Ac Is Not Just AC.
I have just moved house, so of course bits and pieces have come out of the archives.
I have set up a very nicely damped sound room (lounge room), and I am running various bits of reasonably good gear.
In this system, I am running a 2 kVA rated AC filter module followed by a 250V-250V isolation transformer (1 kVA) followed by a 2 kVA variac (an AVO8 provides voltage monitoring but this is audible when connected).
I have found this arrangement to sound bigger but more relaxed and more detailed (better) than the Variac then Iso transformer.
That was on Sat night, and I have not tried repositioning the AC filter to find more (other) differences yet.
Varying the amp AC voltage does not alter the amplifier sound very much, but it does affect the CDP trackability (bunky old Philips for now - today !).
In my new garage workshop, I am running another1 kVA isolation transformer with the earth wire disconnected internally, and a dedicated earth wire grounding the garage audio/video system, and again only the devices in use are connected, audio line levels or power.
So far the informal experiments show that running this dedicated earth wire quite markedly improves the sound of this system.
In this recent experimentation (so far without rigorous A/B testing), my findings are that grounding and isolated AC are sonically important.
In the foreseeable future, I will experiment further with AC filtering and power factor compensation to see what differences I can discern.
Stay tuned !.
Eric.
I have just moved house, so of course bits and pieces have come out of the archives.
I have set up a very nicely damped sound room (lounge room), and I am running various bits of reasonably good gear.
In this system, I am running a 2 kVA rated AC filter module followed by a 250V-250V isolation transformer (1 kVA) followed by a 2 kVA variac (an AVO8 provides voltage monitoring but this is audible when connected).
I have found this arrangement to sound bigger but more relaxed and more detailed (better) than the Variac then Iso transformer.
That was on Sat night, and I have not tried repositioning the AC filter to find more (other) differences yet.
Varying the amp AC voltage does not alter the amplifier sound very much, but it does affect the CDP trackability (bunky old Philips for now - today !).
In my new garage workshop, I am running another1 kVA isolation transformer with the earth wire disconnected internally, and a dedicated earth wire grounding the garage audio/video system, and again only the devices in use are connected, audio line levels or power.
So far the informal experiments show that running this dedicated earth wire quite markedly improves the sound of this system.
In this recent experimentation (so far without rigorous A/B testing), my findings are that grounding and isolated AC are sonically important.
In the foreseeable future, I will experiment further with AC filtering and power factor compensation to see what differences I can discern.
Stay tuned !.
Eric.
yet another source of white papers and experience
Here is a nice article written buy Roger Nichols discussing AC power management in the recording studio.
http://www.equitech.com/articles/power.html
The Roger Nichols web site discussing his vast work can be found here:
http://www.rogernichols.com/
A large resource for white papers, and other balanced power resources can be found here:
http://www.equitech.com/articles/articles.html
from Equi=Tech. http://www.equitech.com/
I spent some time talking to these guys a few years ago. They are very knowledgeable and would seem to understand when pragmatism and idealism can cohabitate and when they must be divorced.
I work in an industry that supplies 48 volt DC to consumers as part of its core product. The reasons, as I understand them, that the phone company does this are many and diverse. Safety and fault tolerance are preeminent. (You didn’t think I was going to say low THD+N did you?)
Here is a nice article written buy Roger Nichols discussing AC power management in the recording studio.
http://www.equitech.com/articles/power.html
The Roger Nichols web site discussing his vast work can be found here:
http://www.rogernichols.com/
A large resource for white papers, and other balanced power resources can be found here:
http://www.equitech.com/articles/articles.html
from Equi=Tech. http://www.equitech.com/
I spent some time talking to these guys a few years ago. They are very knowledgeable and would seem to understand when pragmatism and idealism can cohabitate and when they must be divorced.
I work in an industry that supplies 48 volt DC to consumers as part of its core product. The reasons, as I understand them, that the phone company does this are many and diverse. Safety and fault tolerance are preeminent. (You didn’t think I was going to say low THD+N did you?)
Maybe not......
"Safety and fault tolerance are preeminent"
You have never dropped wrench on a large -48 volt bus in a Central Office. It will almost vaporize.
Many of the things in telephony are done because that was the way they did it about 100 years ago and most new equipment had to be backward compatible. Negative 48 volts is to run off batteries (4 x 12 volt) Some short loop PBXs run on -24 volts. Power cross and lightning strikes on the phone lines are where safety and reliability are the real challenge.
"Safety and fault tolerance are preeminent"
You have never dropped wrench on a large -48 volt bus in a Central Office. It will almost vaporize.
