BFD Humming on it's own...

[daxie]

Hello,

I own my bfd a while now, but didn't have the chance to look into it, cause I had the hum, and measurements showed pretty good response without equalising.

But I want to get it better.

However, I still have a hum, and two of them actually

1) a hum caused by the bfd itself, without anything connected to it, just putting it on introduces the hum (the hum is coming from the bfd itself, not from the speakers)

2) a hum produced by the system, which is caused by my cable tv-connection it seems, cause when I unplug that one, that hum goes away...

I'm using coaxial cables from my receiver to my behringer and behringer to sub, and am using RCA-Mono jack convertors to run them into my bfd...

Thank you for your help!

daxie

[Jerm357]

Wow, so just pluging in the BFD by itself with nothing else hooked to the BFD and its humming. That does'int sound good. Sounds like something is damaged in the BFD and you might have to have it repaired. Not sure what could cause this but maybe someone else can chime in.

[brucek]

a hum caused by the bfd itself, without anything connected to it

Yeah, that's caused by the BFD's transformer itself. It's a mechanical hum that is caused by the interaction between the BFD's metal case and the transformer itself.

It's only a problem if the hum is objectionably loud.

The transformer can be repositioned, but if you're not an electronics guy, you may want to avoid that..

brucek

[Fincave]

Do not know if this will help. I remember reading on the Finnish forum where somebody had the same problem, they lessened the problem by unscrewing the transformer and putting a small piece of rubber mat between the metal case and the transformer, apparently the screws are long enough. Do this at your own risk!!! (I have never even opened my BFD).

[brucek]

they lessened the problem by unscrewing the transformer and putting a small piece of rubber mat between the metal case and the transformer

Yeah, the problem with that is that the transformer remains in the same position. I tried the rubber fix myself and it helped a little.

The only thing that worked in my case was to unscrew the transformer (on my workbench), and then with the power on, rotate it around the area that the wire leads would allow until I found the spot that it was dead silent and then mount it there. Not for the faint of heart and I wouldn't recommend it unless you know what you are doing.

brucek

[daxie]

Well, it's not like it's humming loudly, but when there's an absolute silence in the movie, I can hear it...
Thanks for your info, I might open it up one day...

Any ideas on how to deal with the cable feed related hum? I read it is caused by an improper grounding, but how could I fix/improve this?

thnx

daxie

[brucek]

You can ensure the cable is grounded at the service panel as it enters the house, and if not add a grounding block that you can get at Radio Shack (or have the cable company do it).

You can also add an in-line transformer in the cable itself near the equipment to break the ground loop.

brucek

[blownrx7]

Bruce K wrote:

The only thing that worked in my case was to unscrew the transformer (on my workbench), and then with the power on, rotate it around the area that the wire leads would allow until I found the spot that it was dead silent and then mount it there. Not for the faint of heart and I wouldn't recommend it unless you know what you are doing.

Bruce,
Are you saying the transformer hum you had was caused by some emi interaction with the case/other components rather than purely mechanical hum???

How did you mount it in the new position? Did you drill new holes in the chassis? Did you still use the rubber washers?
TIA

[brucek]

Are you saying the transformer hum you had was caused by some emi interaction with the case/other components rather than purely mechanical hum???

The magnetic field around the transformer is affected by the BFD's metal case. Turning the transformer (tuning it) can reduce the mechanic plate vibration that causes the mechanical hum.

How did you mount it in the new position? Did you drill new holes in the chassis? Did you still use the rubber washers?

hehe, actually I found the most silent spot was on its side on the bottom of the case, so I siliconed it into position. Quiet as a mouse now. Its been glued there for years.

brucek

[Anthony]

Mine is doing the exact same thing. Really annoying! I have some rubber washers (grommets actually), maybe I'll try the isolation first and then try moving it around.

I'm no stranger to the soldering iron, so if I have to add longer leads to fix this, I will.

I'll let you all know how it goes.

[brucek]

Mine is doing the exact same thing. Really annoying! I have some rubber washers (grommets actually), maybe I'll try the isolation first and then try moving it around.

Yeah, mine was quite loud, yet my second unit is completely silent. Luck of the draw.

The thing is, that although there is quite a bit of real estate unused inside, the transformer is too high to mount upright on the bottom plate, so there is very little change you can make while still mounting it on the side wall. The wiggle room doesn't change the hum (in my case anyway).

I found moving it away from the metal on the side wall was the trick, but then I couldn't mount it upright. I decided that siliconing into place was the solution. I don't like to recommend that because the transformer should really be bolted down, and perhaps I should have taken the time to make a new mount, but never did...

Here's a pic of mine.. no soldering needed, just moved a few inches...





brucek

[blownrx7]

A picture is worth a thousand words.
Thanks Bruce!!!

[southworth]

My BFD also hummed a little with nothing attached to it. I found a couple pieces of 3/8"W x 1/2"L x 1/4" thick closed cell foam weatherstripping that I had laying around the house. I then stuffed a small strip under the frame of the transformer and I also removed the original thin foam square thats stuck to the top and replaced it with the other strip. The weatherstripping compresses very nicely to the case and now the BFD sounds a whole lot quieter. I guess that you could try the administrator's suggestion and "tune" the transformer to the cabinet. Once you've determined the best position, you could permanently mount it to a 90 degree angle piece of thin gauge steel using either rubber grommets or rubber washers.

[Jerm357]

Wow, I never knew this was a problem for so many people. My BFD has been silent since I got it, but it seems that these noisy BFD are not so uncommon after all. At lest it seems you guys have figured out a solution.

[Bailman]

I have a hum also and think both the cable signal and transformer are a root cause. I need to recheck things and see whats what. Thanks for the info, fella's.