Hum caused by reciever?

[Inu_Yasha]

I recently went to Home Depot and bought some 3 plug to 2 plug converters in order to fix a ground loop hum that I've been having with my sub. I put on the converter and fired up the sub, and I still got a hum. Thinking something must be wrong with where I placed the plug on the surge protector, I turned off my reciever and noticed that the hum wasn't there anymore. I tried turning the reciever back on and the hum came back! Does anyone know of any way to fix this problem?

[Azeke]

Here are some of possible scenarios:

1) Cable/Satellite grounding issue (if applicable), check to ensure equipment is properly grounded. Disconnect the cable to see if the hum goes away.

2) Try plugging the sub into another outlet that is not connected to your a/v system.

3) Purchase a noise filter.

4) Check your audio and video cables, ensure that they are separated from the power cords.

5) Sub could be defective.

Just my quick thoughts, I'm sure others will offer further advice.
Try to provide a little more detail if possible.

Peace and blessings,

Azeke

[collo]

I've always been wary of lifting the earth. Generally if an appliance has an earth pin, it is because there is a metal case which otherwise could become live if there is a fault within the unit.

Some people have had success with running an extra wire to connect the cases of all their gear together.

I prefer to work out where the problem lies and use isolating transformers or a special cable with the sheath open at one end. See this page on Minimising Hum

regards
Collo

[Inu_Yasha]

I do have an isolating transformer that came with my buttkicker, but when I add that to the loop, it still produces a hum. I was experimenting earlier today with directly connecting my sub to my preamp and the hum was minimized greatly. It appears as though the splitter or buttkickers have something to do with the hum. When the splitter has a free end (no buttkicker) the hum is there but barely audiable. When I attach the interconnect for the buttkicker, the sub starts to hum audiably. I'm really not too sure what's going on in this situation.

[Arneson]

http://www.gbaudio.co.uk/data/ground.htm

This is a good read on the subject.
You may have seen it already.

[Inu_Yasha]

Ok, I've tried a lot of things to try to figure out what could be causing the hum. I noticed that there is no hum with a rca to 1/4 mono plug running straight from the reciever to the power amp. Once I add my cleanbox to the mix, I start getting hum. It seems the higher I turn the amp knob on the cleanbox, the louder the hum gets; if I turn the knob all the way down, I still get some hum so I think the cleanbox is giving off some of the hum.

I also suspect that the XLR to 1/4 cables that I am using could be causing some of the hum as well. When I switch the cable with my microphone's cable, I get less volume but I also get less hum (could it be that it is just proportional to the volume output?).

[Inu_Yasha]

Forgot to metion this strange thing, whenever I put the BFD up to a piece of my metal entertainment center, the hum goes down considerably... Could it be a grounding problem?

[Dennis H]

Hum is almost always a grounding problem.

[---k---]

I beleive that each peice of gear can cause a grounding problem. So that means to get rid of it, you will need a cheater on the BFD, the CleanBox, and the Sub Amp (and maybe more).

I'm not an expert in things electrical. I'm currently running a cheater plug on my BFD and my EP2500 to get rid of the hum. I would wonder though if there is a point where the number of cheater plugs significantly raises the hazzard exponentionally.

I have seen people state that they used the method mentioned by Dennis to solve the problem: run a peice of wire from the case of each peice of gear to each other. So, you would run a peice of wire from your reciever to the amp to the BFD to the clean box (or whatever). Some gear has a screw on the case for this. Others, you'll have to figure out. I think you would still want to use the cheater plugs on all but one of the peices of gear. But the end result is that they all share a single ground now.

[Inu_Yasha]

I beleive that each peice of gear can cause a grounding problem. So that means to get rid of it, you will need a cheater on the BFD, the CleanBox, and the Sub Amp (and maybe more).

I'm not an expert in things electrical. I'm currently running a cheater plug on my BFD and my EP2500 to get rid of the hum. I would wonder though if there is a point where the number of cheater plugs significantly raises the hazzard exponentionally.

I have seen people state that they used the method mentioned by Dennis to solve the problem: run a peice of wire from the case of each peice of gear to each other. So, you would run a peice of wire from your reciever to the amp to the BFD to the clean box (or whatever). Some gear has a screw on the case for this. Others, you'll have to figure out. I think you would still want to use the cheater plugs on all but one of the peices of gear. But the end result is that they all share a single ground now.

I may have to try the wire thing as I have cheater plugs on both the BFD and the EP2500 (amp). The cleanbox's plug is only 2 pronged so I doubt a cheater plug would work on that.

