Crackle and dropout

Maybe someone can help me with an audio mystery that’s going on in my world. Something’s not right in my system and I can’t figure it out. Preamp? Amp? Speakers? Cables? Interference?

Marantz CD6006 CD Player/DAC
McIntosh C27 Preamp
McIntosh MC2200 Amp
Kef 104/2 Speakers

The symptom:

There is this intermittent crackling/clicking sound with a hint of static and a dropoff in sound, but only for a split second. It gets worse the longer I listen.

It happens in both speakers at different times or simultaneously. It’s usually one crackle/click (almost like the sound of a CD skip), a short dropout of sound, then it’s back to normal.

Maybe once a night, it will cut out for a longer time, 3-4 seconds, then come back.

Here’s what I’ve done so far to troubleshoot:

-CD Player: Listened on headphones connected to CD Player. No crackling or dropout on headphones.

-Amp: Listened on headphones connected to amp. No Crackling or dropout.

-Swapped to different Speakers: Connected Elac Bookshelves to system. No obvious issues.

-Bypassed the preamp, connecting CD player directly to amp: No crackling or dropout.

All these tests point to healthy components. I changed speaker cables and interconnects a few weeks ago but I changed them to try and remedy this very problem. The speakers were recapped/refurbished a few months ago. Preamp and Amp were fully serviced last year.

The problem only happens when every regular component of the system is hooked up. I’ll be getting a cheap amp to swap out this weekend to further troubleshoot. Any ideas?



You sure it’s not the preamp?

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The headphones played fine connected to the amp which would indicate the preamp is doing ok.

Did you have the headphones connected to the amp or the preamp. You have said the amp twice now. Also on many preamps the headphone circuit is separate from the line outputs. The problem appears to only occur when you are using the line outputs from the preamp.

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Headphones connected to the amp not the preamp.

So that does not eliminate the preamp as the problem and could be something as simple as bad solder joints on the output jacks. Have you tried both sets of outputs on the C27? The fact that you get no noise by connecting the CD player directly to the amp points to the preamp as the problem.

Yes that would be the case, but the headphones sounded fine connected to the amp which was getting its signal from the preamp.

That would leave the speaker terminals on the amp but you said you didn’t get any noise when you fed the CD player straight to the amp and out to the KEF’s.

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I just did something in the last hour that might have fixed it. Crossing my fingers.

My xfinity cable was touching both speaker cables in a lots of spots. Got the xfinity cable totally out of the way. Been listening for 45 minutes now and haven’t heard the problem. Could be temporary luck. We shall see.

Doubt that was a coincidence as their CATV transmissions are always an issue around stereo systems. I’ve had to run a ground isolation device on the Xfinity cable line in my Family Room from the beginning to eliminate issues with the sound system.

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I think that was it. All the excess of the xfinity cable was wrapped under the shelving for the system. Now I’ve tucked most of it away in the kitchen. Hey, thanks for chiming in!

Glad to try and help. If your in a residence and not an apartment you might want to go outside and check their ground connection as their techs are notoriously sloppy about proper grounding. I go outside about once a year and clean and retighten the ground connection at the outside box. Also might want to source a new coax cable that just reaches from the wall to the cable box. Anyway enjoy now that everything is working.

HumZero – PS Audio

cheap insurance


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I would start with interconnects. Try replacing source to preamp and preamp to amp. If it’s only on one channel try swapping left to right cables. Could be poor connection between the cable and connector or the connector on the cable and the connector on the component.

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Very nice and musical system. I am going to take a guess based on my experience with the KEF 103/3 loud speakers. Considering the age of your KEF 104/2, I am guessing 25 + years, the woofer dust caps have deteriorated and need attention. For the KEF 103/3 the woofers are down facing so for the most part when mine went it was not an urgent need. However, I believe the KEF 104/2 woofer face forward and thus a fix may be more important. Also, the woofers are subject to sag as they age, the spider does not maintain the woofer coil centered in the air gap. This is handled when replacing the dust cap, and then rotating the woofers 180 degrees when remounting them. My KEF 103/3 woofers had a butyl rubber surround and as such are not subject to rot or failure. It is possible the KEF 104/2 uses a different surround and may need the surrounds replaced as well. Also, with that series of KEF speakers the fabric dome tweeter utilized a ferro fluid in the air gap. By now that has dried out and crystalized affecting high frequency response. This too can be repaired by removing the tweeter, disassembling it, cleaning out the old ferro fluid and installing new fluid. The tweeters are no longer available. I have rebuilt several pairs of KEF 103/3 speakers. Good luck.

Here is a video showing the repair process:

KEF 104/2

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Kefs were fully refurbished, donuts, crossover, tweeters etc. I may have found a fix by removing the TV cable line away from the stereo.

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Still curious as to why, before removing the TV cable line, the Elac bookshelves didn’t exhibit the audible interference that the Kefs did. When listening to the Elacs, I might have heard the slightest crackle, but nothing like the crackle/click/dropout of the Kefs.

Yeah, weedeewop. I agree that it’s a musical system. I am thinking of selling the amp. It’s never been recapped, and I just don’t want to deal with that. Vintage is a blessing and a curse.

Considering the McIntosh build quality and the cost of replacing with an equivalent or better, I’d reconsider the recap option, unless of course you were considering a McIntosh MC275.

It’s more a matter of wanting to try some different flavors coupled with the fact that no local place will recap it and I don’t want to ship it to Audio Classics. Also, in the future I might want to try a Maggie and autoformers seem not to be a good match for Maggies.