# Powered Monitor Electrical Hum



## blademaster (Sep 20, 2007)

OK so a few months back (like 2 or 3 months) my church got two Galaxy Audio PA 5X 140 http://72.14.253.104/search?q=cache...140&hl=en&ct=clnk&cd=3&gl=us&client=firefox-a

Well we just recently started raising volumes and I noticed a 60 cycle hum when we had a input running from the board to the powered monitor. First i though of a bad cable, nope. Next I tried removing the ground from the monitor, nope, then i plugged it into the same breaker as the mixer and amp, nope. Then I raised the ground on it, nope. (all previous test using a TS 1/4 plugin from XLR) then with it properly grounded i did the same test using a balanced XLR to the second input, nope. The only thing i can figure is manufacturer defect. This is happening on both of the powered monitors and only on the signal coming from the mixer. any ideas....


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## SHARYNF (Sep 20, 2007)

Is the output of your mixer a Balanced XLR connection, or are you converting from TS to XLR?

Have you physically plugged the monitor into the same OUTLET as the mixer, not just the same breaker?

Have you physically checked the wireing connection on the mic cable XLR connectors?

Sharyn


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## j_blinker (Sep 20, 2007)

Hey Blademaster,

Sounds like you might have been trying to lift the ground using an XLR to TS adapter. There's a good chance that adapter is putting pins 1 and 3 on the ground rather than lifting the ground from your output. If you have a ground hum this would only open the cable up to RF interference over the length of the unbalanced run and at best put the hum onto pin 2. To find out if it is a grounding problem inserting a ground lift on the output of you're board, this should simply break the pin 1 connection at the board, not merge it like a TS adapter. If this doesn't make the source of the problem clear there's an easy way to test the cleanliness of your groundings. Grab you're multi meter and check the voltage between hot and neutral, and neutral and ground on all you're outlets and make sure the outlets are the same, or ideally, run an extension cord and test the voltage between your two grounds. If a voltage different exists between the grounds you've found you're problem. Just because they're on the same breaker they aren't immune to leaky voltage, as the paths their grounds follow is likely very different. Good luck.


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## blademaster (Sep 20, 2007)

the output from the mixer is a true balanced XLR.
yes i did put it on the same outlet as the mixer
no i havent checked the wiring on the XLR cable, though it is a manufactured cable not a diy cable.
I raised the ground on it by using a adapter for the power on the monitor.
the output on the mixer is a balanced XLR out, however the monitor has two inpouts one 1/4 (dont know if it is balanced or not) then we have a balanced XLR. the only way i know of that my church has the capability to lift grounds is using a DI Box,


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## SerraAva (Sep 20, 2007)

Sound of power? Said it is only heard when turning it up. How much more dB does turning it up entail? The other problem might be what is else is plugged into your breaker box, or the breaker box might just be a sub box to another larger breaker box. Trace it to make sure its just your power and no one else's. There might be a shorted ground some where else that you don't know about.

Try unplugging everything and just starting with the monitor plugged in. If you have the 60 cycle, lift the ground. Still there, its in the monitor. If not, go back and add things one at a time to find what the cause is. Might take a while to do it, but you will find exactly what the source is this way. This is assuming you have never had a 60 cycle through the mains before, or have and knew what the problem was. Good luck, hope you find that 60 cycle gremlin.


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## blademaster (Sep 20, 2007)

Naw this isnt in our Mains this is for our Stage monitors. we own the buildings so its our power,period. the power for all the tech stuff is run off a sub-breaker box


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## SerraAva (Sep 20, 2007)

So that means you can eliminate anything that is in loop with the mains. So its in the monitor, a ground short some where in the monitor loop, or just turning it up too loud that its amping nothing. Have you tried a different send off the board just out of curiosity, maybe the send is bad? Also, try an iso-transformer. Its a ground lift that goes through a transformer instead of just cutting off the ground. It goes in line of the mic, or this case send, cable.


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## blademaster (Sep 20, 2007)

The sound thats coming from it is not the same sound as when you are amping nothing, given you can hear it most clearly when it is not running anything but it is a diff sound. no i havent tried using a different out, we have used this one for other things no problem.. I dont have a iso-transformer but i was looking at one...i'll check with the shop today.