[ThomasW]

I assume you're using "Y" splitters? My guess is that they're adding to the problem.

The CleanBox will certainly amplify the hum, since it's job is to boost the signal. The hum is 60Hz and the CleanBox doesn't care if it's 60Hz music coming from the recording or carried on the line as a ground loop.

I'd unplug everything. Then rebuild the system one piece at a time. If/when the hum increases a bunch you know that last piece of gear is causing the problem.

If it's additive with each additional piece of gear, you might consider a balanced power transformer. Those are specifically designed to increase common-mode rejection. They don't eliminate all hum but do an amazing job of cutting it down in my gear. Unfortunately they aren't cheap.

[Arneson]

This is a misnomer, I have a hum in my system, but I'm not hearing it.
It's on the 60' RPTV screen, gently rolling up on a totally black display.
It first occured yesterday when I added a PureAV filter in line with an APC 1000
UPS behind the set.

[Inu_Yasha]

Well... I have something even stranger appearing today... I came in from class and turned on my BFD and EP2500 and the hum was LOUD!!! When I tried playing a song, the bass was incredibly loud as well. I tried removing all the components and putting the system back together piecewise. I was able to locate the hum to the cleanbox. Right now I'm running my sub amp two clicks from off and it's outputting enough bass. One thing I noticed this time though, is that even when I turn the cleanbox amp knob down to zero, I'm still getting hum! When I turn down my amp's knob, the hum goes away. When I did a direct connect of the amp to my reciever, there was no hum. Any ideas now?

[Inu_Yasha]

I assume you're using "Y" splitters? My guess is that they're adding to the problem.

Acutally I'm not using any splitters at the moment; my buttkicker is unhooked. I'm running from the reciever, to the cleanbox, to the BFD, and to the EP2500.

Also, an update on what I posted before; my amp lights are not turning on when receiving a signal but there is plenty of bass in my system.

[Stoney]

Back in the old days.... we used to have to turn the non polarized plugs aruond in the sockets to get rid of hum. I assumed this was because one piece of equipment was out of phase on the 60~ AC from the others. More recently, I have seen 60V AC potential difference when measuring from the chassis of a cable box to the chassis of an amp that had hum. Connecting the two chassis together fixed the hum, but I often wondered if there was the possibility of damaging something by connecting the chassis together. Where did the 60V potential difference go? Was it dissapated accross the wire used to connect them together? Was there a shock potential between the two chassis before they were connected together? Shouldn't the shielding and ground of the interconnects essentially have done the same thing?

Sorry, lots of questions.

I also had a problem in my last house where a humidifier motor plugged into a bedroom socket caused a hum in my sub in the living room. Turn the humidifier off (or like I did- Throw it away!) and the hum went away.

[---k---]

Hum sucks!

I got a gangle of cables going every which way behind my gear. I've tried to tiddy it up, but often switch something and am back to the gangle. A few months ago, I did something and got nasty hum in my system. A simple tug on the BFD and CD player to move it out an inch made the hum go away. Magic! Though, I'm guessing it is one of the interconnects crossing a power cord or something.

I don't know if this is your problem; but I guess what I'm trying to say is that hum is usually caused by grounding differances, but can also be caused by noise from crossing over power cords, dirty power, and probably a few other issues. Sucks...

You could always upgrade your receiver/processor to something with XLR connections (iirc, Outlaw makes a nice, reasonably priced for high-end gear prepro w/ XLR). That would likely solve the problem completely.

[ThomasW]

Back in the old days.... we used to have to turn the non polarized plugs aruond in the sockets to get rid of hum.

Good thinking.... :T

Don't tell UL but I've taken cheaters and filed down the larger lug to do just that...

[Arneson]

Don't tell UL ,

They are on thier way over with a hazmat team,

One place I remember seeing nonpolarized plugs is on the receiver switched AC outlets of older equipment.
Old Crt TV's definetely had a chassis that went live with the plug reversed, specially the RCA's. My hair still sticks up in one place.

An amplified hum is more of a lost ground connection issue, and the missing led's is an interesting clue.

[Jerm357]

Ill tell you what got rid of my hum. I use a EP1500 with a 1/4" mono to rca wire with a Monster cable HTS 1000 MKII power center. I dont know how it works but it does (I just tested it again before I posted this) I pluged the amp into the wall outlet and got the hum pluged it back into the powercenter and its just gone simple as that. If you realy cant figure any thing else out I would realy give it a try. They can be had pritty cheap on ebay and will also protect your gear.

