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Old 14th August 2008, 06:08 AM   #1
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Question Why need an AC conditioner?

Most audio equipment used today employ dual/split rail in which the power supply transformer has two secondary windings and centre tap used as ground point. This is identical to the so-called balanced AC topology used in many AC conditioners. (Please correct me if I am wrong.) They claim that using balanced topology reduces noise and minimizes ground loop problem. I wonder why we need such an extra balanced isolation transformer since the equipment power supply has one already. Is it more cost effective to add EMI filter and transient suppressor prior the original step-down transformer? And we can achieve good performance as well?
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Old 14th August 2008, 07:14 AM   #2
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Default my personal

pc operates from 8.30 in the morning till some times 12.00 in the night this was bought 1998 and now is almost 10 years old and in all its life needed one power supply only to be replaced .....

the reason is that works with a sofisticated power conditioner
( the sofisticated is that id doesnt use this or that technology it actually uses all technologies one behind the other )

is this enough ????

spikes and dirty power especially in my town is a very common thing

now a good conditioner for the power will guarantie not only clean power for your equipment but also aditional safety from a lot of things that may come in to your power and yet transfered to the circuit through the normal 50hz trafo ....

if your psu is switch mode there is not so many chnaces that the dirty power will come inside your device ....but a good spike is possible to destroy the psu it shelf

sakis
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Old 14th August 2008, 09:38 AM   #3
lineup is offline lineup  Sweden
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this one may be good for you
1. INPUT takes your AC mains 230 VAC 50 Hz
2. this is rectified and made into DC Voltage
3. OUTPUT re-creates a new AC 230 VAC at 50 Hz


Is this overdoing and worry too much?

As most of us have good enough sound without extra isolation from MAINS Power Line.
I would say:
Yes, and this is nothing for ordinary diy audio people.

It is more for those audiophiles, that have not sufficient technical knowledge about electronics.
Such people can feel insecure about themselves.
And so they start worry about this and that.

Without having much any valid reasons or substance to backup that worrying.
Quote:
With knowledge comes an understanding,
that can reduce your inclineness to believe in audio ghosts,
where is not very many ghosts around.
But maybe many more audio snakes are around, than some ghosts.
However, there is one thing in your transformer
that can cause some disturbance to deal with.
Nelson Pass has pointed to this issue.
This is smaller DC Voltage levels at your transformer/power supply AC Voltage lines.


Lineup - audio informations, Sweden 2008




Appendix, for those with too much money in the bank:
==============================================
website:
http://www.psaudio.com/products/p1000.asp
review:
http://www.6moons.com/audioreviews/psaudio2/p1000.html
image:
Click the image to open in full size.
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Old 14th August 2008, 03:47 PM   #4
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Basic "power contitioner" in audio is a simple center tapped 1:1 transformer (230/115+115 for EU).
The trick is that the secondary's center tap is wired to earth.
Proper fusing and insulation are needed!
You can add rail filters as extra.
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Old 14th August 2008, 08:13 PM   #5
dmills is offline dmills  United Kingdom
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It is not clear to me that adding an additional centre tapped transformer like that really buys you much if the real power supply is halfway competent to begin with.

I would however second the comment about proper fusing (and possibly other protection measures) for what is effectively a separately derived supply if such a unit is made as an external box.

The issue is that most gear sold into the European market is fused only in the 'live' on the assumption that the neutral is at near earth potential. With a symmetrical supply as described, this is not the case and the other leg may end up inadequately protected giving rise to the risk of fire or shock.
The fix is probably to RCD protect the output with a breaker that will isolate both legs of the supply, such that an earth fault from either leg will trip the rcd due to unbalance between the two currents.
NOTE: Not all RCDs isolate both poles!

Safety note: Make sure you really think through all the fault modes if considering balanced power of this nature, it is not trivial to get it right (from a safety POV), and the consequences of missing some fault mode can be nasty (And, for what it's worth, I am not particularly convinced that just designing the gears power supply correctly is not easier).

Regards, Dan.
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Old 15th August 2008, 01:08 AM   #6
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Hi lineup,

I agree with you! For those have $$$, how about having a private power generator just for audio? This generate very clean source, not filter or regeneration. is it better?
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Old 15th August 2008, 01:28 AM   #7
dmills is offline dmills  United Kingdom
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Small generators tend to be horrible from a regulation and frequency stability perspective, they also often suffer from flat topping as the undersized iron saturates.

Under most circumstances, if given a choice of grid or generator, pick grid.
This is based on doing power for large scale events, and touring shows, but probably applies in spades to this situation as a small machine has a lot less spinning mass then a large one, and tends to not be so conservatively rated. They also tend to be single phase with very dubious voltage regulation unless you get very lucky.

Just design the supply right and go and sweat something more important (Or spend the money on adding to the collection of things to listen to).

A grid fed ferroresonant transformer can help in a really nasty environment (AM Transmitter hut fed by ten miles of overhead line was the last time I needed this).

Regards, Dan.
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Old 15th August 2008, 01:58 AM   #8
lineup is offline lineup  Sweden
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Quote:
Originally posted by panson_hk
Hi lineup,
I agree with you! For those have $$$, how about having a private power generator just for audio? This generate very clean source, not filter or regeneration. is it better?
What is good to put before the audio power supply transformer.

No doubt is good practice to have some filter for frequencies higher than 50/60 Hertz.

There are not too many such signals that will survive passing the transformers magnetic field.
The field in between primary & secondary winding.

But there can be some that do come out on other side.
And will somewhat be found in the secondary AC output.
As an overlay to the 50 Hertz signal.
Most of these small signals will be also filtered away by rectifier diodes + Supply Filter Electrolytic Capacitors.

Then we have the EARTH connection for mains protection fuses.


Mains lines are usually not very clean whereever you may live.
In your own house or some apartment in among many other people.
There are lots of signals from attahed gears:
Computers, Refridgerators, Microowens etc. etc.
Even if the signal level of this elctrical dirt is not very high,
there can be many many different higher freqeuncies.

The basic filter we need is not very complicated.
A good such filter will deal with BOTH asymmetrical and symmetrical signals.
And takes care of the both AC mains lines, as well The Earth.


There are such readymade Mains Filters to buy.
From very basic, to improved and also some more effective & advanced filters.
The prices is nowhere like for one Extra Isolation Transformer = AC Mains Conditioner.
Even for the best mains filters.


If this filter is rated 3 Ampere at 230 VAC, it can pass max 3x230 = 690 Watt.
For your power amplifier or other audio gear.
Here is an image of one basic such filter.
Attached Images
File Type: png mains_filter1.png (5.3 KB, 223 views)
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Old 15th August 2008, 02:00 AM   #9
lineup is offline lineup  Sweden
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And here is the
SCHEMATIC of the same filter module:
Attached Images
File Type: png mains_filter2.png (3.6 KB, 227 views)
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Old 15th August 2008, 09:45 AM   #10
AndrewT is offline AndrewT  Scotland
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and you can buy these filters built into an IEC socket for each piece of equipment.
Rated from 1A to 6A, are cheap and easy.
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