Electrical Interference Noises Through Klipschorns...?

[annt]

So Ive owned a beautiful pair of 1970's Klipschorns for about a year now, I use them with a tube set up and love the way they sound.

I have the speakers tucked into the corners of a bedroom. One of the corners just happens to be where our breaker box is located on the exterior of the house.

A few months ago I started noticing a slight buzz and couldnt figure out where it was coming from.

This week it started up again and I finally realized that the left Klipshorn, where the breaker box is located seems to be picking up some kind of electrical interference. Its a very noticable buzz that starts slowly, peaks and then goes away after 30 minutes or so.

It only seems to happen when the amp is off, so there is nothing powering the speakers (it may happen when im listening to music as well, but I dont notice it). I think it's pretty safe to assume its the break box causing this. The speaker perform flawlessly otherwise.

Has anyone else experienced this and does anyone think this can damage the speakers?

[ricktate]

My guess would be loose connections in the breaker box and after the connection gets warm it stops arcing.After shutting off main breaker going to the box I would check all the connections in the box ...with rubber gloves and insulated screw diver. If not wanting to do it yourself have someone do it for you. I have seen loose connections inside breaker boxes cause a fire before so it could be dangerous. They loosen over time of heating up and cooling down due to loads put on them. Please get it looked at just for safety atleast.

I don't know what else would affect a speaker like that maybe froum member would know more. Rick

[ricktate]

I forgot to ask are you sure its a breaker box or just a meter or switch box? Don't think breaker box is allowed outside I have never seen one outside unless it's weather proof. Rick

[LarryC]

I forgot to ask are you sure its a breaker box or just a meter or switch box? Don't think breaker box is allowed outside I have never seen one outside unless it's weather proof. Rick

My service entrance is on an exterior wall of a corner where my right K-horn sits, just inches away from the crossover on the inside. The breaker box sits on the inside of the foundation wall immediately below that K-horn. I get a very faint buzz through the bass horn, the mid-range, and even (very faint) the tweeter, when the amplifier is not on and the speaker wires are not connected.

There is no such buzz from the left K-horn.

This kind of hum and buzz may be EMI, picked up by the crossover coils and sent to the speakers. You might disconnect your speaker wire to see if you have the same sort of thing.

I looked into shielding, but found it too formidable for my small problem -- ferromagnetic shielding plastered into a large section of the interior wall and perhaps on the floor between the speaker and breaker panel.

Good luck --

[ricktate]

Larry, I got question out to a friend of mine who is electrician see if he knows anyway to shield that from the power grid. You seem to have found whats making the noise though. Rick

[annt]

rick,

same situation as larry with the breaker location.

I have tested with the speaker cables disconnected so the interference definitely seems to be coming from behind the wall.

I actually placed another smaller speaker on top of the klipschorn when I heard the buzz to see if it was recreated with the other speaker but it didnt work.

Im guessing the fact that the Khorns are so sensitive plays a role in picking up the interference.

[djk]

I would check the connections in the box first, and re-do with the proper grease if aluminum wire is used.

Then I would try some 0.047µF ceramic disc capacitors across the mid and HF drivers and see what happens. I suspect the problem is the autoformer picking up EMI/RFI, the caps should help.

[ricktate]

If the crossover is picking up the noise could it be possible to move it farther away , making the wires to drivers longer. Should not take much distance to fix it . Easier than moving speakers...but [Aant..Larry] you should both have someone atleast look at the breaker box thats close to those speakers..I have replaced breaker boxes and have seen some goofy and dangerous situations , I would rather you be safe than sorry....Rick

[Chris A]

does anyone think this can damage the speakers?

I don't believe that you have a problem here.

I'm guessing the fact that the Khorns are so sensitive plays a role in picking up the interference.

Yes.

A few months ago I started noticing a slight buzz and couldn't figure out where it was coming from...It's a very noticeable buzz that starts slowly, peaks
and then goes away after 30 minutes or so.

Maybe a water heater, A/C or heater,
or a refrigerator?

You might try just flipping all the breakers a couple of times (assuming breakers in your box, and not fuses) and listen for any changes in your buzzing sound. Further areas to investigate might include the screw connectors to each of the breaker circuits entering the box - but be careful and switch off all circuits if you decide to tighten any breaker connections. You could simply turn off the breakers one at a time until the buzzing stops (assuming that the problem is on the electrical load side of the box). Then tighten all the connections on the breaker in question. As a long shot, you might try twisting your speaker wires a couple of turns for each foot of length (assuming you have non-coax speaker wires), then listen again.

djk, above, also provided a potential solution path if your dwelling uses aluminum wiring. These connections loosen with time if the breaker connections aren't the proper (i.e., high dollar) ones to use with copper/aluminum connections, and also can indicate that you might have other potential problems such as potential electrical arcing if aluminum is the culprit.

