AudioNervosa

Systemic Development => Amplification and Preamplification => Topic started by: steve on August 30, 2018, 08:19:10 PM

Title: How important is Power Supply Design?
Post by: steve on August 30, 2018, 08:19:10 PM
Below is a link to a white paper I initially wrote in October of 1997, and recently updated. Although basic with little math, my paper deals with multiple purposes and considerations when designing an accurate power supply.

A power supply is much more difficult to design than most think, including designers/engineers I have seen on other boards. The power supply can very easily make or break a design.

cheers

steve

Title: Re: How important is Power Supply Design?
Post by: P.I. on August 30, 2018, 10:39:38 PM
Thank you for posting this Steve.

Power is the heart of any system.  Without good, clean, consistent power we have bupkis.  A brain without a heart is dead.  Muscles without a good heart are worthless.

Clean power is essential, just like clean blood is essential to body health.

This is why I do what I do.  Sending abundant, quiet power to a well designed power supply is what drives me.

Awesome  :thumb:
Title: Something you may not know about Power Supply Design.
Post by: steve on August 31, 2018, 07:20:30 AM
Thank you for posting this Steve.

Power is the heart of any system.  Without good, clean, consistent power we have bupkis.  A brain without a heart is dead.  Muscles without a good heart are worthless.

Clean power is essential, just like clean blood is essential to body health.

This is why I do what I do.  Sending abundant, quiet power to a well designed power supply is what drives me.

Awesome  :thumb:

Absolutely, minimizing problems from the AC power end is absolutely essential.

What is much more difficult in a DC power supply is optimizing the DC filtering system on the other end, where the musical signal "resides".

On other forums, very very few, if any, understand this aspect of the power supply's function. It is extremely difficult, virtually impossible to correctly design a power supply that will optimize the sonic qualities of a component without understanding this. In otherwards, virtually no component on the market has a properly designed DC power supply.
This includes not only the inexpensive models, but all the higher priced ones.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: Nick B on August 31, 2018, 04:34:09 PM
Below is a link to a white paper I initially wrote in October of 1997, and recently updated. Although basic with little math, my paper deals with multiple purposes and considerations when designing an accurate power supply.

A power supply is much more difficult to design than most think, including designers/engineers I have seen on other boards. The power supply can very easily make or break a design.

http://www.sasaudiolabs.com/theory7a.htm

cheers

steve

Thanks for posting your white paper,  Steve, and in a manner that’s understandable. I’m a big believer in noise reduction and that’s why I love Dave’s Uber so much. It would have been such a treat to have heard your products when they were in production.
Nick
Title: Re: How important is Power Supply Design?
Post by: Folsom on September 01, 2018, 02:04:25 AM
I think this shows a clear problem with a fundamental understanding of what switches (transistors/tubes) do. Geddes tried to go down this road, too, and it just isn't so.
Title: Re: How important is Power Supply Design?
Post by: steve on September 01, 2018, 08:20:34 PM
I think this shows a clear problem with a fundamental understanding of what switches (transistors/tubes) do. Geddes tried to go down this road, too, and it just isn't so.

What does your comment have to do with my white paper concerning better understanding of power supplies?

What is the clear problem with understanding of switches, transistors/tubes?
What do switches have to do with understanding a power supply/my white paper? 
What road did Geddes try to go down, as he is deep into speakers, not power supplies?
What "just isn't so"?
Please elaborate in depth on the above questions.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: Folsom on September 02, 2018, 09:07:15 AM
Signal frequency to PSU frequency impedance. It shouldn't be hard to find it in a DIYaudio search.
Title: Re: How important is Power Supply Design?
Post by: steve on September 02, 2018, 04:52:19 PM
Signal frequency to PSU frequency impedance. It shouldn't be hard to find it in a DIYaudio search.

That is only a small part of what I covered in my white paper. So where is your detailed explanation, reference material as I requested? By the way, how do you know the diyers/"experts" are accurate if you only partially understand the subject? (If you had understood the subject, you would have replied to all parts of my white paper.)

To give the readers a sense of the differences between our positions, we are not splitting hairs, nor nit picking small differences.

My scientific white paper is based upon knowledge from the first few weeks of the first semester of electronics engineering. We are not discussing fourth year, nor third year, second year, nor end of first year engineering, but the first few weeks of the first semester in electronics engineering.

Since you are dicing me, Folsom, please explain how an inductor/choke is non-linear.

What do switches/tubes, transistors have to do with understanding how a power supply affects analog audio and sonics?
How did Earl Geddes go down this road (as he is deep into speakers, not power supplies) and thus failed, connected to my white paper?

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: Folsom on September 03, 2018, 10:14:05 AM
Signal has no dependency on power supply impedance for the given signal frequency. PSU impedance is only about attenuating noise that isn't signal. This has been beat to death a great many people on DIYa, and especially by the leaders on the forum (who know more than either of us).

I may have been wrong about an easy search, Geddes may have requested to have it all deleted since it was not true. He had graphs and everything.

Title: Re: How important is Power Supply Design?
Post by: steve on September 03, 2018, 12:11:44 PM
Signal has no dependency on power supply impedance for the given signal frequency. PSU impedance is only about attenuating noise that isn't signal. This has been beat to death a great many people on DIYa, and especially by the leaders on the forum (who know more than either of us).

I may have been wrong about an easy search, Geddes may have requested to have it all deleted since it was not true. He had graphs and everything.

How could you possibly know if the diyers fully understand the subject when you do not understand the subject?
Taking a semester of electronics engineering would help your diyer friends.

Claiming the leaders of the diy forum know more than both of us is obviously trolling.

We are still waiting for your scientific explanation that you claim to have, folsom.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: Folsom on September 03, 2018, 01:19:14 PM
The title of the website does not describe the members found within as a whole. I will gladly take opinions from people that have had very successful ventures in the audio world, and the people who design electronics for much more complicated things that you (or I) have. The website has contributors from everywhere. Many members don't even declare whom they work for. There are loads of ex Harmon employees, physicists, employees at loads of other commercial audio companies, etc etc etc.

This is like the preamp thread at audiocircle where you claim your buffer driving an amplifier will provide zero sonic benefits over the source poorly driving the amplifier.

Let me see if I can explain it really plainly... if the impedance of the power supply had to be equal across the audio band to produce the audio band, it would be no different than saying the power supply must provide a matching frequency to the signal that is being amplified. It should not be hard to see how that cannot be true, has never been, and never will be. You would never see vanishing distortion from a classD based amplifier that's loaded full of inductors.
Title: Re: How important is Power Supply Design?
Post by: steve on September 03, 2018, 02:55:40 PM
The title of the website does not describe the members found within as a whole. I will gladly take opinions from people that have had very successful ventures in the audio world, and the people who design electronics for much more complicated things that you (or I) have.
Which means nothing, as

1. a thevenin equivalent circuit, Kirchoff, Norton etc, 1st semester basic electronics has proven they do not understand basic electronics in an analog application.