Many of the things in telephony are done because that was the way they did it about 100 years ago and most new equipment had to be backward compatible. Negative 48 volts is to run off batteries (4 x 12 volt) Some short loop PBXs run on -24 volts. Power cross and lightning strikes on the phone lines are where safety and reliability are the real challenge.
balanced power
From:
http://www.equitech.com/articles/rep1.html
"The root cause of most studio noise problems has little to do with grounding techniques."
From:
http://www.equitech.com/articles/enigma.html
"Grounding noise is one of the most common complaints from audio engineers"
Written by the same guy. Which is it? Grounding techniques have everything to do with noise problems. This product doesn't address noise on AC line and is really just an isolation transformer with a center tap on the load side.
"This should cancel the reactive currents of the circuit the way."
What are reactive currents? I have never heard the term.
http://www.amazon.com/exec/obidos/t...t_1/002-0939699-6058406?v=glance&s=books&st=*
http://www.amazon.com/exec/obidos/t...t_1/002-0939699-6058406?v=glance&s=books&st=*
http://www.amazon.com/exec/obidos/ASIN/0471838071/qid=937841437/sr=1-1/002-0939699-6058406
P.S. I have read all three of these books and recommend the first two.
From:
http://www.equitech.com/articles/rep1.html
"The root cause of most studio noise problems has little to do with grounding techniques."
From:
http://www.equitech.com/articles/enigma.html
"Grounding noise is one of the most common complaints from audio engineers"
Written by the same guy. Which is it? Grounding techniques have everything to do with noise problems. This product doesn't address noise on AC line and is really just an isolation transformer with a center tap on the load side.
"This should cancel the reactive currents of the circuit the way."
What are reactive currents? I have never heard the term.
http://www.amazon.com/exec/obidos/t...t_1/002-0939699-6058406?v=glance&s=books&st=*
http://www.amazon.com/exec/obidos/t...t_1/002-0939699-6058406?v=glance&s=books&st=*
http://www.amazon.com/exec/obidos/ASIN/0471838071/qid=937841437/sr=1-1/002-0939699-6058406
P.S. I have read all three of these books and recommend the first two.
Hi Fred,
Nope never dropped a wrench across an open (DC) buss bar. I have had a few AC explosions but that is a different story. There is a very good reason why they don’t let me play inside the central offices. I think it’s the curse of evil King Fecal.
My Dad (a machinist recently retired) did however once sheepishly tell me the story of dropping a large screwdriver inside the electric cabinet of a locomotive he was working on... It did vaporize. 600 VDC with a huge current capacity.
In most UPS and Central office DC supplies that Ive seen, there were few places where the bus is left exposed. Sounds like you’ve been there too. Big fuses at the distribution point’s supply distro panels in each equipment rack with a fuse supplying each peace of equipment. Besides safety this minimizes the effects of a single point of failure, attempting to keep one equipment failure from cascading to power outages on more equipment. For anyone contemplating even a small DC supply for their audio gear, Id recommend making the safety cutoffs very easy to see and operate.
I mention safety as a design criteria based on some very old descriptions I read about CO design. providing power to the subscribers with current limiting and surge suppression seemed to be huge concerns.
Ive always wanted to read the Morrison Grounding and Shielding book. The price tag has always caused me to stop short. So much to read, so little time.
I think what the Equitech guys are asserting in the statements you quoted is that while recording engineers typically complain about noise and blame it on grounding, the real issue is noise on the power line. After my effusive recommendations, I have to admit this sounds like marketing talk. There are no substitutes for a well executed and consistent grounding scheme. I do however agree that the Equitech approach will likely minimize the transfer into of RFI on the AC into the audio signal path, especially if good grounding techniques are used.
- Dave
Reactive currents, uhmm I think its a clumsy way of saying induced noise?
Nope never dropped a wrench across an open (DC) buss bar. I have had a few AC explosions but that is a different story. There is a very good reason why they don’t let me play inside the central offices. I think it’s the curse of evil King Fecal.
My Dad (a machinist recently retired) did however once sheepishly tell me the story of dropping a large screwdriver inside the electric cabinet of a locomotive he was working on... It did vaporize. 600 VDC with a huge current capacity.
In most UPS and Central office DC supplies that Ive seen, there were few places where the bus is left exposed. Sounds like you’ve been there too. Big fuses at the distribution point’s supply distro panels in each equipment rack with a fuse supplying each peace of equipment. Besides safety this minimizes the effects of a single point of failure, attempting to keep one equipment failure from cascading to power outages on more equipment. For anyone contemplating even a small DC supply for their audio gear, Id recommend making the safety cutoffs very easy to see and operate.
