Insufficient Power Conditioning?

[Andrew Lee Rubinger]

Hi all:

Noticed something the other day, now that it's ultra cold here in Boston.

I have an electric space heater; when it's on and plugged into the wall sharing the same circuit in the fusebox as the BeePre, I get a very loud hum/buzz that does not change with the volume or balance controls.

Turning off the heater removes the buzz/hum.

So: I have my BeePre plugged into a Furman M-8 Power Conditioner, which I thought was responsible for providing clean power to whatever's plugged into it.  The M-8 claims to filter RF and EMI.

So how is the operation of the heater affecting my BeePre behind the power conditioner?  Is my conditioning solution insufficient?

Thanks in advance!

S,
ALR

[JamieMcC]

I have experienced this last year but as a intermittent and very annoying background buzz and it was electric space heater as it was tripping on and off on its thermostat in a different room. I normally use a gas boiler for central heating and hot water but do have a electric immersion heater that is used on occasion this also has the effect. 

[Grainger49]

I know the obvious answer is to turn off the heater while listening.  I have a heater in my listening room and I do that, and turn off the humidifier too.

But the problem is the heater.  It is putting noise onto the power line. 

You can run a circuit from the other half of the incoming (alternate breakers are on opposite phases) to your system.

You could get a Corcom noise filter, try Digi-Key and Mouser for small ones.  Try it on the heater, it might prevent the noise going back into your circuit.

You might want to contact Furman about the lack of performance in the M-8.  The buzz might be from the motor on the fan.  And there is a wide world of other noise filters and power conditioners out there.

[Andrew Lee Rubinger]

Thanks, all!

And I've just found another source of noise: the outside lights.  So the solution I'm looking for is to isolate my system from bad power.

The bottom line I'm looking for: is it true that I'm running into EMF or RF?  Or is there some other issue with my power that I need a conditioning solution to address?

S,
ALR

[Paul Birkeland]

It sounds like an isolation transformer might be in your future.

I found that outdoor quartz lights are really horrible for power line cleanliness. 

[mcandmar]

Ban all CFL and LED light bulbs, light dimmers, and no name cell phone chargers from the house. Prevention is better than a cure

I also use a mains filter box which was rather effective at removing the high frequency noise and the cracks and pops i used to hear switching lights on/off around the house. Only issue i have now is the large toroid in my main speaker amp growls angrily around midnight, whatever is upsetting it isn't in my house.

I picked up a large toroid isolation transformer on eBay recently which is on my to do list, will be interesting to see if it changes any of the above..

[galyons]

My house is now fully CFL and LED lighting with PWM dimming.  I don't have any noticeable noise issues, but I have all of the components plugged into isolation transformers.  I use PowerVar.  It is pretty much the standard for server rooms and medical equipment here in the SF Bay area.  They are usually replaced every 3-5 years by the industry users, so I get them at fairly cheap prices.  They are quite heavy, so shipping gets to be $$$$$.  I started using them to keep the digital and analog equipment isolated from each other. (Really more to keep the digi-crap out of my TT systems) Now all of my components are on PowerVars.

Cheers,
Geary

[Andrew Lee Rubinger]

I really appreciate everyone's input.  I'll be following up here once this is solved to help others looking forward.

Some follow-up questions, if I may:

* Is this ground loop hum I'm seeing?  Using a multimeter I see that the difference between my (-) and ground is ~.6V with the patio lights off, and ~1.4V with them on.  I should be seeing a number close to 0V, correct?  Will an isolation transformer also be isolating the ground?  It appears some models do not.
* What model PowerVac would be appropriate; there are many.

Again, thank you!

S,
ALR

[Doc B.]

RE LED lamps, we have all sorts of them here at Bottleheadquarters including about a dozen dimmables in the lobby, and they are not a problem.