[ThomasW]

The Monster power center, like similar devices contains ECM (electrical common mode) filters. Those help to reduce hummmm

[Inu_Yasha]

The Monster power center, like similar devices contains ECM (electrical common mode) filters. Those help to reduce hummmm

I wish I would have tried this earlier before I let my dad have my monster power center :M . I just bought me three RS28a's last night so I guess I'm going to have to wait on getting another filtering device...

Just out of curiosity, could a lightning storm mess up the wall sockets and cause something like this? I know that some of the sockets in my apt don't work...

[ThomasW]

Lightning can do all kinds of really nasty things to sensitive electronics.

Taking out only the wall plug would be a bit strange. The obvious thing to look at is a damaged breaker particularly if they're all on the same circuit. If they're not on the same circuit I don't know what to say other than again check the breakers for each circuit

A big lightning surge will leave black scorch marks on the drywall as a calling card.

[ThomasW]

Well... I have something even stranger appearing today... I came in from class and turned on my BFD and EP2500 and the hum was LOUD!!! When I tried playing a song, the bass was incredibly loud as well. I tried removing all the components and putting the system back together piecewise. I was able to locate the hum to the cleanbox. Right now I'm running my sub amp two clicks from off and it's outputting enough bass. One thing I noticed this time though, is that even when I turn the cleanbox amp knob down to zero, I'm still getting hum! When I turn down my amp's knob, the hum goes away. When I did a direct connect of the amp to my reciever, there was no hum. Any ideas now?

Sorry I missed this in my AM fog. This has to be a damaged/defective piece of gear

Getting hum even with the CleanBox dials turned down/off isn't doing anything to change a ground loop since it's still in the signal path and connected to the AC. I'd pull the CleanBox. If the hum goes away I'd send the Box back and get a new one.

[Inu_Yasha]

Sorry I missed this in my AM fog. This has to be a damaged/defective piece of gear

Getting hum even with the CleanBox dials turned down/off isn't doing anything to change a ground loop since it's still in the signal path and connected to the AC. I'd pull the CleanBox. If the hum goes away I'd send the Box back and get a new one.

I found another interesting find today... I tried using my Y splitter to split the signal and send to the cleanbox. When I did that and sent it to my BFD the hum almost went away. Now the main hum I'm getting is comming from when the amp (ep2500) gain knobs are turned up (past the 12 o'clock position), but the problem disappears when I take the cleanbox out of the loop. So is the cleanbox defective?

I also tried different interconnect cables from the reciever to the cleanbox and still had the same outcome.

[ThomasW]

It sounds like the CleanBox is defective or it's insertion in the signal path is causing the problem

[Jerm357]

I remember that you got that clean box off ebay right? Was it new in the box or used?

[Inu_Yasha]

I remember that you got that clean box off ebay right? Was it new in the box or used?

It's new and supposedly the ebay seller is authorized to sell them as well. I'm debating if I am going to return or not, but return is looking like it's going to win...

[soho54]

The clean box I bought new from PE a few weeks ago does the exact same thing. I pulled everything out and hooked it up 500 different ways. I was using XLR cables, so I even tried re-doing the ground pin in them. The only way I could get rid of the odd hum was to plug the CB into a different circuit than the AVR and amps.

There is a guy on AVS with the same problem on a recently bought one as well. Maybe a whole shipment is a little off???

The only thing mine did that you have not said yours does, was that when I turned my AVR off and left the CB and amps on I would get some crazy intensifying feedback though my drivers. My neighbor was not happy with me at all that night. :B

[ThomasW]

There is a guy on AVS with the same problem on a recently bought one as well. Maybe a whole shipment is a little off???

Could be, Behringer builds items in production runs, not continuously. I bought a CleanBox for a friend from PE 2 months ago and it works fine.

[Inu_Yasha]

The clean box I bought new from PE a few weeks ago does the exact same thing. I pulled everything out and hooked it up 500 different ways. I was using XLR cables, so I even tried re-doing the ground pin in them. The only way I could get rid of the odd hum was to plug the CB into a different circuit than the AVR and amps.

There is a guy on AVS with the same problem on a recently bought one as well. Maybe a whole shipment is a little off???