I mention safety as a design criteria based on some very old descriptions I read about CO design. providing power to the subscribers with current limiting and surge suppression seemed to be huge concerns.
Ive always wanted to read the Morrison Grounding and Shielding book. The price tag has always caused me to stop short. So much to read, so little time.
I think what the Equitech guys are asserting in the statements you quoted is that while recording engineers typically complain about noise and blame it on grounding, the real issue is noise on the power line. After my effusive recommendations, I have to admit this sounds like marketing talk. There are no substitutes for a well executed and consistent grounding scheme. I do however agree that the Equitech approach will likely minimize the transfer into of RFI on the AC into the audio signal path, especially if good grounding techniques are used.
- Dave
Reactive currents, uhmm I think its a clumsy way of saying induced noise?
My two cents.
"The laws of Physics in a 3 dimensional spatial universe such as ours allows the possibility for some people not to comprehend it's subtleties."
Reactive Currents or Back EMF as they are called are so real they are design factors in Electric braking systems on anything and everything from Trains to Model cars.
When an electric current is generated an exact force 180 deg out of phase at a harmonic Frequency is also generated. Shorting the commutator introduces these currents through the armature and instantly cancel, or a motors case, collapse all magentic fields and brake the motor.
Though the same law in power transmission seems like pixie dust in nonetheless exists. It happens when you try to modify electron flow in any way shape or form at different intensities and effects. Some effects are not measurable others are more obvious.
One of the very best comments I have seen on this topic in this forum was the suggestion of Electrostatic shielding and using split rail power supplies. This by far is one of the best ways to design noise out of your power supplies.
Isolation transformers and split rail power supplies share a common advantage. That is taking the inherent phase swing of an AC Waveform across two precisely (Bifilar) wound transformers and generating two similar wave forms 180 deg. out of phase to one and other. By summing these in reference to the centre tap they completely cancel each other out. You can try this yourself but be very careful not to eletrocute yourself or you can take my word for it. So instead we hook them up in phase across a load which sees two out of phase signals referencing ground. The Benifit you ask, well just like balanced line level inputs and outputs, any noise finding it's way to ground will have it's reactive current component summed to zero. Without a current component a signal can no longer exist in our space, so it is no more.
You could claim that the signal slips out of our perception only to exist in a two dimensional plane. I would say your insane as it makes no difference what happens to the unwanted signal, it's not in the Audio Path.
Regards
Anthony
"The laws of Physics in a 3 dimensional spatial universe such as ours allows the possibility for some people not to comprehend it's subtleties."
Reactive Currents or Back EMF as they are called are so real they are design factors in Electric braking systems on anything and everything from Trains to Model cars.
When an electric current is generated an exact force 180 deg out of phase at a harmonic Frequency is also generated. Shorting the commutator introduces these currents through the armature and instantly cancel, or a motors case, collapse all magentic fields and brake the motor.
Though the same law in power transmission seems like pixie dust in nonetheless exists. It happens when you try to modify electron flow in any way shape or form at different intensities and effects. Some effects are not measurable others are more obvious.
One of the very best comments I have seen on this topic in this forum was the suggestion of Electrostatic shielding and using split rail power supplies. This by far is one of the best ways to design noise out of your power supplies.
Isolation transformers and split rail power supplies share a common advantage. That is taking the inherent phase swing of an AC Waveform across two precisely (Bifilar) wound transformers and generating two similar wave forms 180 deg. out of phase to one and other. By summing these in reference to the centre tap they completely cancel each other out. You can try this yourself but be very careful not to eletrocute yourself or you can take my word for it. So instead we hook them up in phase across a load which sees two out of phase signals referencing ground. The Benifit you ask, well just like balanced line level inputs and outputs, any noise finding it's way to ground will have it's reactive current component summed to zero. Without a current component a signal can no longer exist in our space, so it is no more.
You could claim that the signal slips out of our perception only to exist in a two dimensional plane. I would say your insane as it makes no difference what happens to the unwanted signal, it's not in the Audio Path.
Regards
Anthony
Re: balanced power
"Reactive currents" is his way of saying what what others would perhaps be more familiar with as "chassis leakage currents."
It's that center tap on the transformer's secondary that's the whole foundation of "balanced power."
Because the safety ground, which is typically tied to equipment chassis and signal reference ground, is tied to neutral at the service panel, the capacitive coupling between hot and safety ground can produce significant chassis leakage currents.
With the safety ground tied to the center tap of the transformer, in an ideal world both hot and neutral couple equally to the safety ground which would eliminate chassis leakage currents and subsequently the noise produced by such leakage currents.
It would also help with noise on the AC line but only in the context of chassis leakage currents by way of the AC safety ground.
