[Welly Wu]

I talked with Mr. Ray Samuels over the phone yesterday. We did some basic trouble shooting techniques and we are convinced there is nothing technically wrong with my Emmeline HR-2. I am intrigued by the possibility that there is a bit of RF/EMI or plain old ground vibration that is rearing its ugly head in the audio chain. To that end, how can I tackle this problem?

Let me describe the problem. I get this either barely audible humming sound or a very noticeable humming sound. It depends on where I locate the power unit attached to my Emmeline HR-2. Before, I had the power unit next to my power conditioner (sans VibraPods). It was good for awhile but changing weather conditions in my neighborhood (i.e., December chills) or higher usage of electrical devices (of which I have plenty in a small bedroom) may be causing this humming sound of late. I never had it occur beforehand. So, when both power units were next to each other by a couple of inches, I'd get it. Whenever I touched either unit with my hands with the juice flowing, the humming hit the roof. Whenever I touched the volume pot on my headphone amplifier, the humming stopped and it was dead quiet.

Then, I physically moved the power unit to my Emmeline HR-2 away from the BPT BP-Jr. II Ultra power conditioner and I made sure one inch of wood separated the two by at least a foot in distance. Voila. The humming sound is gone...for now. It is gone and I learned something.

Does RF/EMI "pollution" really exist and was this a case example? Does simply moving the physical location of components help to cut down on it? How effective are those RF/EMI devices that attach to power cords, inter-connects, etc.? Could the issue be the cheap $3 USD power cord I use to hook up my power unit to the power conditioner?

Anyway, thanks for answering my questions. This got my curiosity going...

 

[akar]

You could put some ferrites on your interconnects.
They are relatively inexpensive and they do actually work.
You can find them at Radio Shack for about $4 each, or eBay for a bit less.

Moving the cables around is the cheapest and easiest solution.
Just be careful about what cables cross eachother.

 

[Gallaine]

You might also try Stillpoints ERS paper. It is supposed to absorb RFI. I bought 3 sheets at $19.95 each but a problem has developed in my Stax 404 headphones so I have been unable to perform any serious listening tests.

RFI/EMI can be a problem - as you found out the hard way. Moving components away from the source of interference can help; field strength if I remember correctly is a function of distance. But components can also be shielded from the effects of RFI/EMI. If the EMI/RFI is being injected into your system through the interconnects or power cords the ferrite rings already suggested might help. I can't really attest to the effectiveness of the rings as I've never used them.

 

[Ray Samuels]

HUUUMMMMMM....
Power conditioners, somethimes, tend to do more harm than any goodness. All power conditioners have big trasformers with huge magnetic fields. They tend to be noisy & they sound, some times, like a motor, vibrating. I do not really recommend any of these devices on the Emmelime HR-2 or on all the other components that I design. The power supply on the Emmeline HR-2 is capable of filtering out the AC line, rectifying, & regulating the voltage & smoothening the DC, in so many repeatable stages. This is said many times before.
Cheers.
Ray Samuels

 

[J.Y.]

tweaks that worked for me in hum-hunting from past experience:

1. Take a piece of wire and try ground the pot to the chasis.
2. Use a cheater plug to isolate the ground.
3. Try taking a piece of wire(heavy gauge works better) and connect the amp and source via screws on the chasis. Somewhat reduces ground loop.
More experimental suggestions
1. Try connecting the RCA shell to the chasis.(usually isolated for reason)
2. connect input ground to output ground with a piece of wire.

 

[PinkFloyd]

ferite rings around your cables and suppress your dishwasher / fridge etc.

 

[PinkFloyd]

Quote:

Originally posted by PinkFloyd ferite rings around your cables and suppress your dishwasher / fridge etc.

