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Occasional buzzing out of left channel

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Posted on July 21, 2014 at 10:13:34
kerr
Audiophile

Posts: 4376
Location: Central Indiana
Joined: November 10, 2003
I'm trying to isolate a problem with my left channel where I get occasional bursts of crackling/distortion. Speaking honestly, I don't know if it's an amp problem or speaker problem (or cables!) so I may have the wrong forum.

What I've done so far is to switch inputs on the integrated (Denon PMA2000R) from the CD input to an AUX input. No good. I only have one set of binding posts on the amp so I can't switch those.

I don't have spare gear, but I'm willing to invest in or borrow whatever I need to isolate the problem but I'm wondering where I should start. Should I try speaker cables first, then interconnects, then amp, then speakers?

Any help would be appreciated and I apologize if I've posted in the wrong forum. Thanks!

 

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Keep the volume down when listening to Pungent Stench and Belphegor - and it'll be OK., posted on July 21, 2014 at 10:36:39
carcass93
Audiophile

Posts: 7181
Location: NJ
Joined: September 20, 2006
Couldn't help it, sorry.




 

Not happening!, posted on July 21, 2014 at 10:47:23
kerr
Audiophile

Posts: 4376
Location: Central Indiana
Joined: November 10, 2003
What's Plan B? :)

 

Amplifier, posted on July 21, 2014 at 13:29:15
hawkmoon
Audiophile

Posts: 903
Location: cleveland
Joined: July 11, 2003
I had a similar situation several months ago and it turned out to be a defective part in my amp. If you could borrow an amp and you could find out for sure.

Good luck

 

Need more detail but lots can be done to isolate the problem..., posted on July 21, 2014 at 17:55:06
AbeCollins
Audiophile

Posts: 46280
Location: USA
Joined: June 22, 2001
Contributor
  Since:
February 2, 2002

Don't rule out dirty connectors like RCA jacks, interconnect cable plugs, speaker wire connectors, and speaker terminals. But beyond that.....

There are several methodical steps you can take to isolate the problem. A common method is sometimes called half-splitting which is helpful if you have no idea where the problem originates. In general, you split the problem in half and see in which half the problem persists, then you split the problem in half again, and so on until you narrow it down. This is most helpful in serial electronic circuits, like an amplification chain.

--

First, does the crackling noise happen only while playing music? What happens if you disconnect all input sources and turn up the volume? Does the crackling noise occur?

By removing all input sources and checking for noise, you can potentially eliminate the input source as the cause. If the noise occurs with NO INPUT source, then it's obviously downstream with the Denon or speaker cables / speakers.

--

If the noise only occurs while playing music, what happens when you swap the Left and Right channel interconnects going from your CDP to the Denon? Does the noise remain in the Left channel or does it move to the Right channel?

If it moves, then the problem is not in the Denon but in your CDP or interconnects going from the CDP to the Denon.

If the noise does not move to the other channel, then the problem is in the Denon, speaker cables, or speakers.

--

Swap the Left speaker AND wires to the Right channel output, and the Right speaker AND wires to the Left channel output.


For clarity, physically swap the speaker locations too, moving the Left speaker to the Right side, and the Right speaker to the Left side.

Does the noise move to the Right or does it remain in the Left?

If it moved to the Right when you moved the speaker cables / speakers, then the problem is not in the Denon but in the speaker cable or speaker.

If the noise did not move then the problem is in the Denon.

--

If you want to further isolate the problem, the Denon should have a switch on the back labeled Power Amp Direct Mode, and RCA input jacks which will allow you to bypass the Denon's preamp and run directly into its amp section. Does your CDP have a volume control or do you have ANY other source component with volume control?

If yes, then switch to Power Amp Direct Mode and run your source into the RCA jacks associated with this mode.

Does the noise still exist? If yes, then the noise is in the amp section of your Denon integrated. If no, the noise is likely in the preamp section.

NOTE: For the test above, I'm assuming that the PMA-2000R has the Power Amp Direct Mode feature. My newer PMA-2000IVR does.

--

If the problem is in fact with the Denon, you can either troubleshoot it further with a DMM, signal injector, signal tracer, or oscilloscope if you have one..... Or get in touch with Denon or a reputable service tech for repairs.

Good luck.


 

Thank you!, posted on July 22, 2014 at 04:44:53
kerr
Audiophile

Posts: 4376
Location: Central Indiana
Joined: November 10, 2003
Your response was as perfect as I could ever hope for. Thanks, Abe!

 

RE: Occasional buzzing out of left channel, posted on July 22, 2014 at 17:54:58
Rod M
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Contributor
  Since:
March 1, 1999
As Abe mentioned, the first thing is to swap L/R on the CD player and see if the problem moves to the opposite channel. If it stays in the left, then it's the amp, speaker or cable. Swap the speaker cables from L to R. Does it move again? If so, it's the amp.

If it's the amp, it could be a dirty volume or other control. Does it make the noise if you move the controls up and down? If not, then it could be a cap or other part. Do you leave it on? Does it do it when it's just been turned on for a certain period and then behave? I have an old 2270 that does that. If I just leave it on, it's fine and dandy.



-Rod

 

RE: Occasional buzzing out of left channel, posted on July 23, 2014 at 08:31:57
kerr
Audiophile

Posts: 4376
Location: Central Indiana
Joined: November 10, 2003
Hi, Rod:

The most confounding thing about it is that it only distorts when it feels like it. It doesn't do so at any set times such as when it's first turned on, when I crank the volume, and such. It'll play music fine upon turn-on for 20 minutes and then crackle one day, the next day it'll crackle after 20 seconds.

Consequently, I'm going to have to sit right in front of the speakers and wait before I can see what each test results in. :)

I may try leaving it on as well. Thanks for the tip.

 

RE: Occasional buzzing out of left channel, posted on July 23, 2014 at 08:53:07
AbeCollins
Audiophile

Posts: 46280
Location: USA
Joined: June 22, 2001
Contributor
  Since:
February 2, 2002

Intermittent problems are often the most difficult to diagnose and fix. Sometimes you just wish the equipment would fail outright!

A couple tips for finding intermittent problems. You can try to use hot and cold to see if you can cause the problem to occur more consistently, or to squelch it. A small heat gun directing heat to the suspect area, or a can of freeze spray used in a similar manner. You can spray individual components or area of a circuit board. Look for cold solder joints, reheat suspect solder joints. Carefully flex a section of circuit board by applying pressure to see if you can cause the problem to occur. Apply slight pressure to individual components. Of course be very careful with live circuits.

Intermittents are a PITA.



 

Sounds like a failing caps...., posted on July 23, 2014 at 19:08:37
kuma
Audiophile

Posts: 10272
Location: IN
Joined: July 8, 2001
Does it happen on all front end equipment?

Have you tried a different source?

 

It's the amp, posted on July 26, 2014 at 14:29:49
kerr
Audiophile

Posts: 4376
Location: Central Indiana
Joined: November 10, 2003
While I was hoping it was the I/C's or speaker cables :)... it is indeed the amp. And it has a new manifestation - it also blares at times, as if the volume was turned up but only in one channel.

Thanks to all for your assistance!

 

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