It's 9:03 AM here. Be sure and note that in my dossier.
se
Fred Dieckmann said:
"Reactive currents" is his way of saying what what others would perhaps be more familiar with as "chassis leakage currents."
It's that center tap on the transformer's secondary that's the whole foundation of "balanced power."
Because the safety ground, which is typically tied to equipment chassis and signal reference ground, is tied to neutral at the service panel, the capacitive coupling between hot and safety ground can produce significant chassis leakage currents.
With the safety ground tied to the center tap of the transformer, in an ideal world both hot and neutral couple equally to the safety ground which would eliminate chassis leakage currents and subsequently the noise produced by such leakage currents.
It would also help with noise on the AC line but only in the context of chassis leakage currents by way of the AC safety ground.
It's 9:03 AM here. Be sure and note that in my dossier.
se
I'm already doing this.
I did not mention that the amp and cdp are 2 wire powered units, connected via audio isolation transformers, and both cabinets tied together and to the dedicated system ground (the earth through connection is disconnected within the AC iso transformer box).
I know that safety is reliant on the dedicated earth wire, but this setup gives extraordinarily quiet (hum AND noise) system operation, and sonics are dead clean, and very pleasant.
Eric.
I did not mention that the amp and cdp are 2 wire powered units, connected via audio isolation transformers, and both cabinets tied together and to the dedicated system ground (the earth through connection is disconnected within the AC iso transformer box).
I know that safety is reliant on the dedicated earth wire, but this setup gives extraordinarily quiet (hum AND noise) system operation, and sonics are dead clean, and very pleasant.
Eric.
In the Trunk Carrier Terminal where I grew up, the - 48 V no break supply was provided by 22 (I think) 2.2V cells, each the size of a 20" television.
This Dc power was reticulated around the room via massive buss-bars, each 1cm thick, by 15 cm high.
The battery could supply pretty much infinite current, so it was strictly verboten to be on top of the racks whilt wearing a finger ring, necklace or watch, and all tools were required to be insulation covered.
I have seen safety tutorial photos of these buss-bars where most of the metal is simply missing, and severed fingers and severely burned wrists due to stupid mistakes.
I have also seen a safety training video (Fluke DMM company ?), showing the perils of using the incorrect fuse types in high power switchboard applications.
The faults induced and filmed showed catastophic, and dangerous EXPLOSION of the complete swithboard cabinet.
High power stuff is not to be messed with.
Eric.
This Dc power was reticulated around the room via massive buss-bars, each 1cm thick, by 15 cm high.
The battery could supply pretty much infinite current, so it was strictly verboten to be on top of the racks whilt wearing a finger ring, necklace or watch, and all tools were required to be insulation covered.
I have seen safety tutorial photos of these buss-bars where most of the metal is simply missing, and severed fingers and severely burned wrists due to stupid mistakes.
I have also seen a safety training video (Fluke DMM company ?), showing the perils of using the incorrect fuse types in high power switchboard applications.
The faults induced and filmed showed catastophic, and dangerous EXPLOSION of the complete swithboard cabinet.
High power stuff is not to be messed with.
Eric.
well
"Reactive currents" is his way of saying what what others would perhaps be more familiar with as "chassis leakage currents."
No they are not. Go read the website and stop making it up as you go along. When are you going to stop bluffing?
http://www.equitech.com
I believe there is often still an impedance mismatch from nuetral to ground with respect to AC ground depending transformer design and chassis safety ground strategies. I have played with balanced power and found the advantage seemed to be in the isolation transformer and not the center tap of the secondary. Most of the "technical literature" reads like advertising copy to me,
but I have read 4 books on grounding and 5 on transformer design. These products are very expensive and don't get rid of the distortion in the AC waveform. Some of the claims are very suspect to me. I will leave it to the "armchair physist and engineers." Been there and done that. Read the references if you actually want to learn something.
"I mention safety as a design criteria based on some very old descriptions I read about CO design. providing power to the subscribers with current limiting and surge suppression seemed to be huge concerns."
I designed power cross and lightning protection circuit for telecom line cards. It's a bitch. The big things are fusable resistor networks that have to open under very specific conditions. Getting more than one vendor that can make them work was a nightmare.
"Reactive currents" is his way of saying what what others would perhaps be more familiar with as "chassis leakage currents."