2. Successful means what? A large company with a huge marketing strategy. Cosmetics sells more than solid designs.
I think it is interesting to note that Martin DeWulf, a criminal defense attorney and music lover, investigated and wrote an article titled "Truth be Told" which discussed how shills and certain groups work on forums.

3. You accept their opinions, but Thevenin equavilent circuits, Kirchoff, Norton, etc. are not opinions, but fact.
 
4. So how do you know if they are marketing or providing real science.
You don't. Afraid you have been suckered my friend.

Quote
The website has contributors from everywhere. Many members don't even declare whom they work for. There are loads of ex Harmon employees, physicists, employees at loads of other commercial audio companies, etc etc etc.

At least you admit there are shills, conflicts of interest, employees on the diy forums. We have found such as well on Stereophile forums, AK forums etc. One company, a room acoustics company, demands their employees post and push agendas, to sell more room acoustic treatments since their jobs depend upon sales. 

Quote
This is like the preamp thread at audiocircle where you claim your buffer driving an amplifier will provide zero sonic benefits over the source poorly driving the amplifier.

Not a coherent statement. I also never manufactured, nor possessed a buffer of any kind over the decades.

Quote
Let me see if I can explain it really plainly... if the impedance of the power supply had to be equal across the audio band to produce the audio band, it would be no different than saying the power supply must provide a matching frequency to the signal that is being amplified. It should not be hard to see how that cannot be true, has never been, and never will be.

A non-coherent, non-scientific statement? An understanding of a Thevenin Equivalent Circuit, Kirchoff, Norton, etc, explains how the power supply affects the sonics.

It can easily be proven that musical signal current "flows" through the power supply "filter" capacitor of an analog stage.
I am afraid the diy leaders have played you for a suckered folsom.

In the bottom diagram, musical signal current flows through both the series 0,47uf coupling capacitor and RG to ground, and through series RL and power supply capacitor C1 to ground. In the diagram, the plate of the tube is the musical AC signal source, reference is ground with an oscilloscope S. Capacitive reactance is calculated as Xc = 1/ 2pi x F x C.

At mid band Xc is like a resistor. Musical current flow is the AC rms voltage divided by Xc1 + RL (5k).
Musical current through the coupling capacitor is AC rms voltage divided by Coupling capacitor Xc + Rg (100k).

Usually, RL,C1 has many times more musical signal current than through 0,47uf coupling cap and Rg. As such, the power supply filtering system will affect the sonics more.

I think you are killing the reputation of the diy community by pushing their snake oil. As I have mentioned before, this is
first semester electrical or electronics engineering, not even second year.

I would be very wary of anything the diyers preach folsom.

cheers
steve
Title: Re: How important is Power Supply Design?
Post by: P.I. on September 03, 2018, 08:35:34 PM
I don’t have a dog in this fight.  Saying that Thevevin, Norton, Kirchhoff are not to be ignored.  Having built several of Folsom’s P/S boards I can attest to their excellence performance.

But!

What Steve says is true IME.

I need to go back and look at the design methodology with Folsom’s amps.  They do sound great!

Might I suggest a day of introspection to assess positions?

Whatever. Makes for a great read... :shock:
Title: Re: How important is Power Supply Design?
Post by: steve on September 03, 2018, 09:43:17 PM
I don’t have a dog in this fight.  Saying that Thevevin, Norton, Kirchhoff are not to be ignored.  Having built several of Folsom’s P/S boards I can attest to their excellence performance.

You are not part of the dog fight, P.I. and thanks for the information. So folsom does have a financial stake. Interesting, and now I understand why the attack on my white paper.

By the way, that basic white paper could be used by any college class for source information, and contains information which is found in any electronics engineering textbook.

If he is building class D amps, the design is already public domain, so just copy.

He reminds me of a local company here, who initially copied others designs, then he found Dave, who does his designing.

Quote
But!

What Steve says is true IME.

You are quite correct P.I. They are absolutely critical if one wishes an accurate analog design. However, a novice could just copy any of a "million" analog schematics. It is done all the time by diyers.

The question is how accurate are the designs in terms of sonic quality? To be truly accurate is incredibly difficult, and time consuming. And it takes a lot of expertise.

Quote
I need to go back and look at the design methodology with Folsom’s amps.

I would also be interested as well. It is a chip amp. The design is by engineers, inside the chip.

Quote
Might I suggest a day of introspection to assess positions?

No need on my end. The white paper is simple 1st semester electronics engineering information, who principles etc are in college textbooks. Been known for a hundred years.

I deal with laws, and special proprietary setup listening tests that I developed, to actually check for component accuracy in absolute terms, not simply specs or auditions. In fact, I developed two listening testing methods, so I can compare and see if there is a discrepancy.

I get attacked over a basic white paper that any college class would use as source information, and contains information which is found in any electronics engineering textbook. Surprise, surprise.  :lol:

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: TomS on September 04, 2018, 06:58:39 AM
Steve,

The white paper is good stuff. Thanks also for clear thinking and speaking the truth, it's most refreshing.

I remember those first EE courses well. Those fundamental laws remain the same and need to be thoroughly understood to do good work that passes muster. Prof's William Hayt and Gerry Neudeck or their TA's personally drilled it into me back then. The creative art comes in when one ventures off the script of application notes and textbook reference designs (other people's work), and the designer tries something original or unique. Their exams always had a few of these "ringers" on them you'd never seen before, just to make sure we used our brains to think for ourselves. Fortunately, the analysis using those laws, remained the same, and never let you down. Thinking you could somehow "trick" or conveniently ignore them never worked out well  :) Then, of course, there is the effect of real world factors - components, circuit layout, variability, etc. to deal with. As you know, that's part of the fun in it.

For the benefit of all, I hope everyone tries to keep it a respectful and informative dialog. Please carry on.
Title: Re: How important is Power Supply Design?
Post by: steve on September 04, 2018, 11:58:29 AM
Steve,

The white paper is good stuff. Thanks also for clear thinking and speaking the truth, it's most refreshing.

I remember those first EE courses well. Those fundamental laws remain the same and need to be thoroughly understood to do good work that passes muster. Prof's William Hayt and Gerry Neudeck or their TA's personally drilled it into me back then. The creative art comes in when one ventures off the script of application notes and textbook reference designs (other people's work), and the designer tries something original or unique. Their exams always had a few of these "ringers" on them you'd never seen before, just to make sure we used our brains to think for ourselves. Fortunately, the analysis using those laws, remained the same, and never let you down. Thinking you could somehow "trick" or conveniently ignore them never worked out well  :) Then, of course, there is the effect of real world factors - components, circuit layout, variability, etc. to deal with. As you know, that's part of the fun in it.

For the benefit of all, I hope everyone tries to keep it a respectful and informative dialog. Please carry on.

Thank you Tom for those kind words. Much appreciated. As you stated, there is a lot more to consider, such as layout, variability etc.

As just a couple of examples to demonstrate Tom's fine points, for the general public's consumption.

This example I have not seen anywhere except in tube manuals, is how the input Z of either a tube or solid stage gain device can vary.