[Paul Joppa]

...
* Is this ground loop hum I'm seeing?  Using a multimeter I see that the difference between my (-) and ground is ~.6V with the patio lights off, and ~1.4V with them on.  I should be seeing a number close to 0V, correct?  Will an isolation transformer also be isolating the ground?  It appears some models do not....

It's always difficult to tell what the source is.

What - exactly - are "(-)" and "ground"? If you are comparing signal ground vs power line safety ground, then you have missed the connection between them; fixing that (bad solder joint?) should be a pretty dramatic improvement. But maybe you meant something else?

Ground loop hum can be identified by testing in isolation - no inputs, no outputs. Turn the level all the way down, use headphones or a sensitive voltmeter on the outputs. Then add one by one the inputs and see if any of them generate the noise. If you must use a power amp and speakers to detect the noise, try using cheap crap interconnects and compare with heavy-duty ones (that have a lower resistance shield). Make sure both power and pre amps are connected to the same outlet.

[Andrew Lee Rubinger]

What - exactly - are "(-)" and "ground"? If you are comparing signal ground vs power line safety ground, then you have missed the connection between them; fixing that (bad solder joint?) should be a pretty dramatic improvement. But maybe you meant something else?"

This is measured by putting multimeter leads directly into the power cable that would ordinarily be plugged into the BeePre.  Ground is the power ground, (-) is one of the AC leads that isn't the one which gives me a reading of ~114V.  So that measurement is power coming out of the wall, without the BeePre in the picture at all.

The hum is audible when I have no inputs connected, and exists regardless of input switch, balance pot, or volume pot setting.  Removing the output from the BeePre (and disconnecting it from the amp) makes the sound go away, so I can ensure it's not the amp having the issue.  Usually the BeePre sounds just fine; the buzz/hum is occasional and is affected by other things plugged into the same circuit/fuse, so I've deduced that the power is an issue.

S,
ALR

[Grainger49]

It sounds like you are chasing this down.  Just to be sure, try a different pair of interconnects between the Bee Pre and the amp.

It is quick and easy.  It might work, probably not.  But it needs to be eliminated.

[HF9]

I've always had good luck with the lower cost PSAudio power conditioners (e.g. the Duet). I'm getting ready to put together a power line filter from Classic Valve, which may look diminutive from the number of parts, however you'd very be surprised how little is in some commercially available audiophile "power conditioners", so once it's done I can report back. Might not be for a month or so...

http://www.classicvalve.ca/tubepcb-1.html#POWER

From the documentation: "designed to take care of common and differential mode noise and surges with a grounded supply, can to some extent reduce RFI that is picked up by the power lines"

(I have no commercial affiliation to Classic Valve FYI... although if I did, I could be making hella money on every $9 board sold! -j/k-).

[Paul Joppa]

This is measured by putting multimeter leads directly into the power cable that would ordinarily be plugged into the BeePre.  Ground is the power ground, (-) is one of the AC leads that isn't the one which gives me a reading of ~114V.  So that measurement is power coming out of the wall, without the BeePre in the picture at all....

This is measured by putting multimeter leads directly into the power cable that would ordinarily be plugged into the BeePre.  Ground is the power ground, (-) is one of the AC leads that isn't the one which gives me a reading of ~114V.  So that measurement is power coming out of the wall, without the BeePre in the picture at all....

Thanks - that helps narrow it down a lot.

You are measuring what is called by electricians the voltage between neutral and ground. That is a lot of noise for that measurement, though sadly not at all uncommon  :^(  The usual solution is to have a separate circuit for the technical gear - not always practical though. An alternative is an isolation transformer, preferably with a noise filter as well.

114v is unusually low; we have seen some hum problems with low line voltage into BeePre. That issue is normally not sensitive to other noise sources on the same power system, so I can't say that's what is going on, but if you should get an isolation transformer, look for one that can step up the voltage a bit.

[Paul Birkeland]

a reading of ~114V.  So that measurement is power coming out of the wall

Call your power utility and complain, they may be able to bump you up to 120V.