Ken L said:
I agree with the powewrvar. I knew when I turned on the blender and the music suffered that all was not well in my apartment. After using a powervar the noise is gone when the blender and the neighbors vacuum. I use at my Dad's house a powervar then another line filter to his tube amplifiers. This works out very well. I paid very low prices for my powervars. Just be patient and do not get caught up in a bidding war. These are always available on epay just wait for one at a good price like I did twice now. I also bought two gatekeepers from Welborne. These will be used with my tube amp in my apartment. Positive Feedback did a review on the Gatekeeper. Since it is a build it yourself kit I hope it fits with the DIY theme at this site. John C.
Ha, ha. Not sure if i fully agree but i'd never take advice on PS from someone who believes that
And that in a SE amp supply where every tiny bit of wire is audible. Unless, of course, you rely on a prosthetic devices for hearing.
My experience with mains filtering has been mostly negative. All iso transformers i've ever tried steal dynamics and round all edges nicely. Maybe they make for 'black backgrounds' and make digital less painful but there is always a price to pay.
For a less invasive mains filtering you may want to investigate John Risch's filter design.
I used to be curious about that too. Especially at the time when physics occupied most of my days (very long ago). Recently, though, i've noticed that a relatively physics-free environment is very conductive to improving the sound of my system.
I just wish my ears were still as functional as they used to be when i was last capable of understanding SY's questions about the eigenfunctions of a hamiltonian
Bah, I can't resist. I'll do the physics.
<Uber-paragraph warning>
I don't know what a typical level of line noise represents, so let's say we get a 1ms transient of 160V on the peak of the sine wave (bringing peak level to approx. 320V). This hits the 300V 100mA power supply, which consists of a transformer, your pick of full wave rectification (FWCT or FWB are electrically equal) and 50uF cap input, 10H choke and 100uF final cap. Assuming no loss in the transformer (something like this would be attenuated nicely by leakage inductance), that makes a 300V peak transient at the rectifier, for a total 600V peak on top of the sine wave. Now, assuming this gets fully rectified (...and it gets more humerous yet...), you get 300 additional volts on the capacitor in 1ms. Q = VC so I = dQ/dt = dV/dt * C, thus the current during this transient, rectified and fed to the first filter capacitor, is I = (300 / .001) * 0.000 05 = (thousands cancel) 300 * 0.05 = 30 *0.5 = 15 amperes. This additional burst of energy adds 0.5 * 0.000 05 * (300^2) = 2.25 J of energy, enough to power the electronics for 75ms (300V * 0.1A = 30W = 30J/s, 2.25 J / (30J/s) = .075). It represents a surge power of 2.25J / .001s = 2.25kW (surge current 15A * 300V rise does NOT equal 4.5kW, because P = VI requires a voltage difference at the same point in time), again, unlikely through the transformer. So we now have 600V on the first cap, what effect does the following L+C have? First of all, during the charging pulse itself, I will assume no effect, this isn't quite true but it yields V = dI/dt * L > dV/dt (= 300,000) = d2I/dt2 * L, a nasty double derivative that has little effect in the 1ms (but hints at resonance). So I'll take the assumption that after this transient, 300V suddenly appears on the cap-input side of the choke. V = dI/dt * L so 300 = dI/dt * 10H > dI/dt = 30A/s. That sounds like a lot, but like I said, it could only power the amp for 75ms, in which time (if C1's voltage didn't fall, of which it does, quickly) the inductor's current would increase to 2.25A. Similarly absurd to the power transformer, but not as much for my case. So consider that, assuming a linear rise to 2.25A during those 75ms, i.e. average current drawn from the first capacitor is 1.125A for 75ms, the cap's voltage would drop by 1.7kV, to -1100V! This is self-defeatingly absurd so I will mention that what in fact will happen is a slow, damped LC resonance. It might go for a cycle or three at 1 / [2 pi sqrt(LC)] (C = 50*100 / (50+100) = 33.3uF as seen by the choke) = 1 / [2*pi*sqrt(333.33)] = 8.7Hz (the bouncing would last around 0.3s). The resulting amplitude, starting at 300V on C1, would appear as +/-150V (minus decay) on C2 starting after maybe 1/4 or 1/2 period. This would bring the plate supply to 150V to 450V as it bounces, certainly a cause of hesitation and variation in gain and distortion, depending on just how the amplifier reacts. But this also represents a lightning strike or so... I should damn well hope you can hear some effect from that!
