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Old 8th April 2010, 11:57 PM   #61
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Quote:
Originally Posted by anatech View Post
Hi Printer2,
Hi Chris.

Quote:
Not really. We have touched on that, and even pointed out that the wall supply is distorted due to the capacitor input type filter used most often.
Sorry, mainly my way of directing thought towards this issue not trying to say others did not feel it also important.

Quote:
The portion used is less than you may think. You can figure it out in terms of conduction angle in degrees. This will allow you to figure it out closely because you also know the frequency.
I was just using those numbers as an example to focus our attention on the part that is important. I am new here and wanted to keep my posts simple so all could understand.

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Only in the case of a power amp or really silly preamplifier. The dirty power that is referred to is higher frequency stuff that does tend to end up in the audio signal by way of the (generally) poorly designed power supplies in consumer equipment. It can matter.
Everything in life can matter. But the question is how likely in the OP's current situation will he need twisted power lines in metal conduit?

Quote:
Those two concepts are not tied together. The HF noise on a since wave may possibly get into the internal circuitry. The equipment does load the peaks of the the wave form, and sometimes internal filtering is used to prevent that noise from getting out.
Sometimes internal filtering is used to prevent that noise from getting out? I would think that is pretty much the function of a power supply other than to store energy.

Quote:
The repetition rate is normally at 120 Hz, unless there is a half wave rectifier which then creates a 60 Hz repetition rate. The bursts of noise will have a wide spectrum of frequencies.
Which is what I have been saying. This burst of energy the capacitors get every cycle has more high frequency content than what is coming down your 120V line. Those filter capacitors are there to deal with it.

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Larger capacitors tend to create more problems. More is not always better, but it can make good ad copy.
I meant big capacitors relative to the rest of the piece of electronic equipment we are talking about. Generally they are the largest capacitors hanging about.

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And I'll try to make sure the lights are on the other phase before doing anything else.
You only have one phase coming in your home. If you have your stereo on one 120V leg and a noisy device on the other 120V leg of your 240V service the two currents sum together and go in and out of your 240V lines to your house. Any difference goes through the ground from your panel.

Quote:
Most AC power cable is twisted already. If you want to reduce noise pickup or radiation, buy a shielded cable (they make them).
We are talking about house wiring here were we not? I am not really familiar with the twisted stuff for houses.

Quote:
Some surge protectors channel the HF hash onto the ground, that's not really where you want it to go. Also, all extra series resistance should be avoided. You even made that point earlier.
The ground is precisely where you want the noise to go. Where would you put it?

Quote:
So why are you crusading? It doesn't look like you have read th previous posts.
-Chris
I have read the previous posts. At least using the transformer got turfed. I was trying to explain why the conduit and using twisted cable for power wiring is unnecessary. I do not think it crusading, my saying that the new plan of attack by the OP is a waste of time.

I had spent some time learning about protecting military equipment from conducted and radiated EMI from the kHz range up into the GHz. I have worked in industrial and hospital environments. While I am no expert on all things audio or power related I have seen a few things. Just thought I would give my opinion. I'll try to keep my posts down as not to seem to be crusading.
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Old 9th April 2010, 01:15 AM   #62
rdf is offline rdf  Canada
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Quote:
Originally Posted by anatech View Post
Hi rdf,
What brand of toroid did you test?
Hi Chris. Can't recall, maybe Avemco (?), harvested from ITC cart machines. Within the audio band I didn't see any real difference to choose from between them and Hammond filament transformers. I'ld expect that, it would be a very poor EI indeed that didn't make a solid effort to 20 kHz. Above that, you may have a point but that's awfully easy to filter in tube supplies.

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Last edited by rdf; 9th April 2010 at 01:19 AM.
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Old 9th April 2010, 02:29 AM   #63
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I know an isolation transformer worked perfectly for a recording studio project and I would use one again. I spent two weeks with a scope and spectrum analyzer, impedance metering hammering ground rods before things got quiet, so this is my experience. Audiophiles have one high-gain (phono preamp) device whereas a recording studio runs a dozen microphones into a console with a lot more gain, which shows you line noise and RF like nothing you can imagine.