No they are not. Go read the website and stop making it up as you go along. When are you going to stop bluffing?
http://www.equitech.com
I believe there is often still an impedance mismatch from nuetral to ground with respect to AC ground depending transformer design and chassis safety ground strategies. I have played with balanced power and found the advantage seemed to be in the isolation transformer and not the center tap of the secondary. Most of the "technical literature" reads like advertising copy to me,
but I have read 4 books on grounding and 5 on transformer design. These products are very expensive and don't get rid of the distortion in the AC waveform. Some of the claims are very suspect to me. I will leave it to the "armchair physist and engineers." Been there and done that. Read the references if you actually want to learn something.
"I mention safety as a design criteria based on some very old descriptions I read about CO design. providing power to the subscribers with current limiting and surge suppression seemed to be huge concerns."
I designed power cross and lightning protection circuit for telecom line cards. It's a bitch. The big things are fusable resistor networks that have to open under very specific conditions. Getting more than one vendor that can make them work was a nightmare.
Attachments
Acts Of The Gods.
The controller lines out in the fields have multiple shunt gas arrestors and varistors, and the boards are covered in more 5.1V zeners than you can count.
I have repaired boards where half the IC packages are BLOWN apart, and tracks vaporised and without trace.
Can lightning be completely protected against ?.
I repair big system retic gear - BirdBrain (tm).
The controller lines out in the fields have multiple shunt gas arrestors and varistors, and the boards are covered in more 5.1V zeners than you can count.
I have repaired boards where half the IC packages are BLOWN apart, and tracks vaporised and without trace.
Can lightning be completely protected against ?.
Re: well
I've read their web site a number of times over the years, thank you.
When I said that "reactive current" is his way of saying chassis leakage current, it was a kind way of saying that he hasn't much understanding of what's actually going on and what he's ultimately attempting to describe is a reduction in chassis leakage currents due to parasitic coupling into the safety ground due to the fact that the safety ground is tied to neutral at the service panel. Which leaves you with a 120 volt potential between hot and safety ground and a virtually 0 volt potential between neutral and safety ground.
As for bluffing, try again. I discussed this issue regarding Equi=Tech's claims in a rather lengthy thread on balanced power over on AA over two years ago.
See: http://db.audioasylum.com/cgi/m.pl?...lanced+power+equi=tech+steve+eddy&r=&session=
Such an impedance mismatch between neutral and safety ground is pretty much irrelevant. It's that 120 volts you've got between hot and safety ground and the capacitive coupling between the two that gives rise to leakage current problems. The only coupling you get between neutral and safety ground is due to the resistive voltage drop across the neutral line.
Let's say you've got 100 feet of 12 gauge wire for your neutral. That comes to about 0.16 ohms. Carrying 10 amps, that gives you a voltage drop of 1.6 volts. Rather insignificant compared to the 120 volts across the hot lead relative to the safety ground.
Well, an isolation transformer basically just isolates you from the mains AC safety ground and any leakage currents flowing through it due to other equipment on the line. And that can certainly be an advantage in itself. Using the center tap helps further reduce leakage currents due to the equipment tied to the isolation transformer.
What some have done to achieve "balanced power" without resorting to center tapped isolation transformers is to set their components to work on 220 volts and power them from a 220 volt line. Now the safety ground is the center tap between the two 110 volt lines.
Yes. Equi=Tech is very marketing driven. Rather like Bose. "Better Sound Through Marketing."
Well of course not. That's a whole other issue. Balanced power only addresses leakage current issues.
se
Fred Dieckmann said:
I've read their web site a number of times over the years, thank you.
When I said that "reactive current" is his way of saying chassis leakage current, it was a kind way of saying that he hasn't much understanding of what's actually going on and what he's ultimately attempting to describe is a reduction in chassis leakage currents due to parasitic coupling into the safety ground due to the fact that the safety ground is tied to neutral at the service panel. Which leaves you with a 120 volt potential between hot and safety ground and a virtually 0 volt potential between neutral and safety ground.
As for bluffing, try again. I discussed this issue regarding Equi=Tech's claims in a rather lengthy thread on balanced power over on AA over two years ago.
See: http://db.audioasylum.com/cgi/m.pl?...lanced+power+equi=tech+steve+eddy&r=&session=
Such an impedance mismatch between neutral and safety ground is pretty much irrelevant. It's that 120 volts you've got between hot and safety ground and the capacitive coupling between the two that gives rise to leakage current problems. The only coupling you get between neutral and safety ground is due to the resistive voltage drop across the neutral line.
Let's say you've got 100 feet of 12 gauge wire for your neutral. That comes to about 0.16 ohms. Carrying 10 amps, that gives you a voltage drop of 1.6 volts. Rather insignificant compared to the 120 volts across the hot lead relative to the safety ground.
Well, an isolation transformer basically just isolates you from the mains AC safety ground and any leakage currents flowing through it due to other equipment on the line. And that can certainly be an advantage in itself. Using the center tap helps further reduce leakage currents due to the equipment tied to the isolation transformer.