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## SHARYNF (Sep 20, 2007)

You might make up a cable that is xlr to xlr but has the shield disconnected use it at the amp end, and try that also disconnect the xlr cable from the mixer, leave it attached to the monitor and see if the problem is still there 

BUT:
It is possible that the monitor has a pin one problem where they are using the shield and ground connected to gether, Many times I have found when you have an input that has balanced AND unbalanced, this occurs, since the unbalanced TR Jack connects the two together along with the chassis. In general, I go into the connection plate and disconnect the tr 1/4 jack completely, since in effect what this is probably doing is converting the xlr input to unbalanced. An other option is to get a balancing Isolation transformer, like Whirlwind makes, but If they will let you I would pul the plate and carefully disconnect, make sure that the ground and shield is not connected together, and and tape up the wires individually. I would be willing to bet that is the problem

Sharyn


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## blademaster (Sep 20, 2007)

ok the problem disappears when it is disconnected from the board at either end. we dont have a iso-transformer. would me hooking a di box into it help me at all....
the likelyhood of me being able to pop it open is almost nil it almost certainly voids the warranty and right now i am disliked by most ppl in my church except the for one of the two ppl that can give me permission to open it up... but i honestly dont think it is unless it is a part of the manufacturer's specs, we have two and both are behaving like this, they are from the same batch those...
tried a diff send and we still have issues...


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## SHARYNF (Sep 21, 2007)

I'd try to disconnect the ground on the XLR pin one cable connection at the speakers.(open up the connector on the cable )

Di is not likely to do the trick, typically the output is mic level and the input is unbalanced line level

What the test you did is telling us in all probablity is it is not the cable acting as an antenna, but it is the ground potential difference between the two systems, in all likely hood it is what I call a pin one problem, so as I said above lift the ground on the INPUT CABLE, not the power cord

Sharyn


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## avkid (Sep 21, 2007)

If you use one these devices, you don't have to go cutting cables:
http://www.fullcompass.com/product/231502.html
Yes, I know it's expensive.
But it's Whirlwind, so it will outlive us all!


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## blademaster (Sep 21, 2007)

Thanks avkid, that would help me a lot if i could afford it. it really will outlive us all. My church almost a year ago got two DI Boxes made by Groove Tube, well we are extremely abusive on out equipment, they stopped working after a few gigs. our two IMP2 are still running fine.  indestructible

I can try to check with the local shop and see if they have one in their.


bit of useless knowledge, Whirlwind salespeople are willing to drive over their DI Boxes to prove how indestructible they are.


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## avkid (Sep 21, 2007)

A simple splitter with an iso for the split will accomplish the same thing.
These have a good reputation and are very affordable:
http://www.audiopile.net/products/Electronics/MST-103_mic_splitter/MST-103_cutsheet.asp


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## mixmaster (Sep 21, 2007)

SHARYNF said:


> I'd try to disconnect the ground on the XLR pin one cable connection at the speakers.(open up the connector on the cable )
> Di is not likely to do the trick, typically the output is mic level and the input is unbalanced line level
> What the test you did is telling us in all probablity is it is not the cable acting as an antenna, but it is the ground potential difference between the two systems, in all likely hood it is what I call a pin one problem, so as I said above lift the ground on the INPUT CABLE, not the power cord
> Sharyn



I wouldn't be so quick to discount the DI box. Most DI boxes are basically impeadance matching transformers and work both ways. I suspect this is not a ground problem as much as an impeadance problem. 
I had a similar situation once. A drummer wanted to use the amp with his Electronic kit as a powered monitor so we fed his amp off the board with a XLR to TRS adapter, and dialed in a mix that was heavy on the kit. Anyway, his amp buzzed like crazy. To add to the confusion, this was about 10 min before curtain. Tried lifting the AC ground on his amp (unsafe) without any luck. We replaced the adapter with a DI with the ground lift switch, everything was great. Unfortunately, because of the time factor, we couldn't do any further testing. 

I suggest trying a DI box temporarily. Cable from the output of the mixer to the XLR jack on the DI box. Cable from the a 1/4" jack on the DI box to the input of your powered monitor. Start with the ground in. If the DI box alone solves the problem, you have an impedance mismatch. An line matching transformer could be a permenant fix. If you have to lift the ground then you have a ground loop somewhere. 
Happy Hunting


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## SHARYNF (Sep 21, 2007)

Difference of experience here, while some of the di's can be run either way, typically they are also padding the signal down from line in to mic out, so you will loose too much signal level, need to boost it back up and that could cause problems

the Cheapest first test is to simply open up the xlr connector going to the amp, unsolder the pin 1 wire and test it
I agree, A whirlwind LBS would be the best for this, and well worth the price
Sharyn


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## j_blinker (Sep 25, 2007)

It's been suggested a few times that a D/I might solve this problem. I'm not saying it won't, but other than most D/I's having a switch that lifts ground (simply disconnects pin 1) I haven't read any explaination as to why it might do so. The only impedance issue I can think of is your board is presenting too high a load for the amp. This would cause voltage loss and would create a pretty nice antenna. Mixmaster, you're making me nervous with you're AC ground lifting. Be careful or we'll lose you to the lampis as you'll be able to light a light bulb just by touching it.


