Hum from Nearfield Monitors.

[NLAlston]

Hi,

I have a pair of Behringer 2031A monitors which are emitting a rather loud humming sound. They were working just fine before I bought a studio type desk station for my equipment. Everything is set up just as it was before (regarding the electrical connection), but just on a desk now. The Monitors are powered via my battery backup/surge connector block (as was before, also) and now emits a loud humming noise throughout the total periods of their operation. Any advice on what I might do to alleviate this?

[RAK]

Originally Posted by NLAlston

Hi,

I have a pair of Behringer 2031A monitors which are emitting a rather loud humming sound. They were working just fine before I bought a studio type desk station for my equipment. Everything is set up just as it was before (regarding the electrical connection), but just on a desk now. The Monitors are powered via my battery backup/surge connector block (as was before, also) and now emits a loud humming noise throughout the total periods of their operation. Any advice on what I might do to alleviate this?

How, and to what, are the monitors connected? Unbalanced cable issue perhaps?

[dementedchord]

putting aside any argument as to the berh speakers first make sure it's them and not something else sending the hum to them... ie. do they hum when the inputs are pulled??? in checking that you'll probably want to disconnect from the mixer side as alot of companies grnd the input when not connected and may not reveal if it is the speaker... good luck... if you get more info keep asking...

[NYMorningstar]

Check your mixer if you are using one and make sure you aren't just getting feedback from a condensor mic.

[NLAlston]

Thanks all.

My monitors are connected to a heavy duty tri-plug, and the singular end is inserted into my battery backup/surge protector box.

[ssscientist]

Originally Posted by RAK

How, and to what, are the monitors connected? Unbalanced cable issue perhaps?

That's not what RAK was asking.

He was asking about the audio connection, not the electrical.

You can tell a balanced 1/4" cable from an unbalanced one by the tip, ring and sleeve on both ends - unbalanced cables just have a tip and a sleeve.

.

[NLAlston]

OK. Let's see if I can give an appropriate answer to what was asked. On both ends of my cables there is the tip, sleeve and a single black ring just following the recessed area behind the tip.

[RAK]

Originally Posted by NLAlston

OK. Let's see if I can give an appropriate answer to what was asked. On both ends of my cables there is the tip, sleeve and a single black ring just following the recessed area behind the tip.

What you described is an unbalanced 1/4" cable. Also known as TS, for Tip-Sleeve.

I just looked up your monitors on Behringers site, and they accept XLR or TRS (Tip-Ring-Sleeve) connectors, which are both balanced. TRS cables have two black rings.

So I don't know what you're connecting the monitors to, but if that piece of equipment also accepts a balanced plug (TRS or XLR) try going to that, and see what happens.

Without getting into any specifics, details, or nuances, balanced cables reject noise.

As for power, you might also try an Iso Transformer.

Hope this helps.

[NLAlston]

Thanks Rak.

As you can tell, I know very little about such things. I had thought that the single ring meant mono - and that the doubled ring stood as a designator for stereo signals. I will try as you have suggested, because that humming is truly aggravating.

[RAK]

Originally Posted by NLAlston

Thanks Rak.

As you can tell, I know very little about such things. I had thought that the single ring meant mono - and that the doubled ring stood as a designator for stereo signals. I will try as you have suggested, because that humming is truly aggravating.

You're not entirely wrong there. The single ring (TS) has 2 wires (+signal, ground), the double ring (TRS) has 3 wires (+signal, -signal, ground).

So on a TRS cable you can send a L&R stereo signal, or you can send a mono signal down both (+/-).

The cable itself is the same, it's just a matter of what you do with it.

[mrT]

Originally Posted by NLAlston

Thanks Rak.

As you can tell, I know very little about such things. I had thought that the single ring meant mono - and that the doubled ring stood as a designator for stereo signals. I will try as you have suggested, because that humming is truly aggravating.

Might just be a ground loop. Is all of your equiptment grounded at only 1 place? do you have stuff plugged into two different outlets on the wall?

[mixsit]

What all is connected in your system? Basic trouble shooting is eliminating variables and zeroing in on the cause.
As mentioned before, do they hum by them selves? If so- end.

Connect them to just one source, both powered at the same plug, nothing else connected to the source. If the hun comes back it still could be the source at fault.
Conect them to comething else as a source (a spare cd player, tuner? Watch out if these are non-adjustable full level-out here.)

How long are the audio connections? I have a mackie 2408 that hums' suck ass with 18' on the main outs balanced or otherwise that is fine with six feet.
Wayne

[NLAlston]

Originally Posted by mrT

Might just be a ground loop. Is all of your equiptment grounded at only 1 place? do you have stuff plugged into two different outlets on the wall?

MrT,

All of my equipment is sharing the one double-plug electrical outlet. One thing which may be of importance is this: just before changing my setup to accomodate the acquisition of my studio station, I was having to deal with an adapter plug for the two-pronged eletrical outlet. I purchased & installed one of those GFCI outlets there in its stead.

I also just tried something which was suggested by a responder. I pulled the signal cable free from one of my monitors, then turned it on. There was a low staticy sound, for about 5 seconds, then total silence. The other speaker (still connected as it was) continued with that initial staticy noise AND the humming (continuous).

[ridgeback]

Originally Posted by NLAlston

MrT,

All of my equipment is sharing the one double-plug electrical outlet. One thing which may be of importance is this: just before changing my setup to accomodate the acquisition of my studio station, I was having to deal with an adapter plug for the two-pronged eletrical outlet. I purchased & installed one of those GFCI outlets there in its stead.

Hold the phone... 2 wire with ground or two wire with no ground feeding the outlet?