What some have done to achieve "balanced power" without resorting to center tapped isolation transformers is to set their components to work on 220 volts and power them from a 220 volt line. Now the safety ground is the center tap between the two 110 volt lines.
Yes. Equi=Tech is very marketing driven. Rather like Bose. "Better Sound Through Marketing."
Well of course not. That's a whole other issue. Balanced power only addresses leakage current issues.
se
Still Bluffing
First of all so everyone will know what leakage current beyond a buzzword to throw around:
http://www.condorpower.com/public/condor/pdfs/An113.pdf
"Such an impedance mismatch between neutral and safety ground is pretty much irrelevant. It's that 120 volts you've got between hot and safety ground and the capacitive coupling between the two that gives rise to leakage current problems. The only coupling you get between neutral and safety ground is due to the resistive voltage drop across the neutral line."
Wrong again....... It is very relevant with Balanced AC power when neutral is swinging half the AC voltage. Remember Balanced AC power, that was is what the discussion was about. Also there is common mode noise on line and neutral
which again makes neutral very relevant.
Part of my job was in EMC compliance including radiated and conducted noise on the AC line. You are still bluffing and/or quite misinformed on the subject. And I thought Grey had no shame.......... This is becoming way too much work straightening people out on this stuff.
"I've read their web site a number of times over the years, thank you."
I would go read it again if I were you......better yet read some engineering text instead of the advertising claims. Some more propagada from the Equitech web site:
"As finer and finer resolution is demanded in todays modern digitial interfaces of all varieties, shapes and sizes, the need for refined balanced power technology will continue to grow. Perhaps one day it might even become a mandatory requirement because of its environmental as well as its technical advantages. Often, no other power conditioning device or active filtering system is required to maintain the cleanest possible active current wave form and a noise-free signal reference in any technical facility. Sensitive electronic systems of all varieties perform more accurately and reliably. The difference in equipment performance (as reported to us often) can be astonishing."
I wonder if it cures arthritis too?
/ Not an engineer but plays one on the web.
First of all so everyone will know what leakage current beyond a buzzword to throw around:
http://www.condorpower.com/public/condor/pdfs/An113.pdf
"Such an impedance mismatch between neutral and safety ground is pretty much irrelevant. It's that 120 volts you've got between hot and safety ground and the capacitive coupling between the two that gives rise to leakage current problems. The only coupling you get between neutral and safety ground is due to the resistive voltage drop across the neutral line."
Wrong again....... It is very relevant with Balanced AC power when neutral is swinging half the AC voltage. Remember Balanced AC power, that was is what the discussion was about. Also there is common mode noise on line and neutral
which again makes neutral very relevant.
Part of my job was in EMC compliance including radiated and conducted noise on the AC line. You are still bluffing and/or quite misinformed on the subject. And I thought Grey had no shame.......... This is becoming way too much work straightening people out on this stuff.
"I've read their web site a number of times over the years, thank you."
I would go read it again if I were you......better yet read some engineering text instead of the advertising claims. Some more propagada from the Equitech web site:
"As finer and finer resolution is demanded in todays modern digitial interfaces of all varieties, shapes and sizes, the need for refined balanced power technology will continue to grow. Perhaps one day it might even become a mandatory requirement because of its environmental as well as its technical advantages. Often, no other power conditioning device or active filtering system is required to maintain the cleanest possible active current wave form and a noise-free signal reference in any technical facility. Sensitive electronic systems of all varieties perform more accurately and reliably. The difference in equipment performance (as reported to us often) can be astonishing."
I wonder if it cures arthritis too?
/ Not an engineer but plays one on the web.
Re: Still Bluffing
And nothing in that piece contradicts anything I have said on the issue of leakage current.
It's irrelevant in balanced power as well. There's ALWAYS going to be an impedance mismatch between neutral and ground. That's because your REFERENCE is ground. Duh!
What matters in a BALANCED situation is the NEUTRAL impedance versus the HOT impedance referenced to ground. Not just the neutral impedance. If THOSE two impedances are the same, then you've got balance. At least on the one end.
And ultimately the rejection of common-mode noise is going to be dependent on what you're driving. Which in this case will be the primary of your power transformer. And it's worth noting that transformers are very tolerant of source impedance imbalances.
The input of your power transformer will have a very high common-mode input impedance and because it's not center tapped and tied to ground, it floats and can provide considerable common-mode rejection even if it's driven from an unbalanced source.
At least at low frequencies.