Tim
<Uber-paragraph warning>
I don't know what a typical level of line noise represents, so let's say we get a 1ms transient of 160V on the peak of the sine wave (bringing peak level to approx. 320V). This hits the 300V 100mA power supply, which consists of a transformer, your pick of full wave rectification (FWCT or FWB are electrically equal) and 50uF cap input, 10H choke and 100uF final cap. Assuming no loss in the transformer (something like this would be attenuated nicely by leakage inductance), that makes a 300V peak transient at the rectifier, for a total 600V peak on top of the sine wave. Now, assuming this gets fully rectified (...and it gets more humerous yet...), you get 300 additional volts on the capacitor in 1ms. Q = VC so I = dQ/dt = dV/dt * C, thus the current during this transient, rectified and fed to the first filter capacitor, is I = (300 / .001) * 0.000 05 = (thousands cancel) 300 * 0.05 = 30 *0.5 = 15 amperes. This additional burst of energy adds 0.5 * 0.000 05 * (300^2) = 2.25 J of energy, enough to power the electronics for 75ms (300V * 0.1A = 30W = 30J/s, 2.25 J / (30J/s) = .075). It represents a surge power of 2.25J / .001s = 2.25kW (surge current 15A * 300V rise does NOT equal 4.5kW, because P = VI requires a voltage difference at the same point in time), again, unlikely through the transformer. So we now have 600V on the first cap, what effect does the following L+C have? First of all, during the charging pulse itself, I will assume no effect, this isn't quite true but it yields V = dI/dt * L > dV/dt (= 300,000) = d2I/dt2 * L, a nasty double derivative that has little effect in the 1ms (but hints at resonance). So I'll take the assumption that after this transient, 300V suddenly appears on the cap-input side of the choke. V = dI/dt * L so 300 = dI/dt * 10H > dI/dt = 30A/s. That sounds like a lot, but like I said, it could only power the amp for 75ms, in which time (if C1's voltage didn't fall, of which it does, quickly) the inductor's current would increase to 2.25A. Similarly absurd to the power transformer, but not as much for my case. So consider that, assuming a linear rise to 2.25A during those 75ms, i.e. average current drawn from the first capacitor is 1.125A for 75ms, the cap's voltage would drop by 1.7kV, to -1100V! This is self-defeatingly absurd so I will mention that what in fact will happen is a slow, damped LC resonance. It might go for a cycle or three at 1 / [2 pi sqrt(LC)] (C = 50*100 / (50+100) = 33.3uF as seen by the choke) = 1 / [2*pi*sqrt(333.33)] = 8.7Hz (the bouncing would last around 0.3s). The resulting amplitude, starting at 300V on C1, would appear as +/-150V (minus decay) on C2 starting after maybe 1/4 or 1/2 period. This would bring the plate supply to 150V to 450V as it bounces, certainly a cause of hesitation and variation in gain and distortion, depending on just how the amplifier reacts. But this also represents a lightning strike or so... I should damn well hope you can hear some effect from that!
Tim
Hi,
Could have stopped right there and then....
Let's just say that with a well made powerxformer and a well designed powersupply the effect of powerline noise should be minimal.
However, about 75% of the commercially made goodies out there not only create noise of their own, they also let most of the incoming noise through quite nicely.
The calculations shown should do nicely for a single occurence of a linevoltage spike.
Reality sadly is quite different; if you analyze powerline noise you will find an almost continous series of peaks and noises riding it simultaneously, continuously AND at a wide variety of frequencies.
In short noise can appear at the secondary side of a transformer in basically three forms: common-mode, transversemode, and electromagnetic.
A book covering this topic and well worth reading is:
Morrison, R., Grounding and Shielding Techniques in Instrumentation, John Wiley and Sons, New York, 1967.
There are plenty of others but this book is one of the reasons I always recommend using narrow band powerxformers such as EI cores for audio use and promote the use of : conductive foil beween primary and secondary windings to be firmly bonded to ground besides a Farady shield inbetween windings.
Cheers,
Could have stopped right there and then....
Let's just say that with a well made powerxformer and a well designed powersupply the effect of powerline noise should be minimal.
However, about 75% of the commercially made goodies out there not only create noise of their own, they also let most of the incoming noise through quite nicely.
The calculations shown should do nicely for a single occurence of a linevoltage spike.