Let's take a tube. The grid is not infinite impedance (Z) by any means, simply due to some DC leakage current caused by various problems. These include

1. a minute amount of gas,
2. cathode material vaporizing and depositing on the grid itself,
3. heating of the grid from the cathode's proximity, causing emission, etc. etc.

Second example, a variable. Of just as much or larger concern are the internal capacitances present. Grid to Cathode,  Gate to Source) are generally fairly small, but still relevant. An input capacitance of just 1.5 pf, lowers the Grid input
Z to ~5.3 megohms at 20khz (grounded cathode, source).
 
A much greater problem is the Miller capacitance, which is 1+ Av gain times the Grid to Plate capacitance (Base to Collector, Gate to Drain). The Grid input Z again drops significantly with frequency.

For example, with a 12AX7 tube, the G/P capacitance is ~1.7 pf. Let's use 50 as the gain. The Grid to Plate Miller capacitance is ~86pf, plus ~2pf G/C, plus stray capacitance. Let's just use 88pf. The Grid input Z now drops to only ~89k ohms at 20khz.

If one uses a 100k grid resistor, paralleling the 89.7k ohm Z, we get ~47k ohms Grid input Z at 20 khz. (Let's forget any phase angles.) So much for the 100k ohm resistance we think is the Grid input Z. Normally, however, 47k ohms is not a problem since the coupling capacitor's Xc is very very low. However, there is almost always a "but" to consider.

But, what if the preceding stage has a plate load resistor (RL) of 100k ohms. Its load line will substantially shift due to the 47k ohms load connected in parallel (at 20khz). So the harmonic and intermodulation distortion (IMD) products will almost certainly increase as the frequency rises.

With a 6DJ8 type tube, this is not quite the problem since the RL is much lower, maybe 5k ohms. However, the load line will shift to some extent as the frequency increases.

cheers

steve

ps. What the heck. Let's do an example with a 6dj8 type tube.

G/P capacitance is ~1.4pf.
G/K capacitance is ~3.5pf
Av gain               is 10 (20db gain)

Grid input Capacitance is ~14pf + 3.5pf = ~18pf
Grid input Z at 20khz =  ~442k ohms (12AX7 is ~ 89k ohms)



Title: Re: How important is Power Supply Design?
Post by: rollo on September 06, 2018, 07:21:33 AM
    The heart of every component is the PS.


charles
Title: Re: How important is Power Supply Design?
Post by: tmazz on September 06, 2018, 02:18:40 PM
I had an engineering professor as an undergrad who explained and amplification device, whether a tube or a transistor in very simple terms. said that a gain device to not really "amplify" anything. What it is actually doing is modulating a low voltage input signal against a higher voltage power supply rail.

Now we all know that is is much more complicated than that when you look down into the minutia, but this simplistic concept can easily drive home the point of how important power supplies are in audio applications. If the input signal is simple being used to drive changes in the higher voltage of the power supply output is is fairly obvious that and noise, hash, voltage fluctuations or anything other than a perfectly flat B+ voltage will ultimately become part the output signal as distortion of some type.

Now a great power supply in and of itself cannot guarantee great sound as there are many other things that also need to be done right. However cutting corners and building a sub par power supply, while it may not lead to poor performance, will certainly limit the performance of the component, no matter how good the rest of the design is.

And while there can be varying opinions of what constitutes the "best" power supply designs (and some of them have been debated already in this thread)  going back to the original question posted in this thread I think we can all pretty much agree that power supply design is pretty much the bedrock of any high end audio component.
Title: Re: How important is Power Supply Design?
Post by: Folsom on September 07, 2018, 12:36:27 AM
I'm not going to go in circles talking about power supply caps that magically become signal capacitors...

And I'm not going to work against all the absurd assertions.

What I will leave you with, is that I've never designed any kind of classD amplifier, EVER. I'll leave the algebra exercises to you. May you produce many thrilling products with it.
Title: Re: How important is Power Supply Design?
Post by: steve on September 07, 2018, 07:50:44 AM
I'm not going to go in circles talking about power supply caps that magically become signal capacitors...

And I'm not going to work against all the absurd assertions.


We are not talking magically become "signal capacitors", but AC signal current through a capacitor. In this case AC musical signal current.

Folsom, three engineers in this string alone state my white paper is correct, as well as the RCA Radiotron Designers Handbook (26 engineers, 1960 edition), for starters.

The diy "leaders" have obviously mislead you and others.

Here is a schematic of a signal generator and two legs, each with C1 in series with R1 to ground. Notice the left C1 and R1 are opposite of the right R1 and C1. Please "check" the correct response(s)?

A. Signal generator current flows through neither left or right series resistor and capacitor.
B. Signal generator current flows through the left C1/R1.
C. Signal generator current flows through the right R1/C1.

This is basically a high school electronics question.


Title: Re: How important is Power Supply Design?
Post by: Folsom on September 07, 2018, 10:11:36 AM
I'm not saying your circuits or math are wrong. It's the conclusion: " The power supply should properly handle all frequencies when supplying DC to a stage. This is virtually never considered let alone addressed in any designs, including the least and most expensive designs."

Now I'm done.
Title: Re: How important is Power Supply Design?
Post by: Nick B on September 07, 2018, 11:03:28 AM
Is there a way to test these diverging opinions?
Nick
Title: Re: How important is Power Supply Design?
Post by: richidoo on September 07, 2018, 01:07:33 PM
Now I'm done.

Why be "done?"
Title: Re: How important is Power Supply Design?
Post by: gander on September 07, 2018, 01:11:18 PM
Is there a way to test these diverging opinions?
Nick

Sure, compare the two ideas by actually building each of them, and then measure and hear the differences.  I can't tell you how many times I have bought gear based on theory, and my ears were often disappointed.  There is no substitute for actually building multiple versions of a thing and listening to the differences.

And there are other possibilities of course.

For my current power solution for my LDR passive preamp and my small summer Tripath stereo amp (I would use my tube preamp in the summer if it was cooler here! I hate the heat in Las Vegas), I currently use 12V BatCaps as the power source, with iFi-Audio DC iPurifiers for each and I'm very pleased with the results.  But who knows what I might try in the future?

Just my 2 cents.

Gary
Title: Re: How important is Power Supply Design?
Post by: steve on September 07, 2018, 01:34:47 PM
I don't know how not to be offensive; how does one respond to someone who can't answer my basic high school electronics question above, can't provide any info from engineering books, even high school books, and lies by claiming he know more than two EEs, and me, claiming my white paper is a fraud.

The Thevenin Equivalent Circuit, Kirchoff laws, and Norton Laws must be obeyed. Can't sneak around it folsom, as hard as you might try. Diy community is clearly losing reputation as they argue against those laws.

Ok, the capacitive reactance, Xc, of decoupling capacitor is in series with RL. Thevenin proves that. The basic "high school" equation for Xc is 1/2PI times F times C. 1/2PI x F x C. So RL total is RL plus Xc.