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## SHARYNF (Sep 25, 2007)

The only time in an emergency that I would look at removing the ac ground on a device would be with a notebook ac power supply. If you look at the design, you have three wire in, two wire dc out, and on occasion these can drive you crazy. Amps connected to Mixers is a definite never, if you had a problem you could be sending ac into the ground, back out to the mic, with serious safety issues. 

In my experience an impedance mismatch typically either produces a signal level problem OR a serious restriction in the frequency response.


Sharyn


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## museav (Sep 26, 2007)

What is the source at the console and what input are you running into on the Hot Spot? Where are the gain settings on the console and the monitor? The Hot Spot inputs will accept a wide range of signals, from mic to line to instruments, and the PA5X140 supposedly senses whether it is a mic or line signal and automatically adjusts for that. However, it may still simply be a gain structure issue. Have you tried varying the level at the console and does that affect the noise at the speakers or let you turn down the speaker's input level? Do you have another powered speaker that you coudl use to see if it has exhibits the same problems?

According to the product data, the 1/4" input on the PA5X140 is balanced. There is also 24VDC phantom power on the XLR.


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## mixmaster (Sep 26, 2007)

j_blinker said:


> It's been suggested a few times that a D/I might solve this problem. I'm not saying it won't, but other than most D/I's having a switch that lifts ground (simply disconnects pin 1) I haven't read any explaination as to why it might do so. The only impedance issue I can think of is your board is presenting too high a load for the amp. This would cause voltage loss and would create a pretty nice antenna. Mixmaster, you're making me nervous with you're AC ground lifting. Be careful or we'll lose you to the lampis as you'll be able to light a light bulb just by touching it.



Hey Blinker
first of all, if you read my post carefully you see that I noted this as an unsafe practice. I would _*never*_ under _*any*_ circumstances run a show with any of my equipment grounds lifted. I was shocked once as a result of someone elses' stupidity and one trip to the ER is plenty. I am not advocating this as a permenat solution for anything.
That said, the problem was one of those last-minute things that make this job fun and I didn't have a lot of time for testing. I knew from previous experience that the ground in this venue was a bit dirty. I did a quick check with the ground lifted to see if removing the possibly dirty ground solved the issue of the buzz and then I restored the ground. This was the quickest test to check the most logical failure point. Had the issue been a dirty ground, we would have abandoned the whole contraption as I wouldn't have let him do the show with a bad ground any more than a missing one. As it was, a DI box fixed the problem and the show went fine. I have used a "backwards" DI box several times since in situations where I need a quick temporary fix for a buzz that doesn't go away by breaking the shield.
Anyway, under normal circumstances you're positively correct. One should never lift an AC ground. Safety is something I take seriously. I'll leave the light bulb stuff to the lampies


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## SHARYNF (Sep 26, 2007)

museav said:


> What is the source at the console and what input are you running into on the Hot Spot? Where are the gain settings on the console and the monitor? The Hot Spot inputs will accept a wide range of signals, from mic to line to instruments, and the PA5X140 supposedly senses whether it is a mic or line signal and automatically adjusts for that. However, it may still simply be a gain structure issue. Have you tried varying the level at the console and does that affect the noise at the speakers or let you turn down the speaker's input level? Do you have another powered speaker that you coudl use to see if it has exhibits the same problems?
> According to the product data, the 1/4" input on the PA5X140 is balanced. There is also 24VDC phantom power on the XLR.



Brad might have found the problem IF the XLR CONNECTION has 24 volts Phantom power, and you are feeding this back into a line out on a mixer you are bound to have problems, plus phantom power uses the ground connection.