Interwinding capacitance causes common-mode rejection to decrease as frequency increases. So while you may achieve high common-mode rejection around the power line frequency, it will be considerably less at higher frequencies so both power line harmonics and RF will start slipping through.
Straightening out what? You haven't demonstrated that YOU have any particular understanding on this issue. All you can do is point to web sites and talk about some job you had. When are you going to learn to make an actual argument of your own and address points directly? Pointing to web sites and your employment history does not an argument make.
Earth to Fred. Why are you yammering on as if I were agreeing with what's on Equi=Tech's web site? Did you bother to actually read the link I provided in the previous post? Here's what I said about the technical writings on their web site:
<i>In addition to numerous factual errors, their fundamental premise is simply flat out wrong.</i>
Wake up, Fred!
I'm NOT agreeing with what's said on their web site. I'm saying that balanced power DOES have benefit with regard to leakage current but NOT in the way Equi=Tech claims it does.
What you should be looking for is a cure for your obtuseness.
se
Fred Dieckmann said:
And nothing in that piece contradicts anything I have said on the issue of leakage current.
It's irrelevant in balanced power as well. There's ALWAYS going to be an impedance mismatch between neutral and ground. That's because your REFERENCE is ground. Duh!
What matters in a BALANCED situation is the NEUTRAL impedance versus the HOT impedance referenced to ground. Not just the neutral impedance. If THOSE two impedances are the same, then you've got balance. At least on the one end.
And ultimately the rejection of common-mode noise is going to be dependent on what you're driving. Which in this case will be the primary of your power transformer. And it's worth noting that transformers are very tolerant of source impedance imbalances.
The input of your power transformer will have a very high common-mode input impedance and because it's not center tapped and tied to ground, it floats and can provide considerable common-mode rejection even if it's driven from an unbalanced source.
At least at low frequencies.
Interwinding capacitance causes common-mode rejection to decrease as frequency increases. So while you may achieve high common-mode rejection around the power line frequency, it will be considerably less at higher frequencies so both power line harmonics and RF will start slipping through.
Straightening out what? You haven't demonstrated that YOU have any particular understanding on this issue. All you can do is point to web sites and talk about some job you had. When are you going to learn to make an actual argument of your own and address points directly? Pointing to web sites and your employment history does not an argument make.
Earth to Fred. Why are you yammering on as if I were agreeing with what's on Equi=Tech's web site? Did you bother to actually read the link I provided in the previous post? Here's what I said about the technical writings on their web site:
<i>In addition to numerous factual errors, their fundamental premise is simply flat out wrong.</i>
Wake up, Fred!
I'm NOT agreeing with what's said on their web site. I'm saying that balanced power DOES have benefit with regard to leakage current but NOT in the way Equi=Tech claims it does.
What you should be looking for is a cure for your obtuseness.
se
Uh Oh
"What matters in a BALANCED situation is the NEUTRAL impedance versus the HOT impedance referenced to ground. Not just the neutral impedance. If THOSE two impedances are the same, then you've got balance. At least on the one end."
The problem is that they are usually not balanced for the AC input to equipment. That's why swapping line and neutral can make a big difference in sound on a lot of equipment.
"It's irrelevant in balanced power as well. There's ALWAYS going to be an impedance mismatch between neutral and ground. That's because your REFERENCE is ground. Duh!"
How can you have impedance mismatch between two nodes? I was talking about the line to ground verses neutral to ground impedance mismatch. As for reference to ground, signal ground, chassis ground, AC ground, or earth ground. They are different and have voltages with respect to each other. Ground is a very simplistic buzzword for an actual refence node in a circuit.
Providing references and web sites is to point to well researched information with enough detail to actual go into a subject in some detail. Arguments filled with buzz words that most of readers (and some of the posters) have no idea as to meaning of, seem to be counterproductive. I am really not here to argue but to try educate and learn. Many people are grateful for links by experts on a particular subject. The books I refer to are those required for my job and education. I try to stick to the ones I own or have actually read.
I READ BOOKS AND REFERENCES BECAUSE I DON'T KNOW IT ALL LIKE SOME PEOPLE ON THE FORUM.
I like to learn and share useful information based on work experience, books, and good articles on the web. They only other person I have seen get bent out of shape by that is Grey Rollins. I can't control what some people think of my experience and credibility, but I will be happy to send someone to resources with more knowledge than I have on a subject. Think of me as a reference librarian. If wanted to listen to opinions by people half informed about a subject I guess there is always talk radio for that. I am sorry you are so perturbed by attempts provide. The problem is that your get some knowledge on a subject and you think you are an expert on the subject. I don't claim to know everything about a subject and try to keep speculation within the limits of my experience and education on a particular subject. Your post resembles something that MikeK would post. I believe he is in the sin bin presently.