RL total varies with frequency, so the gain varies with frequency. The tonal balance is altered when one changes the value of the decoupling capacitor (Xc).
 
That is iron clad first semester electronics, maybe even high school. Anyone who does not believe that is pushing snake oil.

Folsom, still waiting for you to answer my above question with A, B, C possible answers.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: steve on September 07, 2018, 02:33:09 PM
Is there a way to test these diverging opinions?
Nick

Sure, compare the two ideas by actually building each of them, and then measure and hear the differences.  I can't tell you how many times I have bought gear based on theory, and my ears were often disappointed.

Gary

Gary, the difference is theory is not law, but Thevenin, Kirchoff, Norton are laws. The answer is it was not the laws, but the so called theory that failed you. Their theories don't follow the laws, as folsom and his diy leaders just demonstrated through folsom's posts. You have been cheated Gary.

Secondly, designs that did not sound right? I agree Gary. They were probably making up theories, instead of using laws.

------------------
For general public consumption.

Not surprising since most designers either don't understand the laws, or follow the laws, especially diyers. Some large companies either don't understand the laws, or they don't want you to understand. Marketing, shilling, con jobs is big business. 

For instance, capacitors have ESR, DA, and inductance problems. So whose capacitors are accurate? Well, every manufacturer claims his is. So who is right? Well, if you read some forums strings, and diyers, either one of two opinions exist.

1. All capacitors sound the same. Surprise, your component does not sound right (although junk capacitors and parts, poor designs were used, poor venue for testing, poor selection of music etc.).

2. We tested different brands and found, X, brand was the best. Problem is, they tested wrong, so the best, most accurate capacitor, Y, became extinct, because Y was judged bad by incompetents.

True example. X capacitor was judged to be better than Y etc. because Y was bright sounding in the circuit. But the problem was the value of the capactors tested were too small of value. If the proper size were used, Y would have won.

(How did this happen? Because years ago, SETs guys had problems with overloading their small amplifiers and a burp would be heard. We can eliminate the burp by using a smaller capacitor. (Of course, the frequency response won't be flat.)

They would use 0,47uf, 0,82uf coupling capacitors (tube circuits), to eliminate burp, gain more prominent midrange. But it sounded thin with Y capacitor. But X capacitor sounded better because it was designed to sound more full, for a given value/size. So Y capacitor went into the bin, and became extinct.

Eliminating the burp also allowed individuals to use less efficient speakers, so larger marketing audience.
A few, even reasoned that the old time radios used them, better midrange, so who cared about natural bass, the full range anyway.

I have tested many brands, and the most accurate sounding capacitor (and fairly inexpensive) is now extinct. All the other inferior caps are still being sold, still the best. And now we have the super expensive caps, which I can't afford to test. 

Improper testing, and improper size by individuals and diyers led to the crappy state we are now in. It is all about money and looks.

So that is why theory has a bad reputation. Use poor designs/theory, and poor quality parts, which don't follow the laws of science.

But the laws are still in force and they do work. That includes parts quality as well. If they would follow them, components would sound a lot better. But anyone can make a buck if they call themselves a designer and push the snake oil. Who is to know?

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: gander on September 07, 2018, 02:47:53 PM
Is there a way to test these diverging opinions?
Nick

Sure, compare the two ideas by actually building each of them, and then measure and hear the differences.  I can't tell you how many times I have bought gear based on theory, and my ears were often disappointed.

Gary

Gary, first, these are not theories, but laws. So what happened that the laws failed you? The answer is it was not the laws, but the amateurs who failed you. Don't blame the laws.

Secondly, disappointed in what? Designs that did not sound right? Not surprising since most designers either don't the laws, or follow the laws, especially diyers. And some large companies either don't understand the laws, or they don't want you to understand. Marketing and shilling is big business. 

For instance, capacitors have ESR, DA, and inductance problems. So whose capacitors are accurate? Well, every manufacturer claims his is. So who is right? Well, if you read some forums strings, and diyers, either one of two opinions exist.

1. All capacitors sound the same. Surprise, your component does not sound right (although junk capacitors were used).

2. We tested different brands and found, X, brand was the best. Problem is, they tested wrong, so the best, most accurate capacitor, Y, became extinct, because Y was judged bad by incompetents.

True example. X capacitor was judged to be better than Y because Y was bright sounding in the circuit. But the problem was the value of the capactors tested were too small of value.

Why? Because years ago, SETs guys had problems with overloading their small amplifiers and a burp would be heard. We can eliminate the burp by using a smaller capacitor. (Of course, the flat frequency response won't be flat.

They would use 0,47uf, 0,82uf coupling capacitors (tube circuits), so no burp and more prominent midrange. But it often sounded thin. But X capacitor sounded better because it was designed to sound more full, for a given value. So Y capacitor went into the bin, and became extinct.

I have tested many brands, and the most accurate sounding capacitor (for less than $30.00) is now extinct. All the other inferior caps are still being sold.

Improper testing, and improper size by diyers and others led to the state we are now in. It is all about money and looks, not sound.

So that is why theory has a bad reputation. Of course, many if not most make up theory to SELL their products. And unfortunately, many if not most either don't follow the laws of electronics, or their marketing theory doesn't follow the laws of electronics.

But the laws are still in force and they do work. That includes parts quality as well.

cheers

steve

Steve, are you seriously attacking me now and trying to make me seem less than you?  You can stop that right now. I'm very impressed by your knowledge and I bow to it, but it means nothing in what audio is really about.

Please go build something superior and let us listen to it.

The only thing that is really important is, how does it sound and how does it make you (me) feel?  I'm a violinist and I've solo'ed with orchestras, I've been an orchestra director and music educator, and I'm an inventor with 3 patents awarded to me in the area of sound and acoustics. I have degrees in music performance and pedagogy, performance, and computer science.  I know what music is supposed to sound like and how I want to feel from my music. This is the only thing in audio that counts.

You don't have the right to try to make me or anyone else less than you. Be respectful, work and play well with others.

Jeeeeesssshhhhhh

Gary

Title: Re: How important is Power Supply Design?
Post by: steve on September 07, 2018, 02:53:30 PM
Is there a way to test these diverging opinions?
Nick

Sure, compare the two ideas by actually building each of them, and then measure and hear the differences.  I can't tell you how many times I have bought gear based on theory, and my ears were often disappointed.

Gary

Gary, first, these are not theories, but laws. So what happened that the laws failed you? The answer is it was not the laws, but the amateurs who failed you. Don't blame the laws.

Secondly, disappointed in what? Designs that did not sound right? Not surprising since most designers either don't the laws, or follow the laws, especially diyers. And some large companies either don't understand the laws, or they don't want you to understand. Marketing and shilling is big business. 

For instance, capacitors have ESR, DA, and inductance problems. So whose capacitors are accurate? Well, every manufacturer claims his is. So who is right? Well, if you read some forums strings, and diyers, either one of two opinions exist.

1. All capacitors sound the same. Surprise, your component does not sound right (although junk capacitors were used).

2. We tested different brands and found, X, brand was the best. Problem is, they tested wrong, so the best, most accurate capacitor, Y, became extinct, because Y was judged bad by incompetents.