Possibly you need to get a trs to female XLR adaptor and connect your xlr cable to the trs jack for input
Sharyn


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## blademaster (Sep 27, 2007)

we are having the issues on both of our powered monitors (same model #, serial# is one digit diff). also we are having the same issues whether running it on 1/4 input or XLR input. unfortunately when i did the test for the 1/4 input it was only TS because we lack the proper adapters. i can look into a price tag for it though. i would love it if i could manage to get a hold of a male TRS to Male XLR cable in tucson, *hint hint* anyone in tucson, az able to help out. i can try removing pin one from it anjd see if that helps however that is going to require me to actually use tools .


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## avkid (Sep 27, 2007)

Here's a ridiculous idea, call the dealer the church bought them from.
Or any dealer for that matter, they might know if there any defective lots floating around.

I know some people in Tucson, but they will charge you.

For technical support, service or repair call 1-800-369-7768 or email Aaron at [email protected]


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## jkowtko (Sep 27, 2007)

Better yet -- send them to me! I'll try them out on Smokey Joe's, which we're doing in December, and I'll let you know if they worked okay 

Seriously, if there is a problem with these monitors that they don't handle the grounding well, I'd like to know. I was considering picking up a couple of them myself. 
However it doesn't seem likely that the monitors would be defective ... I'd think we would have heard about this type of problem before if they were.

Otherwise, the first rule of thumb when troubleshooting -- isolate the problem ... find out when it works, and when it doesn't. I can't tell from the above threads that you have been able to find out when it works. I assume you tried the obvious of using different cords and plugging into different outputs from the mixer (group out, channel direct out, aux out, utility out, etc). Does it work when connected anywhere on your board? If not, I would try to find a different board and/or find another venue nearby where you can bring the speakers and try them out with their equipment.


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## avkid (Sep 27, 2007)

jkowtko said:


> try to find a different board and/or find another venue nearby where you can bring the speakers and try them out with their equipment.


Heck, go to your local music store with them.
Notice I say local(as in mom and pop) the Banjo Center frowns on this type of thing.
Probably better ask the pastor before you go taking stuff out of the building though.


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## blademaster (Sep 27, 2007)

Ok guys i think i moved past my own stupidity. i verified and double checked that it was plugged into the same outlet as the board and the hum disappeared. crap i hate it when i do stupid things. oh well. ok. i just did a ton of tests with this new knowledge. http://stoney.djfaithmusic.com/tests_run.xls
also all these tests where done using Group out 3 on our A&H GL2200 32ch.


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## SHARYNF (Sep 28, 2007)

AHH yes the faulty ground connection. I have had endless arguments with electricians on this, the ones used to home office shop wiring simply don't understand. It is very common in churches etc where in many cases where the volunteer does the work and it is not done properly.

What happens is a variety of the following

Sometimes some one replaces the outlet, and gets the hot and neutral connection reversed, or the neutral and ground connection reversed. The cheap 3 light tester will find the first problem but NOT the second.

Code allows for the use of metal conduit for the ground connection, and to save money, the contractor will not pull a green ground wire thru to all the outlets. Works fine for lights, but for audio is a mess, over time the conduit connections corrode, weaken get disconnected, or sometimes wind up touching something that could be a ground say for instance the conduit runs in such a way that it is strapped to something else, and that for instance is a water pipe, or the conduit from another circut, now you have multiple paths to ground, and you get a potention difference, and a hum 

Sometimes a sub panel is installed, and the person gets the neutral bar grounded to the box, now you have again two ground connections.


For hum free audio, you either need 
To plug everything into the same outlet, (if the interconnection of ground on the same circuit is bad you will get hum even if it is on the same circuit. Obviously this many times is not practicle but in some places I have had to run an extension cord all the way from the stage back to the mixer at FOH just so everything was on the came outlet. 
Isolation transformers on the line that interconnect also work, and fix the problems also.

Bring a distro, have it hooked into the main panel and then YOUR wiring is what goes from the distro to your units.

Get an electrician to fix the ground, I recommend if at all possible, changingn to ground isolated outlets, and then having a complete ground wire pulled. This is not cheap, and sometimes it is easier to have them simply run a new set of circuits for you on stage and FOH and have the new connections all have a complete isolated ground only connected to the service ground at the main panel.

Another thing to keep in mind that a lot of people miss is that surge protector strips that have gone bad, will work but have ground problems. This is why in general for amps for instance people tend to just have a quad box, no Surge protector, and a voltage regulator/ups for the FOH equipment, and then have isolation transformers on the line feeds. 