When I worked as a tech in medical research and they had a commercially made shielded room for the "experiments", involving brain cells (micro-volts, preamp gains of a few thousand). It had an isolation transformer and dedicated ground from the 6th floor down to the basement. Not my idea but it worked, the room was electrically quiet enough.
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Old 9th April 2010, 04:32 AM   #64
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Lightbulb AC Wiring Losses

I did a quick calculation (not to be confused with speculation) on a 50' run of 14AWG NMD with a 120VAC source and 15A load, to compare use of larger wiring.
I could not find any EMI/RFI line filter specs with DC resistance, so who knows the voltage drop (at 60Hz). I thought it would be silly to save 0.05 ohms on your wiring and then add say 0.1 ohm with the filter.

P.S. - Jim, I hope your 12ga. stranded/litz wire meets electrical code, for insulation flammability, voltage etc. I'd hate for the inspector to have you pull it out.
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Old 19th April 2010, 03:39 PM   #65
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Hi everyone.

I've been in Spain for the past week, so have not had a chance to look at this thread.

Still no conclusion yet. It sounds like the braided wire and steel pipe are a waste of time. It looks like (from the last post) that I need a heavier wire still to make the ~50' run across the house. Perhaps 8 ga to keep the drop less that 1%.

I have already moved the feed breaker to the top of the panel, and will check to make sure the light breaker for that room is on the other side of the panel (although it seems the 220 for the dryer and oven could cause cross-contamination if either appliance are running while the light is dimmed and the stereo is playing). I suppose I could keep the dryer and/or oven off while listening to the stereo critically...

PS I am enjoying the back and forth here on all the related subjects coming up due to my original question. I am learning a lot!
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Old 19th April 2010, 05:06 PM   #66
ChrisA is offline ChrisA  United States
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Originally Posted by Jim Leach View Post
I have already moved the feed breaker to the top of the panel, and will check to make sure the light breaker for that room is on the other side of the panel (although it seems the 220 for the dryer and oven could cause cross-contamination if either appliance are running while the light is dimmed and the stereo is playing).!
If your service entrance panel is like mine, the order of the breakers inside will make no difference because that are all connected to the same think copper bus.

You best best, is to simply use a large enough gauge of wire and then very near the point of use have a good transformer/filter

If you have a refridgerator or dryer running _anyplace_ in the house and it's acoustic noise,that it sends throught ehdrywall and air will hugly overshadow any electrically noise.

Just this weekend I made some quick mesurements with a microphone and fond the noise from my sun's PC power supply fan was far larger then any electrical noise. And his PC was upstairs (one floor up and one closed door away.

A better use of your time and money is to worry about stuff that has a 10x or 100x larger effect on the sound. And this is acoustic noise. contruction technique can have a HUGE effect. For example have then place rock wool insulation in every space inside all interior walls. Use sound deadening board under the drywall. You can also attach the drywall with sound isolation clips, these are cheap and made a huge difference. Building codes allow this as these techniques are used for shared walls high end in multi-unit housing. The best is to use every technique, staggered studs, sound borad, isolation clipps and double layers of 5/8 drywall. All this is approved and to code. and not really expensive and will matter more than 100 times more then the kind of wire you use., maybe much more than 100 times depending oon the layout of the rooms Other small things mater a lot. For example interior doors, use the solid wood kind and not the hollow ones that, and weather stripping on interior doors makes them almost sound proof. In a few places in my house I use double french doors that can be closed to seal off the noise from one area to the others and the 6 foot wide glass still allows an open look. Buy double glasses dors and they are much more sound proof. All this adds up and is cheap and easy to do during construction.

The point here is to identify the important stuff and don't worry abot what does not matter (like the order of circuit breakers that share a power bus.)

