Hi,
I read that if you reverse your mains connections on a power Tx primary it changes the sound of CD players amps etc!
I have tried this and it gives a very slight change in the sound!
In the UK the mains supply has a live and neutral + earth. The neutral is at a very close potential to earth! So this is a possible thought!
The mains transformer has a start and end of the winding, so if you connect the live to the start of the winding as the coil comes to the end you have a shield of neutral connected windings at the end of the coil (shielding the live supply). If you connect the other way around you have the live on the outside of the winding! Ok torroids are self screening?
Is this the same in other countries?
Regards
M. Gregg
I read that if you reverse your mains connections on a power Tx primary it changes the sound of CD players amps etc!
I have tried this and it gives a very slight change in the sound!
In the UK the mains supply has a live and neutral + earth. The neutral is at a very close potential to earth! So this is a possible thought!
The mains transformer has a start and end of the winding, so if you connect the live to the start of the winding as the coil comes to the end you have a shield of neutral connected windings at the end of the coil (shielding the live supply). If you connect the other way around you have the live on the outside of the winding! Ok torroids are self screening?
Is this the same in other countries?
Regards
M. Gregg
Do you agree that we want to shield mains Tx. The sound difference is very slight, however with valve systems anything that helps shield should be of help! I am refering to standard transformers here! If the Tx has designated connections then go with Those shown!
Regards
M. Gregg
Regards
M. Gregg
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This could be caused by interwinding capacitance and a poorly filtered power supply allowing high frequency noise from the mains to get through to supply rails. The solution is an interwinding electrostatic screen, and better power supplies. As the winding polarity is presumably random between different equipment, some people would find that making this change would make the sound worse rather than better.
Or it could just be the placebo effect. My bet is that it is the placebo effect.
Or it could just be the placebo effect. My bet is that it is the placebo effect.
gosh - my bad! I just reversed the wiring on my desk lamp and its brighter - somehow the light moved more to the edges an dmore clearly defines stuff on my desk! Also, the room seems slightly bigger, and I swear teh colour has somehow become deeper.
I'm gonna try it on the washing machine - I've heard my clothes will come out cleaner...
I'm gonna try it on the washing machine - I've heard my clothes will come out cleaner...
That could be to do with how 'clean' the mains is? Everyone's cooking thier evening meal, making cups of tea/coffee etc etc. Just a thought? Nothing to do with reversing the polarity. Do that and the clocks go backwards and you come home before you've gone out!!
You don't have a metal refinery with arc furnaces or DC drives turning on creating transients. My bet is that it is the placebo effect.
Regards
M. Gregg
Greg,
If you are hearing a difference, then you are hearing a difference. Don't let these "joking *******" put you down.
Why are you hearing a difference? If you inspect the schematic you'll most likely see some caps from the mains inputs to chassis gnd - and in the interest of saving every penny, this may not be symettrical. Hence one way around more noise may be induced into the signal ground. This is an educated guess.
Regards, Allen
If you are hearing a difference, then you are hearing a difference. Don't let these "joking *******" put you down.
Why are you hearing a difference? If you inspect the schematic you'll most likely see some caps from the mains inputs to chassis gnd - and in the interest of saving every penny, this may not be symettrical. Hence one way around more noise may be induced into the signal ground. This is an educated guess.
Regards, Allen
I see what you are saying. One end of the primary is held close to ground potential while the other goes from +/- the mains voltage. This is true both in Europe and North America. Also I see where you are correct that one end of the secondary is near the iron core while the other end is nearer to the outside.
But, the magnetic flux inside the iron core is determined be current not voltage. Current is equal in all parts of the wire. The only thing that effects the secondary is the magnetic flux in the core.
But I think the electric field, if there is any outside of the transformer might depend on the way you connect the primary to mains. If the sound is different then may something is coupled via the electric field.
I'd like to know how these listening tests were done. Did the listener know if the polarity was changed between sessions? The proper way to do the test is to, before each session flip a coin and either change the polarity or not, then have the listener write down what he hears. Later you look for a correlation between written notes and polarity. Use any other method and physiological effects dominate.
How was the test done?
But, the magnetic flux inside the iron core is determined be current not voltage. Current is equal in all parts of the wire. The only thing that effects the secondary is the magnetic flux in the core.
But I think the electric field, if there is any outside of the transformer might depend on the way you connect the primary to mains. If the sound is different then may something is coupled via the electric field.
I'd like to know how these listening tests were done. Did the listener know if the polarity was changed between sessions? The proper way to do the test is to, before each session flip a coin and either change the polarity or not, then have the listener write down what he hears. Later you look for a correlation between written notes and polarity. Use any other method and physiological effects dominate.
How was the test done?
The players I normally see are the better ones with "real" transformer supplies, but my comments are applicable to switch mode supplied ones as well, perhaps there even more applicable.
Regards, Allen
No. The primary has NO earth connection at any point. The frame may be earthed, but the circuit is above ground.
True physically, but in terms of polarity, the situation is changing at 100 (or 120) times a second...
ahhhh there's the rub!
The test is actually quite easy, and so far I have found a measureable difference in every transformer tested, with the exception of shielded units.
Isolate the core of the transformer, like resting on a board or rag. Tie one of the secondary leads to the core (I typically chose the lead that is closest to ground when the circuit is actually assembled. Repeating these tests on a completed circuit in its final state has always given me the same result.)
Energize the primary of the transformer with hot and neutral from your wall.
Measure AC voltage (ideally a high impedance meter, not analog) from core to earth ground at the wall. Record voltage.
Swap the polarity of the primary, essentially switching position of hot and neutral wires. Repeat measurement from core to earth. Record voltage.
The test connection with the higher voltage is the one where you are placing the hot wire on the higher capacitance lead (this is stray capacitance from lead to core/secondary). In the permanent installation, you want to install the neutral wire from the wall on that higher capacitance lead.
The higher capacitance lead will permit more noise to pass through the stray capacitance to either core (acceptable) or secondary (worst). By minimizing the voltage applied to this high stray lead, you minimize the noise injection. Since the neutral is bonded at the panel, the tendency for the neutral to pick up noise is less than the hot. Yes, the neutral does have noise, but this method attempts to minimize it.
So not only do I accept the audibility of the swap, but I can prove there is a difference by archaic measurement and circuit modeling.
Isolate the core of the transformer, like resting on a board or rag. Tie one of the secondary leads to the core (I typically chose the lead that is closest to ground when the circuit is actually assembled. Repeating these tests on a completed circuit in its final state has always given me the same result.)
Energize the primary of the transformer with hot and neutral from your wall.
Measure AC voltage (ideally a high impedance meter, not analog) from core to earth ground at the wall. Record voltage.
Swap the polarity of the primary, essentially switching position of hot and neutral wires. Repeat measurement from core to earth. Record voltage.
The test connection with the higher voltage is the one where you are placing the hot wire on the higher capacitance lead (this is stray capacitance from lead to core/secondary). In the permanent installation, you want to install the neutral wire from the wall on that higher capacitance lead.
The higher capacitance lead will permit more noise to pass through the stray capacitance to either core (acceptable) or secondary (worst). By minimizing the voltage applied to this high stray lead, you minimize the noise injection. Since the neutral is bonded at the panel, the tendency for the neutral to pick up noise is less than the hot. Yes, the neutral does have noise, but this method attempts to minimize it.
So not only do I accept the audibility of the swap, but I can prove there is a difference by archaic measurement and circuit modeling.
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