Studies On Residential Power Line Noise - Part 1

bilbeau

Nope ya cant convince me that you can hear the difference between a 10.00 cord and a 100 dollar cord. Aint no way no how!!!!

Your ears can deceive you. Sometimes we hear what we hope to hear.

Like I said show me what the scope shows on the outputs of the power supply. Show me the outputs with a regular cord then with a high dollar cord.

I cant go by someones hearing. One day you can hear up to 20KHz next day only to 19.9KHz

I have worked around B52 aircraft repairing avionics systems for years so my hearing is not what it once was so tell me why would I hear any difference.

I'm not doubting the findings of the input power. After twenty plus years of being in the electronics field I have seen plenty of dirty AC power. I just cant see how 6 feet of wire is going to clean that up.

DarqueKnight

It will be difficult finding someone on this forum who is brave enough to go poking around inside an energized power amp with an oscilloscope. Most, if not all, of the guys around here who had those kinds of balls went over to the Audioholics forum (www.audioholics.com).

Good luck with your research.

reeltrouble1

hopefully the recommendation will not fly so high as to be missed.

RT1

ben62670

bilbeau wrote: »

Nope ya cant convince me that you can hear the difference between a 10.00 cord and a 100 dollar cord. Aint no way no how!!!!

Just a curiosity question. Why do you think he is trying to convince you that you can hear a difference? I don't really think he cares if you can hear a difference. He doesn't sell any of the products he has mentioned. He like other hear love the hobby, and he (I think) is looking for ways to measure scientifically what he hears. It's his trade.
DK please correct me if I am wrong.
Thanks
Ben

DarqueKnight

bilbeau wrote: »

Nope ya cant convince me that you can hear the difference between a 10.00 cord and a 100 dollar cord. Aint no way no how!!!!

OK...but please be advised that no "convincing" was attempted.

bilbeau wrote: »

Your ears can deceive you.

I agree...and that deception can be a very good thing. Every time I listen to my SDA's, my ears deceive me into believing that sound is coming from in front of, above, behind, to the sides of and in between the speakers. Sometimes, if the recording quality is really, really good, my ears deceive me into thinking that there are real three dimensional people in the room making the music, rather than two wooden boxes, some assorted wire, and electronics.

bilbeau wrote: »

Sometimes we hear what we hope to hear.

Actually, I go into a cable or component evaluation with negative bias. The more expensive the cost of the cable or component, the higher the negative bias. I hope (wish) that I don't hear an improvement, or that the improvement will be so small that the cost to upgrade will not be justified. I would prefer to keep money in my pocket.;)

bilbeau wrote: »

Like I said show me what the scope shows on the outputs of the power supply. Show me the outputs with a regular cord then with a high dollar cord.

I did show the differences in oscilloscope measurements at the outputs of my amplifiers when power cords were switched in part 2 of this series. We can then infer that there must be differences at the output of the power supply inside the amp, therefore, I don't think it is necessary to go poking around inside my amps. However, I'm sure there are other meter pontiffs who would relish that sort of inquiry. Finding one shouldn't be too difficult...if you know where to look.

bilbeau wrote: »

I cant go by someones hearing.

Nor should you. Kudos.

bilbeau wrote: »

One day you can hear up to 20KHz next day only to 19.9KHz.

I have not read any scientific studies on the day to day variances in human hearing sensitivity, but would enjoy learning about it. Can you point me to some literature on the subject?

bilbeau wrote: »

I have worked around B52 aircraft repairing avionics systems for years so my hearing is not what it once was...

That can be a blessing and a curse. Thanks for the insight into your personal frame of reference.

bilbeau wrote: »

...so tell me why would I hear any difference.

bilbeau wrote: »

I'm not doubting the findings of the input power. After twenty plus years of being in the electronics field I have seen plenty of dirty AC power. I just cant see how 6 feet of wire is going to clean that up.

Some things are difficult to understand.

ben62670 wrote: »

Just a curiosity question. Why do you think he is trying to convince you that you can hear a difference?

I wondered about that myself.

ben62670 wrote: »

I don't really think he cares if you can hear a difference.

You are correct, sir.

ben62670 wrote: »

He doesn't sell any of the products he has mentioned.

Correct again. I would also like to add that I would prefer it if I could achieve my home audio and video goals with the fine products sold at Walmart. No luck so far.:(*

---

*But he's patient.

pinecone

DarqueKnight,

I am just getting started with audio measurements and really enjoy your posts.
I am trying to replicate some of your measurements so I can learn and was wondering what probe you are using and how you have it hooked up to the 2012?

Thanks for your time, I appreciate your help.

DarqueKnight

pinecone wrote: »

I am trying to replicate some of your measurements so I can learn and was wondering what probe you are using and how you have it hooked up to the 2012?

Tektronix P2220 probe connected to channel 2 of the oscilloscope. I use channel 2 because of the red trace color compared to the yellow color on channel 1. Red photographs better.

When taking voltage measurements from the wall or end of a power cord, don't connect the ground lead of the oscilloscope probe as you would with a multimeter.

The probe tips are too short to fit into the Line side socket of a wall plate or power cord. To take these types of measurements, I inserted a multimeter probe into the wall or cord and used the probe's hook clip attachment to connect to the other end of the multimeter probe cord.

Enjoy.

tonyb

Man DK, all this talk of photograghs, probes, clips, tips.....your turning me on. LOL !!

wkjeffers

3rd harmonics are common for ac to dc conversion. ie. electronics.

wkjeffers

also not e that CFL bulbs and LED bulbs contain ballasts that create huge amounts of harmonics. Power quality studies project that if a factory were to convert to all CFL bulbs, there DC drives might not work correctly because of all the harmonics. Also I have seen LEd bulbs completely wipe out an FM station signal due to the RF interference.

oldmodman

Giant isolation transformer.

I live very close to TRW and they have a monthly electronic & ham radio swap meet in their parking lot. And I bought a two hundred pound "scientific" isolation transformer from the TRW surplus department.