And I quote:

Is the stereo close to the fridge (like within a foot or two)? If not,
radiated energy is not your problem and interconnects will not solve it
(provided they are shielded in the first place). The problem sounds like noise
on the power line. The magnitude depends on the impedance of the power
feed and (possibly) on the condition of the fridge thermostat contacts.
It will be different for the same equipment from house to house
which is often frustrating when trying to recreate the problem somewhere
else.

Neglecting the thermostat's condition, when the fridge kicks in the compressor
draws enormous amounts of peak current. The sudden demand causes a voltage
drop all over the house that has a fast rise/fall time (lots of harmonics).
These harmonics will often get coupled right through the transformer
onto the chassis of some or all components in a stereo system. This ground
current is heard as a pop. If the fridge thermostat has dirty contacts, the
arc that is made adds to the garbage that gets sent out on the power line.

Attacks on the problem can be mounted in various ways. Lowering the
impedance of the utility feed is usually not an option, except if the
fridge and stereo are on the SAME BREAKER. Change that! A garden-variety
surge arrestor is usually composed of an MOV across the line plus a few support
components--it works by trimming off transients above a certain voltage
(usually about 250 volts on a 110v surge supressor). But, the MOV is
pretty ineffective against noise below its voltage theshold, or
against "common mode" noise whose voltage rides both hot and neutral
equally. To suppress this kind of interference, a better surge arrestor
is needed which is effective against differential AND common mode RF noise.
Such a device contains inductors to slow incoming transients and
inhibit noise. You'll need to run all your components from the
same suppressor. These types of suppressors typically start at $30 retail.

But, before you go and buy one, try a couple of things. First, put your
inexpensive surge arrestor at the fridge if it is rated to handle the
fridge's load. Nipping a fast transient in the bud at the source
will often be very effective. The voltage of the transient at the
source will often be enough to trip the MOV. This will be ineffective
against the turn-on voltage drop noise, though.

For those with electrical experience, you can wire an MOV (available
at Rat Shack) across the compressor motor power input, after the thermostat.
This will suppress arcs across the thermostat nicely! I wouldn't
recommend this for anyone without experience as you're playing with
possible injury and fire if the job is not done correctly.

Then, tie the chassis of each piece of your gear to the pre-amp (under
the phono ground screw) with a piece of small braid. Solder removal
wick, as sold at Radio Shack makes a good grounding braid. Firmly
attach the wire at all ends. Also, try tying a braid from the preamp
ground point to the utility safety ground (if you don't have any
equipment with a three prong plug already). Remove the attachment
to the safety ground only if the problem gets worse with the
braid attached.

The above has cleared up many like problems for me in the past.

 

[Welly Wu]

Thanks for all of your help!

My bedroom is located pretty far away from my kitchen and a decent distance away from my home theater rig. I've solved the humming sound problem by moving the Emmeline HR-2 power supply farther away from my BPT BP.Jr II Ultra power conditioner. Furthermore, I put a solid 1/2" thick piece of wood (my large table) between both black boxes. Voila! The humming sound is gone forever! I guess all that RF/EMI talk isn't all voodoo when one experiences it firsthand, no?

I don't think I need ferrite core plugs. However, I'll keep that in the back of my mind if the humming sound every rears its' ugly head again.

Thanks a lot guys!

 

[PinkFloyd]

Quote:

Originally posted by Welly Wu Thanks for all of your help! My bedroom is located pretty far away from my kitchen and a decent distance away from my home theater rig. I've solved the humming sound problem by moving the Emmeline HR-2 power supply farther away from my BPT BP.Jr II Ultra power conditioner. Furthermore, I put a solid 1/2" thick piece of wood (my large table) between both black boxes. Voila! The humming sound is gone forever! I guess all that RF/EMI talk isn't all voodoo when one experiences it firsthand, no? I don't think I need ferrite core plugs. However, I'll keep that in the back of my mind if the humming sound every rears its' ugly head again. Thanks a lot guys!

Your bedroom may be a mile from your kitchen but it could be on the same mains ring as your household appliances......... try installing a dedicated mains spur