Reality sadly is quite different; if you analyze powerline noise you will find an almost continous series of peaks and noises riding it simultaneously, continuously AND at a wide variety of frequencies.
In short noise can appear at the secondary side of a transformer in basically three forms: common-mode, transversemode, and electromagnetic.
A book covering this topic and well worth reading is:
Morrison, R., Grounding and Shielding Techniques in Instrumentation, John Wiley and Sons, New York, 1967.
There are plenty of others but this book is one of the reasons I always recommend using narrow band powerxformers such as EI cores for audio use and promote the use of : conductive foil beween primary and secondary windings to be firmly bonded to ground besides a Farady shield inbetween windings.
Cheers,
Well I'm certainly not qualified to speak to all of the technical issues, but a simple used Stancor isolation transformer ($37 on ebay) and two line conditioner/surge protectors using the JR recipe at the site below stopped the noise I was hearing when the ceiling fan or the light dimmers were in use.
http://www.geocities.com/jonrisch/surge.htmhttp://www.geocities.com/jonrisch/surge.htm
http://www.geocities.com/jonrisch/surge.htmhttp://www.geocities.com/jonrisch/surge.htm
One thing that hasn't been mentioned is the fact that most PLC's have components that take the constant spikes on the power line, acting as sacrificial components, thus sparing the power supplies in my expensive equipment.
I'd much rather have to replace a cap in my power line conditioner every ten years than have to try to fix the power supply in a CD player or whatever... My AC is noisy enough that I have to replace the surge protectors on my computer, etc. every year.
Good power line conditioners also isolate individual component power supplies from each other. I've had my power wedge for over ten years and it made an immediate improvement. Got a demo model for cheap and it's been worth every penny. I got it for a Rotel RCD-855 (tweaked to the max, of course) that made noise every time the fridge came on. And yeah, it did it before it was modded. The power wedge solved the problem.
It's all the convincing I needed.
I'd much rather have to replace a cap in my power line conditioner every ten years than have to try to fix the power supply in a CD player or whatever... My AC is noisy enough that I have to replace the surge protectors on my computer, etc. every year.
Good power line conditioners also isolate individual component power supplies from each other. I've had my power wedge for over ten years and it made an immediate improvement. Got a demo model for cheap and it's been worth every penny. I got it for a Rotel RCD-855 (tweaked to the max, of course) that made noise every time the fridge came on. And yeah, it did it before it was modded. The power wedge solved the problem.
It's all the convincing I needed.
Layberinthius said:
Is it perceptions of price that causes people to so confidently sully the reputation of another? I mean, what has Audio Consulting done to deserve, what did you say, "shunning"?
I visited Serge of AC at last years CES in Vegas, and thought his gear was among the best I'd heard. I mean, really wonderful. By the way, the LC filters you mention are really quite common in industrial contexts as passive harmonic filters. They constitute one alternative means of addressing AC nasties becoming ever more of a problem for not only those in audio (Europe has recently legislated in respect of this problem), other alternatives being active harmonic conditioners and balanced AC transformers.
But I needn't have visited Serge's room in LA to have known he builds great stuff. I had departed several years from high end DIY audio pursuing school. When I returned to the audio field, I decided I would try solid state and purchased an Aleph amp and a top-grade Sony SACD player. I then slowly lost interest in reproduced music, though not because of the Aleph amp. A few years later, I had a cd player modified using Audio Consulting output transformers which, I'm happy to say, substantially improved my audio system and rekindled my interest in reproduced audio. I purchased the Aud Consulting TXs on spec because, unlike our poster above, I found discussions on the Audio Consulting website insightful.
I'd happily refer anyone to Serge's products. He's a wonderful man with a PhD in chemistry---no slouch by way of scientific training and insight.
fdegrove said:
Rather smaller than I knew!
By the way, for those possibly interested in Serge's AC filtering methods, I heard the effect Serge's harmonics conditioning makes in his Vegas set up and thought it to improve the sound in the few hours' listening I enjoyed. FWIW, his copper-wound mains isolation transformer is very high quality, as is his smaller $ilver variety. I've found both to improve my system.
I view his Silver Rock OPTs with the same feeling that got me into this audio thing in the first place.
There is one undenying fact that will forever go against high prices for something so good.
Most will not be able to experience the same effects of the person whom is rich.