Sharyn


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## blademaster (Sep 28, 2007)

so basically there is nothing i can do other than running a 200 ft electric cord back to the booth? or get the electrician to rewire it? out of our entire booth we use two outlets and two power strips. our equipment on those power strips is wireless equipment and our music playing equipment.


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## blademaster (Oct 3, 2007)

ok I did another test and I think I have finally narrowed it down far enough. the test i did was almost exactly like the first one i did in my attached xls sheet previously except i did it on stage instead of in the booth
XLR to 1/4 stereo with and without gnd lift on AC showed a result of a hum without the lift and works prefectly with. I'm thinking that the problem is actually two problems, first it is a ground issue overall (though the precise problem with ground eludes me) plus a issue in the circuitry of the amp in determining if it needs the phantom power or not on the XLR. 
what do y'all think?


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## avkid (Oct 3, 2007)

blademaster said:


> I'm thinking that the problem is actually two problems, first it is a ground issue overall (though the precise problem with ground eludes me)


You might have the neutral and ground bonded at a subpanel. They should only be bonded at the service entrance.

> plus a issue in the circuitry of the amp in determining if it needs the phantom power or not on the XLR.
> what do y'all think?


There is no such thing, amps don't supply or use phantom power.


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## j_blinker (Oct 3, 2007)

Sounds like you've narrowed it down to one problem, the pin 1 connection between your board and amp. I join in avkid's confusion about why phantom would be present on the output, and if it was a multimeter between pin 2 (or 3) and 1 on the output in question will read (approx.) +48V DC and then you will have identified a second (and unlikely) problem which wouldn't be audible even if it did exist.

If simply lifting the ground removes the problem then a simple ground lift at the board should answer your problem. You seem reluctant to get hands on with your wiring, and for less than $10 in materials you could build your own ground lift and practice the art of solder. Great chance to find a multimeter and get a feel for how to quickly check whether the power in a room is going to give you any trouble. 

And to explain what I believe your ground issue to be: The voltage on the signal and return ( pin 2 & 3) has to be in reference to another voltage, Ideally this is zero and is ground. When voltage makes its way onto ground the difference between the signal and the reference (ground) changes, this change is audible. Since AC changes is polarity in 60Hz cycles, when this power gets onto the ground we hear it as a 60Hz tone. How voltage gets onto the ground is often the less obvious answer as there are many ways to do this.


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## blademaster (Oct 4, 2007)

There is no such thing, amps don't supply or use phantom power.[/QUOTE]

Allow me to correct my speech, previously it was stated that the circuitry in the monitor can detect a mic line in that require phantom power.

Wouldnt it be a safety hazard to do a gnd lift on the board? I am a little bit hesistant to start doing wiring for a few reasons, first because i have never done it, second, because i lack the tools, third, because ppl in leadership above me want me to make as few changes as possible, fourth, because I lack proper space to work on it.
Plus where would i find instructions on how to build a ground lift for $10

And to explain what I believe your ground issue to be: The voltage on the signal and return ( pin 2 & 3) has to be in reference to another voltage, Ideally this is zero and is ground. When voltage makes its way onto ground the difference between the signal and the reference (ground) changes, this change is audible. Since AC changes is polarity in 60Hz cycles, when this power gets onto the ground we hear it as a 60Hz tone. How voltage gets onto the ground is often the less obvious answer as there are many ways to do this.[/QUOTE]

How would i verify what the main AC or subpanel AC ground is, like verify if it has been done properly.


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## avkid (Oct 4, 2007)

blademaster said:


> How would i verify what the main AC or subpanel AC ground is, like verify if it has been done properly.


Call an electrician.


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## j_blinker (Oct 4, 2007)

I did a little digging and the engineers specs for your box state that the XLR connection carries +24V DC. I'll have to get back to you on how this might affect a boards output circuitry. If you suspect it might be the cause of some of your grief then a simple female XLR to TRS would let you avoid the problem. Sorry if I was unclear about what I meant by ground lift. I didn't mean to lift the ground off the boards AC; this would be unsafe and floating the boards chassis could affect your whole system negatively. I was reffering to a fem to male XLR adapter with the shield disconnected inserted between the board and amp; this is the $10 ground lift. Less than $3 for each connector (cause of course your gonna buy neutrix) and 6" of mic cable. simply solder pin 2 to pin 2 and pin 3 to pin 3, and trim back the exposed shield and don't connect it. This is all a grnd lift is. 

How much experience do you have with soldering and using a multimeter?