Anybody want to hear about my passive aggressive preamp? LOL
http://www.psychpage.com/learning/library/person/pa.html
whoops........ another reference.
"What matters in a BALANCED situation is the NEUTRAL impedance versus the HOT impedance referenced to ground. Not just the neutral impedance. If THOSE two impedances are the same, then you've got balance. At least on the one end."
The problem is that they are usually not balanced for the AC input to equipment. That's why swapping line and neutral can make a big difference in sound on a lot of equipment.
"It's irrelevant in balanced power as well. There's ALWAYS going to be an impedance mismatch between neutral and ground. That's because your REFERENCE is ground. Duh!"
How can you have impedance mismatch between two nodes? I was talking about the line to ground verses neutral to ground impedance mismatch. As for reference to ground, signal ground, chassis ground, AC ground, or earth ground. They are different and have voltages with respect to each other. Ground is a very simplistic buzzword for an actual refence node in a circuit.
Providing references and web sites is to point to well researched information with enough detail to actual go into a subject in some detail. Arguments filled with buzz words that most of readers (and some of the posters) have no idea as to meaning of, seem to be counterproductive. I am really not here to argue but to try educate and learn. Many people are grateful for links by experts on a particular subject. The books I refer to are those required for my job and education. I try to stick to the ones I own or have actually read.
I READ BOOKS AND REFERENCES BECAUSE I DON'T KNOW IT ALL LIKE SOME PEOPLE ON THE FORUM.
I like to learn and share useful information based on work experience, books, and good articles on the web. They only other person I have seen get bent out of shape by that is Grey Rollins. I can't control what some people think of my experience and credibility, but I will be happy to send someone to resources with more knowledge than I have on a subject. Think of me as a reference librarian. If wanted to listen to opinions by people half informed about a subject I guess there is always talk radio for that. I am sorry you are so perturbed by attempts provide. The problem is that your get some knowledge on a subject and you think you are an expert on the subject. I don't claim to know everything about a subject and try to keep speculation within the limits of my experience and education on a particular subject. Your post resembles something that MikeK would post. I believe he is in the sin bin presently.
Anybody want to hear about my passive aggressive preamp? LOL
http://www.psychpage.com/learning/library/person/pa.html
whoops........ another reference.
SILLY BILLIES...
Hi,
Stop fighting guys, please???
Yes, and that's about all that's relevant to the average DIYer here.
None of us bozos are ever going to be able to afford industrial isolation techniques so why not 'splain to all the importance of correct mains polarity before going down to the big blue?
It's easy to determine, easy to get right and does make for a major audible difference.
Please?
Hi,
Stop fighting guys, please???
Yes, and that's about all that's relevant to the average DIYer here.
None of us bozos are ever going to be able to afford industrial isolation techniques so why not 'splain to all the importance of correct mains polarity before going down to the big blue?
It's easy to determine, easy to get right and does make for a major audible difference.
Please?
Hey, here's something that got me curious, and since I've got all the experts here in one room and it's marginally related to the topic at hand...
In another thread, people were talking about DC components on power lines (I noticed that everyone concerned about it was European which may or may not be relevant). Now, I couldn't imagine how I could get DC on my power line (well, I thought of some odd ways, like unidirectional current pulses by some large piece of equipment plugged into the same circuit, but nothing that seemed applicable to home audio), and went to measure. I used a DC voltmeter. I used an oscilloscope. I used a crude magnetometer on my power transformer core. I looked for residual magnetization on a transformer that had been plugged it for a while. Tried it during the day. Tried it during the night. Couldn't find any DC.
So, my questions are, is this some kind of phenomenon like the Belt Effect, or does it actually exist?
How can DC get onto a home power line?
If so, what's the order of magnitude of this voltage?
Is there a measurement method to detect it that I'm not using but I should?
In another thread, people were talking about DC components on power lines (I noticed that everyone concerned about it was European which may or may not be relevant). Now, I couldn't imagine how I could get DC on my power line (well, I thought of some odd ways, like unidirectional current pulses by some large piece of equipment plugged into the same circuit, but nothing that seemed applicable to home audio), and went to measure. I used a DC voltmeter. I used an oscilloscope. I used a crude magnetometer on my power transformer core. I looked for residual magnetization on a transformer that had been plugged it for a while. Tried it during the day. Tried it during the night. Couldn't find any DC.
So, my questions are, is this some kind of phenomenon like the Belt Effect, or does it actually exist?
How can DC get onto a home power line?
If so, what's the order of magnitude of this voltage?
Is there a measurement method to detect it that I'm not using but I should?
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