Power line conditioner cuts high frequency ? - AVS Forum
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post #1 of 61 Old 02-03-2009, 08:20 AM - Thread Starter
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I installed a Panamax power line conditioner on my HI FI system to reduce electrical noise due to old house wiring, and no grounding. Well, it does lower the buzz, but also cut some high frequency also. I tried it with my son's tube amps ( for guitar ) same thing, he did not like the sound. Could it be defective, or do power line conditioners filter electrical noise and high frequencies also ? Mine says noise filter up to 50 db, and there's a higher model that filters up to 80 db . Will thge higher one filter even more frequency, or less ? Confused.
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post #2 of 61 Old 02-03-2009, 09:35 AM
 
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but also cut some high frequency also

The DC power supply in your amp also filters out high frequencies....that's its purpose.
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post #3 of 61 Old 02-03-2009, 10:31 AM - Thread Starter
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What I meant, is I lost part of the high frequency with the conditioner. Sound is brighter without it, and I was asking if a better one will retain same quality, or will reduce more of the high frequency, or I have to live with that with a line conditioner.
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post #4 of 61 Old 02-03-2009, 01:09 PM
 
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The AC fed to your power supply is filtered, removing all 'frequencies', resulting in flat line DC. This DC is then modulated by the power transistors, producting an AC waveform.
It doesn't matter what a "power conditioner" does to the incoming AC, it'll be converted to DC anyway.
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post #5 of 61 Old 02-03-2009, 02:46 PM
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A power "conditioner" won't change the frequency response of your system.

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post #6 of 61 Old 02-03-2009, 03:49 PM
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To make the above comment more complete, a power conditioner won't change how your system sounds at all. If one is needed, all it will do is make the input ac of your system more stable, but there are internal circuits that convert the input to dc, then to ac through a chopper circuit, which outputs a higher hz ac for use with a smaller transformer. However, during the dc stage the power supply can be used to deal with most fluctuations, as such, most fluctuations get filtered before the dc is converted back to ac, giving the system better ac to use than the input ac. Simply adding a power conditioner will only make the input ac more clean, though, unless you were experiencing fluctuations so great that the device was having trouble operating, i don't think you would need a power conditioner.
However, ignoring that, a power conditioner cannot affect the output audio of the amp, let alone its frequency response, which is modulated by the input signal.
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post #7 of 61 Old 02-03-2009, 03:58 PM
 
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but there are internal circuits that convert the input to dc, then to ac through a chopper circuit, which outputs a higher hz ac for use with a smaller transformer.

This is called a switched mode power supply, common in PC's not so common in linear amplifiers.

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However, during the dc stage the power supply can be used to deal with most fluctuations, as such, most fluctuations get filtered before the dc is converted back to ac, giving the system better ac to use than the input ac.

No, the point of the SMPS is to provide low voltage high current, efficiently. The Chopped DC is rectified and filtered back to DC....high frequency AC is pretty useless, unless you're making a plasma lamp. BTW, the chopped DC looks much much worse the the incoming sine wave....certainly not better.

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unless you were experiencing fluctuations so great that the device was having trouble operating

If your AC fluctuates to the point where the equipment doesn't work properly, you have much bigger problems then a "power conditioner" can cope with. Also, if it doesn't contain motor driven variacs, how does a "power conditioner" regulate voltage?
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post #8 of 61 Old 02-03-2009, 04:23 PM
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Unless there's something really wrong with your amplifier -- either a bad power supply, or a really bad design. There are some guitar amps (especially tube amps) that do not properly filter out AC noise. In those cases, things like balanced power or power conditioners actually will help.

If there is an actual difference in sound (and not just a placebo effect), then one or two things are true:
1) There's a design problem or wear-out problem with your amp.
2) You were so used to the noise from the power lines that the removal of that noise (leaving only intended signal) actually startles you.

However, for 2) to be true, 1) pretty much needs to be true anyway.
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post #9 of 61 Old 02-03-2009, 04:36 PM
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Quote:
Originally Posted by duvetyne View Post

This is called a switched mode power supply, common in PC's not so common in linear amplifiers.

Oh, ok, what is the name of the type that is used commonly in linear amps?

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No, the point of the SMPS is to provide low voltage high current, efficiently. The Chopped DC is rectified and filtered back to DC....high frequency AC is pretty useless, unless you're making a plasma lamp. BTW, the chopped DC looks much much worse the the incoming sine wave....certainly not better.

My understanding is that you would rectify the ac to dc, then chop the dc to create ac again (though possibly a bit messier ac), but at a higher hz, then run this through a transformer to lower its voltage, then rectify it to dc for use. This way, with the higher hz ac you could use a much smaller transformer to step down the voltage (as lowering voltage at the ac stage through inductance is more efficient than other means with dc). Or is this incorrect?
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post #10 of 61 Old 02-03-2009, 05:24 PM
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Does it suppress surges as well?
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post #11 of 61 Old 02-04-2009, 10:21 AM
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Most power amps are linear, and most use conventional line-frequency power supplies. And an increasing number use switch-mode power supplies, as more designers gain competence with that technology.

