dedicated cicuit ? (1 Viewer)

[Ilya]

The opinions above on the sub are probably correct. If it's humming with nothing but the power and no interconnects, it's probably something in the sub. You could possibly bring it over to a friend's house, plug in the power there and see if it still hums. Most manufacturers ask you to try this as part of troubleshooting (no interconnects). If it still hums, they usually ask you to send it in for repairs as it is probably the sub. The dedicated circuit has plenty of benefits (I run a 10ga 30amp at home), but don't do all that just to eliminate hum from the sub. It's probably the amp or bad electronics in the sub.

 

[MikeTC]

I second two 20A d-circuits, its the easiest and cheapest to run.

Both of my subs (different sub) hum when the LFE input is not connected/disconnected. Try connect your receiver's LFE output to it while keeping both plug into the same circuit.

 

[Brad Russell]

Had the cable guys over for a couple of hours yesterday. I was getting a real nasty hum whenever tha cable was hooked up. It looks like I have a problem somewhere in my house wiring that is cascading in to the dedicated circuit. After checking every possible scenario we hooked up the HT to a power converter in the cable guy's truck. No hum from the cable and no hum from the sub. We tested upsatirs and it is fine. So somewhere I have a bad ground in my house wiring. Not sure how it is affecting the new dedicated circuit but it appears to be. I'll be calling an electrician and I'll let everybody know what happens.

Thanks for all the help!

Brad

 

[MikeWh]

Not sure how it is affecting the new dedicated circuit but it appears to be.

Likely because it's on the same phase, like we were guessing. Dedicated doesn't mean totally isolated-- all the circuits on a single phase share the same physical copper, at least up to the transformer outside your house.

 

[Wayne A. Pflughaupt]

Brad,

Had the cable guys over for a couple of hours yesterday. I was getting a real nasty hum whenever tha cable was hooked up.

It’s pretty common to get a ground loop from the cable feed. There are various things that can be done about it, none of which require the attention of an electrician. For instance, a ground loop isolator built into a pair of RCA cables (like they often use for car stereos) is one thing you can try as is two 75-300 ohm transformers connected back-to-back. Do a search on “ground loop” for more details, as well as other solutions.

Regards,
Wayne A. Pflughaupt

 

[Brad Russell]

Wayne,
I thought about that. But because they installed the cable and the hum on my subwoofer showed up a year ago after the cable was disconnected, I figured I have them diagnose it before I started buying ground loop eliminators. So basically I had two different hums. A low-level 60hz hum from the sub regardless of connections and a very loud hum whenever the cable was hooked up coming from all speakers. While doing some testing, the technician would sporatically measure voltage on the ground wire (even when connected to the new dedicated circuit). When we powered everything from the power inverter in his truck both hums went away. I'll let every know what happens when the electrician comes next week.

Brad

 

[Brad Russell]

Well I promised an answer. Last night the electrician came over and after checking a few things, we found that the real loud nasty hum from the cable was an inter action with the Crown D-150 aII that I'm using to run a sub with. Used a cheater plug and everything is fine now. The PSB powered sub still hums though. So I've still got some investigating to do. Whats weird is that when we hooked the system to the cable guys inverter in his truck, all hums went away, both the one from the Crown without a gound lift on it, and the PSB. Anyway thanks for everyones help.

Brad

 

[Wayne A. Pflughaupt]

Brad,

I hope you didn’t pay this electrician much, because he really didn’t do anything for you. I can’t believe that a professional electrician would recommend the use of a cheater plug, which is a known safety hazard.

But in some respects I’m actually not surprised. As far as I know, ground loops only show themselves as a problem with audio and video electronics, and most electricians know little or nothing about that stuff.

If I may comment on this and some of your previous posts:

What about when your sub hums and only has a two prong plug to begin with? Everything else goes through the HTS 1000 as well but it is the only thing that hums.

