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Discussion Starter · #1 ·
Hello everyone,

To start, I'll begin to say thanks for reading and helping with your suggestions.

Our HT room structure/audio wiring finally received its final terminations along with logical end to end keystones were installed. Also Shorten'd stock terminated ends with better IEC male/female connectors.

My problem has always plagued the system, however; this time around it seems worse.

Gear:

Anthem - MRX-300
Epson - 8500UB
Stewart Firehawk 110"
Marantz - MA-500 (5)
Sony - PS3
Channel Master CM7400
Furman
Yorkville PS-1700
Hybrid Audio Technologies i6(7)
Arc Audio - Arc 15" (4)

Music
Bryston BP25
Bryston 4BST
Bryston BCD-1
PS Audio DAC
Wadia 170i
Hybrid Audio Technologies (custom) L8v1, C5, L1Pro

Power
60a Sub Panel w. four 15a circuits


*********
PROBLEM:
*********
The Subwoofer preout on our Anthem MRX300 connects to a keystone RCA jack.. thru the wall into another keystone jack. When I turn my Yorkville Power amp on with the RCA input connected to the keystone jack we get 60hz buzz through my preamp. This amp has a factory IEC plug since I wanted to make sure this wasn't a issue before cutting the cord

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Tests performed:
************
- Remove the RCA with the Yorkville amp powered up -- buzz goes away :)
- Remove the power cord with the rca connect buzz goes away
- Chose a different 15a circuit and the buzz returns
- Connect my Bryston 4BST to the the same Keystone - NO BUZZ
- Connect a demo test subwoofer cabinet with a plate amp - No BUZZ -

*******
First Setup with Identical gear except Behringer Power
*******

Prior to the yorkville amp, I owned a Behringer EPX2000 and the buzz was there. I never really bothered to trace the problem until our wiring was complete and correct.

Looking forward to your thoughts

Cheers
:yikes:
 

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Have to say I'm lost reading the above. :scratch: So do you think it's the Yorkville Power amp causing the problem?

My behringer ep4000/2500 suffer from ground loop hum, so for now I have shoved them well out of the way in my loft, and at my own risk, disconnected the earths from the plug top's. 'no more hum' I am going to run a seperate earth of the casings to a copper stake in the garden.
 

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I'm having a little trouble understanding your post also. If you have a subwoofer that's buzzing, disconnect it and place a shorting plug across its input. No buzz - subwoofer eliminated. Next plug the sub back in and place the shorting plug on the other side of the wall - no buzz, that link is eliminated. Work your way back to where the sub connects to your amp this way. If the buzz stays, its the amp or something feeding the amp. Disconnect all the amp inputs and see if you have buzz - if yes, it's the amp. If not, start connecting inputs, one-at-a-time and see what input creates the buzz. Narrow the problem down and if you find an input creating the buzz, work toward the source with a shorting plug. You should eventually narrow the source of your buzzzzzzz down.
 

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This can fix a hum & buzz problem ( inserted between the pre-amps LF output and the following sub-bass amplifier ) .




Full-Range signal ( ie; full bandwidth ) will require these .



Granted, all of the above are expensive fixes .

( A similar, but much cheaper solution ) can be secured using with the construction of some custom cables .

You'll need to closely compare the bandpass specs of each choice & then choose what is best for your situation ( somewhat akin to choosing between a 192-256K MP3 file or going with fully lossless PCM reproduction ).

Alternately ; You could always have a professional install service review your existing wiring schemes & layouts ( to find out what has gone astray, leading you to need these band-aid type solutions ) .


Now my question, "Why are you asking for help ( like this ) within the REW forum ( rather than one of the HTS Forums dedicated to implementing HTPC ) " ?

:sn:
 

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A few things jump out at me:


Power
60a Sub Panel w. four 15a circuits
All HT circuits should be on the same service leg (phase), not spread across both service legs.

Also, what’s the ground situation for your sub panel? The ground should run back to the building’s main grounding stake, the one your main panel is connected to. It’s okay to have a local ground for the sub panel, that would isolate the HT gear from the rest of the house, but that local ground should be tied to the main ground.

A few things you didn’t try with your troubleshooting:


The Subwoofer preout on our Anthem MRX300 connects to a keystone RCA jack.. thru the wall into another keystone jack.
Try running a cable straight from the pre-amp to the subwoofer amplifier. Possibly there’s a problem with your in-wall cabling or connections.