[NLAlston]

Originally Posted by ridgeback

Hold the phone... 2 wire with ground or two wire with no ground feeding the outlet?

Four wires in the outlet box (two hot, two neutral) with no ground. Our home is an older one (built, I believe, in the 40's), which we purchased about 4 years ago. I intend to get the wiring professionally updated, as soon as finances permit. But, in the meantime, I wanted to get away from using three-pronged adapters, and the consensus on the best alternative measure was to install GFCI outlets.

So - no, there is no ground wire servicing that (and a few of the other) outlets in our home. I really hope that this doesn't spell possible doom for my equipment. If there is a better, safer method (short of being able to have our wiring properly updated) to ensure satisfactory usage, please advise.

[ridgeback]

Originally Posted by NLAlston

Four wires in the outlet box (two hot, two neutral) with no ground. Our home is an older one (built, I believe, in the 40's), which we purchased about 4 years ago. I intend to get the wiring professionally updated, as soon as finances permit. But, in the meantime, I wanted to get away from using three-pronged adapters, and the consensus on the best alternative measure was to install GFCI outlets.

So - no, there is no ground wire servicing that (and a few of the other) outlets in our home. I really hope that this doesn't spell possible doom for my equipment. If there is a better, safer method (short of being able to have our wiring properly updated) to ensure satisfactory usage, please advise.

Well it seems that was the only equipment change made. Grounding can always be an issue when it comes to any sound gear. Technically, installing a GFCI on a two-wire no ground system is a smart move and we are required by the NEC to do so in my trade. But thats another story.
If you're using the exact same cords for connections and you have checked all that, we might have a phase problem. Are there any appliances plugged into that circuit down stream? Anything with a motor in it?
The end all solution to eliminating power issues would be to have an electrician drop 1 new GROUNDED circuit at your recording location. This would serve only that location. You don't need to rewire the whole house and it wouldn't cost an arm and leg to do it. We're pretty good at sneaking wires in walls without damage. This might or might not solve the problem but it would eliminate that possibility and serve you well down the road. That gear really should be grounded and on it's own circuit.
Sorry if this doesn't help your immediate situation but it's good advice I think.

[RAK]

So did you try the balanced audio cables?

[NLAlston]

Originally Posted by ridgeback

Well it seems that was the only equipment change made. Grounding can always be an issue when it comes to any sound gear. Technically, installing a GFCI on a two-wire no ground system is a smart move and we are required by the NEC to do so in my trade. But thats another story.
If you're using the exact same cords for connections and you have checked all that, we might have a phase problem. Are there any appliances plugged into that circuit down stream? Anything with a motor in it?
The end all solution to eliminating power issues would be to have an electrician drop 1 new GROUNDED circuit at your recording location. This would serve only that location. You don't need to rewire the whole house and it wouldn't cost an arm and leg to do it. We're pretty good at sneaking wires in walls without damage. This might or might not solve the problem but it would eliminate that possibility and serve you well down the road. That gear really should be grounded and on it's own circuit.
Sorry if this doesn't help your immediate situation but it's good advice I think.

Ridgeback,

When you asked about a motorized appliance being tied in "down stream', are you in reference to something being on another outlet on the same line as the concerned one? If my assumption is on the mark, I cannot - as yet - give a definitive answer. I say this because the previous owners seemed to have jury-rigged quite a bit here, especially on the electrical side. Initially, this home was a single, then added onto and changed to a double (we thought that it would make a nice, large single for our family, and have been in the process of converting it to such). Whoever did the electrical work, before, did (IMO) a messed up job of it. The only lines that I am certain of are the two 220v service runs (one each for upper/lower areas). Regarding the 110v lines, I am going to have to take the time to find out just what is being handled by each. I remember shutting off a breaker, once, and finding that it cut out something upstairs, as well as the intended outlet downstairs. This, in fact, happen on more than just that one breaker. I now have one of those two-piece electrical units which allows one to match outlets with their respective breakers. So, this should really serve to enlighten me as to what is on what.

I didn't mean to get so long-winded on this, but hoped that it would help to illustrate, a little better, what was going on here. And, for the record, I want you to know that I find your suggestion to be VERY SOUND advice - regardless as to whether or not it would alleviate my equipment issue. I appreciate it much.

[NLAlston]

Originally Posted by RAK

So did you try the balanced audio cables?

Not yet, Rak. I won't be in the position to get them until later this evening, or maybe some time tomorrow.

[ridgeback]

Just let me know how I can help further.

[TexRoadkill]

Try turning off the AC/Heater and unplug the fridge and turn off any fans. I live in an older house and have to do that everytime I record.

[SonicAlbert]

None of these suggestions really addresses the fact that the only thing that changed (apparently) was the studio desk. They are all good suggestions though.

So yes, going to balanced cables could be a good idea assuming that the gear feeding the monitors has balanced outputs. But the original problem could still be there.

It seems to me that if literally *nothing* changed except the desk, the problem could be the placement of the monitors in relation to other pieces of equipment. Or it could also be caused by how the cables and power wires are run. Power and audio cables should never run parallel, but cross at right angles. It is also possible that there is a power supply like a wall wart or lump in line near the audio cables now that wasn't there before. Or the speakers could be nearer a computer monitor or other source of interference.

Those are the areas I would look at first.

[COOLCAT]

yeah, the desk. is it a rack mountable type desk with metal rails?
maybe the rails are now connecting some kind of chasis ground hum between units?

not that I've ever heard a desk causing this issue, but I have seen unit to unit issues at work, although usaully it helps to have them all wired together chasis to chasis.

just a SWAG.