistance between the two pins would be variable.

A potentiometer is a three terminal device. with a fixed resistance between two pins, and the third pin somewhere in between, depending on the positition of the slider/wiper.


You can make a variable resistor out of a pot by just not using the third terminal.

Also, it is possible to have a rotary volume switch - those stepped attenuators used in higher end amps to reduce the gain mismatch between the pots are essentially rotary switches, and not technically potentiometers
 
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