True example. X capacitor was judged to be better than Y because Y was bright sounding in the circuit. But the problem was the value of the capactors tested were too small of value.

Why? Because years ago, SETs guys had problems with overloading their small amplifiers and a burp would be heard. We can eliminate the burp by using a smaller capacitor. (Of course, the flat frequency response won't be flat.

They would use 0,47uf, 0,82uf coupling capacitors (tube circuits), so no burp and more prominent midrange. But it often sounded thin. But X capacitor sounded better because it was designed to sound more full, for a given value. So Y capacitor went into the bin, and became extinct.

I have tested many brands, and the most accurate sounding capacitor (for less than $30.00) is now extinct. All the other inferior caps are still being sold.

Improper testing, and improper size by diyers and others led to the state we are now in. It is all about money and looks, not sound.

So that is why theory has a bad reputation. Of course, many if not most make up theory to SELL their products. And unfortunately, many if not most either don't follow the laws of electronics, or their marketing theory doesn't follow the laws of electronics.

But the laws are still in force and they do work. That includes parts quality as well.

cheers

steve

Steve, are you seriously attacking me now and trying to make me seem less than you?  You can stop that right now. I'm very impressed by your knowledge and I bow to it.
Please go build something superior and let us listen to it - that is the only thing that is really important. How does it sound to you and how does it make you feel?

Jeeeeesssshhhhhh

Gary

I was simply giving a history lesson to the public, and how the marketers/ less qualified designers work. Theories are theories, and laws are laws. You got cheated Gary. I guess I could have simply stated such, so my apologies and I restructured my previous post.

My apologies.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: gander on September 07, 2018, 02:59:02 PM
Is there a way to test these diverging opinions?
Nick

Sure, compare the two ideas by actually building each of them, and then measure and hear the differences.  I can't tell you how many times I have bought gear based on theory, and my ears were often disappointed.

Gary

Gary, first, these are not theories, but laws. So what happened that the laws failed you? The answer is it was not the laws, but the amateurs who failed you. Don't blame the laws.

Secondly, disappointed in what? Designs that did not sound right? Not surprising since most designers either don't the laws, or follow the laws, especially diyers. And some large companies either don't understand the laws, or they don't want you to understand. Marketing and shilling is big business. 

For instance, capacitors have ESR, DA, and inductance problems. So whose capacitors are accurate? Well, every manufacturer claims his is. So who is right? Well, if you read some forums strings, and diyers, either one of two opinions exist.

1. All capacitors sound the same. Surprise, your component does not sound right (although junk capacitors were used).

2. We tested different brands and found, X, brand was the best. Problem is, they tested wrong, so the best, most accurate capacitor, Y, became extinct, because Y was judged bad by incompetents.

True example. X capacitor was judged to be better than Y because Y was bright sounding in the circuit. But the problem was the value of the capactors tested were too small of value.

Why? Because years ago, SETs guys had problems with overloading their small amplifiers and a burp would be heard. We can eliminate the burp by using a smaller capacitor. (Of course, the flat frequency response won't be flat.

They would use 0,47uf, 0,82uf coupling capacitors (tube circuits), so no burp and more prominent midrange. But it often sounded thin. But X capacitor sounded better because it was designed to sound more full, for a given value. So Y capacitor went into the bin, and became extinct.

I have tested many brands, and the most accurate sounding capacitor (for less than $30.00) is now extinct. All the other inferior caps are still being sold.

Improper testing, and improper size by diyers and others led to the state we are now in. It is all about money and looks, not sound.

So that is why theory has a bad reputation. Of course, many if not most make up theory to SELL their products. And unfortunately, many if not most either don't follow the laws of electronics, or their marketing theory doesn't follow the laws of electronics.

But the laws are still in force and they do work. That includes parts quality as well.

cheers

steve

Steve, are you seriously attacking me now and trying to make me seem less than you?  You can stop that right now. I'm very impressed by your knowledge and I bow to it.
Please go build something superior and let us listen to it - that is the only thing that is really important. How does it sound to you and how does it make you feel?

Jeeeeesssshhhhhh

Gary

I was simply giving a history lesson to the public, and how the marketers/ less qualified designers work. Theories are theories, and laws are laws. I guess I could have simply stated such, so my apologies.

My apologies.

cheers

steve

You're fired from my classroom, if you were teaching for me.
Title: Re: How important is Power Supply Design?
Post by: steve on September 07, 2018, 03:13:53 PM
Is there a way to test these diverging opinions?
Nick

Sure, compare the two ideas by actually building each of them, and then measure and hear the differences.  I can't tell you how many times I have bought gear based on theory, and my ears were often disappointed.

Gary

Gary, first, these are not theories, but laws. So what happened that the laws failed you? The answer is it was not the laws, but the amateurs who failed you. Don't blame the laws.

Secondly, disappointed in what? Designs that did not sound right? Not surprising since most designers either don't the laws, or follow the laws, especially diyers. And some large companies either don't understand the laws, or they don't want you to understand. Marketing and shilling is big business. 

For instance, capacitors have ESR, DA, and inductance problems. So whose capacitors are accurate? Well, every manufacturer claims his is. So who is right? Well, if you read some forums strings, and diyers, either one of two opinions exist.

1. All capacitors sound the same. Surprise, your component does not sound right (although junk capacitors were used).

2. We tested different brands and found, X, brand was the best. Problem is, they tested wrong, so the best, most accurate capacitor, Y, became extinct, because Y was judged bad by incompetents.

True example. X capacitor was judged to be better than Y because Y was bright sounding in the circuit. But the problem was the value of the capactors tested were too small of value.

Why? Because years ago, SETs guys had problems with overloading their small amplifiers and a burp would be heard. We can eliminate the burp by using a smaller capacitor. (Of course, the flat frequency response won't be flat.

They would use 0,47uf, 0,82uf coupling capacitors (tube circuits), so no burp and more prominent midrange. But it often sounded thin. But X capacitor sounded better because it was designed to sound more full, for a given value. So Y capacitor went into the bin, and became extinct.

I have tested many brands, and the most accurate sounding capacitor (for less than $30.00) is now extinct. All the other inferior caps are still being sold.

Improper testing, and improper size by diyers and others led to the state we are now in. It is all about money and looks, not sound.

So that is why theory has a bad reputation. Of course, many if not most make up theory to SELL their products. And unfortunately, many if not most either don't follow the laws of electronics, or their marketing theory doesn't follow the laws of electronics.

But the laws are still in force and they do work. That includes parts quality as well.

cheers

steve

Steve, are you seriously attacking me now and trying to make me seem less than you?  You can stop that right now. I'm very impressed by your knowledge and I bow to it.
Please go build something superior and let us listen to it - that is the only thing that is really important. How does it sound to you and how does it make you feel?

Gary

I was simply giving a history lesson to the public, and how the marketers/ less qualified designers work. Theories are theories, and laws are laws. I guess I could have simply stated such, so my apologies.

