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Hum in powered peakers (especially EONs)


GREGHUX

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Just got myself an EON 15 Gen 2 for stage sound - I am very impressed. But because its not new I'm a bit careful to make sure everything is 'normal' and one thing I have noticed is a hum (50Hz here in Australia - would be 60Hz in US). Its very low level (would not be noticeable unless all around was quiet), but still it is there. It is present even when there is no sound source or cable plugged in, and the level is independent of the position of any of the pots, whether they be level or EQ settings. This says to me that its the power amp which creates this small amount of hum. The level is also not affected by flouro lights.

My feeling is that this is normal - but can someone else who has these (or similar powered speakers) confirm? Remember I'm only talking a very low level.

 

Thanks

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The EON 15G2 I had was very sensitive to a variety of things. To eliminate hum I ran it many times with a 3-prong AC adapter (which you should NOT do because the electrical ground is eliminated and that is not safe, etc).

 

If anyone in a club turned a florescent light on, or someone powered-up an amp, you could hear a LOUD, 'click' through the EON...exagerated by the big horn.

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Do a google search for ground loop.

 

While many here will not recommend lifting the ground wire on any piece of equipment (for safety reasons, electrocution is a possibility), it is a way to quickly determine if a ground loop is the source of your problem.

 

I recently had a ground loop problem in my rack case. I lifted the ground on every piece of equipment except the amp and the problem was solved. I still have continuity to ground on every piece of equipment via the rack rails and the the metal casing of all the equipment and for good measure I use a GFI at the wall.

No guitarists were harmed during the making of this message.

 

In general, harmonic complexity is inversely proportional to the ratio between chording and non-chording instruments.

 

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I thought a ground loop could only occur if I had equipment plugged in, which I did not. The speaker is on its own - for this test there were no cables plugged in except for power.

 

keysplease - yes I noticed that when I turn on the fluouros in the room that there are pops through the speaker as the light comes on. But the hum itelf does not change in level.

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As I am prone to do, I answered without completely reading the initial post. Sorry.

 

It would appear you do not have a ground loop problem. Just for the hell of it what happens if you lift the ground anyway?

 

I jumped in because I had a ground loop problem a few months ago. It would be great if a few guys here with more technical chops would respond.

 

(I'll make it point to read slowly and completely. :) )

No guitarists were harmed during the making of this message.

 

In general, harmonic complexity is inversely proportional to the ratio between chording and non-chording instruments.

 

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Without an input to the amplifier the wires to the connector, and the connector itself will act like an antenna of sorts, the amplifier will of course try to process whatever signal it can find on the input. Try the same test with a loading plug with a resistor in it that matches the typical impedence of the device you are connecting to it....like, 600 ohms.
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Clavinovaguyusa

Yes that is not a bad idea. There are 3 inputs to terminate. All are set to line level. I did try terminating input 1 by using a signal source (my keyboard) but this resulted in no change.

 

BTW: Perhaps my description of 'hum' is a bad one. It does sound around 50Hz, but it does NOT sound sinusoidal (as you would expect from mains related hum). I noticed that my old power amp is producing a similar tone - might be related to the old wiring in the building (a bad earth?).

 

I might try the speaker somewhere else - even a different house with newer wiring just to see if it makes a diference (now that I think of it, we've had problms with bad earths in this part building beofore - 'tingling taps in the shower' no less!).

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I don't know the technical jargon for the problem, but I returned the ElectroVoice SxA250 powered speakers because of a continual low-level buzz that, while not noticable at regular rock or blues band volume, was too much for quieter solo piano work. I got the Mackie SRM-450s which, with the same set up, had no extraneous buzz.

 

The EVs sounded great otherwise and were significantly less weight to haul around, but the buzz drove me crazy playing piano alone.

aka âmisterdregsâ

 

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I am getting a buzz and occasionals pops when i turn the Eon G2 on or off.

 

Is it a defect in the design? Anyone?

The difference between what the most and the least learned people know is inexpressibly trivial in relation to that which is unknown
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Originally posted by GREGHUX:

Actually Buzz is a better word to describe what I'm hearing.

What you are hearing is probably RF interference that is being rectified inside the speaker's amp. Its coming from a dimmer switch or certain kinds of power supplies.

 

The suggestion of putting a terminating plug in the inputs to see if it goes away is a good one. Unfortunately you can't just go down to Freddies[1] and buy one - I think you wil have to make it.

 

You can also try putting some ferrite cores on the power cable near the speaker. Its possible for the power connections to pick up RF as well as the signal ones - the chord acts as an aerial.

 

[1]The local Oregon super market. But it has clothes and tools and paint and electronics and garden stuff and homewares as well.

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There are 2 Eon G2's at a club i play at ( there are refrigerators in this restaurant too ) that both have the buzz. Plus my personal Eon has the same buzz.

 

Gauge of ext cords?? Would that help? I need to fix this poor design problem with JBL

The difference between what the most and the least learned people know is inexpressibly trivial in relation to that which is unknown
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Last night I had a rehearsal. I had to try hard to hear to the buzz - its really low level and will not not concern me now that from the response I've had, it appears to be 'normal'. Didn't get around to turning off all the applicances in the building one by one - but I will and will report my findings here!

 

To answer the questions posed above - extension cords are short (3m / 10ft), and don't run anywhere near other powered devices. As far as gauge goes, I'm not sure - but in Austrlalia the gauge will be thinner since we use 240VAC and therefore current requirements are around half yours (assume you are in USA). But who knows what the power cable routing is like inside the wall cavity. I'd say it is likly an RF thing being picked up somewhere in the system, as suggested by Byrdman. Need to see what happens when I move the speaker to a different location / building as well.

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Well I've done my tests. If I power down everything in the house apart from the speaker I still get the hum. Perhaps the power in my neighborhood is not very 'clean' - or perhaps its the speaker.

 

Suraci. Does your personal speaker prodcuce the hum when there are no inputs feeding it, and when you have it powered up at home?

 

Does anyone know the relationship between the serial number and the age of the item? Mine has serial number 15G2/230-12022. I'm guessing that's December of 2002 (not sure about the last 2).

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