Also, disconnect the antenna feed from your Channel master, and/or disconnecting the channel master from the system. Often because of convenience, installers ground an antenna to a separate ground from the main electrical ground. Grounding the antenna or cable service to say, a water pipe is a method commonly used. Either way, you end up with the equipment connected to two paths to ground, and that’s where you get a ground loop.

Naturally, it's best to eliminate a ground if at all possible. Earl noted some good last-resort remedies. You might also wade through the BFD Hum Thread for more ideas on how to deal with a ground loop.

Regards,
Wayne
 

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Discussion Starter · #6 ·
Have to say I'm lost reading the above. :scratch: So do you think it's the Yorkville Power amp causing the problem?

My behringer ep4000/2500 suffer from ground loop hum, so for now I have shoved them well out of the way in my loft, and at my own risk, disconnected the earths from the plug top's. 'no more hum' I am going to run a seperate earth of the casings to a copper stake in the garden.
My apologies for the confusion in describing my situation. No i don't believe at this time the yorkville is the root cause, since similar symptoms were present before recent wiring changes :huh:

I'm having a little trouble understanding your post also. If you have a subwoofer that's buzzing, disconnect it and place a shorting plug across its input. No buzz - subwoofer eliminated. Next plug the sub back in and place the shorting plug on the other side of the wall - no buzz, that link is eliminated. Work your way back to where the sub connects to your amp this way. If the buzz stays, its the amp or something feeding the amp. Disconnect all the amp inputs and see if you have buzz - if yes, it's the amp. If not, start connecting inputs, one-at-a-time and see what input creates the buzz. Narrow the problem down and if you find an input creating the buzz, work toward the source with a shorting plug. You should eventually narrow the source of your buzzzzzzz down.
To clarify, the buzzz is not passing thru the subwoofers. The buzzzz is passing thru our Anthem Receiver, then to our Marantz amps. Pardon my :huh: but what is a shorting plug?

This can fix a hum & buzz problem ( inserted between the pre-amps LF output and the following sub-bass amplifier ) .


Full-Range signal ( ie; full bandwidth ) will require these .

Granted, all of the above are expensive fixes .

( A similar, but much cheaper solution ) can be secured using with the construction of some custom cables .

You'll need to closely compare the bandpass specs of each choice & then choose what is best for your situation ( somewhat akin to choosing between a 192-256K MP3 file or going with fully lossless PCM reproduction ).

Alternately ; You could always have a professional install service review your existing wiring schemes & layouts ( to find out what has gone astray, leading you to need these band-aid type solutions ) .

Now my question, "Why are you asking for help ( like this ) within the REW forum ( rather than one of the HTS Forums dedicated to implementing HTPC ) " ?

:sn:
:sn: sorry about posting inside REW forums - could this thread be moved ?
I purchased a Jensen ISO-MAX filter for when I ran Digital Cable. Results were favorable; however the buzz remained. I may give those a try if I cannot solve this hum.

A few things jump out at me:


All HT circuits should be on the same service leg (phase), not spread across both service legs.

Also, what’s the ground situation for your sub panel? The ground should run back to the building’s main grounding stake, the one your main panel is connected to. It’s okay to have a local ground for the sub panel, that would isolate the HT gear from the rest of the house, but that local ground should be tied to the main ground.

A few things you didn’t try with your troubleshooting:


Try running a cable straight from the pre-amp to the subwoofer amplifier. Possibly there’s a problem with your in-wall cabling or connections.

Also, disconnect the antenna feed from your Channel master, and/or disconnecting the channel master from the system. Often because of convenience, installers ground an antenna to a separate ground from the main electrical ground. Grounding the antenna or cable service to say, a water pipe is a method commonly used. Either way, you end up with the equipment connected to two paths to ground, and that’s where you get a ground loop.


Regards,
Wayne
Wayne, the main panel is located in my garage 60' away. I applied for a permit with the city and certified electrician installed a fresh 100a service Siemens panel in the garage. Also the sub panel is fed directly from the garage into my basement using (IIRC) 6-3 cable with a 60a breaker at the main panel. 8 15a breaker in the sub panel. 4 breakers are feeding the HT/Music room, 2 are spares 2 are for basement lights and receptacles. I had the electrician come back after I encountered the initial hum with the legacy Behringer Amp. He confirmed the wiring was correct and that my cable service provider is to blame. Since we watch very little cable we moved to an OTA tv service.