My apologies.

cheers

steve

You're fired from my classroom, if you were teaching for me.

First of all, this is my string, I started it, and my classroom, not yours. So why did you post here if you don't' like electronic laws or my white paper? It would not be to support your fellow diyer folsom, would it?

A decoupling power supply capacitor does handle musical signal content and has reactance, and also alters the frequency response vs frequency. That is the law, not theory.

I even edited my last post to differentiate between what I wanted the public to understand vs the small amount replying to you.
And I even apologized to you.

I do have one advantage in that I have applied the laws to my system and been able to compare with many other systems, over the years and even decades, that others have not.

Now this come back from you.... If you don't like science laws or my scientific white paper, then don't post.... and exit this string. I was nice enough to reply, and give you reasons why theory did not satisfy what you heard/experienced.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: Nick B on September 07, 2018, 04:59:35 PM
Ok, it was good and quite informative while it lasted. I’m not able to make any judgments on who’s right or wrong as the technical discussion is way above me. What I do know is that Steve is an accomplished designer and Folsom makes great sounding products according to Dave, whose ears I trust and whose Uber I love. And then there’s Gary who loves diy and whose cables I use and they sound really good. So my final words are “pacem in terris “ or I’ll lock the thread
Title: Re: How important is Power Supply Design?
Post by: rollo on September 10, 2018, 10:45:08 AM
   Boys boys play nice. Yes known laws dictate the basics, but but sometimes different approaches within the laws render different outcome.
   We cannot become so ruled by law that we cannot imagine. We would not go forward if we did. All I know changing a cap in the power supply gives me a different sound.
   Give me a better PS and I'll give you better sound. John Lennon "Imagine"

charles
Title: Re: How important is Power Supply Design?
Post by: P.I. on September 10, 2018, 10:54:50 AM
   Boys boys play nice. Yes known laws dictate the basics, but but sometimes different approaches within the laws render different outcome.
   We cannot become so ruled by law that we cannot imagine. We would not go forward if we did. All I know changing a cap in the power supply gives me a different sound.
   Give me a better PS and I'll give you better sound. John Lennon "Imagine"

charles
+1  on everything.

Give me a crappy linear power supply and I'll give you back a much, much better one.  Ain't gonna be the be all and end all, but it will certainly sound a lot better than stock.

Saw this thread take a left hand turn and pretty much decided then to not stoke the fire.   :roll:
Title: Re: How important is Power Supply Design?
Post by: steve on September 10, 2018, 07:49:05 PM
Hello Everyone,

Let me first state that it is amazing how good the sound is when a truly great power supply design is used. Anyone can get pretty good sound by being off on their power supply design, and pretty good is what you'll get. Getting the best is another matter. It is not as simple as just switching to poly caps etc. One has to consider the entire design.

It seems that my white paper was a bit too complicated, so I will start at the beginning and go step by step and prove the power supply decoupling capacitor not only handles musical signal current, but also alters the frequency response of an audio stage.

I will even do most of the mathematics, but I will also provide the equations in case one is interested. I will use a series of figures to help.

For those who wish to skip the points below, and get a quick summation, the points below prove that power supply  filter capacitor (C1) is in series with RL, so actually RL + C1 (AC resistance/capacitive reactance Xc). Since Xc is frequency dependent, RL + Xc changes with frequency, and the gain of the stage is frequency dependent, so the frequency response is not flat.

Since RL has AC musical signal current flow, C1 does as well; in fact some 15 or more times Ccoupling capacitor and Rg in my example.

C1 capacitor also has AC voltage, musical signal voltage on its positive terminal. All these can be easily measured so they follow the laws of electronics.
Thus my white paper is correct.

For the rest of us, relax, take your time, and let’s get started. At the bottom of this post are Figures A, B, C etc. I also provided them in .pdf format at the very bottom in case some prefer .pdf.

Here we go.

1.   Figure A is simply a 10 volt DC battery with a 10k ohm (10,000 ohm) load resistor, resistor placed across it’s terminals. 1 ma (1 thousandths of an ampere) current flows through the resistor. The equation is: Current = voltage divided by resistance.
I = E / R

2.   Figure B is a 10 volt AC source with a 10k ohm load resistor. Again, 1 ma. of AC current is also flowing through the resistor. The same equation as point 1. This applies for whatever audio signal; 60hz, 1,000hz, 10,000hz are examples of AC, or a musical signal.)                     

3.   Next, Figure C is the same 10 volt AC source with a 10k ohm load resistor. However, I divided the 10k ohm resistor into a 4k ohm resistor Rp connected in series with a 6k ohm resistor RL. Again 1 ma. of current flow. I = V / R. The output AC voltage is calculated: Output = 10 volts x (6k / 6k +4k). 6 volts.

Relax, feel free to refer back because we will be coming back to these points.

4.   Next, Figure D is a typical gain stage triode circuit, and Figure E is the AC Thevenin Equivalent Circuit of Figure D. No DC voltage is applied. This will be covered later. (Engineering textbook, Semiconductor and Tube Electronics, by James G. Brazee).

5.   In Figure E, X is our AC source, Rp is the tube plate resistance from the specification sheet, and RL is our plate resistor to B+.  (I made up my own tube with specs sheet of Mu = 10, Rp is 4k ohms.)

6.   Figure E, RL is grounded at  point H.

7.   Notice Figure E, we have AC voltage source with Rp in series with RL to ground, just like in Figure C, because it is the same circuit. (The equation again is 10 volts x (RL / RL + Rp), or 10 x (6k/6k + 4K) = 6 volts AC.) All this can be easily measured to verify in our basic tube circuit.

8.   Our tube circuit will not work without DC voltage applied. But RL at H point to ground would short out the DC power supply.

9.   So let’s add the DC battery voltage to our Thevenin Equivalent Circuit Figure E? The result is Thevenin Equivalent Circuit Figure F, which deals with both AC and DC voltages.

10.   What is the difference between Figure E and F? One difference is power supply filter capacitor C1 is added so our B+ does not short to ground.

11.   Secondly, RL is not directly connected to ground anymore at H, but through C1 to ground.

12.   So we have a voltage divider, like Figure C, but with an additional part, C1. So we have our AC source, Rp, RL, and C1.

13.   Now, we need to understand that C1 has AC resistance (Xc). (Actually reactance but let’s keep it simple with no phase angles.)

14.   So now the AC output voltage = 10 x (RL + Xc / RL + Xc + Rp

15.   But what value is the AC resistance (Xc)? That depends upon the frequency.

16.   (The AC resistance (Xc) is calculated:   1 / 2PI x F x C. That is 1 divided by 6.28 times Frequency in hz times Capacitance in Farads.) As one can see, Xc is frequency dependent.

17.   So in our voltage divider, the output voltage will depend upon the frequency since RL + Xc changes with frequency..

18.   I have thus proven that the output voltage varies with frequency, thus the frequency response is not flat. (Thevenin Equivalent Circuits have been used in engineering circuits for decades and decades.)

The AC source we used can be simply musical voltage.