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## museav (Oct 4, 2007)

There may be some confusion. The monitor in question is intended to have a microphone connected directly to the XLR input. The internal electronics has circuitry that automatically detects whether the input signal is mic or line and apparently does provide phantom power on the XLR.

When you really get down to it, grounding problems are actually in the audio electronics and not in the grounding, this is the Pin 1 problem that has become a common topic. Properly designed audio equipment should work with any code compliant power grounding without a problem, the signal ground should be grounded at the connections and not pass through the active electronics signal path within audio devices. There is an AES Standard, AES48-2005, "AES standard on interconnections - Grounding and EMC practices - Shields of connectors in audio equipment containing active circuitry" addressing this and many newer pro audio products are designed to be "pin 1 compliant". However, many products are not and most older products do not incorporate the AES48 information, thus the need to continue to address the problems via the grounding system.

I believe that the ground lift being suggested is the signal ground and not the power (safety) ground. Lifting the safety ground is indeed dangerous as well as being a code violation, and the practice should be limited to being used as a momentary diagnostic tool, if at all.

I personally think that a high quality input transformer such as one from Jensen or Lundahl on the line feeding the monitor and located at the monitor might be a good solution.


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## avkid (Oct 4, 2007)

If you don't have $80 laying around for proper transformer this will work.
http://www.audiopile.net/products/Adaptors_Connectors/Adaptors/CA-301-GL/CA-301-GL_cutsheet.asp


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## SHARYNF (Oct 4, 2007)

I would question this speaker's abilty to detect if it is a mic or a line feed and then decide to provide phantom power, It is possible, but not very likely. I would quess that it uses the trs connection for line, and the xlr for mic level.

You have several choices

One is make up a cable that can lift the audio ground, I would suggest that this be an xlr to trs cable, since I am guessing that the speaker really expects line level in on the trs connection

you could get a isolation transformer, this will break the feed of Phantom power and eliminate the problems also, without seeing how you have the mixer and levels set it it POSSIBLE that you are feeding a very low level signal from the board to the amp and again this could be confusing this supposed circuit that can detect mic vs line ( most properly designed system would have just added a swtich to turn off phantom power.

BUT BASED ON YOUR TEST I THINK IT IS A DIFFERENT PROBLEM 

The fact that running them all on the same electrical outlet eliminated the hum does point to the system having a pin one problem. Basically this is when the connection for the audio signal shield pin one, is connected to the ac ground on the equipment. This is an incorrect design, but is common. Here again, simply make cable that on the end at the speaker/amp has the audio shield pin one lifted. 

Long term if you don't want to drive your self crazy, you need to get the ac ground fixed. Standard electrician is not likely to be able to do it, will argue that there is a continuous ground, but is not likely to be able to detect that there are multiple ground connections in the circut.

Sharyn


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## blademaster (Oct 4, 2007)

j_blinker said:


> I did a little digging and the engineers specs for your box state that the XLR connection carries +24V DC. I'll have to get back to you on how this might affect a boards output circuitry. If you suspect it might be the cause of some of your grief then a simple female XLR to TRS would let you avoid the problem. Sorry if I was unclear about what I meant by ground lift. I didn't mean to lift the ground off the boards AC; this would be unsafe and floating the boards chassis could affect your whole system negatively. I was reffering to a fem to male XLR adapter with the shield disconnected inserted between the board and amp; this is the $10 ground lift. Less than $3 for each connector (cause of course your gonna buy neutrix) and 6" of mic cable. simply solder pin 2 to pin 2 and pin 3 to pin 3, and trim back the exposed shield and don't connect it. This is all a grnd lift is.
> How much experience do you have with soldering and using a multimeter?



how much experience does none qualify as? i know the concepts of it, but like most of things in life knowledge doesnt count as much as experience. I did a test with a female XLR to TRS on stage and it still had a hum until i put a AC gnd lift. now i might be able to drag up some connectors and do the 6" patch cable without shelling out money.  i will see what i can do next time i am there. unfortunately i usually get your responses right after i leave.  i will talk to ppl and see what i drudge up.


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## blademaster (Oct 4, 2007)

j_blinker said:


> I did a little digging and the engineers specs for your box state that the XLR connection carries +24V DC.