A small fraction of power amps are non-linear--e.g., class D. Some use a conventional supply, but probably most of them now use switch-mode supplies. If you can design class D well, then it's not too much of a stretch to understand switching supplies.

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post #12 of 61 Old 02-04-2009, 10:21 AM
 
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what is the name of the type that is used commonly in linear amps?

typically a linear supply, a transformer, rectifier and capacitor.

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My understanding is that you would rectify the ac to dc, then chop the dc to create ac again (though possibly a bit messier ac), but at a higher hz, then run this through a transformer to lower its voltage, then rectify it to dc for use.

Yes, that's what I said.
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post #13 of 61 Old 02-04-2009, 10:23 AM
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Non-industrial mains voltage regulators often use tapped autoformers, with control circuitry that automatically selects appropriate taps that will maintain the output voltage within the desired range.

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post #14 of 61 Old 02-04-2009, 10:24 AM
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Quote:
Originally Posted by duvetyne View Post

typically a linear supply, a transformer, rectifier and capacitor.

Such a supply is not linear at all, whether it is a switch-mode or a line-frequency conventional type.

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post #15 of 61 Old 02-04-2009, 10:44 AM
 
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Quote:
Originally Posted by Bob Lee (QSC) View Post

Such a supply is not linear at all, whether it is a switch-mode or a line-frequency conventional type.


There are many misnomers in electronics....just read these forums for a good example.
I wonder why the transformer, rectifier, capacitor combination is called a linear supply?


http://en.wikipedia.org/wiki/Power_supply
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post #16 of 61 Old 02-04-2009, 11:38 AM
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Quote:
Originally Posted by duvetyne View Post

Yes, that's what I said.

Ok, i was just confused why you stated "high frequency AC is pretty useless, unless you're making a plasma lamp" when in fact the high frequency ac, in my post, was to increase the emf to then use a smaller transformer... so it is then in fact not "useless."
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post #17 of 61 Old 02-04-2009, 12:04 PM
 
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in fact the high frequency ac, in my post, was to increase the emf to then use a smaller transformer... so it is then in fact not "useless."

How does frequency increase "the emf"?
The high frequency allows the use of a physically smaller transformer, physically smaller and lower capacitance capacitors, and finer regulation.
In your post you stopped after the chopper circuit, there was no final rectifier or filter that why I mentioned that high frequency AC is pretty useless...what uses high frequency AC?
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post #18 of 61 Old 02-04-2009, 12:40 PM
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Quote:
Originally Posted by duvetyne View Post

How does frequency increase "the emf"?
The high frequency allows the use of a physically smaller transformer, physically smaller and lower capacitance capacitors, and finer regulation.
In your post you stopped after the chopper circuit, there was no final rectifier or filter that why I mentioned that high frequency AC is pretty useless...what uses high frequency AC?

I guess i figured you'd assume it would be rectified...
And the universal emf equation provides proof of the increase in emf with frequency.


Which allows the core flux density to be less for the same voltage, preventing saturation from happening sooner.
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post #19 of 61 Old 02-04-2009, 01:32 PM
 
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And the universal emf equation provides proof of the increase in emf with frequency.

Only if all parameters are held constant and frequency is changed....and, of course, this is for sinusoidal waveforms only...so it doesn't really apply to the chopped waveforms present in SMPS.

I guesss I figured you'd understand the equation you posted.
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post #20 of 61 Old 02-04-2009, 01:50 PM
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Quote:
Originally Posted by duvetyne View Post

I guess I figured you'd understand the equation you posted.

No need to be rude, my comment was a fair one, as it could very well have been assumed that the ac would be rectified.
And the resulting signal is still close enough to sinusoidal (if the chopper circuit contains a pulse width modulator) to at the very least loosely match the equation. I'm no mathematician so i was not able to provide an exact equation for the purpose.
But, obviously it still applies, even loosely, as the outcome is as it predicts. Even if the other variables are not held constant, an increase in frequency does increase electromotive force, assuming of course you don't intentionally alter the other variables to make it not... but that is true for any equation.
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post #21 of 61 Old 02-04-2009, 02:59 PM
 
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No need to be rude,

Take your own advice, I responded in kind.

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And the resulting signal is still close enough to sinusoidal

I'm guessing you've never seen this on a 'scope, if you think it's a sine.

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an increase in frequency does increase electromotive force,

Not according to the equation you posted....or the other laws of physics.

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I'm no mathematician so i was not able to provide an exact equation for the purpose.

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post #22 of 61 Old 02-04-2009, 03:32 PM
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Quote:
Originally Posted by duvetyne View Post

Take your own advice, I responded in kind.

I was never rude to you, and if it seemed that way, you've misunderstood.

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I'm guessing you've never seen this on a 'scope, if you think it's a sine.

The problem with the turn this discussion has taken is that, from what i can tell, there are a ton of different chopper circuit designs. As such, its hard to tell which we are referring to. I know you can get "simulated" sine wave depending on your inverter design. As such, i said "close", which of course is dependent on your own personal definition of close.

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Not according to the equation you posted....or the other laws of physics.