19.   Figure K is what you would see as the actual schematic circuit that we discussed.

20.   If we calculate or measure the AC musical signal current through C1, it will be at least 15 times the musical signal current through the coupling capacitor/Rg combination. I am lenient due to Y (a resistor or choke) siphoning off some AC musical current.

21.   We can calculate or measure the AC voltage at C1 but we need to know the frequency. At 20hz, a 20uf capacitor has 400 ohms Xc. The equation is: 6 AC volts x (Xc \ Xc + RL) The answer is approximately 0,2 volts AC. The C1 AC voltage will vary with circuit gain, C1’s value, Rp, RL, AC frequency.

Not only is the white paper correct, but goes further, because capacitors have ESR, internal inductance, and self resonance problems. Even very small capacitors have problems since tonal balance is so easily perceived.

See Walter Jung and Richard Marsh have an article “picking capacitors” that includes measurements, resonance problems, ESR, DA etc.

https://www.yumpu.com/xx/document/view/23313452/picking-capacitors-part-1-walt-jung
http://www.reliablecapacitors.com/pickcap.htm

Cheers

Steve


(http://sasaudiolabs.com/Thevenin%20EQ%20Circuit%20A%203.jpg)

(http://sasaudiolabs.com/Thevenin%20EQ%20Circuit%20A%204.jpg)
Title: Re: How important is Power Supply Design?
Post by: steve on September 12, 2018, 05:12:14 PM
Here is an abbreviated version, just a couple of points for those who feel overwhelmed by my above post, yet wants to see some proof that the power supply capacitor does handle musical signal current, has voltage across it, as well as causes non linear frequency response by its changing AC resistance vs frequency.

(http://www.sasaudiolabs.com/Thevenin%20EQ%20Circuit%20A%205.jpg)

The top diagram is a typical schematic circuit and lower diagram is the Thevenin Equivalent Circuit of the top diagram, including both AC and DC voltages.

We just have a simple series voltage divider consisting of Rp (tube plate resistance), RL resistor, and power supply capacitor C1's AC resistance/Xc (varies with frequency). The equation is Xc = 1 / 6.28 x F x C.    Xc = 1 / 6.28 x Frequency HZ x Capacitor's value.

Proof that the frequency response varies with frequency due to power supply capacitor C1.

Cheers

steve
Title: Re: How important is Power Supply Design?
Post by: Nick B on September 13, 2018, 03:36:13 PM
Ok, it was good and quite informative while it lasted. I’m not able to make any judgments on who’s right or wrong as the technical discussion is way above me. What I do know is that Steve is an accomplished designer and Folsom makes great sounding products according to Dave, whose ears I trust and whose Uber I love. And then there’s Gary who loves diy and whose cables I use and they sound really good. So my final words are “pacem in terris “ or I’ll lock the thread

Steve,
Thanks for the simplification. You may be be teaching at a 3rd grade level, for example, but I feel like I’m still in preschool. I am trying to remember what C1 means when I reread your post.....Not all is lost however, for I do know the difference between AC and DC....Tesla vs Edison. And I always opt for the upgraded/best power supply when available. Please continue with your posts as I continue to play catch up via various means
Nick
Title: Re: How important is Power Supply Design?
Post by: steve on September 13, 2018, 08:28:32 PM
Ok, it was good and quite informative while it lasted. I’m not able to make any judgments on who’s right or wrong as the technical discussion is way above me. What I do know is that Steve is an accomplished designer and Folsom makes great sounding products according to Dave, whose ears I trust and whose Uber I love. And then there’s Gary who loves diy and whose cables I use and they sound really good. So my final words are “pacem in terris “ or I’ll lock the thread

Steve,
Thanks for the simplification. You may be be teaching at a 3rd grade level, for example, but I feel like I’m still in preschool. I am trying to remember what C1 means when I reread your post.....Not all is lost however, for I do know the difference between AC and DC....Tesla vs Edison. And I always opt for the upgraded/best power supply when available. Please continue with your posts as I continue to plat catch up via various means
Nick

Your welcome Nick. I try not to teach down, but I don't know the general public's level, I don't wish to insult anyone, but I also want all to understand if possible. Knowledge is power.

C1 is a power supply "decoupling" capacitor. Capacitor C1 will tend to pass an AC signal while preventing the DC voltage from shorting to ground. Passes AC while blocking DC is a nice way of putting it.
We will call AC resistance (Xc).

A capacitor blocks DC but tends to pass AC.

A resistor provides resistance to both AC and DC.

A choke tends to block AC but tends to pass DC.

General statements but pretty good at helping us to understand our basic circuit.

A resistor's resistance value is simply what is stated on the resistor, for either AC or DC.

For any capacitor, the DC resistance is approximately infinite. Makes sense since a capacitor blocks DC.


For a capacitor, the AC resistance (Xc) = 1 / 6.28 x Frequency in hz x Capacitance in farads (ufd is millionths of a farad).

For 10 ufd capacitor:

Xc = 1 / 6.28 times 20hz times 0,00001 farads = 796.178 ohms AC resistance.

At 200 hz, Xc = 1 / 6.28 x 200hz x 0,00001 farads = 79.6178 ohms AC resistance.

At 5k hz, Xc = 1 / 6.28 x 5000hz x 0,00001 farads = 3.184 ohms AC resistance.

If any questions so far, please feel free to ask.

Cheers

steve

         
Title: Re: How important is Power Supply Design?
Post by: steve on October 21, 2018, 08:09:41 PM
Ok, we learned that Xc1's AC resistance (Xc1) varies with frequency.

By definition, we know that Rp's DC and AC resistances are the same at audio midband. By defintion, we also know RL's DC and AC resistances are the same at audio midband.

Checking reply #34, we see that Rp is in series with RL is in series with Xc1 to ground. Since Xc1 varies with frequency in the audio band, Rp + RL + Xc1 varies with frequency.

Since Rp + RL + Xc1 varies with frequency, the gain is also going to change vs frequency.

Since the gain changes vs frequency, the output signal voltage will vary with frequency.

I hope this helps one to understand how the power supply capacitor is not only in the musical signal path, but also alters the gain vs frequency. If you have a question, or don't understand something, please ask.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: steve on October 27, 2018, 11:20:25 PM
    Yes known laws dictate the basics, but but sometimes different approaches within the laws render different outcome.
   We cannot become so ruled by law that we cannot imagine. We would not go forward if we did. All I know changing a cap in the power supply gives me a different sound.

charles

I have decided to respond to your post Charles. In my article, one cannot sometimes use different approaches within the laws as the laws are the laws. One cannot work around Xc = 1/6.28 x F x C. One cannot also work around E = I x R because
one does not like it.

One cannot say no signal current flows through the power supply filter capacitor because we don't like it. One cannot say
a capacitor is perfect either, because they are not. They work because of laws.

Out of all the comments Folsom posted, his clearest stated position, which I will address is:

A capacitor does not create its own signal. The problem is current flow. (Let's keep this simple.)

