Space Heaters & Electrical Noise + On/Off problems

[artto]

I'm not sure what could be causing this. I've never experienced this before, at least not with this calibre of equipment.

PROBLEM 1: When I run a a certain space heater (other ones don't do it) in my music room, after a while, say, 1/2 - 1 hour, the Crown D-60 power amps start making a noticeably audible noise/hum, the mechanical transformer type of 60Hz hum. This is not coming from the speakers. The amps are always on but in this case nothing is playing thru them. Keep in mind that because this is a temporary thing, the heater is on the same circuit as the audio equipment, AND, at the moment I don't have the isolated power supply hooked up. There is only two stages of power conditioning on the front end of the audio equipment ( a pair of Furman).

PROBLEM 2: When the space heater is running the McIntosh MX130 preamp/control center keeps shutting down after 30 seconds to a few minutes. It seems as though after its been on for a while it stays on. However, like today, no space heater on and after I turned it on it stayed on.

Any insight to these phenomena?

[Speedball]

Something about the resistance in those heaters and I don't know what. Last week while trying out one of my older amps a very loud hum started when my wife began using the hair dryer. I started shutting it down every night after that.

[Guest " "]

for problem 1)

you either have whats refered to as a reverese power factor...simply put...the appliance is casuing an inductance wave that is sending voltage harmonics thru your transformer based devices....if this is the case (higly unlikey) you either need to use an isolation transformer (which will buzz/him instead) or use power factor correction capacitors to correct your reverse power factor to a forward leaning one.

more likely and easier to fix...your heating device is not of a coil type and not of a quartz type but a panel type that basically acts like a silicon diode reulting in DC (pulsating DC) being sent to your transformer devices. The fix for this is a DC block device. you can buy one, or if you are electrically inclined...make one. I have a few schematic's up on a recent thread.

[artto]

 for problem 1)

you either have whats refered to as a reverese power factor...simply put...the appliance is casuing an inductance wave that is sending voltage harmonics thru your transformer based devices....if this is the case (higly unlikey) you either need to use an isolation transformer (which will buzz/him instead) or use power factor correction capacitors to correct your reverse power factor to a forward leaning one.

 more likely and easier to fix...your heating device is not of a coil type and not of a quartz type but a panel type that basically acts like a silicon diode reulting in DC (pulsating DC) being sent to your transformer devices.  The fix for this is a DC block device.  you can buy one, or if you are electrically inclined...make one.  I have a few schematic's up on a recent thread.

 

 

Thanks. You NYC guys always seem to have the answers to these type of questions. Must be the power problems encountered in your higher usage/density region. I guess I'm just surprised that the Crown amps were affected by this. I used to have a Crown DL-2 & its associated power supply to "power" the system. I don't recall experiencing this problem back then when everything was powered from the Crown DL-2 Power Module.

[artto]

 Can you monitor the voltage on that circuit? If you reduce the AC voltage enough, I think the D60 transformer will hum. And, the preamp might shut down if the voltage gets low enough. Maybe the space heater is pulling so much current the voltage is sagging. 

I experienced this in my shop last winter using a high power space heater. Worth a quick check.

That's another interesting thought Mark. Yes, I can/do monitor voltage ~ one of the Furman units monitors voltage & current. The space heater is not connected thru it, just to an outlet on the same circuit, further down line, about 40 feet. The space heaters (either one that I use) are run on "low". The current draw shouldn't be any where near the 20 amp capacity with all the other stuff, but I can see the voltage pull-down off the 120V mark LED monitor. The other heater that caused the D-60's to hum was kinda scary. I put it for use on the other side of the basement on a different circuit. No problems there so far.

[artto]

Yes, it would be less than 120V. Its an LED type display. 105V is "center" (amber). 110, 115, 120V (green). 100, 95, 90V (red). The last (third - green) LED will go out, actually kind of weave on and off, but more off than on.

[artto]

Yes, it would be less than 120V. Its an LED type display. 105V is "center" (amber). 110, 115, 120V (green). 100, 95, 90V (red). The last (third - green) LED will go out, actually kind of weave on and off, but more off than on.

 

So, you are between 110 and 105. I'd say that could be the trouble. I guess the easy troubleshoot here is to have the heater on, get the hum going in the Crown, and then shut the heater off and see if hum drops away. 

That's exactly what I did! And it went away. Other heaters don't cause a problem with the hum, but possibly with the voltage sag. I guess I didn't think the MAC would be so sensitive to that, being made in NY and all that........LOL But maybe that old Crown DL-2 Power Module was doing more than I thought.......it WAS for sale

[djk]

Most inexpensive heaters, hairdryers, slow-cookers, 300W quartz floor-lamps, all use a half-wave rectifier when set to 'low'.

The DC imposed on the power line causes mechanical transformer buzz.

If your neighbor next door is on the same transformer, their use of said appliances will cause noise in your house.

A DC blocker will probably fix the problem, as will an isolation transformer (the isolation transformer will buzz though, mount in a remote location).

[Guest " "]

ditto to what djk said