Well, then the design of many switch mode power supplies defy the laws of physics. From your own link:
"High frequency and high voltages in this first stage permit much smaller step down transformers than are in a linear power supply."
Higher frequencies cause an increase in the emf to achieve less flux density for the same voltage, again, preventing the saturation from being reached as soon. This either allows an increase in capacity or a reduction in size.
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post #23 of 61 Old 02-04-2009, 04:03 PM
 
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This either allows an increase in capacity or a reduction in size.

When you figure out what this means, come back and we'll discuss it like two educated adults.

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Well, then the design of many switch mode power supplies defy the laws of physics.

If you say so.
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post #24 of 61 Old 02-04-2009, 05:56 PM
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Quote:
Originally Posted by duvetyne View Post

When you figure out what this means, come back and we'll discuss it like two educated adults.

I'm at a loss if i am incorrect. Looking around i found another wikipedia page on transformers specifically, and it states:
"The EMF of a transformer at a given flux density increases with frequency.[12] By operating at higher frequencies, transformers can be physically more compact because a given core is able to transfer more power without reaching saturation, and fewer turns are needed to achieve the same impedance."
Which unless i am misunderstanding something confirms what i thought.
The wiki page
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post #25 of 61 Old 02-04-2009, 06:23 PM
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Can't think of any reason why a power conditioner should change the FR of the system.

Just because there is a knob doesn't mean you should turn it.
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post #26 of 61 Old 02-05-2009, 04:59 AM - Thread Starter
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Originally Posted by whoaru99 View Post

Can't think of any reason why a power conditioner should change the FR of the system.

Probably I did not explain what I mean properly. It's not frequency change, but Sound with the conditioner sounded like strangled, less dynamics, like sound coming through a napkin instead of straight. And that was the case in my stereo system complete ( amp and rest of components going through it ) and then with my son's tube guitar amp also. Clarity was reduced.
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post #27 of 61 Old 02-05-2009, 10:02 AM
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Quote:
Originally Posted by zeiter View Post

Probably I did not explain what I mean properly. It's not frequency change, but Sound with the conditioner sounded like strangled, less dynamics, like sound coming through a napkin instead of straight. And that was the case in my stereo system complete ( amp and rest of components going through it ) and then with my son's tube guitar amp also. Clarity was reduced.

If the power line conditioner removed "buzz" then the rest of what you hear may be due to your general perceptions being altered by the removal of the buzz.

It's well known that different parts of the audible spectrum change our perceptions of other parts of the spectrum. For example, raising the bass will tend to make most people more receptive to a raised treble.
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post #28 of 61 Old 02-05-2009, 10:44 AM
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Quote:
Originally Posted by zeiter View Post

Probably I did not explain what I mean properly. It's not frequency change, but Sound with the conditioner sounded like strangled, less dynamics, like sound coming through a napkin instead of straight. And that was the case in my stereo system complete ( amp and rest of components going through it ) and then with my son's tube guitar amp also. Clarity was reduced.

OK. I could believe this..the dynamics part, anyway. I experienced the same phenomena, but I was running four pretty good sized power amps (1,230W total output) from one filtered power strip.

I noticed the deficiency in dynamics only when using most of the amplifer's potential. No noticable problems with it at low to moderate levels for me.

My solution was to put the amps directly to the wall on a dedicated circuit.

Just because there is a knob doesn't mean you should turn it.
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post #29 of 61 Old 02-05-2009, 02:22 PM - Thread Starter
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I use a 380 w/c amp for a total of 760 w and notice it even at normal listening. In fact the conditioner has a high current bank which does not limit current, yet effect is audible. My son's tube guitar amp is a 30 watts, and he could feel it clearly when we plugged the conditioner, and that's why I was asking the question if I was to buy one of the more expensive higher end ones ( like Panamax M5300 or M5400 ), would it solve problem ( maybe my conditioner is cheap ( Panamax M4300 ), or something else. Also my salesman did not advise to use the M5400 with voltage regulator, and according to him this is best suited to computers, and for Audio I could go for the M5300 without voltage regulation. Now I have a thousand opinions...
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post #30 of 61 Old 02-06-2009, 06:57 PM
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zeiter, basically your power conditioner provides surge protection and AC noise filtering. What it does not do, as apparently assumed by all, is regenerate new, clean AC. For that you're looking at over ten times what you paid for your Panamax, for example PS Audio's Power Plant Premier.

Your description of constricted dynamics and muffled/veiled sound almost exactly parallels my experience with entry-level conditioners. Plan on spending $500 and up for a conditioner that doesn't degrade (or actually improve) your sound. Even then, most conditioners, including yours (sorry!), can't provide enough combined steady-state and peak current demanded by many power amplifiers such as yours.

It appears your salesman, cognizant of your equipment and AC quality, sold you a conditioner inadequate for your needs. Or he sold you an inadequate conditioner without knowledge of your equipment and AC quality. Either way, if I were you I'd get a refund and go elsewhere. And don't let anyone tell you that a-v equipment doesn't benefit from voltage regulation, especially if your AC is crummy.

Trust your own ears. Buy what sounds best that you can afford.
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