Like I said, that fan in a PC in another room matters more. The sound of water in pipes matters too, You can buy platic isolators for water pipe. drill oversize holes and the isolator goes between the pipe and the hole. For waste lines, cast iron is much quiter than PVC but expensive you use it onlyon the vertical drops.
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Old 19th April 2010, 05:31 PM   #67
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Quote:
Originally Posted by ChrisA View Post
You best best, is to simply use a large enough gauge of wire and then very near the point of use have a good transformer/filter
That was the plan (more or less) however the transformer (which I posted photos of) seems to have been shot down by the collective here. It has a good amount of capacitance in it, and may be the right thing (I always thought so) but then some think it may add more noise than it removes...

Quote:
Originally Posted by ChrisA View Post
If you have a refridgerator or dryer running _anyplace_ in the house and it's acoustic noise,that it sends throught ehdrywall and air will hugly overshadow any electrically noise.
I am aware of the acoustic noise issue. All floors and ceilings are insulated. The floor of the 'media room' will be braced to prevent it resonating as well. Interior walls are not acoustically insulated unfortunately, and I am not pulling more Sheetrock down just to do that. Seriously considering a second 5/8 layer (over the 3/8 used originally) for the rest of the room in question. This is a bit outside the scope of this original question however...

Quote:
Originally Posted by ChrisA View Post
Just this weekend I made some quick mesurements with a microphone and fond the noise from my sun's PC power supply fan was far larger then any electrical noise. And his PC was upstairs (one floor up and one closed door away.
Very interesting observation! Time to chuck the PC then I guess!

Quote:
Originally Posted by ChrisA View Post
A better use of your time and money is to worry about stuff that has a 10x or 100x larger effect on the sound. And this is acoustic noise. contruction technique can have a HUGE effect.
These things are being considered/addressed...

Quote:
Originally Posted by ChrisA View Post
The point here is to identify the important stuff and don't worry abot what does not matter (like the order of circuit breakers that share a power bus.)
But at the same time, if there is a 'better' way to feed the power, why not do it that way? It costs the same- all I did was try to reduce the influence of other electrical equipment in the house from having an affect on the power feed to the stereo rig.

Quote:
Originally Posted by ChrisA View Post
Like I said, that fan in a PC in another room matters more. The sound of water in pipes matters too, You can buy platic isolators for water pipe. drill oversize holes and the isolator goes between the pipe and the hole. For waste lines, cast iron is much quiter than PVC but expensive you use it onlyon the vertical drops.
Waste lines are all copper. All pipes (that I have access to) are insulated with typical foam; penetrations with 'great stuff' fire block. Both bathrooms are to be demo'd/replaced and the pipes at these areas will be similarly treated. Again, a bit off topic from the original one, but welcome advice nonetheless!
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Old 19th April 2010, 06:13 PM   #68
wa2ise is offline wa2ise  United States
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If you're having major renovation done, maybe it makes sense to replace all easily accessible romex house wire with "BX" cables. AKA "AC" IIRC. This cable has the neutral and ground wires inside the flexible armor as a twisted pair, about one twist every 2 inches. This looks similar to balanced shielded microphone cable but with heavier wire. This will act as a reverse shield, to contain hum and powerline noise.
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Old 19th April 2010, 08:05 PM   #69
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I think if that is used, the boxes will have to be changed to ones accepting round connections. The ones in the walls now are designed for 'romex' flat solid wire.

That might be a good idea; however not practical right now...
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Old 24th April 2010, 01:45 PM   #70
joeyou3 is offline joeyou3  United States
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No ground rod or combination of will clear a fault by tripping a 20 amp breaker. I am a Senior Electrical Inspector and training officer for the city of Los Angeles (retired).
Best ground is isolated, However, if you are using a metal boc Two ground wires must be run, one isolated and the other a normal ground. Isolated grounds must come directly from the MAIN service panel and go directly to your Isolated ground receptacle. Best run in metal conduit for isolation from noise. Ground rods are only for lightning and High voltage faults to service entrance wires, most caused by auto vs utility pole. If you want I can give you a copy of Grounding essentials Powerpoint ny Tom Trainor, Previous Chief Electrical Inspector and President if IAEA.
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