The only thing mine did that you have not said yours does, was that when I turned my AVR off and left the CB and amps on I would get some crazy intensifying feedback though my drivers. My neighbor was not happy with me at all that night. :B

You know what... I never tried hooking the cleanbox up to a cirucit that does not contain my AVR equipment. I know that my power lines do have some problems as some of my sockets don't work around my apt (and they call these apts luxury :roll: )

soho, try doing what I did and use a Y splitter to split the signal and then hook the output up on BOTH ends. This will force the cleanbox to turn on both outputs. That really helped a lot for me.

As you said, if the cleanbox and amps are on and the avr is off, then you'll get a crazy loud groundloop going through the speaker (in my case it could be the BFD as well).

[soho54]

soho, try doing what I did and use a Y splitter to split the signal and then hook the output up on BOTH ends. This will force the cleanbox to turn on both outputs. That really helped a lot for me.

I'm already using a stereo signal. I have my AVR set up with no sub. It is all downmixed to the mains which run through the CB to a CX2310 xover. This splits the signal to the mains and stereo subs amps at 65hz.

It isn't a standard 60hz hum. I know because I am one cheater plug away from that. It was a problem for a few days until I moved the outlet setup around, but it is gone now other than my lightswitch popping now. ??? There is no hum, so I am letting it ride. :roll:

[Inu_Yasha]

I'm already using a stereo signal. I have my AVR set up with no sub. It is all downmixed to the mains which run through the CB to a CX2310 xover. This splits the signal to the mains and stereo subs amps at 65hz.

It isn't a standard 60hz hum. I know because I am one cheater plug away from that. It was a problem for a few days until I moved the outlet setup around, but it is gone now other than my lightswitch popping now. ??? There is no hum, so I am letting it ride. :roll:

By lightswitch popping do you mean when you turn the lights on or off that the sub pops? I had that problem too, but that went away and now I'm having the problems that I described above. I need to see if I can change my wall outlets, but I'm kinda cramped as far as space is concerned. I'll try that sometime over the weekend when I'm done with my classes.

[soho54]

By lightswitch popping do you mean when you turn the lights on or off that the sub pops?

Yeah, the overhead light or fan. It isn't just the sub, it was a full range pop. :E When I switched the outlet the CB was plugged into it stopped along with the hum. Now the actual switch on the wall makes a faint pop. ???

Here a is a link the the guy on AVS with the same problem. Link

[soho54]

When I think about it, I don't think there was any problem at all the first few days. I thought maybe I just hadn't noticed the problems, but I'm pretty sure I would have noticed these problems right away. I just remember turning it on one day, and it was there.

[Inu_Yasha]

When I think about it, I don't think there was any problem at all the first few days. I thought maybe I just hadn't noticed the problems, but I'm pretty sure I would have noticed these problems right away. I just remember turning it on one day, and it was there.

Same thing as my problems! This is definately strange in that you and I are having like problems! Maybe we just got some out of a bad batch?

[Edge540]

I will add one more to the "problem" list. I am running my sub off of an EP2500, which was feed directly from my AVR. I have had no hums at all until i installed a CleanBox last night. Now there is a slight hum out of the sub. I havent investigated it yet, but will try some of the suggestions here. Will let you know the results.
Eric

[soho54]

Congratulations!
Welcome to the club!
:B :B :B

No, wait... :cry:

[Inu_Yasha]

I will add one more to the "problem" list. I am running my sub off of an EP2500, which was feed directly from my AVR. I have had no hums at all until i installed a CleanBox last night. Now there is a slight hum out of the sub. I havent investigated it yet, but will try some of the suggestions here. Will let you know the results.
Eric

If you're at the light hum stage, you're only at the beginning. Soon you'll start running into the same problems that soho and I are running into. Definitely keep us posted. One thing that worked for me, and I got almost all of my hum to stop now, is running one of the output cables as balanced, and the other as unbalanced. I also used a Y splitter and ran both to my BFD (or amp); now I'm able to turn down the amp and kill almost all of the hum.

[ThomasW]

While looking at Behringer stuff I came across the Behringer DI800.

I understand what their intended use is for this product. But looking at it's features I wonder if it might be a better option than the CleanBox? A bit more $pendy, but it provides servo-balanced output, has a fixed +20dB of gain, so level adjustments would be limited to the subout from the receiver and or the input level controls for the power amp.

It has a ground lift switches. If it will break a loop between a guitar or keyboard and a power amp, it should be effective for the DIY sub builder needing help.

Someone with CleanBox issues might grab one of these from PE and check it out. With their 45 day return policy only the cost of shipping is lost should it not do the job.