Chris

[steve sells]

I am an IBEW electrician, Hard to tell with
out me testing things, but start by checking to see if the electrical box
housing is grounded (as it should be) will shield some, also moving the XO coil
position in relation to the panel as suggested will diminish the effects of EMI.
Are there any old style fluorescent ballasts from lighting in your house? those
are notorious for 120Hz hum, as well as multiples of that due to 60HZ frequency
of US power grid, 100Hz (from the 50Hz) for UK systems.

this is a start if you are not 100%
confortable in your electrical panel, call a electrician for a safety inspection
( that can be a free estimate) if he sees a loose wire will most likely correct
that as a courtesy

[LarryC]

Are there any old style fluorescent ballasts from lighting in your house? those are notorious for 120Hz hum, as well as multiples of that due to 60HZ frequency of US power grid, 100Hz for UK systems.

Excellent point, and I've had problems along similar lines myself. My lighting-source buzzes were from transformer-based halogen lights, rather than ballasts, but that buzz had a lot sharper sound.

In my case, it took replacing a dimmer light switch marked "for incandescent lights only" with one marked "for electronic" lights. Lighting store employees aren't always alert to this. The change really worked.

Oddly, the buzz was louder on the side away from the service and breaker box. Dunno why.

[WMcD]

Larry beat me on this one.

Radio amateurs (hams) have been reporting interference from the transformers used with low voltage halogen lights as well as outdoor low voltage systems, and sometimes chargers for drills and the like. This arises because the transformers are not the classic type. Rather the system chop the AC 60 Hertz up to 15000 Hertz (and there are harmonics much higher up and these can even jam garage door opener systems). This 15000 Hertz thing is done because thel transformers used are much more efficient at high freqs and thus can be smaller. The source can be other items in the house too like lamp dimmers.

The source of Electromagnetic Interference (EMI) can be hunted down using a portable AM radio tuned to a place on the dial where there are no broadcast stations sending. This is usually the high end at 1700 Hertz (or the low end). You may have a Tap Tunes type bathroom radio or an emergency radio which receives AM broadcast.

Going around the house and outside you'll have to twist the radio around because the internal ferrite bar antenna is directional.

It might well be that the the bad noise is being transmitted around the house by the electrical wiring (so it gets into the breaker box) and your speaker feed wire is acting like an antenna. The speaker wire might be near a.c. wiring in the wall near the box, or even wiring outside, or in the basement.

Even if the source is not found, I'd suggest using some ferrite bead type filters on the speaker wire near the speaker. Try two at the speaker end and maybe two at the amp end. Maybe move all four to the speaker spaced at about three inches. You've seen these on feeds to computer LCD's where they keep the EMI from radiating. But they also work to keep EMI from getting into your feed wire.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=110-452

Let us know.

WMcD

AB9BE

[LarryC]

Well, I've read your magnum opus 3 X, and can't find a single place where I "beat" you -- your depth and knowledge are at the pinnacle, so I don't even try!

I did have isolated ground circuits installed, and switched house wiring near the equipment to metal-clad and re-routed it away from speakers and equipment. Those moves had very little effect.

The darn hums, buzzes, and RFI gremlins are really, really tough to deal with at times. Fortunately, I've never had to try things like you suggest. Not yet, anyway.

[steve sells]

Larry, one thing I didnt mention, that could be part of your problem could also be from the transformer on the pole, we had that happen at one office I was tracing down noise in, FYI ballast/transformer is a coil of wire, the newer electronic light ballasts are not as much of an issue as the older style

[LarryC]

part of your problem could also be from the transformer on the pole

Interesting! The EMI is only in the one speaker, so it's probably from a source that's very close just to that K-horn. In the lighting, the Juno transformers are only a few years old, so are probably newer. The replacement wall paddle-type off-on-dimmer switch almost totally took care of the left-side buzz.

Again, the two EMI"s were quite different: the right (breaker/entrance side) is a very low level, very constant, and very subdued hum, while the left side had a sharper buzz that varied quite a bit for no apparent reason. It was much worse before I changed the paddle switch.

[WMcD]

Larry,

I think you and Steve had very good observations. So I credit you, and I should add Steve too. You two beat me in a way.

Hams come from a culture where the source of a signal should be found. My ham brothers go on fox hunts for transmitters using receivers with directional antennae. The good guys and bad guys are trying to find the other's location. It is the same in warfare.

Therefore it is natural that we hunt down the problem with an AM receiver.

It is a bit alarming that people go into big investments in changes to their household wiring without determing the source of the problem.

Further. The hams are looking for sources which are detected by very sensitive receivers. Our horn loaded speaker are better reveivers than other speakers. But they are really, in comparison to radio receivers, very poor.

It should not take much to make them even poorer radio receivers by the use of ferrite beads.

WMcD

[WMcD]

Let me also suggest twisting the feed line to the speakers.

By way of background, most people have heard of the term "twisted pair" refering to telephone lines, and the pairs of wire in CAT5 are twisted, too.

This is done to make sure any outside field is imposed equally on both wires in the pair. Overall, one wire is not more affected by the field by being closer -- the twisting means the wires alternate being close to any outside source.

When we "listen" to the signal on the wire pair we are actually detecting the difference in voltage between the two wires. Thus a signal (in this case the outside field) which is common to both wires has no effect on the difference (a type of common mode rejection).

This is part of making the feed wires function as poorer antennae.

WMcD

[steve sells]

you said the magic word DIMMER?!??!! that never occured to me to mention because they are such noise generators, most people avoid them because of that. Have you tried turing off that cutcuit to see if the noise goes away?