Where did you dig up the specs on it? i couldnt find them. a circuit diagram would be beneficial


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## j_blinker (Oct 5, 2007)

You gotta start somewhere, sooner's better than later. If you do have a ground issue then the TRS connector won't change anything, but i agree with the previous posts that your better off to avoid the XLR just to make sure. I was in the shop when i looked up the specs, and a full circuit diagram. I think I googled the model number with words like manual and phantom power. They were on 3rd party retail sites, happy hunting.


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## blademaster (Oct 5, 2007)

So then on sunday i will go ahead and see what all i can pull off, unfortunately the only person that i am aware of that has a soldering iron that is on the team is out of town this weekend so i will call him when he gets back and have him bring the soldering iron. Any tips on it?


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## avkid (Oct 5, 2007)

Buy a soldering for the love of god!
A decent one is like $10.
Rosin core solder.


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## museav (Oct 6, 2007)

Okay, here's the scoop straight from the manufacturer. First, the ability to handle varying inputs from mic to line to instrument is handled by the level control being an active gain stage. Second, phantom power is always on for the XLR input. Finally, they have had infrequent problems with pin 1 of the XLR being broken at the circuit board. They recommend trying the 1/4" connection; it is balanced, accepts line level and does not have phantom power. All you would need to try this is a female XLR to male 1/4" TRS adapter, something like this http://www.hosatech.com/hosa/products/gxp-143.html, or a cable with an XLRF on one end and a 1/4" TRS on the other, like this http://www.hosatech.com/hosa/products/cxs_microphone.html.

You may still have grounding issues, but using the 1/4" input would seem to eliminate many of the other variables.


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## blademaster (Oct 6, 2007)

museav said:


> Okay, here's the scoop straight from the manufacturer. First, the ability to handle varying inputs from mic to line to instrument is handled by the level control being an active gain stage. Second, phantom power is always on for the XLR input. Finally, they have had infrequent problems with pin 1 of the XLR being broken at the circuit board. They recommend trying the 1/4" connection; it is balanced, accepts line level and does not have phantom power. All you would need to try this is a female XLR to male 1/4" TRS adapter, something like this http://www.hosatech.com/hosa/products/gxp-143.html, or a cable with an XLRF on one end and a 1/4" TRS on the other, like this http://www.hosatech.com/hosa/products/cxs_microphone.html.
> You may still have grounding issues, but using the 1/4" input would seem to eliminate many of the other variables.




Well shucks, that is amazing, and thus this is why I love controlbooth.
And the only thing I would ask museav is to give a link for where you got this info because unfortunately my ideas are always questioned


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## museav (Oct 6, 2007)

No link, I happen to know some people at Galaxy Audio, one for almost 20 years, so I asked them directly about the situation and received the information I shared.


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## SHARYNF (Oct 7, 2007)

HI Brad
Don't you think it is a bad idea to always have phantom power on with the xlr inputs? or at least warn people to use the trs connection for line level? Sending phantom power back up a line connection can cause a variety of problems

Sharyn


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## museav (Oct 7, 2007)

Sharyn,

The online specs for the PA5X state for the inputs "One ¼" balanced One XLR balanced, with +24 VDC phantom power" while the Architect and Engineer specs on the product data sheet note "The mixer section shall include one balanced (differential) input using a 1/4-inch phone plug connector and one +24 VDC phantom powered balanced (differential) input using an XLR connector." So the fact that the XLR has phantom power on it seems pretty clearly stated.

Perhaps more relevant, the PA5X User Manual identifies the XLR input as "MIC (XLR) INPUT - Balanced input with 24 VDC phantom power for electret microphones." From that it seems that the XLR input is intended primarily as a mic input.

That being said, I agree that making the phantom power switchable would potentially make the XLR input more useful and better labeling and/or descriptions might avoid confusion, I will pass that observation on.


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## SHARYNF (Oct 7, 2007)

Since people rarely have access to the manual who might be connecting it up at an event, what does it say on the actual speaker itself by the connector?
Sharyn


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## blademaster (Oct 7, 2007)

SHARYNF said:


> Since people rarely have access to the manual who might be connecting it up at an event, what does it say on the actual speaker itself by the connector?
> Sharyn



Well see thats the lucky thing is first off all to my recollection it says nothing and second people ask me questions like that right after I leave church.


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## museav (Oct 9, 2007)

It looks like the labeling certainly could be clearer, both the 1/4" and XLR are apparently labeled simply as mic/line inputs, which is true but not as complete as it could/should be. If nothing else, labeling that the XLR has 24VDC phantom on it would probably help. I'll definitely pass this on.


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