No. Some people can get things right by accident, or by copying standard practice - which in most cases happens to be right.banat said:
He is free to choose how he builds his amps. He is free to tell others. I am free to point out the flaws in his thinking. Let us be completely clear: censorship is not the issue. An idea may be true or false, helpful or unhelpful; it cannot be true for one person and false for another. That is to confuse preference with truth.
That would depend on your definition of "bad" and "good"; what measurements were made and what sound you prefer. The envelope distortion we have been talking about ought to be measurable, but I doubt if it often gets measured.
All theories are still theories until they become physical law. Engineers and scientists in the respectable field should prove or disprove the theory or even refine the theory to get tested again, over and over. Because if there is any exceptions, it can't be a law yet.
very few designs I have seen use all of the potential of the tube.
even using "local feedback" which is only a reference move.
ripple doesn't really become a big mu changer till you get up past 60% of the operating range. That was one of reasons why there was a lot of stages in older designs compared to the newer ones (so I was told).
I also want to point out its not the capacitance that makes the low ripple but the total filter effect of the circuit.
so there is two ways you can go filtering with c-l-c: high capacitance, low inductance or low capacitance and high inductance.
Some go for the first one because it more affordable to build
so there is two ways you can go filtering with c-l-c: high capacitance, low inductance or low capacitance and high inductance.
Some go for the first one because it more affordable to build
OK. You don't understand what science means by the word "theory". That is quite common among non-scientists.DavesNotHere said:
You appear to be questioning circuit theory, on the grounds that it is just a theory. If so, how do you design circuits with no theory to guide you?
OK. You don't understand what scientists mean by the word "law". According to your idea, Ohm's Law is not a law because it has exceptions.
Ripple is not the issue in this discussion.
True but irrelevant, as ripple is not the issue.
When I build I use appropriate formulas. Most are based off of laws and theories. Others are mathematical constructs of the circuit.
Then what is the issue?
Plus I would like to see any exceptions to Ohm's law and Kirchoff's law
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Years ago, I used photofllash caps, actually decades ago !! Today. easily my favorite is a WIMA DC LINK with four leads as a main supply cap, and in almost all cases, I bypass main caps with smaller ones.
HERE is am interesting comment from about 2010 : John Hasquin, wrote this :
In all our engineering books we are taught that a high capacitance power supply is good. The authors imply that the low impedance of the capacitor will be able to deliver current to the output tube quickly and prevent voltage sag. On the surface this looks good on paper. However, it could be more wrong. Once the capacitor has used its low impedance to source current, it then uses that same low impedance to hog any and all available current to regain its charge.
The problem with high capacitance power supplies is they will always be in direct competition with the output tube. At 20Hz a 220uF capacitor has an impedance of 36 ohms and an impedance of only 0.036 ohms at 20KHz. Compare the capacitor’s impedance to the internal resistance (Rp) of most output tubes. When a transient comes along and the output tube demands current from the power supply which device will get its fill first? What the power supply looks like is a series feed with two current sinks; one being the capacitor and the other being the output tube. Ohm’s Law tells us which device will get the lion’s share of the current flowing from the power supply. It is a simple fact that the capacitor will always rob the output tube for available current in order to maintain its charge. The very instant the output tube demands more current a slight voltage drop occurs and the capacitor immediately begins to compete with the output tube for current. This is why over stuffed power supplies always sound slow. The over stuffed power supply prevents the output tube from reproducing dynamics.
People seem to put their head in the sand and believe that a capacitor is always sourcing low impedance current for the goodness of the output tube. No one ever bothers to look at what happens when the capacitor is trying to recharge.
Is there a way for one with poor to mediocre test equipment to go about looking for, or measuring, something like this?
Win W5JAG
Sure!! Use your ears and brain, one of the very best instruments possible. Go to a LIVE un-amplified music concert, and use that as your reference.
Jeff
Yes, the humblest of an AC coupled oscilloscope can visualize (and eventually measure) it.
One of the really disturbing things I have learned in the past year, is that I just do not hear distortion unless it's really gross.
My ears are good for a lot of things, but, a distortion analyzer they are not. Maybe that is a blessing when you think about it.
Win W5JAG
The above mentioned person (John Hasquin) did very poor job learning basics of electronics.
All derivatives of this junk science are still junk no matter what.
Or vice versa, say, the B+ modulated by the audio signal. it is not a difficult task.
well I try not to glaze over things.
I take these things as observations with circuit conditions. So they are true to the condition but they are not global enough to make formulas nor append to an electronic theory's formulas.
Jeff
-Thanks for pointing on those very attractive WIMA DC LINK caps ! , they are something very new for me , I have to try them for sure .
- about low vs high value capacitance based PSU`s ,
in order to get extremely fast recharge rate for that B+ low value capacitor you should try PSU based on one good designed and executed SMPS unit , they are cheap,available and pretty reliable today , on that SMPS secondary side you can use your favorite vacuum tube rectifier instead of standard fast SS rectifier .
-Thanks for pointing on those very attractive WIMA DC LINK caps ! , they are something very new for me , I have to try them for sure .
- about low vs high value capacitance based PSU`s ,
in order to get extremely fast recharge rate for that B+ low value capacitor you should try PSU based on one good designed and executed SMPS unit , they are cheap,available and pretty reliable today , on that SMPS secondary side you can use your favorite vacuum tube rectifier instead of standard fast SS rectifier .
It is best if all formulas are based on on correct laws and theories. Even better, understand where the formulas come from so you are aware of their domain of applicability so you don't use them when they are not valid.DavesNotHere said:
Ohm's Law and Kirchoff's two laws are very different animals. Ohm's Law is approximately true for many conductors (the 'ohmic' ones!) and not true for others (e.g. some semiconductors or semiconductor arrangements). It is not a law of nature.
Kirchoff's Current Law is based on charge conservation. It is always true everywhere, as no violation of charge conservation has ever been seen and none is expected to be seen. However, you need to take account of any node where charge can accumulate.
Kirchoff's Voltage Law is based on the conservative nature of the static electric field. This means that it can be exactly described by a potential. It is true provided that the circuit loop in question is not subject to any changing magnetic fields, or that such fields can be confined to one or more components so they don't affect the loop as a whole.
I hope you can see that knowing where a 'law' comes from can help you apply it correctly.
Complete nonsense. He doesn't appear to understand that it is the cap which supplies the output stage. If Hasquin is an EE then I can only assume he must be one of these modern EEs who knows all about computers or ergonomics or societal impacts and not enough about circuits.drlowmu said:
I think you would need a 'scope and an audio sig gen which can step its output up and down. These days a computer could probably be used. Look for variations in the output envelope during or just after peak input.w5jag said:
No stepped attenuator, at least not one that I can switch fast enough. I wonder if hitting the input hard with, say, a 1 KHz square wave, and looking at the B+ rail to see if it follows, would be sufficient to reveal this kind of power supply defect?
Would this power supply defeciency / anomoly also show up as wierd / bad square wave response at an amplifier output?
Win W5JAG
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