Insufficient Power Conditioning?

[Andrew Lee Rubinger]

Very helpful, folks.  I'll try some things this week and report back here.

A little irritating: the power issues coming out of the wall disappeared yesterday, which makes diagnostics a bit tricky.

S,
ALR

[Paul Joppa]

Suggests it migh be industrial - closed on the weekend. Or a neighbor on vacation?

[Andrew Lee Rubinger]

Thought this may be helpful in describing my power issues.

 

Similar to anyone?  Note that in this video I've attempted to introduce a TrippLite Isolating Transformer, which has not helped (in some ways makes it worse, as evidenced by the now-pulsating sound as shown in the video).

Do we know what is causing this, and how I might rectify (excuse the pun) it?

S,
ALR

[Doc B.]

What kind of lights are the outdoor lights?

[Andrew Lee Rubinger]

Incandescent, old-school "Edison" ones.  Is that relevant?  I thought the deal was in trying to isolate the power to be "clean"?  Which I thought the isolating transformer was supposed to do, no?  Or does that not buffer against a ground loop?

[Grainger49]

Andrew,

So, no noise till you turn on the outside lights.  Then pulsing and it continues even after the lights are turned off.  Sounds like some oscillation is set up.  But usually oscillation is high frequencies. 

I think the type of lights you DO have will deepen the mystery.  Dan (Doc) expected something that normally generates noise like Quartz or LED.

Is there anything else on the outside light circuit other than the incandescent lights?

Do you have the BeePre input selected shorted?

[Doc B.]

You might try measuring the wall outlet voltage while you turn the lights on to see if there is a significant change. Are the lights just connected to a regular switch, or is there maybe a motion detector circuit or a timer or something else incorporated with the lights?

[Andrew Lee Rubinger]

So, no noise till you turn on the outside lights.  Then pulsing and it continues even after the lights are turned off.  Sounds like some oscillation is set up.  But usually oscillation is high frequencies. 

Actually, there is a hum there without the lights that this particular recording didn't pick up so well; sometimes it's much louder.

I think the type of lights you DO have will deepen the mystery.  Dan (Doc) expected something that normally generates noise like Quartz or LED.

Just incandescent.

Is there anything else on the outside light circuit other than the incandescent lights?

Yep: the LED television (which when on can also increase the humming volume) and other misc A/V things.

Do you have the BeePre input selected shorted?

I'm not sure what this means?  The buzzing is not affected by the BeePre input selector, balance, or volume pots.

S,
ALR

[Andrew Lee Rubinger]

You might try measuring the wall outlet voltage while you turn the lights on to see if there is a significant change. Are the lights just connected to a regular switch, or is there maybe a motion detector circuit or a timer or something else incorporated with the lights?

Yeah, turning on anything else on that circuit will drop the voltage a bit.  At rest, 118V.  With outdoor lights on, 115V.  With outdoor lights, amp and preamp all on, 114V.  Measurements taken from the leads on the power input of the BeePre.

[Doc B.]

Are those voltages measured with the Tripplite in the circuit?

[Andrew Lee Rubinger]

Are those voltages measured with the Tripplite in the circuit?

Yup.

Worth noting; the TrippLite apparently doesn't isolate the neutral output, only the hot:

Amazon review: "Unfortunately this product has the output neutral line tied to ground"

S,
ALR

[Grainger49]

Andrew,

You had said that there was hum but the laptop speakers didn't produce it. 

Many digital devices put noise onto the ac line.  The isolation transformer will give you isolation but not eliminate it.

A selected open input can pick up noise.  So for testing you take jumpers and jump the right hot to the right ground, the left hot to the left ground at the RCA jacks.  This eliminates a source of noise.

[Doc B.]

Are you getting the same voltage at the outlet with or without the Tripplite in there? I'm thinking you are, but thought I'd better make sure. I'm kinda with PJ that this could be an issue of low voltage at the outlet creating a regulator issue in the BeePre. Can you get the voltage to come up at all if you turn off everything except the amp and preamp? That drop from 118 to 115 or 114 seems pretty big for just a couple pieces of audio gear. I wonder if there is a connection in the house wiring that is less than perfect and creating some resistance. The fact that the outside lights are on the same circuit as wall outlets is, well, it's as bad as my house! We have a furnace, washing machine, microwave and some lights on one circuit. Completely stupid, and you would think I would do something about it besides go downstairs, turn off the washer and reset the breaker every time somebody turns on the microwave the when the washer and the furnace are running.

[Grainger49]

If you have less than positive contact in your light and outlet circuit you should get an electrician (licensed and insured) to come in and make all the terminations over.  The terminations at the outlets should be on the screws not the pins inserted from the rear of the outlets.

Dan, any molded case breaker that has tripped 6 times is no longer tripping at the name plate value.  It should be replaced.  They work on a bi-metalic strip that anneals and changes its value after a half dozen trips.

[Doc B.]

Thanks Grainger, I should indeed replace it and reroute some of the cap appliances on the circuit.