I know that I will never be able to experience Serge's world unless silver suddenly becomes very very cheap.
That will nag me, along with many other aspects of Commercial components for DIY Audio for the rest of my days, as it has done for my father and his brothers.
If all of these components are necessary for a greater pleasure of audio from Mains connected equipment then why haven't we heared such remarkable stories from mass battery operated units?
Would it not be cheaper and simpler to operate a $5,000 battery bank and AC Mains Charger to achieve the same level of confidence in mains 'filtering' than $x0,000 ?
That has always nagged me, the fact that amplifiers are dependant upon mains when infact all it takes is a couple of car batterys (that are charged everyday to maintain the battery) and a well built inverter with pure-sinewave emulation.
I guess in defence of my beliefs I should say that there /ARE CHEAPER WAYS/...
The simple argument that you haven't got enough room for such a setup is foobar at best!
Leave the city, your apartment and the air quality isn't doing you any good, nor is the asbestos.
In the country you could just as easily build a basement large enough for both acoustic benefits and space benefits (not tripping over things).
What good is a high quality setup when you can hear your neighbours yell? or the dog bark?
Rural power is cleaner anyway.
Broadband Internet access is coming to the country, give it another 5 years.
My argument is all good and well, but the requirements are great, an entire social upheaval is required.
Most will not be able to experience the same effects of the person whom is rich.
I know that I will never be able to experience Serge's world unless silver suddenly becomes very very cheap.
That will nag me, along with many other aspects of Commercial components for DIY Audio for the rest of my days, as it has done for my father and his brothers.
If all of these components are necessary for a greater pleasure of audio from Mains connected equipment then why haven't we heared such remarkable stories from mass battery operated units?
Would it not be cheaper and simpler to operate a $5,000 battery bank and AC Mains Charger to achieve the same level of confidence in mains 'filtering' than $x0,000 ?
That has always nagged me, the fact that amplifiers are dependant upon mains when infact all it takes is a couple of car batterys (that are charged everyday to maintain the battery) and a well built inverter with pure-sinewave emulation.
I guess in defence of my beliefs I should say that there /ARE CHEAPER WAYS/...
The simple argument that you haven't got enough room for such a setup is foobar at best!
Leave the city, your apartment and the air quality isn't doing you any good, nor is the asbestos.
In the country you could just as easily build a basement large enough for both acoustic benefits and space benefits (not tripping over things).
What good is a high quality setup when you can hear your neighbours yell? or the dog bark?
Rural power is cleaner anyway.
Broadband Internet access is coming to the country, give it another 5 years.
My argument is all good and well, but the requirements are great, an entire social upheaval is required.
Hi,
Don't underestimate yourself. You're still very young so you'll never know what lies ahead of you.
Silver IS very cheap. Just buy a few meters and use it wisely to get an idea about what difference it can make.
That's certainly an alternative but I'm not sure which one would be the more economical one of the two in the long run.
It should be...
Unless you live in a small country like Belgium, Holland and what have you....
Anyway you look at it, there's an awful lot that you could do yourself. Designing a decent PS is a good start IMO.
Which is why I always insist that to me any circuit is utterly meaningless without the proper PS to go with it....
Cheer up,
Don't underestimate yourself. You're still very young so you'll never know what lies ahead of you.
Silver IS very cheap. Just buy a few meters and use it wisely to get an idea about what difference it can make.
That's certainly an alternative but I'm not sure which one would be the more economical one of the two in the long run.
It should be...
Unless you live in a small country like Belgium, Holland and what have you....
Anyway you look at it, there's an awful lot that you could do yourself. Designing a decent PS is a good start IMO.
Which is why I always insist that to me any circuit is utterly meaningless without the proper PS to go with it....
Cheer up,
Silver isn't that expensive, it's the labor and the know how that makes it so. You could learn how to wind your own transformers if you wanted to make the effort.
None of that stuff is NECESSARY in any way, shape or form unless you decide it is. I think most people would get more pleasure out of buying more music, but that's just me, I guess. Battery powered electronics are a pain. Battery powered tube electronics are a HUGE hassle. I have thought about building a battery powered chip amp with Jordan JX92S monitors, with the source being my 30GB iPod...
It depends on how much your time is worth. To be in the country I'd need to drive an hour each way to commute to my job. People I work with drive further than that, spending 3-4 hours of their life every day driving to and from work. Not me, I like my 15 minute commute, thanks.
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