Wayne, can you clarify what your mean by same service leg? I attached photo of Before and After garage panel wiring and the sub panel

Running a temp cable straight from the the-preamp to the sub amp was conducted and results were identical. I connected the same preamp output cable to a test subwoofer plate amp with no ground plug and no hum replicated.

I will try your antenna grounding suggestions.


Is it safe to remove the ground pin on the yorkville amp? This was a suggestion by a fellow Hometheater shack member.

Thanks again - hopefully my responses make more sense :help:


Image #1 Old Panel
Image #2 New Panel
Image #3 Sub Panel
 

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Is it safe to remove the ground pin on the yorkville amp? This was a suggestion by a fellow Hometheater shack member.

l
If your asking this question, then In a word 'No'. I really shouldn't have suggested that to try, and do not recommend it.

Looking at your DB, the earthing system is your only form of protection, my house circuits are also protested by an RCD, plus I am competent with electrics.
 

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(A) You've stated that the buzz problem ( heard in the main speakers ) was not present when the sub amplifier was a Bryston 4BST ( which I assume has the unbalanced RCA input connector, correct ? ) .

(B) You've also stated the buzz is present when your sub amp is either the Yorkville or the Behringer ( both of which have balanced inputs ) .

(C) Logic says; Your problem lies in the way you are getting the unbalanced signal into an amp that has a balanced connector ( ie; you're using a bogus adapter ) .

(D) Post a pic of the business end of the sub input ( unplugged from the Yorkville ) so we can see what you are using .

(E) FYI, I would make a proper adapter using " shielded twisted pair cable" ( with a drain wire ) and then utilize the shield & drain as a telescoping shield that is tied into the "Sleeve" of a 1/4"-TRS connector.

(F) Wayne has already suggested that you read the BFD sticky on how to properly wire up the ( balanced input ) of the Behringer DSP1142 ( BFD ) unit from an RCA out ( which is essentially the same thing that I just suggested ) .

:sn:
 

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Discussion Starter · #9 · (Edited)
Temp fix is working. Time isn't in my favor for the next 2-4 weeks - so I tried a temp cable with the ground plug removed.
I know this is n'tproper but I will resolve this RCA issue.

Cheers everyone :) and thanks for your help.
 

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avidedtr said:
can you clarify what your mean by same service leg?
If you notice in your new subpanel half your breakers are connected to the large black wire and half are connected to the large red one. Ideally all HT components should be on one or the other, not both. If you have lights on dimmers, definately keep those on the opposite phase from HT gear. This is often unnecessary but problems can arise that would make you wish you had wired it this way. Most residential electricians, unless they are technical gear heads, will probably scoff at the idea. But then again, electricians are indoctrinated to meet minimum code at minimum cost. Minimum code does not make reference to 105dBA @ 0.005 THD. Also, electrical code is based on 60hz AC, not 15 hz audio.
 

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Wayne, can you clarify what your mean by same service leg?
Basically, what phreak said: The two red and black 120-volt (“hot”) service legs are out of phase, meaning one is swinging positive while the other is swinging negative. Circuits for audio systems, and anything connected to them should, should all be on the same leg.

Electricians are trained for “code,” so few of them know anything about proper electrical protocol for audio equipment. The considerations there go beyond mere safety to preventing or at least minimizing noise potential.

A few things jump out at me with your pictures. First, in the old panel picture I see a heavy-gauge green cable connected to the chassis of the box. However, I do not see such a cable in the new box to either the chassis of the box or one of the ground busses, so I have to wonder how the ground is being accomplished. (The ground busses are the strips with screws where all the bare wires are connected.) There is supposed to be a heavy-gauge wire running from the ground buss (or chassis of the box) to the main ground stake, which is driven 8-ft. into the ground (which is why it’s often referred to as “earth ground”).

Likewise, there is no ground cable apparent in your new sub panel box. In lieu of a ground cable, the sub panel could be physically connected to the main panel. That would provide an adequate ground from a safety perspective, but I wouldn’t trust it for audio-system purposes. There should be a ground cable running from the sub panel box either directly to the ground stake (preferable) or at least to the ground location in the main box.

Another thing you might try with the pro amps is to use a cable that lifts the ground at the ampifier end, as the picture below shows. For XLR connections, you would use Pins 2 (+) and 3 (-).




Regards,
Wayne
 
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