Personally I am suspicious of line conditioners. I’ve seen some of them that actually made noise worse when there was a ground loop involved. I’d try taking the PSB directly to the wall; if it still hums, it’s defective.

So in my opinion you have two problems, a defective PSB sub (provided it still makes noise when connected directly to the wall) and a ground loop induced by your cable feed (unless you find a second ground path somewhere in your house).

I think you should look into methods to address the cable problem. The things I noted in my last post would be a start. Keep us posted.

Regards,
Wayne A. Pflughaupt

 

[Brad Russell]

Wayne
Thanks for your input. I'll try a ground loop isolater. Maybe I should clarify the hum I have talking about.

The PSB has a low level hum as long as it is plugged into power (line conditioner or not). I'll try contacting PSB but I don't expect much from them. I had this problem a couple of years ago about 9 mos. after I bought the sub. The store I bought it from had throw some fits to get Lenbrook to send out a new amp for it. Never the less, that worked for about 2 years and now its back. I guess I could try a local shop but I'm sure Lenbrook is going to be no help.

The cable hum is very loud, can't hear the audio over it, you think it is damaging your speakers type sound. This is the first time I have had cable so I don't know if this is the typical cable hum. The cable guys sure acted like they had never seen it like that before. During the course of testing they tried diferent configurations of grounding and even ran a test line from the pole and still no luck. But, with the electrician, when we took the Crown amp out of the system the loud hum went away. So then I tried a cheater plug and that seemed to work.

The electrician seemed to think everything looked in order, grounding rods and grouned to the water pipe, (He siad you are required to have two.) tight connections, etc. He seemed to think someting in the amp was the problem.

So you can probably guess I'm pretty frustrated. I'll try a ground loop isolater and see if that alows me to not use the cheater plug on the crown. I agree about the line conditioner, I'm not sure it is really doing any good. Sometimes when I ran the cable through the conditioner it lessend the hum so maybe it works a little. Before the cable, the conditioner seemed to not be introducing any problems, so maybe at worst it acts as a surge supressor/powerstrip.

Thanks for all your help!

I'll let you know how the isolater works.

Brad

 

[Gary Thomas]

I've been struggling with a similar problem in my new basement HT. It also is hooked to a dedicated 20amp circuit. The major hum is a result of my Satellite cable...even though it is grounded to the main house ground next to the electrical panel. Most of the hum was eliminated when I ran it through a Belkin surge master for DBS systems. I still get a little hum...

Ground loop isolators, from what I can find on the internet, are not compatible with satellite cables..only CATV. I tried a Jensen product & it totally eliminated the hum...and eliminated the picture!

I have the guy who finished my basement coming over. We also have a second ground attached to the water meter. I'm not sure if it's actually connected to anything in the house, but he will check this out. If it is, he will disconnect it and run it to the whole house ground. Also, I've got the phone line tapped into the house ground before the rod. I'm going to have him attach all of the grounds to the rod at 1 point, rather than having the satellite and phone tap in at different points along the house ground.

We'll see!!!

 

[Gary Silverman]

Gary, the ground wire you refer to as going to your water pipe is actually not a ground, but a bond. You absolutely must leave this wire attached to the water pipe. You run an electroction risk without it, anytime you touch a faucet and you are in contact with any ground. The bond wire keeps the piping system at the same potetial as ground, so there can never be any current flow(the stuff that kills you).

 

[Cary_H]

I'd say using the term "electrocution risk" a bit extreme. First, it would require some sort of fault to make your piping "hot", and second, you'd need to be grounded pretty well yourself. I'd think your home would offer up some pretty attractive locations for this "new" circuit to jump and take out the breaker.
I do agree I wouldn't want to do anything that might compromise my ground, however.

 

[Gary Silverman]

I have a building here at work that we found 15 amps traveling on the ground. Everything seemed okay. It was an accident that we found it.Touch that ground anywhere and touch an unbonded water system and watch what happens!

 

[Cary_H]

Yeah, that's not something you want.