Home Theater Forum and Systems banner

161 - 180 of 330 Posts

·
Premium Member
Joined
·
134 Posts
I ordered the DCI product that many people seem to have good luck with here, I currently have a cheater plug I am using on the BFD.

Where does the DCI product go, between AVR and BFD or BFD and sub ?

Thanks
 

·
Registered
Joined
·
27 Posts
When I ran my Cable/satellite coax into a power/line conditioner first before connecting it to the box it solved my problem, no more hum !
 

·
Plain ole user
Joined
·
11,121 Posts
No, I am saying that it is only a patch on the real problem. You have tied the grounds to the same potential. This is fine, but you should not rely on the ground path through the line conditioner. You should be sure that the cable and sat systems are properly gorunded to the electrical service ground, and that all of the connections are clean and tight. You could still get a ground loop with everything properly grounded, but it is far less likely. Your protection is compromised if you have a bad (or no) ground on any system coming into the home.

Read the material that I linked to.
 

·
Premium Member
Joined
·
134 Posts
I am currently using a cheater plug on the BFD until I sort out my hum problem. I ordered the DCI product which made matters worse.

Working with Dave at DCI we determined it is a SAT receiver issue and come to find out DirectTV never grounded the mast or installed grounding blocks for the cables, that has been remimeded this morning.

Anyway, Dave sent me this article. This weekend I tried the cable modiciation describe on the BFD hum forum with no difference but when I tried the one Dave sent it cust the hum in half. When I put the DCI at the sub as recommended the hum was back being louder.

Tonight I will test again with a properly grounded SAT.
 

Attachments

·
Registered
Joined
·
32 Posts
I just plugged in my new BFD and I have the dreaded "HUM" has anyone come up with any new fixes for this since 10-14-08 "Last Post"? What seems to be best? I checked my grounds they are intact.
Joe
 

·
Registered
Joined
·
46 Posts
I just plugged in my new BFD and I have the dreaded "HUM" has anyone come up with any new fixes for this since 10-14-08 "Last Post"? What seems to be best? I checked my grounds they are intact.
Joe
Hi Joe,

I see that you are using DirecTV as one of your video sources. From what I have seen (and read in this forum), there is a decent probability that your satelite receiver is not properly grounded. I would check that to start with. If that is ok, then I would check your electrical ground wire to ensure that it is tight, with no corrosion.

Let us know what you find.
 

·
Registered
Joined
·
1,405 Posts
I sawed off the end of an extention cable and plugged the BFD into it without the ground. I plugged that into a surge protector. Now when I turn my level up higher past -10dB reference I do not hear the hum in the speakers. :)
 

·
Registered
Joined
·
999 Posts
I still think the brucek's way (post #155 in this thread) is the best method.

Do not connect the cable shield at the AVR source end. Avoid making this connection to avoid a ground loop. Connecting a cable shield every chance you get is great for stopping RF leakage but bad for audio hum caused by ground loops.
 

·
Registered
Joined
·
68 Posts
I still think the brucek's way (post #155 in this thread) is the best method.

Do not connect the cable shield at the AVR source end. Avoid making this connection to avoid a ground loop. Connecting a cable shield every chance you get is great for stopping RF leakage but bad for audio hum caused by ground loops.
Bob,
there are lots of folks out there who've already tried the cable connection I've suggested including myself. In my experience it has always been quieter with the shield connected at both ends. Nobody that tried this cable(I sent quite a few out) has ever said that they created a ground loop or more noise with the shield connected at the source. Quite the opposite in fact, most of the people that tried it wanted to buy the cable.
 

·
Super Moderator
Joined
·
9,234 Posts

Another alternative:
The ground goes to your AVR's chassis/phono/AM ground.
Not sure how or why that would work. The phono ground lug has continuity with all RCA sleeves. IOW, it's no different than tying the shield and black together on the RCA end. Which is no different than using a plain RCA to mono 1/4" plug. Am I missing something? :scratch:

Regards,
Wayne
 

·
Registered
Joined
·
68 Posts
Apparently there are lots of "quality" AVR's out there that have some difference of potential between the Chassis Ground and the Phono Ground that it makes an audible difference.

I run my EP2500's bridged with the gains full open, and it's significantly quieter with the shield connected at both ends.
 

·
Registered
Joined
·
999 Posts
The ideal solution is to never have cable shields carrying any ground current. Rather have a seperate wire "star" ground connection from all the audio equipment to a single point ground. Using "cheater" plugs is okay if you then use the cheater plug's ground lug to implement the star ground connection.

from http://en.wikipedia.org/wiki/Electrical_grounding:

Separating low signal ground from a noisy ground
In television stations, recording studios, and other installations where sound quality is critical, a special signal ground known as a "technical ground" (or "technical earth") is often installed, to prevent ground loops. This is basically the same thing as an AC power ground, but no appliance ground wires are allowed any connection to it, as they may carry electrical interference. In most cases, the studio's metal equipment racks are all joined together with heavy copper cables (or flattened copper tubing or busbars) and similar connections are made to the technical ground. Great care has to be taken that nobody places any AC-grounded appliances (heaters etc) on the racks, as a single AC ground connection to the technical ground will destroy its effectiveness. For particularly demanding applications, the main technical ground may consist of a heavy copper pipe, if necessary fitted by drilling through several concrete floors, so they can all be connected by the shortest possible path to a grounding rod in the basement.
The AC ground the article refers to is not the third wire safety ground but rather the AC neutral line which hopefully (but don't bet your life on it!) also is grounded at the mains electrical distribution box. You do not want to involve the AC neutral in any way with the low level audio technical ground. Any audio equipment that only uses a two connector power cable will need a seperate technical ground from its internal chassis or internal audio signal ground "star" connected to the audio main technical ground point.

http://en.wikipedia.org/wiki/Electrical_wiring_(United_States)
neutral wire is connected to the center tap of the final step-down transformer and is identified by gray or white insulated wire, perhaps with stripes; most commonly bonded to earth for a fixed known path to stabilize the voltages only at the main service panel; many times called the grounded wire. Note that all metallic systems in a building are to be bonded to the panel; e.g., water, natural gas, HVAC piping, etc.
 

·
Registered
Joined
·
68 Posts
Any audio equipment that only uses a two connector power cable will need a separate technical ground from its internal chassis or internal audio signal ground "star" connected to the audio main technical ground point.
Response from popular AVR manufacturers= :yawn:
 
161 - 180 of 330 Posts
Top