Secondly, a power supply decoupling capacitor has signal current flow as I have clearly proven in posts #1, #19 and #33.

Thirdly, we cannot claim the power supply decoupling capacitor impedance (Z) is irrelevant since we have an AC resistance and resistor as a load. Are some going to claim that a resistor across a car battery won't pass current? LOL.

Changing filter capacitors and perceiving different sonics will occur due to different ufd, ESR, DA, resonance, physical construction, materials, and termination techniques. All these different characteristics will affect how the musical signal current flows through the power supply decoupling filter capacitor. Laws are laws.

========

In general, I was initially hoping we could have a nice discussion and learn how a circuit actually works, and in more depth than typical explanations. I am certainly glad two EEs chimed in to support me, as well as my engineering textbooks, RCA Radiotron Designers Handbook, with 26+ electrical engineers, as well my electronics engineering classes.

But it appears the string has been damaged to such an extent, by two, that no one wishes to participate. Maybe next time.

cheers

steve
Title: Re: How important is Power Supply Design?
Post by: steve on July 30, 2019, 08:13:22 PM
I have discontinued my website, at least for now, so all my white papers are not available. However,
the premise that musical signal current flows through the power supply decoupling capacitor is
scientifically correct. I have uploaded a .pdf of my webpage to my initial post.

For ease, I have again drawn out a simple/typical two stage circuit one would see in a schematic,
bottom of this post. Figure 1 is a typical gain stage driving the following stage.
 
Point A is a musical signal output point, with ground as reference. (We typically measure both
DC and AC signal voltages to ground.)

Notice the 2 red lines, which show the AC musical signal current paths from point A to ground.
Notice each red line has only one capacitor and one resistor.

One signal current path is from point A through C1 and Rg1 to ground.
The second musical signal current path is from point A through RL and C (the decoupling capacitor)
to ground.

Figure 2 should be easier to understand as I left out the non essentials for our purposes. We only
need to inspect point A and the two red lines to ground.

Again, one musical signal current path is from point A through C1 and Rg1 to ground.
The second musical signal path is from point A through RL and C (the decoupling capacitor) to
ground. That decoupling capacitor is the last power supply filtering stage.

If we placed an AC current meter, we would measure musical signal current flowing through
each red line. (As a side note, the power supply decoupling capacitor is in the signal path since
it handles some musical signal current.)

----------

As bonus information, RL's resistance value is generally smaller than Rg1's resistance (sometimes much
smaller), so more musical signal current actually flows through the decoupling capacitor C, than
through the coupling capacitor C1.

So C decoupling capacitor quality is even more important than the quality of C1 capacitor.

Knowing true scientific knowledge leads to better understanding of how a circuit works, and what is
important in designing.

Cheers
steve
Title: Re: How important is Power Supply Design?
Post by: rollo on August 01, 2019, 05:39:07 AM
  Thanks Steve for the input and hard work. No EE here just Ears. My ears tell me that a properly designed power supply when compared to another it sounds better.
 Yes Caps in PS will sound different. Dave Slagle made several dry chokes one day to compare to a NOS oil filled cap in a power supply. Slagle apologized to all present after he HEARD the difference. He stated" In all my Engineering years I would never suggest a difference in sound" . BTW it was at Mike Matteras home.

charles
Title: Re: How important is Power Supply Design?
Post by: steve on August 01, 2019, 04:43:50 PM
  Thanks Steve for the input and hard work. No EE here just Ears. My ears tell me that a properly designed power supply when compared to another it sounds better.

charles

I don't know who those individuals are, and I believe you did not mean "choke" when comparing capacitors.
I will just work with your initial comments, which are quite true from my testing and others.

Anyway.

I have seen many many coupling capacitor exchange strings. There is no doubt that different
brand, types, of coupling capacitors influence the sonics.

Yet I notice there are very few strings concerning power supply decoupling capacitors, which almost
always handle more musical signal current than coupling capacitors, and influence the sound so
profoundly.

For general consumption based upon my previous post #39 schematic, and bottom of this post. I changed a symbol
or two, so check the schematics below.

Let me do an example. Let's say we have 20 volts rms at point A in my previous post schematic.
Coupling capacitor C1 is a generous 1ufd. At 1 khz the capacitive reactance (Xc) is 160 ohms.
Rg1 is 100k ohms.
Total reactance is 100,160 ohms.
Current flow through C1/Rg1 is 20 volts rms divided by 100,160 ohms at 1khz. We have
0,00019968 amps of current. That is 0,19968 ma. (0,19968 milliameters of current through both C and Rg1
at 1khz, midband.

Ok, so let's say we run a 12AX7 triode tube, and C is 20ufd, still 20 vrms.
RL is 60,000 ohms.
At 1khz, C reactance is 8 ohms.
Total reactance is 60,008 ohms.
C/RL current flow is 20 volts rms divided by 60,008 ohms at 1khz. We have 0,33328 ma of musical signal
current flow.

1. Signal current flow through C capacitor is 1.669 times higher than signal current flow through C1.
With a different tube, RL values, musical signal current could easily be a factor of 10 or 20 higher than
with a 12AX7 tube. Higher signal current means higher quality decoupling capacitor C.

2. The power supply decoupling capacitor C is usually many many times larger in value to C1 as well,
thus even more important to get the quality of C decoupling capacitor as high as possible.

Cheers
steve

 
Title: Re: How important is Power Supply Design?
Post by: rollo on August 02, 2019, 07:35:31 AM
  Yes a choke. Dave Slagle is known for his autoformers and custom, transformers, speakers and Strain Gauge cartridge.. Cannot remember name of his company. He makes exotic stuff that just sounds wonderful.


charles
Title: Re: How important is Power Supply Design?
Post by: steve on August 02, 2019, 09:17:00 AM
  Yes a choke. Dave Slagle is known for his autoformers and custom, transformers, speakers and Strain Gauge cartridge.. Cannot remember name of his company. He makes exotic stuff that just sounds wonderful.

charles

Hi Charles,

Ah strain gauge cartridge, now I remember Dave. Either way, I am glad to have Dave on board.

Cheers and thanks.
steve
Title: Re: How important is Power Supply Design?
Post by: steve on August 26, 2019, 02:10:34 PM
After some thinking, me being an Electronics Engineer, I still do not find it surprising that a
choke/inductor/interstage transformer etc. would 'sound' different than a capacitor.

The inherent loses, non linearity, tonal balance variations of a transformer/inductor, all make
for sonic differences between it and capacitors, which have their own particular non-linearities.

Back to my previous post/subject (post #41) dealing with AC signal current through two paths,
don't let AC voltage throw you. The same situation applies for DC voltage as well. If one has
two wires, or two resistors connected across a battery, or DC voltage to ground, current would
flow through each wire or resistor.

As I stated before, though, nice to have Dave aboard.

cheers
steve
Title: Re: How important is Power Supply Design?
Post by: P.I. on August 27, 2019, 07:15:19 AM
Steve,

Just wanted to say that all of this has been a great read.

And, yes: Dave Slagle builds wonderful sounding stuff!